How to test batteries?

[littlejohn444]

Do I need to disconnect the leads from all the batteries?

It is a 36 volt system with 6 volt batteries. Do I need a tool other than a battery tester that can put a load on the battery and read the voltage?

If batteries test out what could cause the problem of being fully charged but the cart acts as if it has very little power? It will shudder a little taking off and then won't pull a hill.

[Kudaman]

It's recommended to disconnect the batteries and test individually for the most accurate testing. You will likely find that your batteries are toast. They will hold a surface charge that can give you a good reading on a gauge however the battery doesn't have any life left in it.

[JohnnieB]

A digital voltmeter that will read the battery voltage with two digits to the right of the decimal point is needed. IE: A fully charged 6V battery should read 6.37V about 12 hours after the charger shuts off.

It is true that the cables should be disconnected for absolute measurements, but the parasitic load of keeping the filter capacitors in the controller precharged is very slight compared to the AH capacity of the batteries and they are connected in series, so the same current is passing through them equally and meaningful measurements can be made while the cables are connected.

Automotive type battery testers don't accurately test golf cart batteries because golf cart batteries are different animals than car batteries. They can be used, but you have to understand the differences between SLI (Starting - Lights -Ignition) batteries and Deep-Cycle batteries to interpret the results.


To test cart batteries:
Place on charger and let them charge until charger turns off automatically.
Wait about 12 hours or drive cart about 10 minutes and then wait 15 minutes.
Measure Pack voltage and individual battery voltages.
The pack voltage should be 38.7V. The individual battery voltages should be 6.37V and all withing 0.1V of each other.

Drive cart for about five miles or until it becomes sluggish, wait 15 minutes and measure voltages again.
How much the at-rest voltage has dropped depends of battery age, but they should still be within 0.1V of each other.