Testing Betteries
 

Anyone have a good way of testing 12V deep cycle batteries?

What I was figuring on doing was using a 50watt 12V lightbulb and measuring
voltage with time. The only problem is that this may take a few hours.

Testing Betteries
 

I don't think so. Look he www.batteryfaq.org.

====

Charles T. Low
- remove "UN"
www.boatdocking.com
www.ctlow.ca/Trojan26 - my boat

====

"Rick & Linda Bernard" wrote in message
...
Anyone have a good way of testing 12V deep cycle batteries?

What I was figuring on doing was using a 50watt 12V lightbulb and
measuring
voltage with time. The only problem is that this may take a few hours.

Testing Betteries
 

I don't think so. Look he www.batteryfaq.org.

====

Charles T. Low
- remove "UN"
www.boatdocking.com
www.ctlow.ca/Trojan26 - my boat

====

"Rick & Linda Bernard" wrote in message
...
Anyone have a good way of testing 12V deep cycle batteries?

What I was figuring on doing was using a 50watt 12V lightbulb and
measuring
voltage with time. The only problem is that this may take a few hours.

Testing Betteries
 

On Sat, 24 Jan 2004 05:00:54 -0600, "Rick & Linda Bernard"
wrote:

Anyone have a good way of testing 12V deep cycle batteries?

What I was figuring on doing was using a 50watt 12V lightbulb and measuring
voltage with time. The only problem is that this may take a few hours.


I use a hydrometer, myself. The specific gravity of the cells tells
you what condition they are in. 1.270 is a fully charged lead-acid
battery at 72F. Be sure to get a good hydrometer with a built-in
thermometer and calibration chart because the specific gravity of the
electrolyte is very dependent on temperature.

If you find a cell with gravity lower than the rest, be assured it has
suffered sulphation where the lead sulphate has crystalized and will
soon have a "dead cell", if it's not already.

If the cell has high specific gravity and the battery's voltage
doesn't drop under normal loads, it's fine. Just keep her topped up
with ONLY distilled water.

Of course, AGM batteries you have no way of knowing what the hell is
going on inside the sponges.....

Here's some references for you:
http://www.nwes.com/using_batteries.htm
http://www.thesolar.biz/Measuring_sp...ty_article.htm
http://www.usbr.gov/power/data/fist/...6/3_6_cont.htm
http://www.buchanan1.net/lead_acid.shtml
(people up Nawth need to pay particular attention to the table on
the bottom of this webpage relating to the electrolyte freezing
temperatures as related to cell specific gravity (charge).)
http://www.rpc.com.au/products/efn/e...ries_care.html
http://www.solartech.com/aboutbat.htm

and I think this cool instrument would be a great replacement for the
Link, which I don't think gives you an accurate assessment because the
Link runs on an assumed A-H battery rating and that rating is ONLY
good at a SPECIFIC LOAD CURRENT at a SPECIFIC TEMPERATURE none of you
are running on these batteries. The actual specific gravity is the
ONLY way of actually measuring a battery's condition. This neat
$US110 instrument stuck in one cell will constantly measure that
gravity. Isn't this actually CHEAPER than the Link?!....(c; I know
it's more accurate.
http://www.electrosense.com.au/
Wonder how long it will last in the acid environment?


Larry W4CSC

Is it just me or did the US and UK just capture 1/3
of the world's sweetest oil supply? What idiot wants to
GIVE IT BACK?!!

Testing Betteries
 

On Sat, 24 Jan 2004 05:00:54 -0600, "Rick & Linda Bernard"
wrote:

Anyone have a good way of testing 12V deep cycle batteries?

What I was figuring on doing was using a 50watt 12V lightbulb and measuring
voltage with time. The only problem is that this may take a few hours.


I use a hydrometer, myself. The specific gravity of the cells tells
you what condition they are in. 1.270 is a fully charged lead-acid
battery at 72F. Be sure to get a good hydrometer with a built-in
thermometer and calibration chart because the specific gravity of the
electrolyte is very dependent on temperature.

If you find a cell with gravity lower than the rest, be assured it has
suffered sulphation where the lead sulphate has crystalized and will
soon have a "dead cell", if it's not already.

If the cell has high specific gravity and the battery's voltage
doesn't drop under normal loads, it's fine. Just keep her topped up
with ONLY distilled water.

Of course, AGM batteries you have no way of knowing what the hell is
going on inside the sponges.....

Here's some references for you:
http://www.nwes.com/using_batteries.htm
http://www.thesolar.biz/Measuring_sp...ty_article.htm
http://www.usbr.gov/power/data/fist/...6/3_6_cont.htm
http://www.buchanan1.net/lead_acid.shtml
(people up Nawth need to pay particular attention to the table on
the bottom of this webpage relating to the electrolyte freezing
temperatures as related to cell specific gravity (charge).)
http://www.rpc.com.au/products/efn/e...ries_care.html
http://www.solartech.com/aboutbat.htm

and I think this cool instrument would be a great replacement for the
Link, which I don't think gives you an accurate assessment because the
Link runs on an assumed A-H battery rating and that rating is ONLY
good at a SPECIFIC LOAD CURRENT at a SPECIFIC TEMPERATURE none of you
are running on these batteries. The actual specific gravity is the
ONLY way of actually measuring a battery's condition. This neat
$US110 instrument stuck in one cell will constantly measure that
gravity. Isn't this actually CHEAPER than the Link?!....(c; I know
it's more accurate.
http://www.electrosense.com.au/
Wonder how long it will last in the acid environment?


Larry W4CSC

Is it just me or did the US and UK just capture 1/3
of the world's sweetest oil supply? What idiot wants to
GIVE IT BACK?!!

Testing Betteries
 

You need to borrow a load tester. It is just a heavy duty heat sink which
draws current from the battery. If the voltage drops during the test, the
battery is dying.
I have to borrow one to test my setup come
Spring

--
Dennis Gibbons
dkgibbons at optonline dot net
"Rick & Linda Bernard" wrote in message
...
Anyone have a good way of testing 12V deep cycle batteries?

What I was figuring on doing was using a 50watt 12V lightbulb and
measuring
voltage with time. The only problem is that this may take a few hours.

