High Battery Voltage?

[bobbycason]

What does a 6 volt battery reading 11.XX volts mean? I have one of them doing this and the others are showing 6.XX volts while it was on the charger. I'm going to get more readings in the morning before I leave for work.

It's a 95 Medalist 36v series cart and when I bought the cart the batteries barely had a charge on them, it had been sitting up due to a bad controller. I upgraded the FNR switch, SR48500 controller, and 400a solenoid through ScottieB. I'm hoping I can make them last through the holidays and eventually upgrade to 48v.

[orangeman6]

That reading was while it was on the charger, or after the charger shut off?

[bobbycason]

That was while it was on the charger. I went out last night before bed and the charger was off and got the following readings.

total charge 39.55 (11:00pm)

1) 6.56 6) 6.62
2) 6.56 5) 6.63
3) 6.57 4) 6.61

This morning when I took readings it was:

Total charge 35.07 (5:00am)

1) 6.11 6) 6.21
2) 4.11 5) 6.21
3) 6.17 4) 6.19

Battery #2 was also the battery reading 11.xx volts while on the charger last night.

The batteries are 3 year old US batteries (2200XC) that were almost completely drained when I got the cart.

[Dan33Klein]

Unfortunately your batteries are shot..

[yurtle]

Concur. What you saw while on charge was Battery #2 had the greatest voltage drop, because it's the deadest. In other words, it needed the most voltage to be happy. All are shot.

[bobbycason]

That's what I figured unfortunately :(

Would it be possible that #2 is draining the other 5 and would they still be usable for the time being if I bought another one just to replace #2?

I'm wanting to upgrade to 48v after the holidays so I'd rather not buy a whole six pack of 6v batteries and just wait until I can buy the 8v batteries and charger.

[yurtle]

You can buy a used battery, about the same age as the rest, but how they all perform will depend on what you expect them to do. If you are going to drive very short distances of mainly flat pavement, you may last a few months. However, we don't know the condition of the other five batteries. While they are over 6 volts at rest, they may drop significantly under load.

If you absolutely have to drive it, I'd remove the two worst ones, and place a car battery in the series. Connect a digital multimeter (DMM) on each battery, one at a time, and see what they read while driving, assuming it even moves. If it looks like it may work, don't kill your car battery playing. This is just a poor-man's way of load testing the four.

The abuse of leaving batteries discharged, even for a shorter time than those have seen, results in permanent crippling damage.

[bobbycason]

The cart is completely torn down right now and the batteries are sitting on a piece of plywood under my carport, I hooked them back up like they were after taking them out to try and keep the charger on them. I'm trying to get it ready for a Halloween camping trip. Other than camping the cart will just be used by the kids mostly riding around the yard.

It did move on it's own at one point, after I put the new controller in I drove it around the yard a few times but it was shortly after that I started taking it apart.

[yurtle]

Then I'd try and price a used battery. Forget about the car battery.

[Volt_Ampere]

The one that was reading high voltage under charge is going to make the entire pack sag under load because it has very high internal resistance. You need a whole new set of batteries anyway.