Upgraded DS trouble-shooting - things got hot

[Tom47]

Originally Posted by Steveslf

Tom47, you wrote: "You should read full battery voltage before you press the pedal and 0 volts after you press the pedal.". I believe I experienced the reverse. Full voltage when the pedal is depressed. Is that an issue? I checked between the large solenoid posts.

The solenoid is like a switch. If a switch is open [off], you will read voltage across it. When it is closed [on], you will read 0 volts. it appears your solenoid is not closing when energized.

Like Scotty said, you could have a defective diode causing a feedback of some sort.

[scottyb]

Originally Posted by Tom47

The solenoid is like a switch. If a switch is open [off], you will read voltage across it. When it is closed [on], you will read 0 volts. it appears your solenoid is not closing when energized.

Like Scotty said, you could have a defective diode causing a feedback of some sort.

The solenoid is a make or break connection.
When the pedal is up the solenoid is open. There will be pack voltage on the battery side only when the pedal is up. This is constant (+).
When the pedal is down the solenoid clicks and closes making the connection internally between the 2 sides. When the solenoid clicks closed there will be pack voltage on both sides of the solenoid. (at both big posts). This is true for this system and any solenoid without a precharge resistor on it.

I thought I read he described the solenoid working correctly ... Have you been doing a lot of slow driving around? Can you collect a monitor file using the free Alltrax software and send it to me?

[Tom47]

Originally Posted by scottyb

When the solenoid clicks closed there will be pack voltage on both sides of the solenoid. (at both big posts). This is true for this system and any solenoid without a precharge resistor

This is exactly what you should read. However, unless you jack up the cart for safety and put your voltmeter across the two big solenoid terminals, you won't get a true picture of voltage loss or drop.

Putting the voltmeter leads across the two large terminals will show you 0 volts when the solenoid energizes and pack voltage when it de-energizes.

If you read anything above 0 volts, even 1 volt, when the solenoid is closed, the solenoid contacts are burned, pitted or just not closing. This can give you various volt readings and often still show 48 volts on each terminal to pack negative.

[Tom47]

Originally Posted by scottyb

I thought I read he described the solenoid working correctly ...

He said it was very hot. Probably a loose connection on the main lugs which would have burned the main contact or a loose connection on the coil terminals which would have caused the coil to overheat.

Either way, I really think the solenoid is defective now.

[Steveslf]

Scotty,

Thank you for the detailed procedure. I made it part of the way until I developed some questions as I was proceeding.

The cart, when on all 4 wheels, simply shudders and does not move at all in FWD or REV. When I put it up on stands, the rear passenger wheel spins but has a shudder every 7 seconds or so.
The initial results of the procedure are as follows:
I disconnected the diode from the from the solenoid and it ran the same with the intermittent shudder. I reinstalled the diode and found approx. 48V between the small posts when running. Should I have tested the voltage on the small posts while running without the diode?
I checked the voltage on the large posts but did not yet check continuity until I determine if I should remove all connections from the large posts prior to checking for continuity. There was full voltage across the two large posts when running.

One thing I did find strange, With the run/tow switch turned off and the key turned off, there was some (approx. 5V) voltage across the two large posts? Is this normal? The minimal testing I did perform caused the solenoid to heat up to warm to the touch.

For your other questions:
The standing voltage when the cart quit was approx. 50V
Under load (shuddering) the cart drops to about 49V.
I checked every connection on the cart and found no obvious loose connection.
The battery pack is a set of six new Precision 8V-170-HD batteries.

Question, should large post continuity be checked with empty posts? Once I have that answer, I can run through the rest of the diagnosis you provided.

Steve

[Steveslf]

To answer a previous question, I usually run at or near full throttle for about 20 minutes a day on mostly level streets. The cart ran pretty well with about 27 mph with 20" tires. The day of the breakdown, we were cruising at about half speed for approximately 15 minutes. I was aware of a possible motor heating issue with running at low speeds for an extended time. I checked the motor temp regularly until I was confident I was not heating it up much during my normal evening cruise.

[Lampworker]

FWIW my 2003 DS with Altrax 500 XCT and fsip speed motor was acting similar a couple months ago. It was my mzj-400 solenoid. Replaced it and have been good ever since. Cart would shudder in forward or reverse prior to replacing the solenoid.