Amps, etc.
 

On Tue, 24 Jul 2007 12:09:20 -0400, Jeff wrote:

* wrote, On 7/24/2007 11:10 AM:
The problem with the amp hour meters is (I suspect) they aren't very
accurate. I admit that I've only read the manual on a couple of
different makes but they both talked about initializing the meters and
then later into the manual they mention that you need to re-initialize
(or maybe they said "zero") the meters from time to time..


They are quite accurate in a sense, but I think mine gets confused by
the number and variety of charge sources and sinks. This leads it to
automatically adjust its concept of charge efficiency poorly.
Recently I realized it was using 73% when a better choice was 87%.
However, if you understand that is happening, its easy to compensate.
In my case, I knew that it was losing about 15 Amp-hours a day. A
few hours of charging, as when powering through Wood's Hole is enough
to reset the meter. On a day by day basis, when my alternator charge
rate drops down to around 40 Amps, I know the 450 Amp-hour bank is at
about 90%.

I quite like the basic idea but given that as the battery ages the
charging time changes I cannot see how the meter can be absolutely
accurate and if it is only approximately then I can envision problems
although it certainly seems to make things simpler.


Its better on the usage side than on the charging side. But still,
its infinitely better than nothing.

Well, yes. The output side is just amps times time but when you start
charging it gets difficult as depending on the battery's age you may
need to put back 110% - 125% - ???% of the amp hours that you have
used. This was the part I never could figure out how to compensate
for.

For the moment I use a volt meter and keep a watch on the voltage. I
guess it is sort of a mental gage but I wish someone would invent one
that maybe measured S.G. and compensated for that, automatically
compensate for the ageing battery bank.


Bruce in Bangkok
(brucepaigeATgmailDOTcom)

Amps, etc.
 

On Wed, 25 Jul 2007 00:14:13 +0700, wrote:

On Tue, 24 Jul 2007 12:09:20 -0400, Jeff wrote:

* wrote, On 7/24/2007 11:10 AM:
The problem with the amp hour meters is (I suspect) they aren't very
accurate. I admit that I've only read the manual on a couple of
different makes but they both talked about initializing the meters and
then later into the manual they mention that you need to re-initialize
(or maybe they said "zero") the meters from time to time..


They are quite accurate in a sense, but I think mine gets confused by
the number and variety of charge sources and sinks. This leads it to
automatically adjust its concept of charge efficiency poorly.
Recently I realized it was using 73% when a better choice was 87%.
However, if you understand that is happening, its easy to compensate.
In my case, I knew that it was losing about 15 Amp-hours a day. A
few hours of charging, as when powering through Wood's Hole is enough
to reset the meter. On a day by day basis, when my alternator charge
rate drops down to around 40 Amps, I know the 450 Amp-hour bank is at
about 90%.

I quite like the basic idea but given that as the battery ages the
charging time changes I cannot see how the meter can be absolutely
accurate and if it is only approximately then I can envision problems
although it certainly seems to make things simpler.


Its better on the usage side than on the charging side. But still,
its infinitely better than nothing.

Well, yes. The output side is just amps times time but when you start
charging it gets difficult as depending on the battery's age you may
need to put back 110% - 125% - ???% of the amp hours that you have
used. This was the part I never could figure out how to compensate
for.

For the moment I use a volt meter and keep a watch on the voltage. I
guess it is sort of a mental gage but I wish someone would invent one
that maybe measured S.G. and compensated for that, automatically
compensate for the ageing battery bank.

Bruce and anyone else interested...............
Take a look at www.smartgauge.co.uk
I have a customer that has a Smartgauge and a BMV501 on board. He was
concerned that the BMV was indicating the bank at 86% when the
Smartgauge showed 53%. His bank was sulphated and the Smartgauge was
correct. Continuous Equalisation charges brought his bank back up
(luckily). I put my money on the Smartgauge, And yes I sell them and
fit them but you make your own decisions ;-)



--
Richard

Nb "Pound Eater" Parkend G+S
"Governments are like Nappies, they should be changed often."
(For the same reason)

Amps, etc.
 

"Bob" wrote in message
oups.com...

