Controller in same bag as battery?

grover

New Member
Region
USA
I'm new to electric bike DIY, and I have a question:
I plan on putting my controller in the same bag as my battery, separated by honeycomb insulation. I went for a test ride with this setup, on a cold day, and battery did not get warm, but controller got a little warm, not hot. My concern is when the temperature starts rising, will I have an issue? Is it a bad idea for a controller to be in a bag at all, or should it be mounted to frame for heat dissipation?
 

AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
I would say the answer depends on how hard you're pushing the controller's capacity. Clearly, the controller in the bag gets no air circulation, which it may need to perform to it's full rated capacity.
 

J.R.

Well-Known Member
I'm new to electric bike DIY, and I have a question:
I plan on putting my controller in the same bag as my battery, separated by honeycomb insulation. I went for a test ride with this setup, on a cold day, and battery did not get warm, but controller got a little warm, not hot. My concern is when the temperature starts rising, will I have an issue? Is it a bad idea for a controller to be in a bag at all, or should it be mounted to frame for heat dissipation?
I don't know if you're using a rack or triangle bag, but I have a friend using this bag for battery and controller for 7 years on a rack.


It has a separate compartment for the controller, there's little insulation, just heavy canvas. Really nice bag, very heavy duty. It just looks like any normal rack bag.
 

harryS

Well-Known Member
If this were your typical 1000-1500W kit, and if you will be pounding it at 20" mph this summer, I have seen reports on other forums where the wires have melted right at the bullet connectors when carried in a bag.

Monitor it when weather warms up. If controller gets too hot to touch, like 120F, better give it some air.
 

tomjasz

Well-Known Member
I've been running a 1000W MXUS DD Hub with 48V 20Ah 29E battery. The battery AND controller are in a nylon triangle frame bag. I was concerned at first but 5 years later, no problems!
 

EMGX

Well-Known Member
I just got back from a hilly 25 mile ride, last several miles mostly uphill and very steep in areas. The 11a/22a peak KT controller kept in a bag but not with the battery for my 48v 500w geared hub motor felt very hot. Temp of the controller checked with an infrared laser thermometer was 130 degrees F on one of the flat surfaces, less on the other surfaces. The motor itself was 84 degrees max reading on any surface. Outdoor temp in the 40s. No more bag for this controller.
 

grover

New Member
Region
USA
I just got back from a hilly 25 mile ride, last several miles mostly uphill and very steep in areas. The 11a/22a peak KT controller kept in a bag but not with the battery for my 48v 500w geared hub motor felt very hot. Temp of the controller checked with an infrared laser thermometer was 130 degrees F on one of the flat surfaces, less on the other surfaces. The motor itself was 84 degrees max reading on any surface. Outdoor temp in the 40s. No more bag for this controller.
Thanks for that info EMGX.
I might just make vents on the side of my bag. 41U-DaN7oJL._SY90_.jpg
 

AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
I just got back from a hilly 25 mile ride, last several miles mostly uphill and very steep in areas. The 11a/22a peak KT controller kept in a bag but not with the battery for my 48v 500w geared hub motor felt very hot. Temp of the controller checked with an infrared laser thermometer was 130 degrees F on one of the flat surfaces, less on the other surfaces. The motor itself was 84 degrees max reading on any surface. Outdoor temp in the 40s. No more bag for this controller.
That thermometer kinda puts an end to the guessing don't it! Good idea!

Safe bet things are even warmer inside the controller's case....
 

EMGX

Well-Known Member
I changed the controller location to a protected but very ventilated area under the rear rack, no longer in the controller bag. The hardest part of this install has been trying to tidy up the wiring and I think I have that done now, at least the best I can.

20210224_190813.jpg
 
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grover

New Member
Region
USA
Well..... I did some testing today. I don't have a fancy infrared thermometer, but used the old fashion way of "touching" it. I have 2 controllers from ebikeling that I used, one is in a larger aluminum casing, and one in about 75% of its size... not sure why 2 different sizes, maybe cause they were made in different years. They both are the same 22amp 36v/48v controller.
I went for a ride with each one in the bag, and did some hill climbing. The smaller one got pretty hot, and would imagine it was >120 degree, and the larger one was <100 degrees. I'm think the larger aluminum casing the heat was able to dissipate more. Anyways, I'm gonna mount my controller outside the bag, so I don't kill the controller, wires or the battery. Not that the controllers are that expensive, but the battery is my concern, and the cooler (not cold) I can keep the battery the better.
 

EMGX

Well-Known Member
Follow up:
I just got back from a 26 mile ride with the same long steep grades as when the controller got to over 130 degrees in the controller bag and same outdoor temp in the 40s. Controller mounted without the bag under the rack as shown in my post above it measured 83 degrees at the end of the ride. Only other change was that with the repositioned controller I could use shorter wires from the battery to the controller but I don't think that would have made a 50 degree difference, if anything at all. No more controllers in an enclosure for me.
 
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