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Old 06-06-2012, 08:38   #16
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Re: Batteries Not Holding Charge

Originally Posted by hellosailor View Post
I wonder if part of the problem is "normal" integral alternators at "normal" voltages, versus the gel batteries? And the gel/agm mix?

With a GEl anything mix something will either be over charged or under charged unless you've specifically got a device that can boost or limit voltage to one or the other bank. Most gels charge at 14.1V absorption and AGM's 14.4V+ is more close to the norm. The Odyssey AGM bank I am headed out to work on today is 14.7V so if it was getting 14.1V it would likely not be very happy... GEL's with internal regs can be troublesome if the voltage setting is too high.

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Old 06-06-2012, 23:21   #17
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Re: Batteries are unforgiving

Batteries are unforgiving, I just returned from a boat; that less then one year ago I installed 8 * 8-volt Interstatate bats to make a 32 volt redundant bank from.
I also installed an Outback 3225 Pure -Sine Inverter Comby. Now I counselled the owner in the virtues of a BatMon, Hi-Lo voltage alarms, and batboxes.

He didn't see the need for boxes, alarm or batmon.

Today I get a panic call from the owner with; I just checked the ER after a week cruise, and the alternator has thrown it's belt, and at least 5 of the 8 bats have cracked there tops...I THINK THERE IS SOMETHING WRONG WITH THE INVERTER.

BATS don't die.......THEY"RE MURDERED

CHARGE VOLTAGE is critical. Charge regime is CRITICAL.

No matter what anyone on the internet tells you... ask the bat manufacture what the proper charge/regime is for the bats that you purchased from them.

Oh and by the way, if ya want to combine bats of different styles, whether gel/agm/fla or size, then you better think 2'wce.

i don't hold any value in the ACR's! when we are talking about different sized bats(banks), and different styles of LA's....even though they are all LA's.


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Old 06-06-2012, 23:51   #18
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Re: Batteries Not Holding Charge

Originally Posted by Bill6878 View Post
I appreciate all the responses. Here's an update using everyone's input and some clarifications.
House batteries are GEL 184AH x 3 = 540AH
Engine batteries are AGM 105AH each x 2
All the batteries are connected through the main bus bars
With Everything off there is zero amp draw from all batteries, zero amp draw from alternators
All electronics and refrigerator on, only drawing 7A at main bus bar
Dock charger on registering 43A at 13.5V ( ran all day yesterday, when shut down last night was putting out 10A)
Ran port engine, alternator putting out 42A 14.2V
Started starboard engine with port still running alternator putting out 3.5A, port still carrying load.
Shut down port engine, starboard alternator bumped up to 24A at 13.8V
Main DC panel shuts down at 10.5V so batteries never drain below this. Sorry, left that out earlier.
I'm gonna pull the starboard alternator and have it checked.
Considering the not enough charging theory, I usually start the starboard engine first, right handed thing I guess.
Question now is what voltage should I be looking for from the alternator?
Other people have answered most of your questions about voltages, but It is important to relise if your batteries are taking 42A @14.2v ( or 24a@13.8v) they are a long way from fully charged even if some of this current is running the house loads.
It is difficult to predict soc from acceptance current alone, but somewhere around 50% soc would be close. If I understand correctly this is after a long period on the battery charger the night before before.

Before you ran the battery charger 43A @ 13.5v indicates a pretty flat battery and still accepting 10A @ 13.5v at the end means the batteries were a long way from fully charged ( maybe 65%)
Don't treat theses soc estimates as gospel, but they indicate your batteries are not being fully charged.
If the battery is only charged to 65% you only have 15% capacity left before you hit the 50% nominal recharge mark.
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Old 07-06-2012, 06:59   #19
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Re: Batteries Not Holding Charge

To give you an idea of the the sort of numbers you are looking for my 400AHr gel batteries are now fully charged after a day of solar. The batteries are accepting 0.5A @ 13.7v.

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