I just could not
understand other riders who zoomed past with full dress Honda lead
wings, huge faring, fiberglass saddle bag condos, AND pulling a
trailer. I think there was a mortycycle under all that ****. Sorta
defeated the purpose of a motorcycle I thought. Christ, they
reportedly even had a reverse gear !?! But they seemed to be having
fun............

We call those Hondabagos.

Leanne

Amps, etc.
 

On Tue, 24 Jul 2007 18:41:29 +0100, Electricky Dicky
wrote:

On Wed, 25 Jul 2007 00:14:13 +0700, wrote:

On Tue, 24 Jul 2007 12:09:20 -0400, Jeff wrote:

* wrote, On 7/24/2007 11:10 AM:
The problem with the amp hour meters is (I suspect) they aren't very
accurate. I admit that I've only read the manual on a couple of
different makes but they both talked about initializing the meters and
then later into the manual they mention that you need to re-initialize
(or maybe they said "zero") the meters from time to time..


They are quite accurate in a sense, but I think mine gets confused by
the number and variety of charge sources and sinks. This leads it to
automatically adjust its concept of charge efficiency poorly.
Recently I realized it was using 73% when a better choice was 87%.
However, if you understand that is happening, its easy to compensate.
In my case, I knew that it was losing about 15 Amp-hours a day. A
few hours of charging, as when powering through Wood's Hole is enough
to reset the meter. On a day by day basis, when my alternator charge
rate drops down to around 40 Amps, I know the 450 Amp-hour bank is at
about 90%.

I quite like the basic idea but given that as the battery ages the
charging time changes I cannot see how the meter can be absolutely
accurate and if it is only approximately then I can envision problems
although it certainly seems to make things simpler.


Its better on the usage side than on the charging side. But still,
its infinitely better than nothing.

Well, yes. The output side is just amps times time but when you start
charging it gets difficult as depending on the battery's age you may
need to put back 110% - 125% - ???% of the amp hours that you have
used. This was the part I never could figure out how to compensate
for.

For the moment I use a volt meter and keep a watch on the voltage. I
guess it is sort of a mental gage but I wish someone would invent one
that maybe measured S.G. and compensated for that, automatically
compensate for the ageing battery bank.

Bruce and anyone else interested...............
Take a look at www.smartgauge.co.uk
I have a customer that has a Smartgauge and a BMV501 on board. He was
concerned that the BMV was indicating the bank at 86% when the
Smartgauge showed 53%. His bank was sulphated and the Smartgauge was
correct. Continuous Equalisation charges brought his bank back up
(luckily). I put my money on the Smartgauge, And yes I sell them and
fit them but you make your own decisions ;-)

Thanks for info. I started to read your technical section and the
lights went out but will do more studying later. I've always liked the
idea of a meter that showed amps in/amps out but never was able to
figure out a method of outwitting the time necessary for the chemical
changes to take place during the charging phase.


Bruce in Bangkok
(brucepaigeATgmailDOTcom)

Amps, etc.
 

On Jul 25, 10:46 am, wrote:

Thanks for info. I started to read your technical section and the
lights went out but will do more studying later. I've always liked the
idea of a meter that showed amps in/amps out but never was able to
figure out a method of outwitting the time necessary for the chemical
changes to take place during the charging phase.

Hi,

Just google for 'battery conductance tester', that's basically what it
is.

Whether it's worth having or not IMHO depends largely on whether the
prospective user knows little about electrics and isn't able to use a
hydrometer.

cheers,
Pete.

Amps, etc.
 

"Pete C" wrote in message
ups.com...
On Jul 25, 10:46 am, wrote:

Thanks for info. I started to read your technical section and the
lights went out but will do more studying later. I've always liked the
idea of a meter that showed amps in/amps out but never was able to
figure out a method of outwitting the time necessary for the chemical
changes to take place during the charging phase.

Hi,

Just google for 'battery conductance tester', that's basically what it
is.

Whether it's worth having or not IMHO depends largely on whether the
prospective user knows little about electrics and isn't able to use a
hydrometer.

cheers,
Pete.



Pete, do you propose using a hydrometer everytime you want to know your
state of charge? This could be a couple of times each day, or more.

