How hot do controllers get?

[FeralDog]

How HOT do these controllers get?
I have a controller: says it is 36volt, Limited current 22A , low voltage protect 31.5V .
For brush-less motor 500W-750W: 63V marked on the internal caps.

I note the the controller case is an aluminum finned "heat sink" design.
I was wondering---
#1) If I could use a simple gun metal 'bluing" to stain my controller from silver color to black.
#2) If I mount the controller in an area where it will not get much of a road breeze, will it fry?
Anyone measured the temperature of their controller at various loads, and ambient conditions?

 

[AussieJester]

Castle Control HV110 48v 110amp of mine strangely doesn't even get the least bit warm after a caning :-|

KiM

 

[DeanElectric]

Hi there,

It depends upon the efficiency of the controller, the thermal conductivity of the heatsink, the climate that the controller is running in etc. I would average the efficiency of a MOSFET-based controller to be around 85-95%. So, if you were running at the full-rated power of 750Watts, that would mean approximately 15% (100% theoretical efficiency - 85% actual effeciency) of that power being lost to thermal dissipation of the MOSFET's, so 112.5Watts. Of course, that is the worse case scenario of an 85% effeciency, it is unlikely therefore that your controller will get too hot, and I would give an educated guess that at any one time the controller will be emitting approximately 15-25W of thermal disipation from the MOSFET's. So, the answer to your question would be, the controller is likely to heat up to around 60 Deg C in a temperate climate, obviously less in free-air.

So-not hot

 

[Lyen]

Can you take a picture of your controller so we can tell exactly what you can and cannot do with it?

 

[biohazardman]

Depends on the amperage, load, percent of grade on the road, heat of day, day of the week ect. My GM 36 and 48V controllers were in boxes and panniers and got good and warm in the summer but I would not quite call it hot and they did OK ectept for the regen thing. These were stock controllers with stock motors and not running up the sides of mountains. Controller on the current bike is under the seat and out in the open cuz there was not room in the bag. You could put it where you want it and keep a close watch on it for a while as I did. You can move it into the airflow if needed.

 

[dogman dan]

I've had a brushed controller overheat a few times in summer. 105F, tailwind that makes the flow over the controller less, and nearly zero humidity all combining to defeat the cooling fins on the controller. I have to agree that in normal use, 700 watts or so, not climbing steep long hills, a controller should only get warm. So far, my experience climbing big hills with 20 amp controllers is that the motor overheats first.

But it's pretty well known that the electronics wear out faster if hot compared to warm, so mounting a controller in a place that gets some breeze is a good idea. I usually mount to the front of whatever contains a battery on a rear rack. In use, my ass is an umbrella for it, but it catches breeze as I ride.

Of course in a rainy climate the whole thing is different since waterproofing gets to be most important. I've seen some cool builds where a box with leak proof vents let the controller be inside, yet get ventilation. Adding more heat sink to the controllers housing should also work if the controller needs to be in a box or bag.

Painting or bluing your controller should be no problem. It may radiate best raw, but it will still be able to shed plenty of heat painted.

 

[TMaster]

I measured the temps a few days ago after going almost 9 miles giving it all it had, and my controller surface temp of the aluminum next to where the mosfets was 38C. The mosfets I have; max temp before it burns out or shuts down is 175C, so thats not hot at all in comparison. I'm guessing it was prolly 10C warmer inside the controller though, Id have to put a probe in there, but I'm not going to waste my time haha! I was runing 20-40amps depending. It was only 19C outside temp (65F). My motor was 72-78C on the inside from what I can remember, but I will check it again next time.

 

[ZOMGVTEK]

15 FET stock Golden Motor controller, running 48V of SLA at 60A, and it barely gets warm. When its warm to hot outside allready, and im being as destructive as possible, the motor gets quite warm, the controller is just barely warm.

 

[velowatt]

I used to keep controller (35A brushed "36V" but running 48V) in a bag with batts and switches, no air flow. I never worried about the heat sink until one summer day (about 85 degrees, not that hot) when I was rummaging in the bag for my lunch, I grabbed the controller and it was HOT! Never noted that before or since. I eventually got a 48V 10Ah Headway pack and have it mounted in an "Octivia" box on the rear rack of may recumbent. I use a DC converter to power lights at night, and had an extra cooling fan from an old PC power supply laying around, so I cut a vent hole and mounted the fan so that air is drawn into the box and over the controller heat sink (flows over battery and BMS and drilled some 'exit' holes in the bottom for air to flow out). Everything runs cool. Prbably totally unnecessary, but it satisfies my inner 'geek'.