Battery Question

[jamoore]

I have a 2006 Yamaha G-22 48V I am fixing up to sell. I am trying to figure if the batteries are any good. They are 2018 Trojans that were basically dry and dead when I got the cart. I nursed them back to taking a charge. I am currently using a 48v low amp generic charger (previously used a real 48v charger but that got sold with another cart). Each time I put the cart on a charger for a few hours the batteries will hold a higher charge. I can get them to hold 49 to 50 volts. There has been no use of the cart in between charging. Today I took the cart around the block at pretty much wide open. (I cant do much road testing as they are not legal on streets here). Anyway, I had a simple LED battery gauge hooked up while running. Started with the batteries around 49 (can't remember exact #, yes I know this is not fully charged pack voltage). While riding, the gauge would drop down as low as 45 volts. As soon as I slowed or stopped the voltage would rise back up. Within a minute or two of stopping, the voltage is reading almost back to where I started at 48.8v. Is it normal for battery voltage to drop to 45 while running then climb back up after you stop? I am fairly new to carts. Want to sell this cart and want to be full disclosure to prospective buyer on battery condition. Should I charge the pack longer to see what it holds? I have been a little reluctant to leave it on charge for more than a few hours at a time as the charger is not automatic. As I stated earlier, they seems to hold a little higher each time I put them on the charger. Yes, I know this is the Club Car Forum but that is where the knowledge and activity is and I figured batteries are batteries no matter what cart they are in. As always, I appreciate the assistance and comments here. Joe

[Down South]

Is it normal for battery voltage to drop to 45 while running then climb back up after you stop?

Yes, the voltage will drop under load and climb back up after stop up to several minutes.
I can't help you with the battery condition. After being dry and dead surely didn't help them.
What I'd do is bring the pack up to full charge if you can and check the voltage of each battery after a 24 hour rest period. That will give you an idea of each batteries condition.

[jamoore]

Thanks down south. I was concerned with the drop but glad to hear that is normal. I will keep playing with them. Like I said, each time I put them on the charger for a few hours they hold a little higher charge. I will run the cart up the street a few times (hopefully without being caught) then charge them back up and see how they do. Shame the maintenance guys who used the cart didn't take better care. Nice set of expensive trojans got abused. fingers crossed.

[ThreeCW]

Originally Posted by jamoore

They are 2018 Trojans that were basically dry and dead when I got the cart. Joe

Dry and dead is a bad place to start from. A good set of batteries can last 5+ years if you follow proper charging practices and maintenance. They can also be toast after one year (or less) if proper charging and maintenance is not followed. With batteries that have been left "dead" for a long time (weeks or months), permanent sulfation sets in which can permanently reduce the capacity of your batteries.

Originally Posted by jamoore

I am currently using a 48v low amp generic charger (previously used a real 48v charger but that got sold with another cart). Each time I put the cart on a charger for a few hours the batteries will hold a higher charge. I can get them to hold 49 to 50 volts

A low amp charger will not give you the best chance to recover this battery pack. You are seeing some recovery but a higher amp charger would be increase your chances of "improving" these batteries. I would suggest that given the damage to these cell, you might be lucky to get them to 80%.

Originally Posted by jamoore

Within a minute or two of stopping, the voltage is reading almost back to where I started at 48.8v.

48.8 volts is only about a 58% state of charge. See the attached state of charge chart for more information.

Originally Posted by jamoore

Should I charge the pack longer to see what it holds? I have been a little reluctant to leave it on charge for more than a few hours at a time as the charger is not automatic.

Yes ... definitely charge the pack longer. As per the attached chart, you can safely charge this Trojan pack up to 65 volts finish charge (see attached Trojan information). It might take a few days with a low amp charger to get these cell to a more elevated charge. I suggest you connect your charger and monitor the pack voltage as you charge. As long as your are below 65 volts, then your pack will be safe. Also monitor your charger for overheating ... put it in a place that allows good cooling ... if heating too much, perhaps put a fan on it or let it cool down if necessary.

What charger are you using? I am not aware of any battery charger made in the last 40 years that does not monitor maximum voltage or voltage change with time and automatically shut down.