# Battery Equalization Question



## Rick (May 10, 2002)

We are trying to maintain some 3 year old deep cycle, Marine type batteries. I am charging them with an Iota 55 amp charger, set to 15.4 volts with a plug that is inserted for equalization.

The batteries on the charger today are the better 2 of a bank of 4. 
I put them on the charger at 1245 hours. It is 1735 hours, and the voltage has been stuck at 15.35 volts for 2 hours. I am going to turn off that lovely generator. Is that what you would do? 

How low would you drain batteries in a maintenance cycle before charging? Would you wait 4 weeks before equalizing again? 

I have tried taking temp. and specific gravity readings, but I have yet to feel comfortable measuring accurately. I will try tomorrow after they settle overnight.

Thanks for any thoughts.


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## no1cowboy (May 2, 2004)

I only do an equalization cycle twice a year, and dont like to see my battery bank go below 11.9 before recharging.


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## Jim-mi (May 15, 2002)

Best if you only use 20% off the top.
"every 4 weeks". . .?? Depends on how hard you use them...........

For a 12v system anything below 12.2 would make me nervous ....


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## Rick (May 10, 2002)

These poor batts were down to 11.8 off and on for a few weeks. I would like to double my array to around 260 watts, to power a small Sundanzer freezer , and use these batts for overnight power. I will probably wind up buying a couple of trojans, but I'd like to get a two more years from these.


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## no1cowboy (May 2, 2004)

Marine type batteries are not really made for this type of thing


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## Rick (May 10, 2002)

Thanks for all of your thoughts, and for the chart, #1CB.

For clarification..

These 4 batts have 460 ah in perfect condition. They show 12.9 volts after 16 hours. They charged at over 15 volts for 5 hours. Maybe a little bit long, but I was trying to Hit BW Solar's magic 15.4 volts for 1 to 2 hours.

Would you say that these Marine Batts just could not be depended on as well as four Trojan T-105's (2 pair in series and those 2 pair parallel to make 12 volts and 450 ah ?

Would 2 L-16's (420 ah ) connected parallel be a more reliable (even if more expensive) battery bank, than the 4 T-105's would be?

I also need to decide if I should use the Sundanzer Freezer on a 24 volt system. Any opinions on that? Are 12 volt fans for summer cooling going to be much more expensive? We have been using O2 cool 12 volt fans, and a oscillating Auto fan.


I have assumed all along that I might need to replace these guys, and find some light duty for them. Seems like there is some agreement in the room.

Thanks...


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## Rick (May 10, 2002)

Jim-mi said:


> Best if you only use 20% off the top.
> "every 4 weeks". . .?? Depends on how hard you use them...........
> 
> For a 12v system anything below 12.2 would make me nervous ....


They are currently being kept from dropping below 80 per-cent. 
Can I infer that this would be not too hard of a cycling, and you would not equalize monthly? Another poster said he equalized every 6 months.

How about T-105 or L-16 Golf Cart Batteries. How would you determine how often to equalize them?

Thanks...


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## Jim-mi (May 15, 2002)

From the way you are posting it sure sounds like the biggest part of those bats life is gone.
Fighting to keep them alive will not be a fun thing. . . .plus how much gas to run the gennie . .??
So yes bite the bullet and pop for a new bat bank . . . .given a bunch of cloudy days you will have that needed reserve for the Sun-Danzer to keep your ice cream solid.
As to the--T105's vs the L16's . . . . .for your small system thats kind of a toss up. 
If you use only 20% (or less) off the top of the L16's you should see a 10 year life. 
The Sun-Danzer excepts 12 or 24 vdc.
I prefer 24 and 48v systems . .but seeing as you allready have a very good bat charger (Iota) then might as well go with 12v system.

You have there a real sweet setup; PV panels, good batterys, Sun-Danzer, Iota backup charger . . . . . .That will keep your ice cream solid for a very long time . . . enjoy................


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## idahodave (Jan 20, 2005)

Trojan says to equalize when the specific gravity varies by .015 between cells after charging. Voltage is a poor method of measuring battery charge.


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## mightybooboo (Feb 10, 2004)

L-16 has thicker plates than T-105.


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## Rick (May 10, 2002)

As far as the life left, I guess they are farther gone then I care to admit. I have always been under the impression that cycling down to 50 per-cent was not harmful. I got this from a rep at real goods- :bash: sigh...and I let them reach WAY below 25 per-cent during a recent stretch of cloudy days, for about a week until I could get a charger here....
If you can squeeze 10 years from L-16's, then 50 per-cent must be "harmful".

Are the thicker plates in the L-16 a good thing? It sounds like it!

As far as specific gravity- can anyone comment on how to tell when enough fluid is in the glass tube to consider the thermometer to be floating? I have found it quite difficult to get just the right amount in there to get an accurate reading. I have considered removing the rubber stopper from the bottom, to make it easier to tell when it is definitely floating, but I am concerned that I might break the glass.

Ice cream is definitely NOT my friend, but that is my battle! I lost 55 pounds when we went off grid 3 years ago, and only 5 of them have found me since then.


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## Jim-mi (May 15, 2002)

My apology's for using 'ice cream' as an example.
My SunDanzer does a wonderful job of keeping my homegrown blueberries frozen................hope that helps.

That real goods guy is a salesman . . . .Not a battery guy.


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## idahodave (Jan 20, 2005)

If you're using a hydrometer to determine when to equalize batteries, the absolute reading isn't too important. What is critical is a consistent reading each time you use it. 

Practice making repeated measurements on one cell until they all come out the same. Suck up the same amount of electrolyte each time, release the bulb and jiggle the hydrometer so the float doesn't stick to the side. After you can make consistent readings on one cell, measure the rest. 

One of the endpoints of equalizing a battery is to stop when the specific gravity no longer increases with charge time. If you stop and there's a large difference in s.g. between cells, get ready to buy a new battery.


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## mightybooboo (Feb 10, 2004)

Rick said:


> Are the thicker plates in the L-16 a good thing? It sounds like it!
> 
> .


Yup,good thing.


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