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Old 31-03-2010, 09:39   #1
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Uneven Battery Cells

What does it mean if after charging some of my battery cells read "great" (or whatever) and some of them read "fair"? Does that mean I need to equalize? These are brand new batteries that I bought from Sam's Club. They are GC2 6 volts.
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Old 31-03-2010, 10:03   #2
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Not uncommon for new batteries. Yes, equalize them (only after fully charging) and retest the specific gravity. I infer you have a cheapo hydrometer. It would be of benefit to get one with graduated density readings on it to more precisely define how uneven they are.
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Old 31-03-2010, 13:49   #3
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UNEQUAL BATTERY CELL S/G INDICATES A SCREWED BATTERY!

I'd take the NEW batteries back to the retailer, and have them properly charge/equalize them, or (more likely) replace them; rather than screw around.


If a fully charged battery shows a difference of more than 0.025* to 0.050 (depending upon authority) S/G between any two cells, the battery is unserviceable.

* TM-9-6140-200-14 Lead-Acid Storage Batteries Manual
Battery Specific Gravity Differences.

A solution of higher specific gravity is heavier, per unit volume, than one of lower specific gravity. Therefore the more concentrated electrolyte created during charging sinks to the bottom of the battery jar, creating a gradient in specific gravity.
The gassing that occurs on overcharge serves as a mixer, and makes the specific gravity uniform throughout the cell. To avoid erroneous readings, specific gravity measurements should only be taken after an equalizing charge, and subsequent float charge for at least 72 hours.
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Old 31-03-2010, 14:32   #4
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Quote:
Originally Posted by GordMay View Post
To avoid erroneous readings, specific gravity measurements should only be taken after an equalizing charge, and subsequent float charge for at least 72 hours.
Well I haven't done that yet. I am a little confused about what is going on with my charger, it is an Iota DLS30 and I am confused about whether or not it can equalize. I am also a little confused about whether or not my batteries are even all the way charged. The fan hasn't been turning on so I have been reluctant about leaving it plugged in over night. I wrote to Iota two days ago and they still haven't gotten back to me which is a little irksome.
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Old 31-03-2010, 14:44   #5
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If "some of your battery cells read great" - take the batteries back (you've done all you should have to do)!
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Old 31-03-2010, 14:45   #6
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If "some of your battery cells read great" - take the batteries back!
Right because that means that the battery is "fully charged" right?
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Old 31-03-2010, 15:01   #7
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I would discharge them and recharge several times and check the specific gravity with a good hydrometer as Illusion mentioned. The fan on your battery charger wont come on unless it is getting hot.
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Old 31-03-2010, 15:05   #8
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RIGHT!

These are new batteries, which you fully charged (at least some cells).

Uneven specific gravities indicates an unserviceable battery.

You've got uneven cells.

Take it back, before Sam's can claim that you screwed it up.

If they can equalize it, and bring all cells to full charge (w/in 0.025 S/G), OK - if not, replace.
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Old 31-03-2010, 15:38   #9
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Cool Gord, will do.
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