1999 ezgo Series ???

[busman9]

We have a 1999 series cart,lifted with 23 in tires. It still has the curtis 1206 controller which I know is a weak link on a lifted cart but it has been doing well. Now over night the batteries seem to get weak very quickly. I have charged and let sit,38.4V,metered the batteries while driving and they drop to 5.8V and then climb back to 6.2V while still driving. I would like to test the controller and maybe the motor brushes to see if there is a lack of power to the motor. Please advise THANKS

[Sideways]

I'm no expert by any means but it sounds more like a single battery or two are going bad and bringing the entire pack down.
Test each battery individually.

[busman9]

I have tested each battery:
#1 6.4 at rest 5.92 under a load
#2 6.38 at rest 5.82 under a load
#3 6.38 at rest 5.80 under load
#4 6.38 at rest 5.82 under load
#5 6.4 at rest 5.84 under load
#6 6.37 at rest 5.80 under load

[orangeman6]

Not an expert either, but I agree. Those batteries can no longer handle the initial draw of getting those big tires moving.

[handtools]

I'm no expert either but according to Scotty's SOC chart they seem ok to me. How old are the batteries?

CartsUnlimitedStateofChargeChart.png

[orangeman6]

I know I’ve read those guys say a drop in the pack equal to one battery is where it’s very bad, but the op has 23” (wonder what pressure?) tires on a 36v cart. Some of the batteries are dropping to 20% then going back up once he’s got momentum.

[busman9]

Batteries are 3 years old. Always charged with a DPI charger. Tires have 10 psi. I am thinking of checking them with a VAT40 tester? Good tester for car batteries but not sure for golf cart batteries

[orangeman6]

10 psi? And probably an aggressive tread pattern, right? Thats a big ask for that cart with fresh batteries.

Still curious what the experts say but I have a pretty good idea what they’re going to tell you. Those batteries might still do ok in a stock cart, but they just don’t have enough in them anymore to do what you’re asking them to do. They’re also going to tell you to upgrade the controller but you already mentioned that.

Is anything getting hot? Motor, cables, f/r? Controller? Anything in the high amp delivery system?

[Sideways]

Busman, when your checking the batteries at rest is this after sitting 12hrs once a full charge cycle is completed?

Another thought is the DPI charger's mode setting is not correct for your batteries.

[busman9]

The battery readings where 18 hours after a full charge.I am wondering if I can load test each battery with a VAT40,not sure since it is a deep cycle battery. Wish Johnnie would chime in