Testing Betteries
 

You need to borrow a load tester. It is just a heavy duty heat sink which
draws current from the battery. If the voltage drops during the test, the
battery is dying.
I have to borrow one to test my setup come
Spring

--
Dennis Gibbons
dkgibbons at optonline dot net
"Rick & Linda Bernard" wrote in message
...
Anyone have a good way of testing 12V deep cycle batteries?

What I was figuring on doing was using a 50watt 12V lightbulb and
measuring
voltage with time. The only problem is that this may take a few hours.

Testing Betteries
 

When you say testing, are you referring to determinining the
current state of the battery or the capacity of the battery. Determining
the current state of charge can be done by disconnecting the battery
from all loads, letting it sit for 24 hours and then testing the voltage.
For a liquid lead-acid battery, a full charge will be 12.8v, half
charge is 12.2v. For gels 12.6v and 12.0 are reasonable figures.
As Larry says below, checking the S.G. with a hydrometer is
standard practice if you have liquid batteries. Needless to say that
this can't be done with gels and AGM.

If you are trying to determine the capacity of the battery then a
slow discharge is needed. The manufacturer usually rates the
capacity based upon the 20-hour rate. So it you have a 200AH
battery then discharging it at 10 amps will discharge it in 20 hours.
(discharge is defined as 10.5v in this case). No real need to go that
far, but taking it down to 12.2v would be half capacity and should
take around 10hours. This will give a pretty good indication of the
health of the battery. I usually just turn on enough lights to get up
to the current I need for the test. Of course you have to deal with
people constantly telling you that you have left your lights on.

Good Luck!
s/v Callista

"Rick & Linda Bernard" wrote in message
...
Anyone have a good way of testing 12V deep cycle batteries?

What I was figuring on doing was using a 50watt 12V lightbulb and
measuring
voltage with time. The only problem is that this may take a few hours.

Testing Betteries
 

When you say testing, are you referring to determinining the
current state of the battery or the capacity of the battery. Determining
the current state of charge can be done by disconnecting the battery
from all loads, letting it sit for 24 hours and then testing the voltage.
For a liquid lead-acid battery, a full charge will be 12.8v, half
charge is 12.2v. For gels 12.6v and 12.0 are reasonable figures.
As Larry says below, checking the S.G. with a hydrometer is
standard practice if you have liquid batteries. Needless to say that
this can't be done with gels and AGM.

If you are trying to determine the capacity of the battery then a
slow discharge is needed. The manufacturer usually rates the
capacity based upon the 20-hour rate. So it you have a 200AH
battery then discharging it at 10 amps will discharge it in 20 hours.
(discharge is defined as 10.5v in this case). No real need to go that
far, but taking it down to 12.2v would be half capacity and should
take around 10hours. This will give a pretty good indication of the
health of the battery. I usually just turn on enough lights to get up
to the current I need for the test. Of course you have to deal with
people constantly telling you that you have left your lights on.

Good Luck!
s/v Callista

"Rick & Linda Bernard" wrote in message
...
Anyone have a good way of testing 12V deep cycle batteries?

What I was figuring on doing was using a 50watt 12V lightbulb and
measuring
voltage with time. The only problem is that this may take a few hours.

Testing Betteries
 

Load testers are good for starting batteries but don't really tell
much for a deep cycle battery.

Doug
s/v Callista

"Dennis Gibbons" wrote in message
et...
You need to borrow a load tester. It is just a heavy duty heat sink which
draws current from the battery. If the voltage drops during the test, the
battery is dying.
I have to borrow one to test my setup come
Spring

--
Dennis Gibbons
dkgibbons at optonline dot net
"Rick & Linda Bernard" wrote in message
...
Anyone have a good way of testing 12V deep cycle batteries?

What I was figuring on doing was using a 50watt 12V lightbulb and
measuring
voltage with time. The only problem is that this may take a few hours.

Testing Betteries
 

Load testers are good for starting batteries but don't really tell
much for a deep cycle battery.

Doug
s/v Callista

"Dennis Gibbons" wrote in message
et...
You need to borrow a load tester. It is just a heavy duty heat sink which
draws current from the battery. If the voltage drops during the test, the
battery is dying.
I have to borrow one to test my setup come
Spring

--
Dennis Gibbons
dkgibbons at optonline dot net
"Rick & Linda Bernard" wrote in message
...
Anyone have a good way of testing 12V deep cycle batteries?

What I was figuring on doing was using a 50watt 12V lightbulb and
measuring
voltage with time. The only problem is that this may take a few hours.

Testing Betteries
 

A battery test in an old Ample Power catalog was to charge to 14.4 volts and
hold it there for an hour. Let it rest overnight, and then retest.
12.8 v & higher=good
12.6 to 12.7v=marginal
12.4 to 12.6v=very poor
less than 12.4 v=worthless

"Rick & Linda Bernard" wrote in message
...
Anyone have a good way of testing 12V deep cycle batteries?

What I was figuring on doing was using a 50watt 12V lightbulb and
measuring
voltage with time. The only problem is that this may take a few hours.

Testing Betteries
 

A battery test in an old Ample Power catalog was to charge to 14.4 volts and
hold it there for an hour. Let it rest overnight, and then retest.
12.8 v & higher=good
12.6 to 12.7v=marginal
12.4 to 12.6v=very poor
less than 12.4 v=worthless

"Rick & Linda Bernard" wrote in message
...
Anyone have a good way of testing 12V deep cycle batteries?

What I was figuring on doing was using a 50watt 12V lightbulb and
measuring
voltage with time. The only problem is that this may take a few hours.

Testing Betteries
 

"Doug Dotson" wrote in message
...
Load testers are good for starting batteries but don't really tell much
for a deep cycle battery.
Doug - s/v Callista

====

Doug,

Any idea why is this?

Is it possible to have good sg and still fail a load test? I.e., is a load
test more sensitive than sg? (I presume that sg is more specific than
measuring voltage?) Does it go like that, in terms of accuracy?:

voltage
specific gravity
load testing???

Will an appliance such as a commerically bought load tester be more or less
accurate than doing a long, slow test oneself, such as by leaving lights on?

