Is it normal for a resistor to be warm when not in use?

[RNajarian]

I was going over my cart tonight, checking water, cables etc when I noticed the resistor on my Alltrax Sw200 solenoid was warm.

The charge cycle was long finished and the Delta Q was in maintenance/monitoring mode.

Is this normal?

I took the cart out for a one mile ride then plugged it in and noticed the same resistor was hot.

Again is this normal? The cart seems to drive normally.

Thanks for your insight

[RNajarian]

Sorry correction: Albright Solenoid, not Alltrax.

I was thinking, since the precharge resistor puts voltage on the controller side of the solenoid when it's not energized, and it is directly connected to the +12v part of the circuit it may be normal for it to be warm when the cart is off, key out.

Is my reasoning correct here?

[RNajarian]

Some more info.

Voltmeter displays 51.0 Volts. At the solenoid top posts + terminal registers 50.8 volts and the other side registers 18.6 volts.

The precharge resistor is HOT.

Key is not in the cart. Is this a situation that my controller is going bad? Why is the precharge resistor getting so hot.

Charger in maintenance mode.

[sthreatt]

Disconnect charger and see if resistor cools ..... ???

[movin-on]

Something is drawing power through the resistor when the solenoid is open. Most likely the controller but a short in the motor can cause it also...Disconnect pack pos and neg..Take the 4 cables off the motor and make sure they are not touching anything...Connect the pack pos and neg cables back up...If the resistor still gets hot the controller is the problem..
You can also test the motor with the cables off..Put your meter on the continuity setting...A1 to A2 beep...F1 to F2 beep...All 4 terminals to the motor case.No beep..If that checks out the motor is good...

[RNajarian]

Prior to noticing the warm resistor I replaced two of the four cables going to the motor. Possible something is touching.

I unplugged the charger and 8 hours the resistor was still warm.

I may reconnect the resistor and remove one cable at a time to see which of the two newly installed cables is possibly shorting.

Also note: Last night the voltage on the far side was 18.6 volts. This morning it was 31.6 volts. Possibly there is a short.

[Fairtax4me]

Which side of the solenoid is the Battery Main positive side?
What controller do you have in the cart?

The charger does not charge Through the solenoid. So the resistor being warm has nothing to do with charging.
The resistor is for charging the capacitors in the controller, so if the controller has a bad/failing capacitor it may be drawing more current than normal.
If you switch it to Tow, does the resistor cool off?

[RNajarian]

Thanks everyone for your replies.

This is a series cart. No Tow/Run switch

The battery main positive side is towards the front of the cart. In the photo it is the furthest away..

I removed both of the motor cables I replaced and the resistor still gets warm.

Controller is a FSIP, the manual is attached

What should be the voltage over the solenoid? I’m getting different values.

Is this significant; with the resistor disconnected I get 50.7 volts over the solenoid terminals.

With it connected I get 30.9 volts.

[RNajarian]

I noticed something interesting.

I put the old resistor that came with my SW180 (200a) solenoid on and measured 49.9 volts

I removed the new resistor and took the voltage (no resistor):50 volts

I put the new resistor on the solenoid: 31.9 volts

With the old resistor on (the white rectangular one) it does not seem to heat up.

Could the problem be the new resistor? (I’ll check to see if it’s shorted internally)

EDIT: I put everything back together and drove the cart about 3/4 mile. When I got back the resistor was cool to the touch.

[RNajarian]

Here is some more info which may be helpful.

The measured resistance of the new (suspected shorted) resistor was 467 ohms (I need to try and decipher the writing on it to determine it’s ohm rating)

The measured resistance of the old (good) resistor was 220 ohms (one end of the resistor was removed from the circuit.). This was stamped 10 w 220 RJ. So I am assuming this one is operating within expected parameters.