Inquiring minds just want to know.

kgsc

Okay trying to help a friend diagnose a series cart that just died on him after smelling something electrical. Has Curtis 400 amp controller, HD solenoid, HD reversing contactor, 6 month old 4 gauge wires. Solenoids, main and contactor both click when the pedal is pushed and 37+ volts on both sides of the solenoid when clicked. All main wires are connected and snug/clean. Tried to talk him further through testing but he wasn't comfortable enough to do so.. Going to go up there this weekend armed with a used controller, motor, wiring diagrams and my Ipad to ask help from the experts if needed.

First this is to look for the pack voltage at M- and B- with the sol clicked.

Okay here is the question.. If I disconnect the low voltage wires going to the controller, activate the solenoid and touch B- to M- will the basically send the full pack voltage through the motor ? Yes it will probably arc pretty good but if the motor turns, my issue is the controller or ITS circuit.. I guess I also could remove the B- wire from the controller and get the B- from say 3 batteries so lower voltage..

Am I nuts to try this and is my logic correct ??

BGW

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JohnnieB

The tricky part might be the reversing contactor. If the contactor setup defaults to one direction with no power applied to any of the coils, it work, but if one of the solenoids has to be energized to select a direction, you'll have to pretty much leave the low current control wiring intact.

It depends on where the low current controls pick up B+, but you might be able to move the B+ cable to the main solenoid to a lower voltage while leaving the control wiring at 36V.

With the control circuit working on 36V, you should be able to just move the M- cable over and add it to the B- terminal. The bypasses the MOSFETs and when the pedal is pushed (main solenoid energizes), the motor gets hit with whatever voltage the B+ cable to the solenoid is connected to.

kgsc

Kinda what I was thinking. Leave the activation circuit alone except for the controller, disconnect the b+ main and move it to say 18 volts, connect b- to m- and hit the go pedal. Watch for sparks

benjylafond

I'm not the most electrically inclined guy on the forum, but have him check the fuse to the controller. I was having intermittent problems with my cart after doing every test on high current wires, connections, ITS, pedal box switch, etc. Even got my electrical engineer neighbor involved. We finally figured out the fuse that came with the Alltrax Controller had cracked (not where you can see the fuse connection, but where the metal is "wafered" together one of the layers had a crack in it you could only see by looking at the fuse from the side. Bought a new one and problem fixed.

kgsc

No fuses in this stock system. Got pack voltage on the solenoid and both sides when the go pedal is pushed. Also has voltage on the red wire powering the controller. So at this point it is the motor, controller or the ITS.. Will find out in the next few days..

JohnnieB

You said a 36V series drive with a 400A controller, so the attached schematic ought to be pretty close, except for the reversing contactor.

If the solenoid clicks, I'd check the voltage between B- and M-. Should be FULL pack voltage when pedal is pushed just far enough to make the solenoid click and zero volts when pedal is on floor.

The only thing between B- and M- is the MOSFETs and when they are at 0% duty cycle (pedal up), there should be no amps flowing through the motor and the rest of the high current circuit, so the entire pack voltage will be dropped across them.

With the pedal on the floor, the MOSFETs should be at 100% duty cycle and if the motor is drawing less than 400A (or whatever Amps the controller is rated for), there should be very little voltage dropped across them. (MOSFETs are not perfect conductors and typically drop about 0.1V per 100A of current flow, so if the controller was maxed out at 400A, you would see about 0.4V)

I'm not sure if it is correct for the cart you are working on since you never identified it , but the attached text is for a Curtis 1205 with ITS in a 36V system. The ITS voltages are very different than those for a 1206 series controller.

Attached Images

	36V 1205 schematic.JPG (84.9 KB, 0 views)
	1205 - ITS voltage.jpg (82.6 KB, 0 views)

kgsc

Oops, my bad. 2006 ezgo series, reversing contactor, 4 gauge wires, stock 400 amp long body Curtis, model number is underneath of course, stock motor. Talked with him last night some bending elbows he told me it would "catch" sometimes if the cart was rolling. I'm thinking motor brushes. Will check for continuity this am. That being said, if the motor is the issue I would not see voltage on B- and M- with the solenoid closed correct? Circuit not complete.

JohnnieB

Correct. However, if there is an open anywhere in the high current loop, you won't measure pack voltage between B- and M-.

I like using B- to M- because only the MOSFETs are between those two points. If you don get pack voltage when the solenoid first clicks, just trace the cables back toward the B+ terminal on the battery pack with your voltmeter until you find it and the problem is between the first place with pack voltage and the last place without it.

kgsc

Well, here is the outcome. Buddy pushed the cart and bam, took off no problem. Bad motor or brushes. Pulled motor and pieces fell out. Dropped in a newly rebuilt PQ bandit and off she went. 3+ miles later she died again. Dangit man. Checked voltage at solenoid and no dice. With resistor in place had pack voltage or close on both sides but when pedal pushed it dropped off. Dropped in a newsed solenoid and good to go. Hate we put the motor in but he said good with it because makes the cart faster lol...