(And, one other poster mentioned testing down to 50% charge as more
convenient than testing to 0% charge - isn't it also true that testing to 0%
charge will ruin the battery?)

Charles

(So many questions, such limited memory capacity...)

====

Charles T. Low
- remove "UN"
www.boatdocking.com
www.ctlow.ca/Trojan26 - my boat

====

Testing Betteries
 

"Doug Dotson" wrote in message
...
Load testers are good for starting batteries but don't really tell much
for a deep cycle battery.
Doug - s/v Callista

====

Doug,

Any idea why is this?

Is it possible to have good sg and still fail a load test? I.e., is a load
test more sensitive than sg? (I presume that sg is more specific than
measuring voltage?) Does it go like that, in terms of accuracy?:

voltage
specific gravity
load testing???

Will an appliance such as a commerically bought load tester be more or less
accurate than doing a long, slow test oneself, such as by leaving lights on?

(And, one other poster mentioned testing down to 50% charge as more
convenient than testing to 0% charge - isn't it also true that testing to 0%
charge will ruin the battery?)

Charles

(So many questions, such limited memory capacity...)

====

Charles T. Low
- remove "UN"
www.boatdocking.com
www.ctlow.ca/Trojan26 - my boat

====

Testing Betteries
 

"Charles T. Low" wrote in message
...
"Doug Dotson" wrote in message
...
Load testers are good for starting batteries but don't really tell much
for a deep cycle battery.
Doug - s/v Callista

====

Doug,

Any idea why is this?

Is it possible to have good sg and still fail a load test? I.e., is a load
test more sensitive than sg? (I presume that sg is more specific than
measuring voltage?) Does it go like that, in terms of accuracy?:

The discharge time of a deep cycle battery is influenced by many
things other than SG. The condition of the plates etc all come into
play. While one may be able to draw heavy current for a brief
period that does not necessarily translate into good low power
performance. A long term low current test tells the actual story
since it is how the battery is being used in normal use. The SG
gives the state of charge from a theoretical sense as does the voltage.

voltage
specific gravity
load testing???

Will an appliance such as a commerically bought load tester be more or
less
accurate than doing a long, slow test oneself, such as by leaving lights
on?

A load tester (at least the ones I have seen) can't tell what the
capacity of the battery is. They just give a general idea that the
battery is chemically and physically sound. I built a system a few
years ago that would discharge a battery at a specified rate and then
automatically recharge it all while monitoring. It graphically showed
the capacity of the battery. It was also useful for reconditioning and
breaking in batteries.

(And, one other poster mentioned testing down to 50% charge as more
convenient than testing to 0% charge - isn't it also true that testing to
0%
charge will ruin the battery?)

0% charge and running it all the way down are not the same. 0% discharge
is usually considered to be 10.5v. That is why I figure 50% is good enough.
50% is generally considered the lowest a battery should be discharged in
normal use so doing so will tell what the useful capacity is.

Charles

(So many questions, such limited memory capacity...)

====

Charles T. Low
- remove "UN"
www.boatdocking.com
www.ctlow.ca/Trojan26 - my boat

====

Testing Betteries
 

"Charles T. Low" wrote in message
...
"Doug Dotson" wrote in message
...
Load testers are good for starting batteries but don't really tell much
for a deep cycle battery.
Doug - s/v Callista

====

Doug,

Any idea why is this?

Is it possible to have good sg and still fail a load test? I.e., is a load
test more sensitive than sg? (I presume that sg is more specific than
measuring voltage?) Does it go like that, in terms of accuracy?:

The discharge time of a deep cycle battery is influenced by many
things other than SG. The condition of the plates etc all come into
play. While one may be able to draw heavy current for a brief
period that does not necessarily translate into good low power
performance. A long term low current test tells the actual story
since it is how the battery is being used in normal use. The SG
gives the state of charge from a theoretical sense as does the voltage.

voltage
specific gravity
load testing???

Will an appliance such as a commerically bought load tester be more or
less
accurate than doing a long, slow test oneself, such as by leaving lights
on?

A load tester (at least the ones I have seen) can't tell what the
capacity of the battery is. They just give a general idea that the
battery is chemically and physically sound. I built a system a few
years ago that would discharge a battery at a specified rate and then
automatically recharge it all while monitoring. It graphically showed
the capacity of the battery. It was also useful for reconditioning and
breaking in batteries.

(And, one other poster mentioned testing down to 50% charge as more
convenient than testing to 0% charge - isn't it also true that testing to
0%
charge will ruin the battery?)

0% charge and running it all the way down are not the same. 0% discharge
is usually considered to be 10.5v. That is why I figure 50% is good enough.
50% is generally considered the lowest a battery should be discharged in
normal use so doing so will tell what the useful capacity is.

Charles

(So many questions, such limited memory capacity...)

====

Charles T. Low
- remove "UN"
www.boatdocking.com
www.ctlow.ca/Trojan26 - my boat

====

Testing Betteries
 

These voltages are for liquid lead-acid batteries. Gels and AGMs
are somewhat lower. My AGMs rest at 12.6v when fully charged.

Doug
s/v Callista

"Garland Gray II" wrote in message
news:IFEQb.11797$dd6.309@lakeread02...
A battery test in an old Ample Power catalog was to charge to 14.4 volts
and
hold it there for an hour. Let it rest overnight, and then retest.
12.8 v & higher=good
12.6 to 12.7v=marginal
12.4 to 12.6v=very poor
less than 12.4 v=worthless

"Rick & Linda Bernard" wrote in message
...
Anyone have a good way of testing 12V deep cycle batteries?

What I was figuring on doing was using a 50watt 12V lightbulb and
measuring
voltage with time. The only problem is that this may take a few hours.

Testing Betteries
 

These voltages are for liquid lead-acid batteries. Gels and AGMs
are somewhat lower. My AGMs rest at 12.6v when fully charged.

Doug
s/v Callista

"Garland Gray II" wrote in message
news:IFEQb.11797$dd6.309@lakeread02...
A battery test in an old Ample Power catalog was to charge to 14.4 volts
and
hold it there for an hour. Let it rest overnight, and then retest.
12.8 v & higher=good
12.6 to 12.7v=marginal
12.4 to 12.6v=very poor
less than 12.4 v=worthless

"Rick & Linda Bernard" wrote in message
...
Anyone have a good way of testing 12V deep cycle batteries?

