equalizing

higgins
higgins Solar Expert Posts: 56 ✭✭✭✭
in Solar Beginners Corner #1
is equalizing to do with banks of batteries or cells within a battery?How do i go about it or do i need a certain type of battery charger?
Higgins
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #2
    Re: equalizing

    eqing is more for multiple batteries, but can definitely apply to individual cells as well so i would say both. usually 1 battery does not suffer from the inequities that multiple batteries usually suffer because of variations in the distributions of both charge and load currents differences.
    for eqing it obviously must have that feature to do it.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,640 admin
    #3
    Re: equalizing

    Equalizing a flooded cell bank typically requires around 15-15.5 volts and you want about 5% of the bank's capacity (i.e., 100 AH bank, would charge at 15 volts and 5 amps).

    The two bit issues (as I see them) are:
    1. Batteries are not perfect. Some cells have a bit more capacity than another, other cells may self discharge a bit more, etc... These differences between cells can spread over time. So, when you have, for example, a 12 volt battery... 5 cells could be at 100% charge and one cell could be at 80% state of charge. Now--when you cycle the battery to 80% SOC, the one cell may be at 60% SOC--and begin sulfating (hardening of the lead sulfate). So--you could end up with one sulfated cell in the battery even though the bank appears to be well charged. Also, if you ever take the bank down to 20% state of charge, that one cell is in danger of "reversal" (changing polarity and reverse charging).
    2. The other is just mixing of electrolyte with the bubbling of 5% charge current going through the bank an trying to reconvert any stubborn lead sulfate back into lead and water.
    So--from an energy point of view--Equalization is a loss of energy--Doing it when not needed just costs you power.

    From a battery point of view, equalization is very hard on the plates and the plate grids... The bubbling can cause the soft lead sponge to flake off. Also, the oxygen gas forms around the positive plate--causing the "grid" that holds the lead to corrode and fail...

    Batteries that are heavily equalized/overcharged will use up a lot of distilled water. That can be an indication that too much equalization/charging is being done--And not using any water may mean that not enough charging is being done. For some, cost and problems of getting distilled to a remote site is an issue. Accidentally exposing the plates (not keeping up on adding distilled water when needed) is also a leading cause for early battery death.

    I am sure there are other issues/reasons to equalize (and not equalize). My point being is that a healthy battery does not improve health with equalization. And an unhealthy battery may just have its life extended some when properly equalized.

    Read the battery FAQ's and look up lead acid battery information on the web... There is a lot more out there.

    Deep Cycle Battery FAQ
    www.batteryfaq.org

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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