10w 220 ohm or 10w 470 ohm?

RNajarian · 08-10-2021, 08:57 AM

Cart is a series 48 volt, Albright SW200 solenoid, FSIP (Star) controller.

I ordered, received and installed an Albright SW200 (400 amp solenoid) with resistor and diode for my 48 volt cart last month from one of our site sponsors.

All went well, and the cart seems to drive much better than with my old SW180 (200 amp) solenoid.

I do have a concern.

The green 10w 470 ohm precharge resistor that came with the solenoid is HOT to the touch when the cart is turned off and parked. Voltage matches the pack voltage of 51 volts.

I replaced the 470 ohm resistor with my old 10w 220 resistor taken from the old 200 amp solenoid. This lower rated resistor does NOT even get warm when the cart is sitting and turned off, voltage across the solenoid terminals matches the battery pack.

Is it normal for the 470 ohm resistor to be that hot?

I have read here that the 220 ohm resistors should be used for 36 volt carts and 470 ohm resistors should be used in 48 volt carts.

It there an issue using the 220 ohm resistor on this 48 volt cart?

I tried PMing the sponsor but their mailbox was full.

One last thing. . .

Am I using the voltmeter correctly?
When I measure the voltage over the top of the solenoid I get a number that matches the cart voltage.

The voltmeter connected to the + side of the solenoid and then at the - on the controller also measures the same as the cart voltage . . .

BUT when I measure the voltage at the - on the controller and the other side of the solenoid I get 0 volts. Am I measuring the voltage correctly?

Thank You

Raffi Najarian

scottyb · 08-10-2021, 05:56 PM

I think I sent you this info in an email so I'm posting this here for the benefit of the carting community.

A hot precharge resistor is BIG red flag. The resistor should never be hot to touch. It is getting hot to touch because 2 things are wrong.
1. the controller is on
2. the throttle is calling for power.
This is a situation that is supposed to happen after the solenoid clicks. And then power is sent to the controller through the solenoid.
But if the controller is on and there is throttle input saying lets go the controller calls for power and the only pathway for the battery power is around the solenoid thru the precharge resistor.
Disconnect the solenoid from the batteries until you can solve this problem. If not disconnected the batteries will drain to damaging levels or worse something will go up in smoke or flames

RNajarian · 08-10-2021, 06:42 PM

Thanks for the reply, I didn’t see the email yet.

When I turn the key on I hear the distinctive CLICK and also when I turn the key off.

I installed a 10w 220 ohm resistor and it remains cool.

If there was a problem causing the 470 ohm resistor to get hot then it should also cause the 220 ohm to get hot too.

Thanks

WalterM6 · 08-10-2021, 07:17 PM

There is some sort of measuring error. A 220 ohm resistor should get hotter because of the lower resistance. Check the color code and make sure they are not swapped. The one with 2 red bands and a black is the 220. The 470 should start yellow violet black.

RNajarian · 08-10-2021, 10:17 PM

Quote:

Originally Posted by WalterM6

There is some sort of measuring error. A 220 ohm resistor should get hotter because of the lower resistance. Check the color code and make sure they are not swapped. The one with 2 red bands and a black is the 220. The 470 should start yellow violet black.

I am pretty sure there is no measuring error. Refer to the photos, you can see their respective ratings and Ohm measurements

RNajarian · 08-11-2021, 02:20 AM

Quote:

Originally Posted by WalterM6

There is some sort of measuring error. A 220 ohm resistor should get hotter because of the lower resistance. Check the color code and make sure they are not swapped. The one with 2 red bands and a black is the 220. The 470 should start yellow violet black.

I think I may have found something significant. This was under the heat shrink tubing of the 220 ohm resistor. . .

WalterM6 · 08-11-2021, 08:46 PM

That's the reason it isn't getting hot. That diode is blocking any current. Probably a regen diode like the ones that Alltrax adds on their contactors.

RNajarian · 08-12-2021, 12:58 AM

Yes you are correct. One mystery solved, the 220 ohm resistor had a diode blocking the current.

Now problem 2, why does the 470, ohm resistor get HOT? Motor/controller?