What I was figuring on doing was using a 50watt 12V lightbulb and
measuring
voltage with time. The only problem is that this may take a few hours.

Testing Betteries
 

Thanks; I forgot to mention that.

"Doug Dotson" wrote in message
...
These voltages are for liquid lead-acid batteries. Gels and AGMs
are somewhat lower. My AGMs rest at 12.6v when fully charged.

Doug
s/v Callista

"Garland Gray II" wrote in message
news:IFEQb.11797$dd6.309@lakeread02...
A battery test in an old Ample Power catalog was to charge to 14.4 volts
and
hold it there for an hour. Let it rest overnight, and then retest.
12.8 v & higher=good
12.6 to 12.7v=marginal
12.4 to 12.6v=very poor
less than 12.4 v=worthless

"Rick & Linda Bernard" wrote in message
...
Anyone have a good way of testing 12V deep cycle batteries?

What I was figuring on doing was using a 50watt 12V lightbulb and
measuring
voltage with time. The only problem is that this may take a few
hours.

Testing Betteries
 

Thanks; I forgot to mention that.

"Doug Dotson" wrote in message
...
These voltages are for liquid lead-acid batteries. Gels and AGMs
are somewhat lower. My AGMs rest at 12.6v when fully charged.

Doug
s/v Callista

"Garland Gray II" wrote in message
news:IFEQb.11797$dd6.309@lakeread02...
A battery test in an old Ample Power catalog was to charge to 14.4 volts
and
hold it there for an hour. Let it rest overnight, and then retest.
12.8 v & higher=good
12.6 to 12.7v=marginal
12.4 to 12.6v=very poor
less than 12.4 v=worthless

"Rick & Linda Bernard" wrote in message
...
Anyone have a good way of testing 12V deep cycle batteries?

What I was figuring on doing was using a 50watt 12V lightbulb and
measuring
voltage with time. The only problem is that this may take a few
hours.

Testing Betteries
 

I found this note from Garland interesting.

I know that, not too long ago, I charged a suspect
battery to 14V+ and checking soon after at 12 volts
expected it to be good.
But it was whacked, and I discarded it.

So I am realising, I did not expect the charging volts to
be reflected in an overvolt reading a day later.
But I will, in future!

Brian Whatcott

On Sat, 24 Jan 2004 20:07:55 -0500, "Garland Gray II"
wrote:

A battery test in an old Ample Power catalog was to charge to 14.4 volts and
hold it there for an hour. Let it rest overnight, and then retest.
12.8 v & higher=good
12.6 to 12.7v=marginal
12.4 to 12.6v=very poor
less than 12.4 v=worthless

"Rick & Linda Bernard" wrote in message
...
Anyone have a good way of testing 12V deep cycle batteries?

What I was figuring on doing was using a 50watt 12V lightbulb and
measuring
voltage with time. The only problem is that this may take a few hours.

Testing Betteries
 

I found this note from Garland interesting.

I know that, not too long ago, I charged a suspect
battery to 14V+ and checking soon after at 12 volts
expected it to be good.
But it was whacked, and I discarded it.

So I am realising, I did not expect the charging volts to
be reflected in an overvolt reading a day later.
But I will, in future!

Brian Whatcott

On Sat, 24 Jan 2004 20:07:55 -0500, "Garland Gray II"
wrote:

A battery test in an old Ample Power catalog was to charge to 14.4 volts and
hold it there for an hour. Let it rest overnight, and then retest.
12.8 v & higher=good
12.6 to 12.7v=marginal
12.4 to 12.6v=very poor
less than 12.4 v=worthless

"Rick & Linda Bernard" wrote in message
...
Anyone have a good way of testing 12V deep cycle batteries?

What I was figuring on doing was using a 50watt 12V lightbulb and
measuring
voltage with time. The only problem is that this may take a few hours.

Testing Betteries
 

Not sure what you are saying here?

Doug

"Brian Whatcott" wrote in message
...

I found this note from Garland interesting.

I know that, not too long ago, I charged a suspect
battery to 14V+ and checking soon after at 12 volts
expected it to be good.
But it was whacked, and I discarded it.

So I am realising, I did not expect the charging volts to
be reflected in an overvolt reading a day later.
But I will, in future!

Brian Whatcott

On Sat, 24 Jan 2004 20:07:55 -0500, "Garland Gray II"
wrote:

A battery test in an old Ample Power catalog was to charge to 14.4 volts
and
hold it there for an hour. Let it rest overnight, and then retest.
12.8 v & higher=good
12.6 to 12.7v=marginal
12.4 to 12.6v=very poor
less than 12.4 v=worthless

"Rick & Linda Bernard" wrote in message
...
Anyone have a good way of testing 12V deep cycle batteries?

What I was figuring on doing was using a 50watt 12V lightbulb and
measuring
voltage with time. The only problem is that this may take a few hours.

Testing Betteries
 

Not sure what you are saying here?

Doug

"Brian Whatcott" wrote in message
...

I found this note from Garland interesting.

I know that, not too long ago, I charged a suspect
battery to 14V+ and checking soon after at 12 volts
expected it to be good.
But it was whacked, and I discarded it.

So I am realising, I did not expect the charging volts to
be reflected in an overvolt reading a day later.
But I will, in future!

Brian Whatcott

On Sat, 24 Jan 2004 20:07:55 -0500, "Garland Gray II"
wrote:

A battery test in an old Ample Power catalog was to charge to 14.4 volts
and
hold it there for an hour. Let it rest overnight, and then retest.
12.8 v & higher=good
12.6 to 12.7v=marginal
12.4 to 12.6v=very poor
less than 12.4 v=worthless

"Rick & Linda Bernard" wrote in message
...
Anyone have a good way of testing 12V deep cycle batteries?

What I was figuring on doing was using a 50watt 12V lightbulb and
measuring
voltage with time. The only problem is that this may take a few hours.

Testing Betteries
 

For some reason, I had it that a charged battery rested at 12
volts....

