Any way to bring one battery voltage up?

[buzzmanc]

My pack voltage after charging and letting rest on my 99 series is 37.8 volts. My individual batteries read 3 @ 6.36, 2 @ 6.28, and 1 @6.16. Is there any way to bring this one back up? I have charged it seperately with a 6 volt charger but after a round of golf and a charging it goes to the same reading. I am in the process of upgrading some components to start the switch to 48 volts soon and will buy new batts next year along with a 48 volt charger. I am worried about the new alltrax 400 amp controller finishing off the lower batteries. They are around 3 years old, not sure of the manufacturer as they have no markings. Thanks for the

Chris

[JohnnieB]

I had some luck getting some batteries that would only charge to 85% up to 95% by charging the living daylights out of them.

What kind of amps does the 6V charger put out and what is the battery's on-charge terminal voltage after about 8-12 hours of charging.

If it were my battery pack, I'd put a 6V charger on the one @ 6.16V and 12V charger across the 2 @ 6.28V and charge until the on-charge voltage was above 8.0V, but no more than 8.4V and the hit the whole pack with a 36V charger when they dropped down to about 6.36V. And then run the whole pack through 3 or 4 recharge cycle without discharging them any between cycles.

Then let them rest for 12Hrs and measure the individual battery voltages.
Hopefully the spread between highest and lowest will narrow some.

Hope this helps.

[Hagar]

A good way to evaluate the state of charge of a Lead Acid battery is the Specific Gravity of the electrolyte. With a good Hydrometer the Specific Gravity of a fully charged battery should be between 1275 and 1300. This can be used to see if there is a low cell in a battery since each cell is checked or to identify which battery in a set is the problem. The chemical reaction that produces the electricity lowers the Specific Gravity of the acid in the cells. The electrolyte that is put into a new battery is sulphuric acid dilited with distilled water to 1300 Specific Gravity. Pure sulphuric acid has a specific gravity of 1800. On older batteries it is hard to bring the charge up. A long charge at rate of 2 AMPs may bring the charge up.

[buzzmanc]

Thanks for the input. I believe the charger is only 6 amps at 6 volts. I will try to charge it again to see if it holds. Good idea to charge the other 2 individually as well. I would like to get them all about the same if at all possible. Worst case I guess is buying one new one to get me throught till next year when I get the brand new 8 volts to put in.