Constant short circuiting of batteries to controller. SPARKZ
09-17-11, 12:28 PM
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Constant short circuiting of batteries to controller. SPARKZ
Hi everyone,
I'm working on my second ebike build. It's a 36 volt system, 500 watts. I have three SLA batteries rated at 12 volts, 17AH each wired in series, with positives going to negatives. I have an ebay bought conversion kit. The kit is rated at 36 volts, and again 500 watts. When I first installed the kit, the batteries were undercharged, and I didn't get any sparkz shorting out between the connector, which is a computer cable wired to a two slot connector into the controller. But, now, after fully recharging my batteries with a smart charger, every time I connect the computer cable, it shorts out, leaving carbon on the make end on the negative side, and melting rubber and plastic, and probably leaving carbon on the female side. The fuse which is a 30 amp fuse, is located on the negative cable. I used a multimeter to check the voltage of the total bank, and it's 38 volts.
What can I do to stop the shorting out of the cables? I thought at first it was a short circuit in the cable, but checking the cables show no such thing. I find it interesting that the short constantly happens at the computer cable attachment. The computer cable attachment is the same thing that you'd find in the back of your computer, a three prong connection. There's no ground wire on the system, and like I said, I didn't have this problem when the battery bank was under charged.
Is there a safety circuit I can construct to ensure the voltages are always at 36 volts, is it because the batteries show up as 38 and the system is 36, or am I missing something?
I'm working on my second ebike build. It's a 36 volt system, 500 watts. I have three SLA batteries rated at 12 volts, 17AH each wired in series, with positives going to negatives. I have an ebay bought conversion kit. The kit is rated at 36 volts, and again 500 watts. When I first installed the kit, the batteries were undercharged, and I didn't get any sparkz shorting out between the connector, which is a computer cable wired to a two slot connector into the controller. But, now, after fully recharging my batteries with a smart charger, every time I connect the computer cable, it shorts out, leaving carbon on the make end on the negative side, and melting rubber and plastic, and probably leaving carbon on the female side. The fuse which is a 30 amp fuse, is located on the negative cable. I used a multimeter to check the voltage of the total bank, and it's 38 volts.
What can I do to stop the shorting out of the cables? I thought at first it was a short circuit in the cable, but checking the cables show no such thing. I find it interesting that the short constantly happens at the computer cable attachment. The computer cable attachment is the same thing that you'd find in the back of your computer, a three prong connection. There's no ground wire on the system, and like I said, I didn't have this problem when the battery bank was under charged.
Is there a safety circuit I can construct to ensure the voltages are always at 36 volts, is it because the batteries show up as 38 and the system is 36, or am I missing something?
09-17-11, 09:45 PM
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Switched polarity?
Hmm... I'll try reversing the wires, but it seems to be wired the same way it was before. Still, would a reversed wired battery bank do that?
09-17-11, 10:56 PM
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Well... On the controller there is a red wire.. POSITIVE
There is a black wire.. NEGATIVE.
Make sure positive to positive and negative to negative, BY USING A VOLTMETER!!
NOT by just plugging in switching the wires or you WILL blow the controller!!!!
EDIT: P.S. THE FUSE IS USALLY (99.9% of the time) CONNECTED TO THE POSITIVE SIDE... You mentioned the fuse was on the "negative side"... Check AGAIN with the voltmeter!!!
There is a black wire.. NEGATIVE.
Make sure positive to positive and negative to negative, BY USING A VOLTMETER!!
NOT by just plugging in switching the wires or you WILL blow the controller!!!!
EDIT: P.S. THE FUSE IS USALLY (99.9% of the time) CONNECTED TO THE POSITIVE SIDE... You mentioned the fuse was on the "negative side"... Check AGAIN with the voltmeter!!!
Last edited by Sangesf; 09-17-11 at 11:00 PM.
10-18-11, 05:40 PM
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If you could take some digital photos of the unit and cables I bet that would help.
If you don't have a multimeter, you should be able to find a cheap autoranging multimeter for under $20 if you look around. I got one for $12 years ago and even though I have a better one now, I still use that one a lot just because its so small. Make sure it has voltage, resistance, with an audible continuity tester, and a low current measuring function (mA).. (but be careful measuring current because the cheap ones are not fused)
If you don't have a multimeter, you should be able to find a cheap autoranging multimeter for under $20 if you look around. I got one for $12 years ago and even though I have a better one now, I still use that one a lot just because its so small. Make sure it has voltage, resistance, with an audible continuity tester, and a low current measuring function (mA).. (but be careful measuring current because the cheap ones are not fused)
10-20-11, 02:24 PM
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It is important to distinguish between a " Short " and a " Spark " !
It is normal to get a small spark when you first plug in the battery to the controller, this is caused by the controller's components " capacitors " that go from 0v to battery voltage almost instantly, this makes an ark when the 2 metal contacts get close enough, higher voltages make bigger sparks !!
A short however, would instantly blow the fuse.. this can only happen if you close the loop between the + battery terminal and the - terminal without power limitting components in between ( like the controller ) .
When hooking up + from the battery to the red wire from the controller and the - of the battery to the black wire, does the motor function when you apply throttle ? if it does you dont have a problem..
DO NOT REVERSE THE WIRES TO THE CONTROLLER TO TEST IT... IF YOU GET THIS WRONG YOU JUST MIGHT(LIKELY WILL) BURN THE CONTROLLER UP..
It is normal to get a small spark when you first plug in the battery to the controller, this is caused by the controller's components " capacitors " that go from 0v to battery voltage almost instantly, this makes an ark when the 2 metal contacts get close enough, higher voltages make bigger sparks !!
A short however, would instantly blow the fuse.. this can only happen if you close the loop between the + battery terminal and the - terminal without power limitting components in between ( like the controller ) .
When hooking up + from the battery to the red wire from the controller and the - of the battery to the black wire, does the motor function when you apply throttle ? if it does you dont have a problem..
DO NOT REVERSE THE WIRES TO THE CONTROLLER TO TEST IT... IF YOU GET THIS WRONG YOU JUST MIGHT(LIKELY WILL) BURN THE CONTROLLER UP..
Last edited by Ypedal; 10-20-11 at 03:19 PM. Reason: typo's.
10-20-11, 03:18 PM
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Also..
I would highly recommend replacing those connectors with proper one's.. Anderson Powerpoles are my personal preference, but there are many others like Deans, Bullets, etc etc etc..
Using computer parts on an ebike is a recipe for disaster, someone will make a mistake one day and plug A into a wrong B and bam....
I would highly recommend replacing those connectors with proper one's.. Anderson Powerpoles are my personal preference, but there are many others like Deans, Bullets, etc etc etc..
Using computer parts on an ebike is a recipe for disaster, someone will make a mistake one day and plug A into a wrong B and bam....
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