Equalizing batteries - how much is possible?

[den458]

Am interested in applying what I've read here on battery equalization, but I wonder how far out of equalization can be remedied.

Retired newbie here, engineering background, have new-to-me 48V '99 Club Car DS, 6x8V batteries of indeterminate age & Powerdrive battery charger.

Bought used, sat idle 3 months, initial battery voltage was ~ 36V as I found it. Topped cells properly with distilled water & placed on charger. Charged 5-6 hours, initial rate ~ 16A gradually decreasing to 6A, but goes no lower, did not self shut-off.

I've not tried charging continuously overnight, though I will later if necessary, but I think battery voltage imbalance is the show-stopper right now.

On power up, the battery charger does turn on for ~ 10 seconds, goes off briefly then on again for good.

Battery voltage with charger connected ~ 56.9V, battery voltage with charger removed ~52,6V, next day voltage with cart unused ~48.6V.

Looking at individual battery voltages, cart having sat unused 2 days, ranged 7.90, 7.91, 8.09, 8.10, 8.21, 8.28V. Those are for batteries 1-6 in order, so interesting that voltages are progressively higher, from the red cable connection to the black cable connection.

Based on the JohnnieB SOC chart for 8V batteries, my various batteries are charged between 30% & 80%, & seem to charge no further.

I may be wrong, but I'm guessing the higher charged batteries begin boiling while the poorest charged batteries lack power to continue charging. Though my charger never shuts down, I'm hoping installing the voltage bypass circuits will help the poorer charging batteries to "catch-up" some.

The component cost for building the passive voltage bypass is minimal, I'm planning to order shortly from Newark. I understand the sorting process of matching 2 zener diode devices to target 10.2V total, & do that for 6 bypass circuits. Assembly looks pretty simple, some soldering & shrink tubing.

It's a cheap exercise to try coaxing more life out of these batteries. If batteries ultimately are not salvageable, the bypass devices will find homes on the replacement batteries.

So, my questions are:
1) what minimum 8V battery SOC (state of charge), if any, may yield a recovered battery?
2) what sort of range of equalization can be addressed with these bypass circuits?
3) Is my 0.38V range of voltage difference between batteries solveable with repeated charge / use / recharge cycles?

Appreciate advice from the many battery gurus here, thanks in advance !

[meimk]

After a long period of sitting like that your charger could run as long as 16 hours. Make sure your water levels are good and let it run. The pause, on, off, on again are normal. You're right that they may not come back completely, but you won't really know till you let the charger finish trying to do it's job. Once the charg er has finished, wait 12 hours or so then see where your voltage sits.
In the list of 1 through 6, are there lights or other accessories wired to #1 & #2?

[alangsam]

Keep charging it. You can leave it on for 24 hours then look at the numbers. Then connect it again and let it peak. Then unplug and do it again. Eventually they may come back. I bought a desulfator and recovered a set of batteries that had been sitting for 3 months.

[WalterM6]

If your batteries drop from 52.6 to 48.6 overnight without any use they are shot. Nothing will help them. Do you have any idea how old they are?

[meimk]

Originally Posted by WalterM6

If your batteries drop from 52.6 to 48.6 overnight without any use they are shot. Nothing will help them. Do you have any idea how old they are?

He hadn't allowed the charger to run full cycle yet it was only to 56 on the charger. Normal settling on a partial / incomplete charge.

[yawood]

Originally Posted by den458

...snip...The component cost for building the passive voltage bypass is minimal, I'm planning to order shortly from Newark. I understand the sorting process of matching 2 zener diode devices to target 10.2V total, & do that for 6 bypass circuits. Assembly looks pretty simple, some soldering & shrink tubing...snip...

If you haven't already seen it, this thread from Sergio would interest you: http://www.buggiesgonewild.com/elect...v-battery.html

[Budule]

my cheap self would mark the voltages of each one on a little piece of masking tape , take them all out (beer and pills for the back pain) , get a really good look at all the new things I can now see, battery area may need some work ,

while all this is going on I would have my 12 volt charger hooked up to the lowest battery (set on the lowest amps , maybe an hour at a time) let it rest , check , repeat , and mix or reverser order when I reinstall them...…...on your rebuilt battery tray.....

Then more beer as I revel in my success ….

3 months later , new batteries.....****....more beer I guess

[scottyb]

When wet cell batteries are allowed to sit in a depleted state such as 6v for an 8v battery irreversible damage is done. Save electricity - pull the plug on these and buy the best batteries you can afford.