1999-2000 EZGO st 2+2 36 volt

[Pgriffith]

My brother gave me this golf cart and said he could never get it to go over 10 mph. I replaced the batteries and some wiring, got the motor redone by Plum Quick motors and still have no torque and it will only go about 12 mph. The only thing I haven’t done is change the speed controller. Any suggestions or advice on what I can do to increase the torque and speed?

[golfcartg]

Hi there and congrats on the hand me down cart! It sounds like you’ve already done a lot of the right things especially getting the motor redone by Plum Quick. However, there’s a good chance the speed and torque issues are potentially coming from the batteries themselves. Even though they’re new, it’s not uncommon to see performance issues if the battery pack isn’t putting out the full consistent power needed, especially under load.

Let’s start with the basics and dive into a few tests to get a clearer picture of your power output. First, grab a digital multimeter (DVM) and set it to measure DC voltage. You’ll want to use alligator clips to clip the multimeter onto the main pack positive and negative terminals so you can monitor the pack’s overall voltage while driving. To get a realistic reading, take the cart up a hill or run it at full throttle to put some strain on the system. A fully charged 36V pack, for example, should ideally hold around 38-40 volts under load. But if you see it dropping below 32-35 volts while climbing or accelerating, there’s a good chance the batteries aren’t holding up under demand, and that would directly limit both your speed and torque.

Next, we’ll test each battery individually. Connect the multimeter to each battery (again, using those alligator clips for a secure connection) and repeat the driving test. Each battery should ideally drop only slightly under load. If any battery dips significantly or reads notably lower than the others, it could be a weak link in your pack, and that would pull down the performance of the entire system. Use the attached chart for reference, you never want a resting voltage below 50% state of charge with lead acid batteries to avoid damage.

[Pgriffith]

Thank you for the info. I’ll try that and see what happens. The batteries are brand new. If the voltage does drop and there isn’t an issue with the batteries what else could it be?

[golfcartg]

If you're up for the challenge, we’ll continue running a series of tests with your DVM to track down exactly where the potential performance issue is rooted. This approach avoids the common pitfall of just swapping out parts randomly and hoping for a fix, allowing us instead to tackle the source of the problem head on.

[Pgriffith]

Checked all of the batteries individually and all were good. When going up an incline I still have no torque and voltage drops to 30-31.

[golfcartg]

It sounds like you've found the root of the issue! The voltage drop you’re seeing when climbing an incline suggests that your battery pack is running below its ideal state of charge. With a reading of 30-31 volts under load, your pack is dropping below 50% charge. When the pack’s state of charge falls too low, the batteries can’t supply enough consistent power to handle higher demands such as climbing or accelerating which results in the torque loss you’re experiencing.

To further diagnose the issue, I recommend taking photos, labeling and disconnecting your batteries and performing an individual load test on each battery using a load tester from harbor freight. This will help you assess their health and verify that each one is functioning properly. Once you have tested all the batteries, write down each voltage reading and post them here.

Each healthy 6V battery should maintain a voltage above 5.9 volts during a 10 second load test.

[Pgriffith]

I’ll do. Thanks