Replace batteries

[Duk Dog]

I think I know the answer to my quesion, just needing conformation. When I bought my cart a couple months ago I checked the battery codes and they all were 2007 battereis. When they are fully charged they read between 38.2 and 38.7 usually. When I am driving it the voltage goes down to 36.7. When i let up on the throttle it goes back up to the fully charges reading. I said all that to ask this - should i just go ahead and replace the batteries since they are 5 years old and I truely do not know how well they were taken care of?

As always thanks in advance for your wisdom!

[brad2388]

Well with the throttle pressed thats a loaded battery pack. You really cant tell from voltages from loading them other than a completely dead battery in the pack. How long does it last between charges is the key here. How long can you ride before the voltage goes below 40-50 percent charge level unloaded?

[Duk Dog]

I really do not know to be honest. I have only driven it for about 15 or 20 minutes tops testing the new controller, solenoid and cam switch.

[Nate]

You can drive until the pack reaches 33V under load, if this distance suits your needs then don't replace the pack.
Note: There is no reason to run the batteries to 33V before charging, keep them charged and keep doing what you've been doing, it seems to be working.

[Gonkulor]

Originally Posted by Nate

You can drive until the pack reaches 33V under load, if this distance suits your needs then don't replace the pack.
Note: There is no reason to run the batteries to 33V before charging, keep them charged and keep doing what you've been doing, it seems to be working.

I agree with Nate. Take what he said and keep it in mind but for now don't bother yourself with worry and just use the cart as you intend too.

[Gonkulor]

Originally Posted by brad2388

Well with the throttle pressed thats a loaded battery pack. You really cant tell from voltages from loading them other than a completely dead battery in the pack. How long does it last between charges is the key here. How long can you ride before the voltage goes below 40-50 percent charge level unloaded?

But you could use a load meter and test the individual batteries if you cared to. I have a 1 year old pack and it does the same thing.

[Duk Dog]

Thanks guys, I'll just keep trucking along for now and keep them charged!

[yurtle]

Your "under load" voltage is useful, but the load is unknown. Variables include tire diameter, incline/decline/flat, weights and number of passengers, etc. If you could measure individual batteries under the same load, that would tell you if you have on bad battery.

As long as you keep them fully charged, and watered, you'll have judge when they need replacement based on where you ride, and how hard it is to walk home and tow the buggy back.

I got nine years out of mine, but I was never more than several miles away from home, though on a busy weekend I probably put over ten miles between charges.

Again, depends on usage, but if you choose to keep them, monitor the "under load" voltage drop over time, and that should tell you when to head home and when to buy new batteries.

[JohnnieB]

Sounds like OP has a digital SoC meter.
If so, keep a State of Charge chart handy or make yourself an abbreviated one and paste on the dash, or someplace handy.

Let the batteries rest several minutes after they have been under load and the reading will match up to the chart pretty well.

You'll probably have to experiment with your own battery pack to find out how long it takes them to recover, but voltage on my pack stops climbing after about 10 minutes.

I don't want to discharge below 50%, so my plan is to head home when it gets to 75% (37.3V), but I've yet to reach that point on an outbound leg.

[Duk Dog]

That is a good idea Johnnie B, I'll track it and see what happens.