Amps, etc.
 

On Jul 25, 2:37 pm, "KLC Lewis" wrote:
"Pete C" wrote in message

Pete, do you propose using a hydrometer everytime you want to know your
state of charge? This could be a couple of times each day, or more.

Hi,

For those who know a bit about electrics and can use a hydrometer I
would propose:

Do an energy budget/audit.

Size the battery bank for 40% DoD (depth of discharge) on a normal
days/period of use

Use the hydro to verify the above a few times as well as check the
batts are getting fully charged.

Use the hydro to check a few times that an exceptional days/period of
demand doesn't draw the batts below 80% DoD

Comments???

cheers,
Pete.

Amps, etc.
 

"Pete C" wrote in message
oups.com...
On Jul 25, 2:37 pm, "KLC Lewis" wrote:
"Pete C" wrote in message

Pete, do you propose using a hydrometer everytime you want to know your
state of charge? This could be a couple of times each day, or more.

Hi,

For those who know a bit about electrics and can use a hydrometer I
would propose:

Do an energy budget/audit.

Size the battery bank for 40% DoD (depth of discharge) on a normal
days/period of use

Use the hydro to verify the above a few times as well as check the
batts are getting fully charged.

Use the hydro to check a few times that an exceptional days/period of
demand doesn't draw the batts below 80% DoD

Comments???

cheers,
Pete.




My own energy needs are quite modest. Nav instruments, VHF, stereo, running
and anchor lights, computer (laptop), the occasional cabin light for short
periods (converting to led units). No refer, no power windlass. Of course, I
do need to be able to start-up the iron genny from time to time.

My battery bank is 4 new-this-seasonTrojan T-105's and a 40 amp smart
charger for dockside use. 2 US32 solar panels rated at 64 watts. Voltmeter
always reads "top of the green" at 13 volts after dockside charging, bottom
middle of the green after sailing for a day and anchoring out overnight with
the anchor light lit. Engine starts right up like it has a fully-charged
battery when weighing anchor in the morning. But translating this to "how
much power do I have left?" leaves me paranoid.

Amps, etc.
 

Hi,

If you're able to use a hydrometer, this FAQ tells how to relate
battery 'SG' to state of charge:

http://www.batteryfaq.org/
http://jgdarden.com/batteryfaq/carfaq4.htm
http://jgdarden.com/batteryfaq/carfaq4.htm#soc

Bear in mind 'state of charge' isn't a percentage of the battery's
*rated* capacity, as they lose capacity as they get old or sulphated.

State of charge is a percentage of the *actual* capacity of the
battery, taking into account it's age and condition.

To work out the actual capacity you need to compare the drop in state
of charge to a known amount of charge used.

So if drawing 1 amp for 10 hours (10 'amp hours') from a battery makes
it's state of charge drop by 25%, the actual capacity is about 40 amp
hours when it's fully charged.

If the above battery then reads a 75% state of charge, then
approximately 30 amp hours of charge are available until it's
completely flat. (Though of course it should be recharged when the
state of charge is around 50% or less)

If the above is a bit too then try and get someone to explain it to
you in person as it's a little difficult to do in a short posting.

hope this helps,
Pete.

Amps, etc.
 

On Wed, 25 Jul 2007 08:37:20 -0500, "KLC Lewis"
wrote:


"Pete C" wrote in message
oups.com...
On Jul 25, 10:46 am, wrote:

Thanks for info. I started to read your technical section and the
lights went out but will do more studying later. I've always liked the
idea of a meter that showed amps in/amps out but never was able to
figure out a method of outwitting the time necessary for the chemical
changes to take place during the charging phase.

Hi,

Just google for 'battery conductance tester', that's basically what it
is.

Whether it's worth having or not IMHO depends largely on whether the
prospective user knows little about electrics and isn't able to use a
hydrometer.

cheers,
Pete.



Pete, do you propose using a hydrometer everytime you want to know your
state of charge? This could be a couple of times each day, or more.

It is, or used to be, the practice on submarines. Not much extra work
when you are checking/adding water. The original smart charger was a
sub sailor with thermometer, hydrometer, and voltmeter. Who knows what

those guys are doing now.

Casady