auraslip wrote:I finally re-installed the temp sensor in my motor to find that it gets VERY HOT at what I would consider cruising speeds. At around 1kw it gets up to 95c!
P=I^2R. That's roughly the amount of heat you have to dump.
When you say ventilated, how is it ventilated? Do you have a picture?
Are you putting the motor under stress...like a lot of hills?
Is your wiring heavy enough to carry loads without getting hot?
Is there corrosion inside your hub?
Is the hot sun just plane shinning on your motor?
auraslip wrote:don't higher turn counts have lower resistance?
No. Resistance goes up as the square of the turn count (assuming equal fill factor). This is balanced by the increase in the torque constant and the fact that losses go up at the square of the current. So, you end up with the same amount of heat for a given torque.auraslip wrote: that doesn't make sense because don't higher turn counts have lower resistance?
veloman wrote:I really want to see some improvement in the way ebike motors handle hot weather, even at reasonable speeds. I'm not pumping multi kw into it at all. What a shame..... good thing most of my riding is only 15-30 minutes at a time.....
My controller gets pretty hot too. I can smell it when I bring it in the house, if I take a sniff right near it.
No load speed?
No load current?
Power consumption with mostly cruising at that 55% throttle?
John in CR wrote:In my previous post, the ambient temperature of concern is the air temp the motor sees, which I'm sure does vary quite considerably on a hot Texas day about a foot above the asphalt. A quick test for an overall system problem would be to get out and do the same ride just after sunrise. If it gets hot, then you've got a problem that needs to be addressed before any more far hotter daytime riding, though I'd first try some different speeds on that morning ride to see if faster is cooler. My latest big hubbie really loves to fly, and gets warmer with around town errand rides than it does at WOT up moderate grades.
I thought you already knew that a smaller wheel is better. What are you doing with that 26"?
When we got home, the motor casing was hotter than I had felt on any motor of mine, actually hot enough to hurt a little after a few seconds of holding my hand on it (hottest near the axle).
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