Charger brick - active cooling mod

[Boogieman]

PROBLEM

l opened my 84V Gotway Tesla v1.2 charger as it was always feeling hot.

This is what i found:

1. Inside of lid had obvious "overheat signatures" 

2. Small Capacitors were too hot to touch (and 65°C one was bulging ever so slightly = had been close to pop), also the big choke was seriously hot. Also measured alu hestsink right by the ?mosfet?transistor?

NOTE! Meassuring temp of components was made with an "air probe" = add guess-timated 15-20°C to the values for surface temp, making capacitors around 80°C EXTERNALLY in an OPEN UNIT that do not trap the heat energy. How much accumulates over time, i dont know, but it will be higher temps in a closed charger NO DOUBT

Solution, MOD with active cooling

1. Draw around the active fan area and Drill as many 2mm holes inside that area as possible. Fan was placed right above the small caps and the choke to cool them the most (small 2mm holes because I dont want metal accidentally falling down as it could have if i would have made a large round hole). Make sure drillbit is SHARP (metal drill) or you will have melted plastic at hole entry&exit that is very hard to get rid of nicely (i know, i tried before changing drillbit)

2. Drill exhaust vents at the far end (by the ? transistors?mosfets? and small chokes) to direct airflow past all components including the big capacitors in the middle. I kept the output area a bit smaller than the input to have a slight over pressure inside.

 

3. Got a 5V 50mm fan (so it could be powered by a usb charger), cut an old usb cable and soldered + shrinked the package together.

4. Glued the fan with plastic based "sealant" (silicone would also work i guess) to make sure no air pressure/flow is lost in the "grooves" of the lid (air allways takes easiest way "out") and maximize pressure towards the small holes leading air inside.

5. Added a few cable holders + ties and there it is, working like a charm.

RESULT

Can feel the air blowing through all three exhausts, have yet to do a charge from low battery as the heat develops over time and then meassure exhaust temp. I do not think it will be very high as the heat was/is generated over a long time in a closed compartment (little jest energy per second, but a lot of energy in the long run) , so likely i will just feel a luke warm exhaust air, if even that, as the heat energy is removed instantly every time slice and is likely a lot less than what this simple convection cooling csn hsndle. A.k.a. it should be more than enough to kepp things chill :-)

 

 

Edited August 13, 2019 by Boogieman

[neurokinetik]

Instead of drilling all those small holes, you could use an appropriate-sized hole saw.  I'd also put a grille on the fan.

[Boogieman]

On 8/18/2019 at 6:53 PM, neurokinetik said:

Instead of drilling all those small holes, you could use an appropriate-sized hole saw.  I'd also put a grille on the fan.

Quoting my own words.

On 8/13/2019 at 4:44 PM, Boogieman said:

small 2mm holes because I dont want metal accidentally falling down as it could have if i would have made a large round hole

Fan grille point:

A fan filter and grille is ordered. The problem with filters are that the flow and pressure is affected A LOT. A filter on the WRONG SIDE of a fan can basically remove 80-90% of its efficeincy (worst case start pushing air the wrong way).

But i will try a filter (ordered) out to see how it works, but it seems from trials on this fan that it will sacrifice a lot of the flow and pressure. Tested by just keeping my hand close to the fan intake when spinning, you can feel air being directed the wrong way. (Have been studying this for some time when building my over pressured home cinema cabinet, to maximize pressure and minimize dust, in the end the filter had to be placed AFTER the fan and it made a huge difference vs having filter on "intake side". Best was no filter, but at least i lost a lot less flow and pressure by putting it after the fan...and keeping the amplifiers dust free...basically..by just allowing a small free output port vent.... thus keeping it pressurized. Fans controlled by a PC controller (stand alone unit) with a display so i can see exhaust temp at each cabinet secrion together with intake temp + fan speed for all 4 fans. Have dusted the cabinet once in a year (basically due to being lazy not sealing the glass doors properly msking it suck dust as air "passes by" the doors. The "big vent" by the door basically causes a low pressure zone (in my mind) allowing a tiny bit of dust to be sucked into the cabinet. Its not perfect but a lot better than monthly dusting :-) )

 

results on cooling.

Temp started at 20°C when starting the charge.

After about 10minutes of stabilizing the exhaust temp is at 28-30°C - meaning it removes quite a lot of energy and enough air flow to keep things cool.

The area that was hot before (60+ °C) is now basically at a lower temp than my body (~37°C) when touching it with my hands and feeling "cool".

The warmest area is now the "bottom" of the brick (solder side), that does not recieve a lot of air flow, but its still just luke warm (slightly above body temp 37°C) and there is no way solder will even start to melt at those temps. Meassured temp on "bottom of shell" is 32 when meassured with the air probe, adding 10°C would make 4e°C on the solder side = no problemo.

All in all it seems like a mission success.

)

Edited August 19, 2019 by Boogieman

[Boogieman]

Warmest area is right above the mosfet, still only 34°C

 

[ir_fuel]

Nice.

It would be perfect if you could somehow wire the fan power to the charger.

[Boogieman]

2 hours ago, ir_fuel said:

Nice.

It would be perfect if you could somehow wire the fan power to the charger.

That was my original idea, but my guts weren't there to insert a 5V DC down converter. Now the charger works exactly as from factory, only cooler :-) and should the 5V USB charger that drives the fan fail, its easy to replace (change usb charger and insert the usb cable). I could just put a 1 to 2 splitter in the outlet, should i need more outlets (for the non grounded jacks)

Was "too afraid" to impede charging power & cutoff amps (by adding extras) and thus risking blown Li-ion pack aka 🔥 / bomb

 

My next idea is to add an inline voltage / amp display right at the output cable though. But wanna make sure i dont sink the voltage too much by the load of that display device (or even worse, risk a short). Or i will wait untill the e+wheel charger can be delivered to Europe..or charge doctor starts delivering LOL

 

Fan grille that is coming in looks like this, very similar to the one i used in my home cinema cabinets. Easy to clean filter (snap off frame) and filter is fairly free flowing, but still catches most of the dust. I made some mods removing plastic that prevents flow as well, so with this small diameter i am sure i Will do the same for higher throughout

Edited August 19, 2019 by Boogieman

[Boogieman]

Fan has been in place with FILTER over one summer worth of riding (2020) now and this will be the first cleaning.

Filter sure took the brim of the dust and the fan baldes still look spotless. A few dust specks on the crossbars was all :-)

Cooling works good enough with the filter so o decided to keep it on. It roughly halves the air flow based on feel (wet rear side of a finger feeling how much air at exhaust cools the finger)