Stray Ground

Grinch · 01-25-2013, 07:39 PM

89 CC DS resistor (one solenoid) 36v series cart. I took out my 10A voltage reducer and put in a 30A (nice unit from BU!). To work on the cart I pulled the negative leads off the first battery (main 4g, white battery charger and ground to the power converter), the reverse positive and the positive off the last battery (including the lead to the converter). Once all the work was done I attached the positive, only the positive and found that that I had current running through the frame. Oddly it was only 30 volts. I then hooked up the negative and got 36v. I disconnected the voltage converter and still had the ground. I verified the converter did not have a grounded case. So here is what I am left with: Positive lead connected and the negative off the last post I get 30V on the frame. 36v on the frame with everything connected and 0 if I disconnect the first two batteries. Is it possible that somehow the first or second battery is grounding? I have never seen current with only one wire connected.

Grinch · 01-25-2013, 09:18 PM

Sorry if that was confusing. I'll try to be more clear. With everything hooked up I get 36v negative ground to the frame. If I remove everything from the negative terminal on the number six battery I get 30v negative to the frame. The batteries are a year old and there is very little visible corrosion or dirt. Any thoughts?

Grinch · 01-26-2013, 10:46 AM

Update. I isolated two problems. One, my fog lights grounded. The new voltage reducer shared a common in/ out ground. I disconnected the fog lights. While at it I pulled the batteries and cleaned them. I don't see any leaks and the terminal connections are good. Now I get 24v on the meter when I hook up the #1 batt (passenger side from) positive and frame to the negative. I decide to completely remove the new voltage converter and still get 24v with the electrical system set up the way it was when the cart was born. No lights, horn, radio, nothing but motor and charging circuit. I disconnect the charging circuit. Still 24v. I next check the cart to frame voltage one battery at a time starting with #1. 4v on the frame. Battery #2 positive to frame is 8v. #3 is 12v. You get the point. Each battery seems to be supplying 4v to my problem. Any ideas?

Offtwice · 01-26-2013, 10:56 AM

Strange

Volt_Ampere · 01-26-2013, 10:59 AM

Your meter with no real load will read a high resistance ground which you obviously have. Try putting a 1K resistor in parallel with your meter measurement and you won't see that voltage.

Grinch · 01-26-2013, 11:00 AM

Could you repeat that in a language I might understand? Are you saying his is normal? I can field physics questions but once we go beyond basic electrical, I'm lost. Thanks

Volt_Ampere · 01-26-2013, 11:16 AM

Your voltmeter does not put much of a load on the circuit you are measuring. Even when you think everything is isolated from the chassis, there will be some high resistance leakage to it. Your meter will measure the voltage in series with that high resistance. That is why you do not measure the full battery voltage until you connect a chassis ground. If you put a resistor in parallel with your meter (not a small one or you will fry it) you will see that the measured voltage drops significantly. Bottom line is that I wouldn't worry about it as long as your batteries are clean.

LJ12530 · 01-27-2013, 07:55 PM

Why is the neg battery terminal connected to the frame? I think the term "ground" causes some confusion. I believe Club Car has an isolated system in which the only connections should be between the + and - pack terminals. I'll call the - terminal "reference". I can see that if some loads were connected to the frame and some were connected to the reference you would get some strange readings.
Someone correct me if I'm wrong.

Grinch · 01-27-2013, 08:06 PM

The negative is not connected to the frame. That's just it, nothing is connected to the frame. But if I take a meter and put the red wire from it to the positive on the number one battery and the black wire from the meter on the frame, I get a reading of 24volts. From the pos number 1 to the neg number six batteries ( across the pack, is 38v). This tells me somehow some electricity is getting to the frame and so far Volt-Amp's answer seems to be the best.

Is there a possibility that it is coming from a short in the motor?

LJ12530 · 01-27-2013, 08:17 PM

Sorry...I misinterpreted your problem statement.

01-26-2013, 10:56 AM	#4
Offtwice Member 23082 Join Date: Mar 2010 Location: Spokane Washington Posts: 1,169	Re: Stray Ground Strange

01-26-2013, 10:59 AM	#5
Volt_Ampere Gone Wild Join Date: May 2012 Location: Rio Verde, Az Posts: 7,187	Re: Stray Ground Your meter with no real load will read a high resistance ground which you obviously have. Try putting a 1K resistor in parallel with your meter measurement and you won't see that voltage.

