# A quick Curtis wiring question



## 2fast4u (May 31, 2009)

Here is a diagram of what I was thinking...


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## kittydog42 (Sep 18, 2007)

It won't work that way, because it uses the accessory battery to give the signal to the KSI terminal. The input to the KSI terminal references the B- connection for the ground. Unless you ground your traction pack (not generally advised), you will need to apply anywhere from 12V to full pack voltage to that KSI terminal, from the traction pack. The best way to do this would be to leave it connected as it is, and instead of connecting the output from the pot box switch to the controller, connect it to a relay coil along with a frame ground. Then use that relay to switch 120V from the traction pack to that KSI input.


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## 2fast4u (May 31, 2009)

Thanks for the help. Makes more sense now and I think I got it. Here is another schematic if you don't mind taking a look at.


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## kittydog42 (Sep 18, 2007)

That looks good!


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## honn1002 (Nov 26, 2008)

2fast4u said:


> Thanks for the help. Makes more sense now and I think I got it. Here is another schematic if you don't mind taking a look at.


Hi you don't want to connect the DC-DC converter positive side on the controller's B+ bus bar. Because when the contactor is open the DC-DC tries to get power from the battery via the precharge resistor across the contactor. The precharge resistor would get overheated. It's better to connector the DC-DC positive side on the battery positive.


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## kittydog42 (Sep 18, 2007)

He doesn't show a precharge resistor, but if he did I think you would be right. All things being equal, I would connect the DC/DC positive to the contactor instead of the controller, unless it was really convenient to do it the other way. I guess that is more of a style rule, though, as electrically they are the same.


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## honn1002 (Nov 26, 2008)

kittydog42 said:


> He doesn't show a precharge resistor, but if he did I think you would be right. All things being equal, I would connect the DC/DC positive to the contactor instead of the controller, unless it was really convenient to do it the other way. I guess that is more of a style rule, though, as electrically they are the same.


Need a precharge resistor installed across the contactor to precharge the capacitor bank inside the controller. See new attached schematic. Check Curtis manaul online for the resistor size and value.


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## kittydog42 (Sep 18, 2007)

Curtis does recommend you use a precharge resistor in the installation manual, but many people have gone without. Many people also open and close the contactor with the pot box switch every time the pedal is depressed. There are many ways to build an EV. You should do some research on the subject and decide for yourself how best to proceed.


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## Twilly (Jan 22, 2008)

Wiring the DC/DC this way would leave it on all the time, draining your traction pack. I would use a much smaller relay to turn on the DC/DC with the KSI input


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## 2fast4u (May 31, 2009)

Going to my schematic, the idea was to not have a precharge resistor on the contactor. It only opens when the key is on and wont get many cycles on it. The dc/dc converter is wired so it only comes on when the key is 'on'. The curtis gets turned on and off by the foot switch.


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## honn1002 (Nov 26, 2008)

2fast4u said:


> Going to my schematic, the idea was to not have a precharge resistor on the contactor. It only opens when the key is on and wont get many cycles on it. The dc/dc converter is wired so it only comes on when the key is 'on'. The curtis gets turned on and off by the foot switch.


It looks like your DC-DC doesn't have a remote wire for turn on and off. If it does have a remote you can connect that to the KSI.


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