Cooling for Battery charger in aluminium case

Thread Starter


Joined Sep 6, 2021
Hi Everyone,

I recently completed a self build high power ebike. It has a 72v battery and I bought an expensive Grin Cycle Satiator charger for it which is great ,and a couple of cheap chargers from ebay for charging at work or to take with me when I'm traveling.The cheap chargers are cooled by a fan which is quite noisy and annoying when it's going in the background when I'm at work so I was thinking of transferring the innards of the charger to a diecast aluminium box with some heat sink compound to help the heat dissipate. The cheap chargers are only 3amp and 72v and don't seem to get particularly hot.

Basically I was wondering if anyone has any advice on this? Whether people generally think it's a terrible idea and if not if anyone has any tips on how to apply the heat sink compound to maximise heat dissipation? I would imagine the transformer is the bit that produces the most heat so if I put some heat sink compound connecting that to the body of the diecast case would that be enough? Would it matter if the heat sink compound all over the PCB as long it was the type that doesn't conduct electricity?



Deleted member 115935

Joined Dec 31, 1969
heat sinks / thermal design

Three approaches,

a) experience / best guess

b) experiment

c) simulation

Suggest , that you experiment

Plenty of heat sinks on line,
including box's that are a heat sink, have fins on them.

May be get a thermal couple meter
then some heat sinks , and try

for most application a heat sink pad is more user friendly than grease.

Your needs are not over onerous,

Words to the wise.

A heat sink works best when black, but if its in the sun, it actually bakes the electronics,
so think where its to be used, may be put sun cover over if its a concern.

people do not like accidently touching metal over around 40 degrees.
so if its that hot , depending upon environment, which it self might be over 30 degrees it could be
you might want to again shield.

Think of direction , most heat sink system, even a rectangular box, work better in one orientation than another.

Have look at the CPU / computer market at passive heat sink solutions for examples.

Thread Starter


Joined Sep 6, 2021
Would replacing the cooling fan with a quieter one be a simpler and less costly solution?
The diecast aluminium boxes are quite cheap and it wouldn't require me removing the fan from the circuit board and soldering a new one on which I know from experience is hard to do without damaging other components if you don't have specialist soldering equipments. the aluminium boxes are also waterproof and less likely to get broken in transit and are much more compact (the current charger is mostly filled with the fan and empty space).

it'd be willing to risk breaking one of the chargers as an experiment (they only cost £40) but it'd be good to get a bit of guidance from anyone who has any background knowledge about these things.