2002 club car IQ 48v slows then stops briefly

[Dhnobles]

Hi everyone,
We just picked up a nice 2002 club car IQ 48v a couple of weeks ago. It's got new batteries in it but its had a little issue a couple of times now. After driving it around for a bit, probably 30+ min at maybe 5-8 mph with a couple of passengers the forward movement will start to slow and then basically stop. I can switch to reverse and it's fine but going back into fwd it will barely move. Both times it happened I let it sit for just a short time (maybe 2-3 mins) and then it went fwd just fine. They motor is warm but no so much that you can't touch it and leave your hand there for at least 10-15 seconds before it gets uncomfortable. I did notice that a part of the frame in the back of the battery compartment was pretty warm as well. I'm assuming that the regulator (or something like that) is mounted to the back side of the frame there and is a heat sink for said component. So any idea what might be going on? What can I check. I'm new to carts but am very adept with electronics.

Thanks in advance
Dan

[golfcartg]

Hi Dan, and welcome to the group! Thanks for all the details, they really help. It sounds like you’ve got a nice setup there, and while it’s great that your Club Car has fresh batteries, it’s actually a good idea to check them carefully. New batteries don’t always mean problem free, and even with new installations, there can be issues from slight manufacturing defects, inadequate initial charging, or simply loose or oxidized connections. All these factors can cause power loss over time, especially under load.

To start, let’s do a simple voltage test while the cart is under operation to see how the batteries are behaving when they’re asked to perform. You’ll need your multimeter set to measure DC voltage. Attach a set of alligator clips to the main positive and negative terminals of the battery pack (that’s the main pack positive and main pack negative). This will let you monitor the voltage hands free. While driving at a steady pace, keep an eye on the voltage readout. A fully charged 48V pack should show around 50-52 volts under load, but if the pack voltage consistently dips below 42-45 volts under load, that’s a sign the batteries may not be performing as they should.

After you finish your drive, check the resting voltage (after the cart has been off for about 10-15 minutes). It should ideally show above a 50% state of charge (roughly 48 volts). If it drops below that level, your batteries are nearing depletion already. Consistently running lead acid batteries below this threshold can shorten their lifespan as deep discharge cycles place a strain on battery chemistry leading to early failure.

If your batteries do not seem up to par, take a close look at the cable connections between batteries. Make sure they’re clean and tightly secured, as even slight resistance from a loose or corroded connection can limit power flow, especially when the cart is working hard. Next, move your alligator clips to each individual battery and monitor each battery under load while driving and compare it to the chart. We are looking for one bad battery bringing down the whole pack. If everything checks out here, we can explore other potential causes, but this will give you a solid baseline and might pinpoint the issue.