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Discussion Starter · #1 · (Edited)
I'm still in the early stages of setting up everything electrically. I bought a kit from electricmotorsport.com that came with a Curtis 1238 and a GV200QA-1 contactor. My battery configuration is 96v, and this was specified when placing the order. The contactor is connected to pins 6 and 13.

After the precharge completes, I can hear the contactor click on, as expected. What I didn't expect was for it to hum, and I can feel a slight vibration. The hum is quiet, and I did ensure the lugs were tightened down real good. After about a full minute of being powered on, it gets very warm. Not uncomfortably hot to touch, but it was surprisingly hot while being on for such a short amount of time. It doesn't seem to matter if the motor was running or not.

Are these symptoms normal? If not, how can I go about mitigating it? I don't have a means to re-program the motor controller (or at least I don't think I do) and the warranty is likely expired by now since the parts were purchased about 2 years ago.
Everything else appears to operate normally.
 

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Contactors need full rated coil voltage to latch closed, but once the contacts are shut, a smaller current is enough to hold them in contact. The hum you hear is from the controller applying PWM to the coil to reduce the power being dumped into the coil. Without it, they will get very hot, like 90C. I have main contactors in my battery box that get alarmingly hot. They seem to be doing okay, but it will probably reduce their lifespan. I suspect yours are doing just fine.
 

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Discussion Starter · #3 ·
@OR-Carl Thanks for the info, definitely reassuring. Looking up the datasheet, it says 85C is the maximum operating temperature. Although I don't know if it'll get that hot, I think it's possible it could. I have some follow-up questions:
1. Does the motor controller's contactor output operate at the same voltage as the battery? Or does it step down the voltage at all? The manual doesn't really clarify this.
2. If the answer to 1 is yes, does the motor controller use PWM as a way to artificially lower the voltage to something safer?
3. If the answer to 2 is yes, would it be a bad idea to use a resistor to maybe lower the voltage close to around 60v? I know I don't want to drop the voltage too much lower than that, because otherwise the coil might not get enough voltage due to the PWM.
 

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I am not sure about your specific questions, but it does sound like the contactor you specified has a 48v coil, so it would have to be using the traction battery voltage. Honestly, I wouldnt mess with it. It might be worth revisiting if the contactor burns out and wont latch closed anymore.
 

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I'm still in the early stages of setting up everything electrically. I bought a kit from electricmotorsport.com that came with a Curtis 1238 and a GV200QA-1 contactor. My battery configuration is 96v, and this was specified when placing the order. The contactor is connected to pins 6 and 13.

After the precharge completes, I can hear the contactor click on, as expected. What I didn't expect was for it to hum, and I can feel a slight vibration. The hum is quiet, and I did ensure the lugs were tightened down real good. After about a full minute of being powered on, it gets very warm. Not uncomfortably hot to touch, but it was surprisingly hot while being on for such a short amount of time. It doesn't seem to matter if the motor was running or not.

Are these symptoms normal? If not, how can I go about mitigating it? I don't have a means to re-program the motor controller (or at least I don't think I do) and the warranty is likely expired by now since the parts were purchased about 2 years ago.
Everything else appears to operate normally.
The good news is the1238 has adjustable "pull in" and "hold voltage" for coils and its based on a percentage of battery voltage.

The bad news is its done through low frequency pulse width modulation ....so you can hear it.

The coils usually get about 30-50⁰C above ambient.

Everything appears normal.

The programmer is a Curtis 1313-4331 and it runs about $500, if you want to DIY tuning, just remember that the Curtis 1238 is probably the steepest learning curve but you can basically program the thing to run any motor and make it behave EXACTLY the way you want it to.

Its a great, easily customizable controller but you will do a "deep dive" into 3 phase motor theory and regenerative breaking by the time you get familiar with it.

If you are looking to build and learn ( with emphasis on "learn") I recommend getting the handset and the first thing you do is learn how to "save and restore" your current configuration.
 

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Discussion Starter · #6 ·
The good news is the1238 has adjustable "pull in" and "hold voltage" for coils and its based on a percentage of battery voltage.

The bad news is its done through low frequency pulse width modulation ....so you can hear it.

The coils usually get about 30-50⁰C above ambient.

Everything appears normal.
Great, thanks for the reassurance. Thankfully, it won't be in the cabin so I'm not likely to hear it. It should also be in a place where it can get sufficient ventilation, where it will hopefully get enough cooling.
The programmer is a Curtis 1313-4331 and it runs about $500, if you want to DIY tuning, just remember that the Curtis 1238 is probably the steepest learning curve but you can basically program the thing to run any motor and make it behave EXACTLY the way you want it to.

Its a great, easily customizable controller but you will do a "deep dive" into 3 phase motor theory and regenerative breaking by the time you get familiar with it.

If you are looking to build and learn ( with emphasis on "learn") I recommend getting the handset and the first thing you do is learn how to "save and restore" your current configuration.
Even though the tuning is probably the thing I'd be best at (I'm a hobbyist roboticist), this project is a lot of firsts for me so I'd rather not increase my chances of something going wrong. The car isn't going to be a daily driver so I'm not too concerned about the longevity of the parts, but I don't want them unexpectedly failing either. But, so long as everything is normal, that's all I care about.
 

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Great, thanks for the reassurance. Thankfully, it won't be in the cabin so I'm not likely to hear it. It should also be in a place where it can get sufficient ventilation, where it will hopefully get enough cooling.

Even though the tuning is probably the thing I'd be best at (I'm a hobbyist roboticist), this project is a lot of firsts for me so I'd rather not increase my chances of something going wrong. The car isn't going to be a daily driver so I'm not too concerned about the longevity of the parts, but I don't want them unexpectedly failing either. But, so long as everything is normal, that's all I care about.
I don't know if you want to have the reassurance of a failsafe. I don't use the contactors, but I use only
IMG_6766.JPG
a battery isolation switch. Put one of these around the contactor, in case it fails, and you are stranded. They don't cost a lot and can carry 500-1000A. I use them on my electric motorcycles for weight reasons also. You can get them from Amazon
 
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