Power Drain

[Wirenut]

I have a 1999 G19E Yamaha electric. Unlike one of you other subscribers, I do get power but it will all drain withing driving it about 200 yards. I then have to put the cart in tow mode for the batteries to build up. Then it will go a little. I took it to the dealer I bought it from and he did replace one battery which he said was bad. I then charge it for a day but when I drove it, I got the same results. At night when I tried the lights, the drain is clearly seen by the fact that the more I press the accelerator, the light clearly dim.

Any Ideas?

[golfcartg]

The key here is to start by ruling out the batteries. In an electric golf cart, the batteries are essentially the fuel source, just like gasoline for a car. They provide the power needed to drive the motor and run accessories like lights. If even one battery in the series is weak or failing, it can cause significant performance issues, such as the rapid power drain you’re experiencing. To effectively diagnose the problem, you'll need to perform an individual load test on each battery. This test will tell you if the batteries can hold a charge under a load, which is more telling than just checking the voltage.

To perform an individual load test, you'll need a load tester. After fully charging the batteries, let them rest for a few hours, then test each one separately while applying a load. This will simulate the demands placed on the batteries during actual use. If any battery fails to maintain a voltage under load, it needs to be replaced. Since your cart was still experiencing issues after one battery was replaced, it’s crucial to check all of them. If the batteries pass the load test, we can rule out a direct battery failure. More info on that here

Assuming all the batteries are good, the next step is to verify that all connections are clean, tight, and free of corrosion. Loose or corroded connections can cause high resistance, leading to poor performance and rapid power drain. Check the connections to the batteries, motor, and any associated wiring. Clean them with a wire brush if necessary, and make sure they are tight.

If the batteries and connections are in good condition, you might be dealing with a parasitic drain or a motor issue. A parasitic drain occurs when an electrical component like a voltage reducer or poorly wired lights or accessories continue to draw power even when the cart is off. This can quickly deplete the batteries. To check for this, you would disconnect the batteries and use a multimeter to measure any current draw from the system. Any significant current draw when the cart is supposed to be off indicates a parasitic drain that needs to be identified and fixed.

Finally, if there’s no parasitic drain, the issue might lie with the motor or motor controller. A failing motor can draw excessive current, especially under load, leading to rapid battery depletion. Symptoms like your lights dimming when you press the accelerator suggest that the motor might be drawing too much power. An inspection of the motor and controller would be the next step to ensure they are operating correctly.