95 medalist. cart shudders and jumps

[roughtruck]

I bought the cart from a friend. He was driving the cart around town and it stopped. Hit the gas and carts shudders and jumps forward but no real power or speed at all. I put it up on jack stands and hit the gas it jerks and jumps and somewhat goes. Maybe 3 mph tires in the air. Battery packs fully charged 38.3 v. Test each battery separate 6.3 v. I did a continuity test on motor and a1 to a2 0 and s1 to s2 was also 0. With tires in air dmm on a1 and a2 I show 0 v when soliniod clicks. Gas all the way down I get 10 v on a1 and a2. Wheels spin nice and free. I pulled diff cover off and took carrier out to make sure nothing mechanical broke. No stripped gears everything looks good. The b+ on controller has batt power all the time. So does my f/r switch. But soliniod does click. Any ideas or tests would be great I dont just want to start throwing parts at it. It is a series motor GE. Has lift kit with 22 inch tires.

[Sir Nuke]

seeing as how the solenoid clicks when you push on the "gas"..... you need to start looking at the High Current circuit. the on again off again power leads me to think that you have either a loose connection or contacts in the F&R.

here is a diagram with the high current circuit highlited.

[Sir Nuke]

oh and btw......



CONGRATS on your ride and Welcome to our happy little corner of the net, and to BGW. There is a BIG fridge on the back porch with anything you can think of in it...help yourself...of course only take what you can LEGALLY have. Make yourself at home on one of the big fluffy couches, kick your shoes off, put your feet up on one of the tables, yes we are allowed to do that, mom's, dad's, wive's, husband's, girlfriend's and boyfriend's here don't care....and take it easy.



oh...btw....every once in a while a food fight breaks out...so you may not want to wear nice clothes here.

Welcome!!

[roughtruck]

I took the f/r switch apart. I cleaned the contacts. They didnt look bad. How long will the controller hold power. I checked continuity on soliniod. Open when off 0 when clicks. But on b+ on controller I show 38 v with key off or on.

[JohnnieB]

Originally Posted by roughtruck

I took the f/r switch apart. I cleaned the contacts. They didnt look bad. How long will the controller hold power. I checked continuity on soliniod. Open when off 0 when clicks. But on b+ on controller I show 38 v with key off or on.

There are a bunch of filter capacitors in the controller that will hold power for quite a while, and there may be a 250 Ohm resistor connected between the solenoid's large terminals, which will apply power to the controller's B+ terminal when solenoid contacts are open.

In either case, it appears that power is getting to the controller, so the problem is somewhere between the B+ terminal on the controller and the main negative terminal on the battery pack.

Since you have the rear tires off the ground, connect your DVM between the controller's M- and B+ terminals.

You should get zero volts (or close to it) when the solenoid first clicks a the voltage should increase to full battery pack voltage as the pedal is pressed to floor.

If you don't, check the throttle input to the controller.

If you do, check for cables and connections getting hot.

If nothing is getting hot, check the motor brushes.

[roughtruck]

Cables do get hot. I will check m- and b+ tonight and post

[JohnnieB]

Originally Posted by roughtruck

Cables do get hot. I will check m- and b+ tonight and post

Any cable or connection that gets more than about 10°F above ambient air temperature needs to be fixed or replaced.

The high current cables on a 95 Medalist were 6Ga, which is minimal for stock height (18") tires. With 22" tires, you need at least 4Ga cables.

All 13 cables highlighted in Blue or Red in the schematic Sir Nuke posted above, need to be upgraded.

If there is the possibility you might install a 500A or larger controller at some later date, go with 2Ga.

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You may have more than one problem, but new cables will help the cart run better.

[scottyb]

The stock controller throttle signal should read 1.0v up and 2.7 down with the negative probe on the battery B- and the positive probe on or into the white wire.
Alltrax throttle signal should read 10v up and 6v down with the probes touching the white and black wires (any order).

Which controller does it have?

[roughtruck]

It has stock controller. It does have 4g wires on it. I didnt get a chance to work on it last night. I will ohm out the wires and check what reading at the controller and post what I get. Is there anyway to test the mottor. Other than a continuity acroos the posts.

[roughtruck]

Sorry been awhile since I have had time to work on cart. Since last time I have ohmed all cables and they are all good but replaced them anyway. Rechecked the f/r switch. When I ohm the motor (cables unhooked and motor out of cart) s1 to s2 I get 00.1 ohms a1 to a2 I get 00.1 ohms. Also both a1 to motor body 05.0 ohms and a2 to body 05.0 ohms