On Wed, 25 Jul 2007 16:46:45 +0700, wrote:

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

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

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)
I hope that you enjoy a long read ;-)

BTW as I said I sell and fit them however I do not design and
manufacture them, and its not my site.


--
Richard

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

On Wed, 25 Jul 2007 10:35:06 -0700, Pete C
wrote:

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.
Sorry Pete I cannot relate to the above, it is a far too simplistic.
Here in the UK and I feel also in the US battery capacity is normally
quoted at a 20hour rate.
Therefore in the example offered above - 1A for 10hrs giving a 25%
drop in "State of Charge" the actual original battery capacity would
have been more like 35AH given a Peukert of 1.25

Ok I realise that you used the term "about" but we are talking major %
differences here.

To put the test another way are you saying that if the load had been
100ma for 100hours = 10amp hours your conclusions would have been the
same?
I would then suggest the battery's max capacity would have been 22Ah.

--
Richard

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

On Wed, 25 Jul 2007 08:17:40 -0700, Pete C
wrote:

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???

99% of my customers would not know what a hydrometer was
99% of my customers have no idea what their audit is
70% do not care
30% want to be able to look at something to tell them whether to
charge or not

cheers,
Pete.


--
Richard

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

On Wed, 25 Jul 2007 11:04:43 -0500, "KLC Lewis"
wrote:


"Pete C" wrote in message
roups.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.

And you have 450AH available ;-) I have customers who live on their
boat with less than that!
Paranoid is a bit OTT but aware is sensible.

--
Richard

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

* Larry wrote, On 7/26/2007 12:36 AM:
Lew Hodgett wrote in news:1QTpi.12042$zA4.313
@newsread3.news.pas.earthlink.net:

To replace 375 AH you will require 375/115 = 3.3 hours of engine time.



A pipe dream of battery chemistry. 375AH requires 5 hours (from 50%
discharge, not zero) at 38A, not 115. Batteries charge at 10% of AH
rating, not 30, if you want to convert the electrolyte, giving it time
for circulation.

You've made this assertion many times, and its still completely false.
Or possibly, I have magic batteries. I have 4 Trojan T-105's for a
total of 450 Amp-hours. The 110 Amp alternator, controlled by a Link
2000R generally charges at about 90 Amps, slowly dropping to around
75. At that point, its around 80% full. Continuing to charge, it
goes down to 50, when I figure its close to 90%. The first set of
batteries last 6 years, and were really killed by a sever winter. The
new set is on its third year.

BTW, I don't have double belts, but I cook at least one year.

Larry wrote in
:

A pipe dream of battery chemistry. 375AH requires 5 hours (from 50%
discharge, not zero) at 38A, not 115. Batteries charge at 10% of AH
rating, not 30, if you want to convert the electrolyte, giving it time
for circulation.

I note that my batteries (2 Caterpillar 153-5720 8Ds) are speced at a max
charging rate of 5% of their CCA, which is 1500 A. That works out to 75 A.
Each of the batteries have a rating of 210 AH, which based upon Larry's
math, would be 21 Amps, or 42A for both of them.

That said, this whole discussion doesn't make a lot of sense to me. I
watch my 3 stage regulator charging rates, and it spends very little time
charging at full throttle. When initially turned on, the charger goes into
bulk charging mode and attempts to get the charging voltage up to the bulk
charging voltage. This voltage depends upon the battery temperature and I
have a thermocouple which sends the battery temperature back to the
charger. I've specified a temperature coefficient in the charger (which is
specified in mV/degree C) and as the battery gets warmer, the bulk charging
voltage drops.

Anyhow, I try not to let my batteries get below 12.5V. When I charge the
batteries I see my charger outputting at its maximum charge rate (110A) for
about 15 minutes and then it typically has reached the bulk charging
voltage. Then the charging rate drops as it maintains that voltage. My
typical charging cycle runs for about 1 hour, and at the end of that hour
I'm only outputting about 20A. It will take several more hours for the
rate to drop to 0.

Thus, this talk about charging at some rediculously high rate for X hours
doesn't seem to have much to do with real charging systems

-- GEoff

Lew Hodgett wrote in news:FPWpi.11839$Od7.10372
@newsread1.news.pas.earthlink.net:

Larry wrote:


A pipe dream of battery chemistry. 375AH requires 5 hours (from 50%
discharge, not zero) at 38A, not 115. Batteries charge at 10% of AH
rating, not 30, if you want to convert the electrolyte, giving it time
for circulation.

