Battery charging

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JESSICA
JESSICA Solar Expert Posts: 289 ✭✭
in Advanced Solar Electric Technical Forum #1
Greetings:

As some of you may remember, 4/5 months ago I bought four new batteries ( http://forum.solar-electric.com/showthread.php?t=11474&highlight=trace+batteries )
They have been working fine.
Nevertheless I have noticed that I have not have to add watter, never, because water level, in all cells, have never gone below normal level.
Is this normal/right? Am I doing something wrong? Should I increase voltage setpoints? Is this a symptom of undercharging?
Current setpoints are: Absorb: 28.4 Float: 27.4
My CC is an Outback mx60.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
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    Re: Battery charging

    I would set the Absorb Voltage to 28.8 as a minimum for FLA's. That should get some bubbling going. Of course you're looking for that tricky balance between enough action and too much water loss. Trojan actually recommend 29.6 for theirs. You might want to push the Float up to 27.6.

    One important question: how's the specific gravity reading?
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  • JESSICA
    JESSICA Solar Expert Posts: 289 ✭✭
    #3
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    Re: Battery charging
    Cariboocoot wrote: »
    I would set the Absorb Voltage to 28.8 as a minimum for FLA's. That should get some bubbling going. Of course you're looking for that tricky balance between enough action and too much water loss. Trojan actually recommend 29.6 for theirs. You might want to push the Float up to 27.6.

    One important question: how's the specific gravity reading?

    Thanks for your input, Cariboocoot.

    I don't have a hydrometer, so I have no idea. I bought one more than six months ago, but after two weeks the internet vendor told me it was "out of stock", so...
    When you say "as a minimum", do you mean that even 29 is a "safe" setting? (That's my equalization setting!)
    Anyway, I will follow your recommendations.

    Thanks again.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #4
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    Re: Battery charging

    Just my opinion based on my experience but for a 24 Volt system 28.8 is the normal FLA Absorb set point. I find 28.4 to be a bit low: not enough bubbling going on! :D

    Sometimes we take things for granted around here, like the ease of acquiring things. Even in Canada I can walk into any auto supply store and buy a hydrometer. It may not be the best, but it'll be close enough to tell if things are charging right.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #5
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    Re: Battery charging

    If you have not had to add any water, your absorb voltage/time is probably on the low side... As near as I can tell from reading here, the "right amount" of water to add would be adding to each cell every couple of months (on average).

    29 volts would be 14.5 volts for a 12 volt system... For a flooded cell battery, not very high at all for Absorb voltage set point.

    Do you have any specs. from the battery manufacturer?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #6
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    Re: Battery charging

    One needs to have a hydrometer if one is going to properly manage batteries IMHO,

    Tony
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  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    #7
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    Re: Battery charging

    Agree with cariboocoot, 28.8V is pretty much the standard for FLA batts. The other important setting is how long are you absorbing for and how much do you draw down the battery every day?

    A hydrometer is a must have for flooded batts as it's the only way to really tell if you're charging properly or not.
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  • JESSICA
    JESSICA Solar Expert Posts: 289 ✭✭
    #8
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    Re: Battery charging
    icarus wrote: »
    One needs to have a hydrometer if one is going to properly manage batteries IMHO,

    Tony

    I know. I agree with you all.
    The thing is, I just don't like the idea of sitting in front of my open batteries during 10 minutes, probing each and every cell. I know those gases are not good for my health.
    So, not buying the hydrometer was/is just an excuse.
    In 3 or 4 years I will buy the sealed batts.

    ["Do you have any specs. from the battery manufacturer?"]

    Bill:

    No, no specs. They are very similar to Trojan T105: 225 amps 20 hour rate.
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  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    #9
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    Re: Battery charging
    JESSICA wrote: »
    The thing is, I just don't like the idea of sitting in front of my open batteries during 10 minutes, probing each and every cell. I know those gases are not good for my health.

    You may not need to. I use the hydrometer in 2 ways:
    Firstly to check the general state of charge of my battery bank; I do this quite regularly and since it's just a general sanity check that nothings going horribly wrong, I just check 1 cell. Doesn't even take 30 seconds ;)

    Secondly, much less frequently I'll check that each cell is doing OK so will measure and record the SG of every cell, typically after doing a full EQ. Only do this once every 6 months or so.
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #10
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    Re: Battery charging
    JESSICA wrote: »
    I know. I agree with you all.
    The thing is, I just don't like the idea of sitting in front of my open batteries during 10 minutes, probing each and every cell. I know those gases are not good for my health.
    .

    When your batteries are being charged and bubbling, you could experience some respiratory irritation. So that would not be a good time to have your face over them, or even be near them. However if they're properly vented and allowed to sit, being neither charged or discharged for a couple of hours, pretty much the only gases should be slight traces of hydrogen and oxygen, both of which are abundant in the air we breath, one of which we die without. And even those gases, especially if the batteries are properly vented, should not be measurable different than the everyday air we breath, unless of course we stick our nose down one of the filler holes. And to reduce any possible exposure further still, just have one cell at a time open for testing.
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  • Seven
    Seven Solar Expert Posts: 292 ✭✭
    #11
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    Re: Battery charging

    Sg should be done on a resting battery. Not any real gas being made at that time. I only open one cap at a time and the batts have watermiser caps on so they just flip up.

    You mentioned sealed batteries. Are you talking about AGM? IMO regular FLA are better due to price and the fact that you can check SG to really know what is going on.

    If you do get the glass hydrometer, be sure you unpack every single piece to make sure it is ok, right when you get it.
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  • JESSICA
    JESSICA Solar Expert Posts: 289 ✭✭
    #12
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    Re: Battery charging
    stephendv wrote: »
    You may not need to. I use the hydrometer in 2 ways:
    Firstly to check the general state of charge of my battery bank; I do this quite regularly and since it's just a general sanity check that nothings going horribly wrong, I just check 1 cell. Doesn't even take 30 seconds ;)

    Secondly, much less frequently I'll check that each cell is doing OK so will measure and record the SG of every cell, typically after doing a full EQ. Only do this once every 6 months or so.

    Ok. I stand corrected. (A nice way to say: I am just an ignorant puertorican.)
    I will buy the hydrometer.

    Thanks to all for the advise.
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