Brian W

On Sun, 25 Jan 2004 21:17:45 GMT, Brian Whatcott
wrote:


I found this note from Garland interesting.

I know that, not too long ago, I charged a suspect
battery to 14V+ and checking soon after at 12 volts
expected it to be good.
But it was whacked, and I discarded it.

So I am realising, I did not expect the charging volts to
be reflected in an overvolt reading a day later.
But I will, in future!

Brian Whatcott

On Sat, 24 Jan 2004 20:07:55 -0500, "Garland Gray II"
wrote:

A battery test in an old Ample Power catalog was to charge to 14.4 volts and
hold it there for an hour. Let it rest overnight, and then retest.
12.8 v & higher=good
12.6 to 12.7v=marginal
12.4 to 12.6v=very poor
less than 12.4 v=worthless

"Rick & Linda Bernard" wrote in message
...
Anyone have a good way of testing 12V deep cycle batteries?

What I was figuring on doing was using a 50watt 12V lightbulb and
measuring
voltage with time. The only problem is that this may take a few hours.

Testing Betteries
 

For some reason, I had it that a charged battery rested at 12
volts....

Brian W

On Sun, 25 Jan 2004 21:17:45 GMT, Brian Whatcott
wrote:


I found this note from Garland interesting.

I know that, not too long ago, I charged a suspect
battery to 14V+ and checking soon after at 12 volts
expected it to be good.
But it was whacked, and I discarded it.

So I am realising, I did not expect the charging volts to
be reflected in an overvolt reading a day later.
But I will, in future!

Brian Whatcott

On Sat, 24 Jan 2004 20:07:55 -0500, "Garland Gray II"
wrote:

A battery test in an old Ample Power catalog was to charge to 14.4 volts and
hold it there for an hour. Let it rest overnight, and then retest.
12.8 v & higher=good
12.6 to 12.7v=marginal
12.4 to 12.6v=very poor
less than 12.4 v=worthless

"Rick & Linda Bernard" wrote in message
...
Anyone have a good way of testing 12V deep cycle batteries?

What I was figuring on doing was using a 50watt 12V lightbulb and
measuring
voltage with time. The only problem is that this may take a few hours.

Testing Betteries
 

Not if it is a good battery. Should rest at 12.8v.

Doug

"Brian Whatcott" wrote in message
...
For some reason, I had it that a charged battery rested at 12
volts....

Brian W

On Sun, 25 Jan 2004 21:17:45 GMT, Brian Whatcott
wrote:


I found this note from Garland interesting.

I know that, not too long ago, I charged a suspect
battery to 14V+ and checking soon after at 12 volts
expected it to be good.
But it was whacked, and I discarded it.

So I am realising, I did not expect the charging volts to
be reflected in an overvolt reading a day later.
But I will, in future!

Brian Whatcott

On Sat, 24 Jan 2004 20:07:55 -0500, "Garland Gray II"
wrote:

A battery test in an old Ample Power catalog was to charge to 14.4 volts
and
hold it there for an hour. Let it rest overnight, and then retest.
12.8 v & higher=good
12.6 to 12.7v=marginal
12.4 to 12.6v=very poor
less than 12.4 v=worthless

"Rick & Linda Bernard" wrote in message
...
Anyone have a good way of testing 12V deep cycle batteries?

What I was figuring on doing was using a 50watt 12V lightbulb and
measuring
voltage with time. The only problem is that this may take a few
hours.

Testing Betteries
 

Not if it is a good battery. Should rest at 12.8v.

Doug

"Brian Whatcott" wrote in message
...
For some reason, I had it that a charged battery rested at 12
volts....

Brian W

On Sun, 25 Jan 2004 21:17:45 GMT, Brian Whatcott
wrote:


I found this note from Garland interesting.

I know that, not too long ago, I charged a suspect
battery to 14V+ and checking soon after at 12 volts
expected it to be good.
But it was whacked, and I discarded it.

So I am realising, I did not expect the charging volts to
be reflected in an overvolt reading a day later.
But I will, in future!

Brian Whatcott

On Sat, 24 Jan 2004 20:07:55 -0500, "Garland Gray II"
wrote:

A battery test in an old Ample Power catalog was to charge to 14.4 volts
and
hold it there for an hour. Let it rest overnight, and then retest.
12.8 v & higher=good
12.6 to 12.7v=marginal
12.4 to 12.6v=very poor
less than 12.4 v=worthless

"Rick & Linda Bernard" wrote in message
...
Anyone have a good way of testing 12V deep cycle batteries?

What I was figuring on doing was using a 50watt 12V lightbulb and
measuring
voltage with time. The only problem is that this may take a few
hours.

Testing Batteries
 

Doug,

Thanks, very helpful.

So, does this seem valid to you? - An accurate voltage reading is a good
indicator of a battery's condition, but specific gravity is better, and a
slow load test (to 50%) is the best? Or are they testing different things,
all of which are important? Could it do well on a load test without good
voltage or sg's?

And, what use is a commercial load tester, then? Why do they make them? Is
it better than an sg but not as good as a slow load test?

Thanks again. Charles

P.S. I corrected the spelling of "betteries" - couldn't take it any more!

====

Charles T. Low
- remove "UN"
www.boatdocking.com
www.ctlow.ca/Trojan26 - my boat

====

"Doug Dotson" wrote in message
...
The discharge time of a deep cycle battery is influenced by many
things other than SG. The condition of the plates etc all come into
play. While one may be able to draw heavy current for a brief
period that does not necessarily translate into good low power
performance. A long term low current test tells the actual story
since it is how the battery is being used in normal use. The SG
gives the state of charge from a theoretical sense as does the voltage.

Testing Batteries
 

Doug,

Thanks, very helpful.

So, does this seem valid to you? - An accurate voltage reading is a good
indicator of a battery's condition, but specific gravity is better, and a
slow load test (to 50%) is the best? Or are they testing different things,
all of which are important? Could it do well on a load test without good
voltage or sg's?

And, what use is a commercial load tester, then? Why do they make them? Is
it better than an sg but not as good as a slow load test?

Thanks again. Charles

P.S. I corrected the spelling of "betteries" - couldn't take it any more!

