# Kostov 11" Motor casing tempurature



## TTmartin (Feb 7, 2012)

Can anyone give me some guidance on what sort of motor case tempurature to expect.
I've recently finished my Audi TT conversion, Kostov 11" 192v, soliton1, 73 100 ah sinopoly cells. All seems good but I'm in the touchy feely stage at the moment. 
There is a snap switch in the motor which I have connected to a warning buzzer but I think this would likely only switch when it's nearly to late!
So I've fitted a temp meter with the probe fitted tightly into a bolt screwed into the hole where the lifting eyebolt was. 
After a 25 mile drive (varied sensible driving) ambient temp about 24C the motor case is reading 65C.
1, is this ok?
2, if it is, how hot is acceptable for longevity, not talking race track here.
I realize this would only be a guide for normal situations, as I guess a lot could happen in a motor before the heat transferred to the case.
I mainly ask because I have pretty much enclosed the engine compartment blocking front grill etc so not much air cooling going on from the car moving along, but there are gaps at each side of the engine bay for the motor fan to suck and blow. My understanding, is the motor fan should be capable of cooling the motor?
Any thoughts appreciated.


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## major (Apr 4, 2008)

It depends on the particular motor and duty cycle. But I recall doing rating tests on a well ventilated motor running continuously at load where the outside of the motor frame was 100ºC and the internal parts were within the Class H limits. But on a short time base overload, internal motor temperature could easily be excessive to the point of failure with the outside frame well below even 50ºC. The outer frame temperature is a poor indicator, but I would not be concerned with the level you're seeing if it is taking at least 20-30 minutes to reach that.

Of course, the cooler the motor the better. You should try to duct some clean cool air to the machine. But as for longevity, in a Class H machine, operation at 180ºC on the insulation should give you a half life of 20,000 hours. Cut that in half for every 10º above 180. But brushes will wear faster at elevated temperature so more frequent service would be needed. Try to keep it cooler but no need to worry about 65º after 25 miles


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## TTmartin (Feb 7, 2012)

major said:


> It depends on the particular motor and duty cycle. But I recall doing rating tests on a well ventilated motor running continuously at load where the outside of the motor frame was 100ºC and the internal parts were within the Class H limits. But on a short time base overload, internal motor temperature could easily be excessive to the point of failure with the outside frame well below even 50ºC. The outer frame temperature is a poor indicator, but I would not be concerned with the level you're seeing if it is taking at least 20-30 minutes to reach that.
> 
> Of course, the cooler the motor the better. You should try to duct some clean cool air to the machine. But as for longevity, in a Class H machine, operation at 180ºC on the insulation should give you a half life of 20,000 hours. Cut that in half for every 10º above 180. But brushes will wear faster at elevated temperature so more frequent service would be needed. Try to keep it cooler but no need to worry about 65º after 25 miles


Hi Major,
Helpful thankyou.
Actually at 30 minutes driving it's more like 50C, the longest drive so far was an hour and the motor case was reading 67C
I understand the motor case is not a good indication, I'm just trying to get to know the car and what to expect.
I've sealed the engine bay up to keep the weather out and for streamlining but I think as a compromise I will do as you suggest and create an air duct somewhere, don't want to screw up 2 years of my spare time
Thanks again


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## glaurung (Nov 11, 2009)

Hi, that is about same temperature my Kostov10" gets on my Range Rover.I have not had any problems with that. Well maybe some brush wear, but that could have something to do with the vehicle weight .
Harri


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## mora (Nov 11, 2009)

I disassembled my 9" Kostov when I replaced clutch. I put another temp sensor inside the motor and it is in contact with field windings. I believe this is better way to monitor temperature. I've also wired that snap switch to warning light but its operating temperature sounds too high. EV West had really small infrared temp monitors pointed at brushes and armature if I remember correctly. That's even better. I can drive the motor for one hours at its 1h rated load and windings stay below 70C. Case is less warm but still hot to touch. I'd say you are still within limits and doing good.


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## TTmartin (Feb 7, 2012)

mora said:


> I disassembled my 9" Kostov when I replaced clutch. I put another temp sensor inside the motor and it is in contact with field windings. I believe this is better way to monitor temperature. I've also wired that snap switch to warning light but its operating temperature sounds too high. EV West had really small infrared temp monitors pointed at brushes and armature if I remember correctly. That's even better. I can drive the motor for one hours at its 1h rated load and windings stay below 70C. Case is less warm but still hot to touch. I'd say you are still within limits and doing good.


Hi, 
All good helpful information, thankyou


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## ElectriCar (Jun 15, 2008)

Did either of you ever smell anything after these drives? I can't drive 10 minutes at 60mph without mine smelling when I exit the vehicle. I fear something is wrong. I have a Jabsco 150CFM blower using a 3" duct and it's still baking!


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