# Netgain Classic Controller overheating



## Yabert (Feb 7, 2010)

It sad to learn than Netgain failed to design a good controller...
Well, if you are sure than the water is moving properly in the controller, I think there is nothing to do since water should extract the heat very quickly.


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## dougingraham (Jul 26, 2011)

Make certain that you are getting rid of the heat. Check the exit temp and inlet temp to the controller.

Increase the airflow through the radiator. Increase the coolant flow through the radiator. Make certain there is no bypass on the radiator. The normal radiator systems in cars have a bypass so they heat up quickly and give your heater something to work with. This is exactly not what you want for cooling this.

Assuming everything is working properly the controller cuts back the current to protect itself from overheating. If you managed to move the temp sensor away from the IGBT's all you would do is cause it to destroy itself rather quickly.

Take an ice chest and loop a bunch of tubing through it. Fill it with ice and water and run your coolant through that just before it goes into the controller. That might get you home.

Try using 3rd gear instead of 4th to reduce motor current. The power to the motor is the same but the controller might operate a little more efficiently at a lower motor current and higher motor voltage.


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## loopylupine (Jan 1, 2014)

Yabert said:


> It sad to learn than Netgain failed to design a good controller...


I guess I'm the last to learn...


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## loopylupine (Jan 1, 2014)

dougingraham said:


> Assuming everything is working properly the controller cuts back the current to protect itself from overheating. If you managed to move the temp sensor away from the IGBT's all you would do is cause it to destroy itself rather quickly.
> 
> Take an ice chest and loop a bunch of tubing through it. Fill it with ice and water and run your coolant through that just before it goes into the controller. That might get you home.
> 
> Try using 3rd gear instead of 4th to reduce motor current. The power to the motor is the same but the controller might operate a little more efficiently at a lower motor current and higher motor voltage.


Hi Doug, thanks for those ideas. I can make it home, just can't keep the speed limit unless I start the hill at 60mph (which is fun, but not always possible), so I don't need the ice chest. I'm using 3rd gear at about 3100 rpm for 45-50mph. From netgain manual: 
"From 131F (55C) to 185F (95C), maximum motor current will begin to reduce to zero (for example on a 1000A version controller, at 75C, maximum motor current would be 500A)." 
So, supposedly the controller only "begins" to cut power at 131F, up to 185F, but in my case, the controller restricts motor amps to 300 amps or less as soon as it hits 131, and the temp has never gone over 140. If it would just cut to 500 amps I would have no trouble. What temp would the IGBTs start to fry???


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