08-10-2021, 08:57 AM	#1
RNajarian Gone Wild Join Date: Aug 2020 Location: Los Angeles Posts: 269	10w 220 ohm or 10w 470 ohm? Cart is a series 48 volt, Albright SW200 solenoid, FSIP (Star) controller. I ordered, received and installed an Albright SW200 (400 amp solenoid) with resistor and diode for my 48 volt cart last month from one of our site sponsors. All went well, and the cart seems to drive much better than with my old SW180 (200 amp) solenoid. I do have a concern. The green 10w 470 ohm precharge resistor that came with the solenoid is HOT to the touch when the cart is turned off and parked. Voltage matches the pack voltage of 51 volts. I replaced the 470 ohm resistor with my old 10w 220 resistor taken from the old 200 amp solenoid. This lower rated resistor does NOT even get warm when the cart is sitting and turned off, voltage across the solenoid terminals matches the battery pack. Is it normal for the 470 ohm resistor to be that hot? I have read here that the 220 ohm resistors should be used for 36 volt carts and 470 ohm resistors should be used in 48 volt carts. It there an issue using the 220 ohm resistor on this 48 volt cart? I tried PMing the sponsor but their mailbox was full. One last thing. . . Am I using the voltmeter correctly? When I measure the voltage over the top of the solenoid I get a number that matches the cart voltage. The voltmeter connected to the + side of the solenoid and then at the - on the controller also measures the same as the cart voltage . . . BUT when I measure the voltage at the - on the controller and the other side of the solenoid I get 0 volts. Am I measuring the voltage correctly? Thank You Raffi Najarian

08-10-2021, 05:56 PM	#2
scottyb Happy Carting Join Date: Dec 2007 Location: Southern California Posts: 73,419	Re: 10w 220 ohm or 10w 470 ohm? I think I sent you this info in an email so I'm posting this here for the benefit of the carting community. A hot precharge resistor is BIG red flag. The resistor should never be hot to touch. It is getting hot to touch because 2 things are wrong. 1. the controller is on 2. the throttle is calling for power. This is a situation that is supposed to happen after the solenoid clicks. And then power is sent to the controller through the solenoid. But if the controller is on and there is throttle input saying lets go the controller calls for power and the only pathway for the battery power is around the solenoid thru the precharge resistor. Disconnect the solenoid from the batteries until you can solve this problem. If not disconnected the batteries will drain to damaging levels or worse something will go up in smoke or flames

08-10-2021, 06:42 PM	#3
RNajarian Gone Wild Join Date: Aug 2020 Location: Los Angeles Posts: 269	Re: 10w 220 ohm or 10w 470 ohm? Thanks for the reply, I didn’t see the email yet. When I turn the key on I hear the distinctive CLICK and also when I turn the key off. I installed a 10w 220 ohm resistor and it remains cool. If there was a problem causing the 470 ohm resistor to get hot then it should also cause the 220 ohm to get hot too. Thanks

08-10-2021, 07:17 PM	#4
WalterM6 Gone Wild Join Date: Apr 2017 Location: SE TN Posts: 2,227	Re: 10w 220 ohm or 10w 470 ohm? There is some sort of measuring error. A 220 ohm resistor should get hotter because of the lower resistance. Check the color code and make sure they are not swapped. The one with 2 red bands and a black is the 220. The 470 should start yellow violet black.

08-11-2021, 08:46 PM	#7
WalterM6 Gone Wild Join Date: Apr 2017 Location: SE TN Posts: 2,227	Re: 10w 220 ohm or 10w 470 ohm? That's the reason it isn't getting hot. That diode is blocking any current. Probably a regen diode like the ones that Alltrax adds on their contactors.

Today
BGW	Sponsored Links __________________ This advertising will not be shown in this way to registered members. Register your free account today and become a member on Buggies Gone Wild Golf Cart Forum

08-12-2021, 12:58 AM	#8
RNajarian Gone Wild Join Date: Aug 2020 Location: Los Angeles Posts: 269	Re: 10w 220 ohm or 10w 470 ohm? Yes you are correct. One mystery solved, the 220 ohm resistor had a diode blocking the current. Now problem 2, why does the 470, ohm resistor get HOT? Motor/controller?