Controller cooling

johneb

Pedelecer
Aug 3, 2013
88
3
After many months of other demands on my time, I'm finally back to installing my trike motor. I plan to mount the controller on an aluminum plate below the carrying rack (yes, there is enough clearance for suspension travel!). I intend to buy a small IP-rated enclosure to protect the bunch of connections, but wondered if it would be practical to acquire a larger enclosure to accommodate the controller, too. I had assumed that it needs airflow as it has heatsink-type fins, but as they are often located in bags, perhaps it would be OK? My setup is a Q128 201 rpm motor in a 20" wheel running at 48v, with a KT36 controller. It will be largely used on the flat/gentle inclines, but will need to do a lot of the work (dodgy legs!) and will occasionally tackle more demanding hills.
 

vfr400

Esteemed Pedelecer
Jun 12, 2011
9,822
3,985
Basildon
it depends on how much current you want to use. A 14 amp controller can sit in a bag or other enclosure without any ventilation, so can a 20A one if you never use level 5. It also depends on your motor's maximum speed. Fast motors will draw the maximum current for more time than a slow one.
 
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johneb

Pedelecer
Aug 3, 2013
88
3
Thanks vfr. The Q128 is nominally rated at 201 rpm, although I believe 260 rpm is the actual maximum, and possibly higher, I guess, as I'm using 48v for a 36v motor. Until I have the rig up and running, I don't know how much I'll use level 5. I anticipate that it will rarely be needed as it's quite a powerful motor in a small wheel, so hopefully even the steeper climbs won't stretch it too much. Otherwise, I'm happy to trundle along at 10-15 mph.
 

vfr400

Esteemed Pedelecer
Jun 12, 2011
9,822
3,985
Basildon
I'm pretty sure that the 201 rpm 36v Q128c is actually 260 rpm and it's identical to the 48v 328 rpm Q128C, i.e. they're the same motor.
 
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Nealh

Esteemed Pedelecer
Aug 7, 2014
19,991
8,173
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West Sx RH
My 20a controller in a bag got very hot and thermally cut a few times on a ride, using high PAS level climbing doesn't help and heat builds up.
The extra ali plate it will be fixed to will act as an extra heat sink if controller is in direct contact and if this is tight against the frame then the bike will act as heat sink as well.
 
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