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Jon81SC 11-04-2021 06:03 PM

Opinion on these batteries’ voltage?
 
Bought 2016 Drive 48 volt AC in January. Trojan T875s are 6 years old. Charged them today and voltage readings are between 8.87 and 8.95. Location is in S. Jersey and cart will be stored outside. Likelihood of getting one more season out of them? Thank you in advance.

Volt_Ampere 11-04-2021 06:55 PM

Re: Opinion on these batteries’ voltage?
 
Voltage readings after charging don't mean much. You need to measure voltages under load to see how healthy they are. Six years is a long time for FLA batteries to last. If it's stored outside, you need to keep those batteries fully charged or they will freeze and be toast.

ThreeCW 11-04-2021 09:20 PM

Re: Opinion on these batteries’ voltage?
 
1 Attachment(s)
Attached is a State of Charge Chart for your reference. In order to get a accurate representation of the state of charge, you need to wait 12 to 24 hours for the voltage to stabilize after charging to measure an accurate voltage.

As Volt_Ampere states, since your batteries are getting old, it may be more representative to measure the voltage of the pack and also of each battery when it is under load (driving the cart up a hill provides a good load).

As the State of Charge Chart note on the bottom, a fully charged 48 volt pack should not drop below 42 volts when under load.

Jon81SC 11-05-2021 04:32 PM

Re: Opinion on these batteries’ voltage?
 
V_A & 3 CW - thank you for your interest. How are batteries tested under load as the cart is being driven?

And 3 CW - thank you for the tip to wait 14 - 24 hrs after charging. Did that & the voltage was exactly what it was before I charged them.

Also thank you for the chart - very educational!

Slooooowly learning about golf carts….

Volt_Ampere 11-05-2021 08:02 PM

Re: Opinion on these batteries’ voltage?
 
Hook up a voltmeter to the pack and drive the cart. See what the lowest voltage you see is as you accelerate hard.

ThreeCW 11-05-2021 09:55 PM

Re: Opinion on these batteries’ voltage?
 
3 Attachment(s)
I made up some long leads for my multimeter and used to them for load testing the batteries.

I load tested by driving the cart up a hill at a fairly aggressive speed (i.e. high load) and recorded the battery pack voltage under load and also the voltage of each battery under load.

I tried to have the load on the cart about the same for each test (same hill at approximately the same speed).

You can then compare the voltages to see if one (or more) of your batteries are failing under load ... any failing battery will have an excessive voltage drop compared to the others (and as outlined on the bottom of the State of Charge Chart).


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