01-26-2013, 11:00 AM	#6
Grinch Getting Wild Join Date: Jan 2011 Location: Florida Posts: 117	Re: Stray Ground Could you repeat that in a language I might understand? Are you saying his is normal? I can field physics questions but once we go beyond basic electrical, I'm lost. Thanks Last edited by Grinch; 01-26-2013 at 11:07 AM.. Reason: Text

01-26-2013, 11:16 AM	#7
Volt_Ampere Gone Wild Join Date: May 2012 Location: Rio Verde, Az Posts: 7,187	Re: Stray Ground Your voltmeter does not put much of a load on the circuit you are measuring. Even when you think everything is isolated from the chassis, there will be some high resistance leakage to it. Your meter will measure the voltage in series with that high resistance. That is why you do not measure the full battery voltage until you connect a chassis ground. If you put a resistor in parallel with your meter (not a small one or you will fry it) you will see that the measured voltage drops significantly. Bottom line is that I wouldn't worry about it as long as your batteries are clean.

01-27-2013, 07:55 PM	#8
LJ12530 Gone Wild Join Date: Nov 2011 Posts: 174	Re: Stray Ground Why is the neg battery terminal connected to the frame? I think the term "ground" causes some confusion. I believe Club Car has an isolated system in which the only connections should be between the + and - pack terminals. I'll call the - terminal "reference". I can see that if some loads were connected to the frame and some were connected to the reference you would get some strange readings. Someone correct me if I'm wrong.
LJ12530 Gone Wild Join Date: Nov 2011 Posts: 174

01-25-2013, 07:39 PM	#1
Grinch Getting Wild Join Date: Jan 2011 Location: Florida Posts: 117	Stray Ground 89 CC DS resistor (one solenoid) 36v series cart. I took out my 10A voltage reducer and put in a 30A (nice unit from BU!). To work on the cart I pulled the negative leads off the first battery (main 4g, white battery charger and ground to the power converter), the reverse positive and the positive off the last battery (including the lead to the converter). Once all the work was done I attached the positive, only the positive and found that that I had current running through the frame. Oddly it was only 30 volts. I then hooked up the negative and got 36v. I disconnected the voltage converter and still had the ground. I verified the converter did not have a grounded case. So here is what I am left with: Positive lead connected and the negative off the last post I get 30V on the frame. 36v on the frame with everything connected and 0 if I disconnect the first two batteries. Is it possible that somehow the first or second battery is grounding? I have never seen current with only one wire connected.

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01-25-2013, 09:18 PM	#2
Grinch Getting Wild Join Date: Jan 2011 Location: Florida Posts: 117	Re: Stray Ground Sorry if that was confusing. I'll try to be more clear. With everything hooked up I get 36v negative ground to the frame. If I remove everything from the negative terminal on the number six battery I get 30v negative to the frame. The batteries are a year old and there is very little visible corrosion or dirt. Any thoughts?

01-26-2013, 10:46 AM	#3
Grinch Getting Wild Join Date: Jan 2011 Location: Florida Posts: 117	Re: Stray Ground Update. I isolated two problems. One, my fog lights grounded. The new voltage reducer shared a common in/ out ground. I disconnected the fog lights. While at it I pulled the batteries and cleaned them. I don't see any leaks and the terminal connections are good. Now I get 24v on the meter when I hook up the #1 batt (passenger side from) positive and frame to the negative. I decide to completely remove the new voltage converter and still get 24v with the electrical system set up the way it was when the cart was born. No lights, horn, radio, nothing but motor and charging circuit. I disconnect the charging circuit. Still 24v. I next check the cart to frame voltage one battery at a time starting with #1. 4v on the frame. Battery #2 positive to frame is 8v. #3 is 12v. You get the point. Each battery seems to be supplying 4v to my problem. Any ideas?

01-27-2013, 08:06 PM	#9
Grinch Getting Wild Join Date: Jan 2011 Location: Florida Posts: 117	Re: Stray Ground The negative is not connected to the frame. That's just it, nothing is connected to the frame. But if I take a meter and put the red wire from it to the positive on the number one battery and the black wire from the meter on the frame, I get a reading of 24volts. From the pos number 1 to the neg number six batteries ( across the pack, is 38v). This tells me somehow some electricity is getting to the frame and so far Volt-Amp's answer seems to be the best. Is there a possibility that it is coming from a short in the motor? Last edited by Grinch; 01-27-2013 at 08:06 PM.. Reason: Frog a word

01-27-2013, 08:17 PM	#10
LJ12530 Gone Wild Join Date: Nov 2011 Posts: 174	Re: Stray Ground Sorry...I misinterpreted your problem statement.
LJ12530 Gone Wild Join Date: Nov 2011 Posts: 174

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