Battery/charger problems

[RLTexas]

First, thanks to everyone on this forum, especially Johnny and Scotty, for all the help. I took an old EZGO TXT from near death to mostly functioning thanks to all the help. Back again with another battery/charger issue. Relatively new batteries 2/17 on a cart that is used 1-2x/month. Some friends used the cart and drove it until it died (no longer friends!). Meter was down to 35v. So I have a POS 6 amp 12v charger that I used for 5 hours+ on each pair of batteries (36v). Got meter reading up to 37.1v. Plug in Powerwise charger, clicks on but after 1-2 minutes it shuts off. I tested plug, relay, diodes, etc. on charger and all seem to be ok. Maybe the batteries got too damaged? Water level is good, water is clear, I don't have a hydrolyzer. Tempted to jump the relay and see if I can get them charged a little more. At this point not sure I care if the cart burns up....

[ThreeCW]

35.0 volts is about a 20% state of charge ... which is pretty dead.

I suggest you record each individual battery voltage to see if one (or more) batteries have failed on you. A 6 volt battery with a shorted cell would drop about 2 volts for each shorted cell. In my experience, a shorted battery is not recoverable and when you attempt to charge it, it will not accept a charge.

[RLTexas]

Each battery tests 6.0-6.2 volts. From what I have read, I thought a pack at 37.1v would still work with charger but not sure.

[JohnnieB]

It only takes about 30V to turn on a PowerWise model 28115 charger and you said yours was turning on, but only charging for a few minutes, so the issue isn't turn on, it is premature turn off.

What turns off the charger is the on-charge voltage climbing into the 44V to 46V range, so either the control board is bad and shutting off at a lower voltage than it should, or the on-charge voltage is climbing up to about 45V a lot sooner than it ought to.

Plug charger into cart, but don't plug into AC power, take the top off the cart's charge receptacle so you can measure voltage at the receptacle ends of the black and white charge wires from the battery pack. (This is where the charger senses battery voltage.)

Bypass the relay so the charger doesn't shut off and plug into AC power while monitoring voltage at the charge receptacle with a DVM. It if climbs to ~45V rapidly (1-2 minutes), measure the individual battery voltages. One or more may be a lot higher than the others.

[RLTexas]

Thanks JohnnieB, if you have a link to the relay jump, please forward. I'm hoping that will work because I cant believe that batteries would be shot after only one deep discharge. And I'm pretty sure the 6 amp charger isn't doing too much....

[ardb]

following

[JohnnieB]

Originally Posted by RLTexas

1. Thanks JohnnieB, if you have a link to the relay jump, please forward.
2. I'm hoping that will work because I cant believe that batteries would be shot after only one deep discharge.
3. And I'm pretty sure the 6 amp charger isn't doing too much....

1. How to open charger is on pg-11 of attached manual and the images show what to do.

2. It depends on how deeply they were discharged. If they were dropped down to 1.5VPC (Volts per Cell) or lower, physical damage to the plates could have occurred.

3. The 12V-6A charger has already gotten the pack voltage up to the point at which the 36V PW charger will turn on, so it has done its job satisfactorily.

Bypassing the relay is only temporary modification to be used to troubleshoot and possibly give the batteries a good charge after their abuse.

If any of the batteries has a significantly higher On-Charge voltage than the others, stop charging and replace that battery or those batteries.

If the On-Charge voltage of all six batteries is within about 0.3V of each other, continuing charging until the battery pack's On-Charge voltage climbs up to about 48V. Then remove relay bypass, take cart for a ride and see if charger works normally when plugged into cart after ride.