Good info, thanks. I'll stick with case temp for now--it's a lot easier anyway.
I'm going to put indoor/outdoor temp sensor on each side of the motor case, to see how the natural air cooling works for reducing the temp. These are rated to 158 deg F., and aren't that expensive, if I blow them out. Since it's started the rainy season up here in Seattle, the rain will help to cool it too. :) Mark >-- Original Message -- >From: "Chuck Hursch" <[EMAIL PROTECTED]> >To: <[EMAIL PROTECTED]> >Subject: Re: How much power am I losing? >Date: Wed, 2 Oct 2002 14:35:14 -0700 >Reply-To: [EMAIL PROTECTED] > > >Mark Dodrill wrote: > >> I'm pretty sure I'm pushing the thermal limits of the motor as >it is. I >> live in an area with lots of hills, so even keeping the motor >speed up to >> keep the cooling fan working well isn't enough. >> >> Perhaps someone can tell me what temp levels are okay, and what >is too >> high--case temp, and brush temp is about all I can measure >given how the >> motor is installed. > >When I asked Otmar about sensing motor temperatures, I found out >that unless you have a dragster (such as I have a lo-perf 96V >street car), the case temperature is the way to go, and a lot >less complex than trying to measure brush temperatures. Otmar >indicated a case temperature of 150-degF is as high as the motor >should go. The ADC 8" motor, and probably the 6.7" motor as >well, has an open threaded hole in the case. We went to the VW >shop, purchased a water temperature coolant sensor, replaced the >thermistor in the sensor with a different one from Allied >Electronics, and last but not least machined up a little brass >adapter to fit the VW sensor into the ADC hole. We then hooked >this up to the Rabbit's stock temperature gauge wires. We had to >make an addition, though, that I wasn't planning on, which was to >add 15.4 ohms of resistance to the circuit, as the current in the >temp gauge circuit was apparently overpowering the thermistor. >So now I have a temp gauge reading just at the bottom of the red >band when the case temperature hits about 150-degF. > >If your motor gets real hot, like you can't hold your hand on it, >you need to get something done about it (fan)! There is probably >an internal switch in the motor that you can use to turn on a >light on the dash, but I don't know what temp this triggers, but >it's most likely signifiicantly above 150-degF. > >Chuck Hursch >Larkspur, CA >www.geocities.com/nbeaa > Mark Dodrill