====

Charles T. Low
- remove "UN"
www.boatdocking.com
www.ctlow.ca/Trojan26 - my boat

====

"Doug Dotson" wrote in message
...
The discharge time of a deep cycle battery is influenced by many
things other than SG. The condition of the plates etc all come into
play. While one may be able to draw heavy current for a brief
period that does not necessarily translate into good low power
performance. A long term low current test tells the actual story
since it is how the battery is being used in normal use. The SG
gives the state of charge from a theoretical sense as does the voltage.

Testing Batteries
 

"Charles T. Low" wrote in message
...
Doug,

Thanks, very helpful.

So, does this seem valid to you? - An accurate voltage reading is a good
indicator of a battery's condition, but specific gravity is better,

Yes. But only after the battery has rested under zero load for a while.

and a
slow load test (to 50%) is the best?

A slow load test tells the current capacity of the battery which is what the
battery is being asked to do.

Or are they testing different things,
all of which are important?

Perhaps. I suppost that if you are using the same battery bank for
house and starting, then multiple types of test may be informative.
But for a house bank a slow realistic load test gives the bottom line.
Voltage and SG tests are really telling the current instantaneous state
of the battery. That does not necessarily relate directly to the expected
perfromance under load. One is static the other is dynamic.

Could it do well on a load test without good
voltage or sg's?

I don't see how.

And, what use is a commercial load tester, then? Why do they make them?

To test the high current delivery performance of starting batteries as best
I can tell.

Is
it better than an sg but not as good as a slow load test?

As I said earlier. These are testing different things. SG gives the
current state of the battery, a slow load test tells the capacity of the
battery. A reasonable analogy might be, the amount of fuel you have
in your fuel tank as apposed to how far that fuel will get you at a
given speed. You can measure how much fuel you have by weight or
by volume or by level, but that will not tell you how far you can go
at 10 mph vs 100 mph. The condition of the engine enters into the
equation as well just as the condition of the battery does.

Thanks again. Charles

P.S. I corrected the spelling of "betteries" - couldn't take it any more!

====

Charles T. Low
- remove "UN"
www.boatdocking.com
www.ctlow.ca/Trojan26 - my boat

====

"Doug Dotson" wrote in message
...
The discharge time of a deep cycle battery is influenced by many
things other than SG. The condition of the plates etc all come into
play. While one may be able to draw heavy current for a brief
period that does not necessarily translate into good low power
performance. A long term low current test tells the actual story
since it is how the battery is being used in normal use. The SG
gives the state of charge from a theoretical sense as does the voltage.

Testing Batteries
 

"Charles T. Low" wrote in message
...
Doug,

Thanks, very helpful.

So, does this seem valid to you? - An accurate voltage reading is a good
indicator of a battery's condition, but specific gravity is better,

Yes. But only after the battery has rested under zero load for a while.

and a
slow load test (to 50%) is the best?

A slow load test tells the current capacity of the battery which is what the
battery is being asked to do.

Or are they testing different things,
all of which are important?

Perhaps. I suppost that if you are using the same battery bank for
house and starting, then multiple types of test may be informative.
But for a house bank a slow realistic load test gives the bottom line.
Voltage and SG tests are really telling the current instantaneous state
of the battery. That does not necessarily relate directly to the expected
perfromance under load. One is static the other is dynamic.

Could it do well on a load test without good
voltage or sg's?

I don't see how.

And, what use is a commercial load tester, then? Why do they make them?

To test the high current delivery performance of starting batteries as best
I can tell.

Is
it better than an sg but not as good as a slow load test?

As I said earlier. These are testing different things. SG gives the
current state of the battery, a slow load test tells the capacity of the
battery. A reasonable analogy might be, the amount of fuel you have
in your fuel tank as apposed to how far that fuel will get you at a
given speed. You can measure how much fuel you have by weight or
by volume or by level, but that will not tell you how far you can go
at 10 mph vs 100 mph. The condition of the engine enters into the
equation as well just as the condition of the battery does.

Thanks again. Charles

P.S. I corrected the spelling of "betteries" - couldn't take it any more!

====

Charles T. Low
- remove "UN"
www.boatdocking.com
www.ctlow.ca/Trojan26 - my boat

====

"Doug Dotson" wrote in message
...
The discharge time of a deep cycle battery is influenced by many
things other than SG. The condition of the plates etc all come into
play. While one may be able to draw heavy current for a brief
period that does not necessarily translate into good low power
performance. A long term low current test tells the actual story
since it is how the battery is being used in normal use. The SG
gives the state of charge from a theoretical sense as does the voltage.

Testing Batteries
 

Assuming the battery is in good condition, the open circuit voltage can
be a fair indicator of the charge of a battery if it has been rested and
the surface charge removed.

The specific gravity is a better indicator of charge, but again, the
battery must be in good condition.

In either the SG or the voltage test, a damaged battery may indicate
full charge, but be useless. If a plate has dropped, a battery could be
fully charged but not capable of delivering any current. If the water
is low (or in the case of 'service free' batteries, it is common for the
water to get so low that it just barely touches the bottom of the
plates), the voltage is fine, but it won't light a light bulb.

So, the third test is neccessary occasionally to check the 'health' of
the battery. This will tell you that the battery is capable of
delivering sufficient current. Then once you know you have a healthy
battery the SG or rest voltage will tell you the charge state.



Charles T. Low wrote:
Doug,

Thanks, very helpful.

So, does this seem valid to you? - An accurate voltage reading is a good
indicator of a battery's condition, but specific gravity is better, and a
slow load test (to 50%) is the best? Or are they testing different things,
all of which are important? Could it do well on a load test without good
voltage or sg's?

And, what use is a commercial load tester, then? Why do they make them? Is
it better than an sg but not as good as a slow load test?

Thanks again. Charles

P.S. I corrected the spelling of "betteries" - couldn't take it any more!

====

Charles T. Low
- remove "UN"
www.boatdocking.com
www.ctlow.ca/Trojan26 - my boat

====

"Doug Dotson" wrote in message
...

