Cart slows to a stop on any incline

[JohnnieB]

Originally Posted by RAG

Test 1 volt meter attached to A1 & A2 (armature) and the motor:tires off the ground, pedal to the floor 36 volts forward and reverse. On the ground the carl was roll but 7 volts forward and back.
Test 2 volt meter attached to S1 & S2: tires of the ground .2 volts forward and back. On the ground moving slowly .5 forward and reverse

The Armature and Stator are in series, so when he voltage drop between A1&A2 is added to the voltage drop between S1&S2, you get the voltage applied to the motor and that appears to be 7.2V, which isn't enough to do much of anything.

You get 36V across the armature when the wheels are in the air, so the pot-box throttle and controller appear to be work, maybe not at 100%, but at least working fairly normally without much of a load.

So the question is why do you have 36V across the armature with tires are in the air (no load) and only 7v across the armature when tire are on the ground (normal load)

Possible answers:
1. Battery pack voltage is dropping to about 10V.
2. Excessive resistance the the high current cables, connection and/or contacts is dropping most of the battery pack's voltage.
3. Duty-cycle of PMW output from controller not reaching 100%.

[cgtech]

Best of luck...

[BBBHC]

What kind of batteries did you get? Not all lead acid batteries are created equal. Sounds to me like one of three issues to be the most likely culprit. However, I am not nearly as knowledgeable as those who are already helping you here.

1. Loose terminal connections, and/or multiple wires/cables on posts in wrong order (biggest should go on bottom, followed by smaller terminals). Assuming that the posts and terminal ends were cleaned when installing new batteries.

2. New batteries are not "broke-in" yet. I think this is highly unlikely, as you should still get much better performance than you are describing even with batteries that are not broke-in yet.

3. I feel this is the most likely. The batteries you got are either bad, or not rated for the type of use that a cart requires. What is the brand of your batteries and what are the specs?

[biphase]

Originally Posted by JohnnieB

The Armature and Stator are in series, so when he voltage drop between A1&A2 is added to the voltage drop between S1&S2, you get the voltage applied to the motor and that appears to be 7.2V, which isn't enough to do much of anything.

You get 36V across the armature when the wheels are in the air, so the pot-box throttle and controller appear to be work, maybe not at 100%, but at least working fairly normally without much of a load.

So the question is why do you have 36V across the armature with tires are in the air (no load) and only 7v across the armature when tire are on the ground (normal load)

Possible answers:
1. Battery pack voltage is dropping to about 10V.
2. Excessive resistance the the high current cables, connection and/or contacts is dropping most of the battery pack's voltage.
3. Duty-cycle of PMW output from controller not reaching 100%.

I suspect #3 "Duty-cycle of PMW output from controller not reaching 100%"

The Curtis 1204 series motor controller has a couple of common failure modes that cause it to go into current-limiting far below the rated current of 275 amps. Failure of the internal thermal sensor (thermistor) or a leaking 10 uf capacitor may cause the reduced current limit. The resulting symptom is very weak cart performance.

As a test, bypassing the controller should restore full power but this is a potentially hazardous test an should not be attempted by inexperienced personnel.

[bronsonj]

Originally Posted by RAG

The cart has not been used for about 4 years, and it started slowing down on the incline back then. Just put new batteries in this week and still have a have the same problem.
We tested last night:
Test 1 volt meter attached to A1 & A2 (armature) and the motor:tires off the ground, pedal to the floor 36 volts forward and reverse. On the ground the carl was roll but 7 volts forward and back.
Test 2 volt meter attached to S1 & S2: tires of the ground .2 volts forward and back. On the ground moving slowly .5 forward and reverse

Your charger may not be charging the batteries properly.

Check the full battery pack V without the cart doing anything. If it is 36.3v or less then the pack is dead and needs a charge. If it is 37.1v or higher, leave the voltmeter attached while you take a short ride and see what the pack V drops to.

There are several options as to what might be the cause and battery V is the easiest one to check

[Mooncarter]

RAG, let's try this: You have a DVM and I'm sure you know how to use it. You have new batteries, we all know this.

You have the best guys anywhere trying to help you. Some are engineers, some are really smart guys with years of experience. EZ-GO, Club Car, Yamaha, etc. would be proud to have them on their team.

Take your meter and test the standing voltage on each battery, and post the results here. Nobody can fully help until you do.