Spoken with the vision of a person with his head squarely placed where
the moon doesn't shine.

Plonk

Lew


Sorry you feel that way. Telling them they can recharge by shoving current
like hell into it in 3 hours is still a pipe dream.

Larry
--
While in Mexico, I didn't have to press 1 for Spanish.
While in Iran, I didn't have to press 1 for Farsi, either.
While in Florida, I had to press 2 for English.
It just isn't fair.

Geoff Schultz wrote in
:

I note that my batteries (2 Caterpillar 153-5720 8Ds) are speced at a
max charging rate of 5% of their CCA, which is 1500 A. That works out
to 75 A. Each of the batteries have a rating of 210 AH, which based
upon Larry's math, would be 21 Amps, or 42A for both of them.

That said, this whole discussion doesn't make a lot of sense to me. I
watch my 3 stage regulator charging rates, and it spends very little
time charging at full throttle. When initially turned on, the charger
goes into bulk charging mode and attempts to get the charging voltage
up to the bulk charging voltage. This voltage depends upon the
battery temperature and I have a thermocouple which sends the battery
temperature back to the charger. I've specified a temperature
coefficient in the charger (which is specified in mV/degree C) and as
the battery gets warmer, the bulk charging voltage drops.



The 3-stage charger bulk charges the initial load of electrolyte between
the plates that WILL take a tremendous current and charge with it until
it has been converted back to acid and replated the lead. Then, as you
say, it drops back to give the battery time to recover its electrolyte by
convection back between the plates with a much lower charge current
(stage 2) after the voltage rises from the recharge I alluded to in stage
1. State 2, a more sedate charge rate that prevents you from warping the
plates with 100+ amps by melting them, possibly causing a
short/explosion, continues unabated with short periods of zero current
for charge testing, then turns back on until the test period voltage
remains higher than the natural voltage of the cells, indicating nearly
full charge. It then switches to stage 3 which is a very slow topping
off charge.

Investigating Lew's 115A at 14V massive charge for 3 hours shows 115 X
14V = 1,610 watts being shoved into the battery. At first, this will be
absorbed a lot by the chemical reaction converting back to acid. But, as
the charge between the plates quickly completes and he goes into the
gassing phase converting his water into hydrogen, this power starts being
turned into heat, heating the electrolyte and plates, which are soft to
begin with, an possibly, probably, warping the plate structure,
especially if the cells aren't straight up vertical, such as being heeled
over with sail aloft of sloshing about in the waves. 1,610 watts is a
lot of DC power to pour through a rubber or plastic case...and will not
just go off easily sealed away in those tight battery boxes that insulate
the battery from any air cooling....making the heating problem worse.

He didn't want to hear my sad story, so I hope the rest of you will think
about what I'm saying before the big bang coats your boat with
acid....not a pretty sight at all!

Larry
--
Cursing me won't change physics or chemistry.....

On Jul 26, 7:51 am, Electricky Dicky wrote:

Sorry Pete I cannot relate to the above, it is a far too simplistic.
Here in the UK and I feel also in the US battery capacity is normally
quoted at a 20hour rate.
Therefore in the example offered above - 1A for 10hrs giving a 25%
drop in "State of Charge" the actual original battery capacity would
have been more like 35AH given a Peukert of 1.25

Ok I realise that you used the term "about" but we are talking major %
differences here.

Very good point, to get a good comparison of actual to rated capacity
you'd need to discharge at a 20hr rate.

So for a 40Ah battery this would be 40(Ah)/20(hours) = 2 amps.

cheers,
Pete.

On Jul 26, 7:58 am, Electricky Dicky wrote:
On Wed, 25 Jul 2007 08:17:40 -0700, Pete C
wrote:

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

[stuff snipped....]

99% of my customers would not know what a hydrometer was
99% of my customers have no idea what their audit is
70% do not care
30% want to be able to look at something to tell them whether to
charge or not

Exactly! E-X-A-C-T-L-Y!

If they knew a bit about electrics and could use a hydrometer, they
wouldn't be your customer, as they woundn't need professional help,
would they?

cheers,
Pete.