The discharge time of a deep cycle battery is influenced by many
things other than SG. The condition of the plates etc all come into
play. While one may be able to draw heavy current for a brief
period that does not necessarily translate into good low power
performance. A long term low current test tells the actual story
since it is how the battery is being used in normal use. The SG
gives the state of charge from a theoretical sense as does the voltage.

Testing Batteries
 

Assuming the battery is in good condition, the open circuit voltage can
be a fair indicator of the charge of a battery if it has been rested and
the surface charge removed.

The specific gravity is a better indicator of charge, but again, the
battery must be in good condition.

In either the SG or the voltage test, a damaged battery may indicate
full charge, but be useless. If a plate has dropped, a battery could be
fully charged but not capable of delivering any current. If the water
is low (or in the case of 'service free' batteries, it is common for the
water to get so low that it just barely touches the bottom of the
plates), the voltage is fine, but it won't light a light bulb.

So, the third test is neccessary occasionally to check the 'health' of
the battery. This will tell you that the battery is capable of
delivering sufficient current. Then once you know you have a healthy
battery the SG or rest voltage will tell you the charge state.



Charles T. Low wrote:
Doug,

Thanks, very helpful.

So, does this seem valid to you? - An accurate voltage reading is a good
indicator of a battery's condition, but specific gravity is better, and a
slow load test (to 50%) is the best? Or are they testing different things,
all of which are important? Could it do well on a load test without good
voltage or sg's?

And, what use is a commercial load tester, then? Why do they make them? Is
it better than an sg but not as good as a slow load test?

Thanks again. Charles

P.S. I corrected the spelling of "betteries" - couldn't take it any more!

====

Charles T. Low
- remove "UN"
www.boatdocking.com
www.ctlow.ca/Trojan26 - my boat

====

"Doug Dotson" wrote in message
...

The discharge time of a deep cycle battery is influenced by many
things other than SG. The condition of the plates etc all come into
play. While one may be able to draw heavy current for a brief
period that does not necessarily translate into good low power
performance. A long term low current test tells the actual story
since it is how the battery is being used in normal use. The SG
gives the state of charge from a theoretical sense as does the voltage.

Testing Batteries
 

On Mon, 26 Jan 2004 22:12:53 -0500, "Charles T. Low"
wrote:

Doug,

Thanks, very helpful.

So, does this seem valid to you? - An accurate voltage reading is a good
indicator of a battery's condition, but specific gravity is better, and a
slow load test (to 50%) is the best? Or are they testing different things,
all of which are important? Could it do well on a load test without good
voltage or sg's?

No. The voltage of 6 cells depleted to 50% of charge, as low as you
should go, is nearly the same as one at 85% charge....when there is no
load. If you're not pulling a constant current through the internal
resistance of the battery, it doesn't drop until the battery is WAY
TOO DISCHARGED.

Specific gravity is the ONLY real way to monitor cell condition and %
of charge because the A-H rating of a battery CHANGES as load changes.
(Notice how the rating printed on the side of the battery is at an X
amp rate.) The more the load current, the lower the amp-hour rating
of the battery really is. But, it's specific gravity ALWAYS tells the
real story. It's just a pain in the ass to measure.....until I found
this Australian instrument I find really neat.

And, what use is a commercial load tester, then? Why do they make them? Is
it better than an sg but not as good as a slow load test?

The load tester INCLUDES that PREDICTABLE current load that pulls down
the voltage from the internal series cell resistance caused by
discharge coating the plates with insulating lead sulphate as it
discharges and a weakening acid concentration as it is used up. It is
useable as a predictor of % of charge, but not as accurate as specific
gravity.'

It is also used in troubleshooting to find that dead cell. When you
load 6 cells in series and one of them is dead, the 50A load really
draws it down hard by the 2V lost in the dead cell. It was never
intended as a charge meter, but a troubleshooting tool.


Larry W4CSC

Is it just me or did the US and UK just capture 1/3
of the world's sweetest oil supply? What idiot wants to
GIVE IT BACK?!!

Testing Batteries
 

On Mon, 26 Jan 2004 22:12:53 -0500, "Charles T. Low"
wrote:

Doug,

Thanks, very helpful.

So, does this seem valid to you? - An accurate voltage reading is a good
indicator of a battery's condition, but specific gravity is better, and a
slow load test (to 50%) is the best? Or are they testing different things,
all of which are important? Could it do well on a load test without good
voltage or sg's?

No. The voltage of 6 cells depleted to 50% of charge, as low as you
should go, is nearly the same as one at 85% charge....when there is no
load. If you're not pulling a constant current through the internal
resistance of the battery, it doesn't drop until the battery is WAY
TOO DISCHARGED.

Specific gravity is the ONLY real way to monitor cell condition and %
of charge because the A-H rating of a battery CHANGES as load changes.
(Notice how the rating printed on the side of the battery is at an X
amp rate.) The more the load current, the lower the amp-hour rating
of the battery really is. But, it's specific gravity ALWAYS tells the
real story. It's just a pain in the ass to measure.....until I found
this Australian instrument I find really neat.

And, what use is a commercial load tester, then? Why do they make them? Is
it better than an sg but not as good as a slow load test?

The load tester INCLUDES that PREDICTABLE current load that pulls down
the voltage from the internal series cell resistance caused by
discharge coating the plates with insulating lead sulphate as it
discharges and a weakening acid concentration as it is used up. It is
useable as a predictor of % of charge, but not as accurate as specific
gravity.'

It is also used in troubleshooting to find that dead cell. When you
load 6 cells in series and one of them is dead, the 50A load really
draws it down hard by the 2V lost in the dead cell. It was never
intended as a charge meter, but a troubleshooting tool.


Larry W4CSC

Is it just me or did the US and UK just capture 1/3
of the world's sweetest oil supply? What idiot wants to
GIVE IT BACK?!!

Testing Batteries
 

Thanks, Doug, and also to Argonauta, and to Larry W4CSC. (Some of the
information conflicts, but that's not the first time that's happened!)

So, to summarize:

-voltage and sg measure charge but not capacity;
-commercial load testers might be for testing starter batteries, esp. if
something is wrong and you're trying to figure out what;
-slow load testing makes more sense for deep cycles functioning in that
role.

(Of course, Darden's site says that 200 deep discharge cycles is a good
battery's life span - so if you test it, have you used up one?)

(Larry: It also gives charge/voltage tables, which suggest that you _can_
measure charge quite accurately from resting voltage - but I am prepared to
believe in more accurate types of measurement than this.)

By the way, I happen to know that a battery can have high-normal resting
voltage and be completely useless, as this thread asserts: no current draw
from it, but basement sg's - this happened to me last summer. Perhaps I
hadn't rested it, after attempted charging, nor removed the surface charge.

Charles

====

Charles T. Low
- remove "UN"
www.boatdocking.com
www.ctlow.ca/Trojan26 - my boat

====

"Doug Dotson" wrote in message
...

"Charles T. Low" wrote in message
...
Doug,

Thanks, very helpful.

So, does this seem valid to you? - An accurate voltage reading is a
good
indicator of a battery's condition, but specific gravity is better,

Yes. But only after the battery has rested under zero load for a while.

and a
slow load test (to 50%) is the best?

A slow load test tells the current capacity of the battery which is what
the
battery is being asked to do.

Or are they testing different things,
all of which are important?

Perhaps. I suppost that if you are using the same battery bank for
house and starting, then multiple types of test may be informative.
But for a house bank a slow realistic load test gives the bottom line.
Voltage and SG tests are really telling the current instantaneous state
of the battery. That does not necessarily relate directly to the expected
perfromance under load. One is static the other is dynamic.

Could it do well on a load test without good
voltage or sg's?

I don't see how.

And, what use is a commercial load tester, then? Why do they make them?

To test the high current delivery performance of starting batteries as
best
I can tell.

Is
it better than an sg but not as good as a slow load test?

As I said earlier. These are testing different things. SG gives the
current state of the battery, a slow load test tells the capacity of the
battery. A reasonable analogy might be, the amount of fuel you have
in your fuel tank as apposed to how far that fuel will get you at a
given speed. You can measure how much fuel you have by weight or
by volume or by level, but that will not tell you how far you can go
at 10 mph vs 100 mph. The condition of the engine enters into the
equation as well just as the condition of the battery does.

Thanks again. Charles

P.S. I corrected the spelling of "betteries" - couldn't take it any
more!

====

Charles T. Low
- remove "UN"
www.boatdocking.com
www.ctlow.ca/Trojan26 - my boat

====

"Doug Dotson" wrote in message
...
The discharge time of a deep cycle battery is influenced by many
things other than SG. The condition of the plates etc all come into
play. While one may be able to draw heavy current for a brief
period that does not necessarily translate into good low power
performance. A long term low current test tells the actual story
since it is how the battery is being used in normal use. The SG
gives the state of charge from a theoretical sense as does the
voltage.

Testing Batteries
 

Thanks, Doug, and also to Argonauta, and to Larry W4CSC. (Some of the
information conflicts, but that's not the first time that's happened!)

So, to summarize:

-voltage and sg measure charge but not capacity;
-commercial load testers might be for testing starter batteries, esp. if
something is wrong and you're trying to figure out what;
-slow load testing makes more sense for deep cycles functioning in that
role.

(Of course, Darden's site says that 200 deep discharge cycles is a good
battery's life span - so if you test it, have you used up one?)

(Larry: It also gives charge/voltage tables, which suggest that you _can_
measure charge quite accurately from resting voltage - but I am prepared to
believe in more accurate types of measurement than this.)

By the way, I happen to know that a battery can have high-normal resting
voltage and be completely useless, as this thread asserts: no current draw
from it, but basement sg's - this happened to me last summer. Perhaps I
hadn't rested it, after attempted charging, nor removed the surface charge.

Charles

====

Charles T. Low
- remove "UN"
www.boatdocking.com
www.ctlow.ca/Trojan26 - my boat

====

"Doug Dotson" wrote in message
...

"Charles T. Low" wrote in message
...
Doug,

Thanks, very helpful.

So, does this seem valid to you? - An accurate voltage reading is a
good
indicator of a battery's condition, but specific gravity is better,

Yes. But only after the battery has rested under zero load for a while.

and a
slow load test (to 50%) is the best?

A slow load test tells the current capacity of the battery which is what
the
battery is being asked to do.

Or are they testing different things,
all of which are important?

Perhaps. I suppost that if you are using the same battery bank for
house and starting, then multiple types of test may be informative.
But for a house bank a slow realistic load test gives the bottom line.
Voltage and SG tests are really telling the current instantaneous state
of the battery. That does not necessarily relate directly to the expected
perfromance under load. One is static the other is dynamic.

Could it do well on a load test without good
voltage or sg's?

I don't see how.

And, what use is a commercial load tester, then? Why do they make them?

To test the high current delivery performance of starting batteries as
best
I can tell.

Is
it better than an sg but not as good as a slow load test?

As I said earlier. These are testing different things. SG gives the
current state of the battery, a slow load test tells the capacity of the
battery. A reasonable analogy might be, the amount of fuel you have
in your fuel tank as apposed to how far that fuel will get you at a
given speed. You can measure how much fuel you have by weight or
by volume or by level, but that will not tell you how far you can go
at 10 mph vs 100 mph. The condition of the engine enters into the
equation as well just as the condition of the battery does.

Thanks again. Charles

P.S. I corrected the spelling of "betteries" - couldn't take it any
more!

====

Charles T. Low
- remove "UN"
www.boatdocking.com
www.ctlow.ca/Trojan26 - my boat

====

"Doug Dotson" wrote in message
...
The discharge time of a deep cycle battery is influenced by many
things other than SG. The condition of the plates etc all come into
play. While one may be able to draw heavy current for a brief
period that does not necessarily translate into good low power
performance. A long term low current test tells the actual story
since it is how the battery is being used in normal use. The SG
gives the state of charge from a theoretical sense as does the
voltage.

Testing Batteries
 

(Of course, Darden's site says that 200 deep discharge cycles is a good
battery's life span - so if you test it, have you used up one?)

True, but a deep discharge is something that shouldn't be done in
normal practice. IMHO a 50% discharge is sufficient to get a pretty
good idea of capacity. Especially since a 50% discharge is what is
done in normal use.

Doug
s/v Callista