Cooling of ecu and other electronics 1

[MBGraham]

On our 98 Mercedes E320 (*and other Mercedes of similar era) The ECU, transmission control unit and other electronic modules are housed under the hood in what they call an apparatus case. It is a closed compartment. At the very bottom under the other electronics and wiring, there is a small blower. It draws air from the interior of the car and blows into the case (not sure where it leaves). This blower is powered off the same relay as the ECU and the starter. The blower is rated for a 4000hr life. I have had 2 fail in 250k km. Seems like a poor system seeing not all cars have working A/C and cool cabin temperatures.

My question, is - How do other manufacturers cool their electronics? Have any come up with anything better than a blower/fan? How about a Peltier cooler? I will have to repair mine before long but would like to install something better. My A/C doesn't work and cabin may be warmer that ambient air!

 

[BrianPetersen]

Most are passive. Sometimes the controllers are within the passenger compartment. VW likes putting those below the base of the windshield in the same compartment where the windshield-wiper linkage lives and where the HVAC blower draws in outside air. My current car (Fiat) has the body control module attached to the instrument panel (within the passenger compartment) and the powertrain control module under the hood but without any active cooling. My motorcycles all have the ECU either under the rider's seat, or up front near the instrument cluster. None have active cooling.

 

[MBGraham]

Having been built in 1998, our car was an early adopter of complex electronic controls. A little later models used a more reliable brushless blower for the electronics box. Unfortunately it won't physically fit in the 98 model. I believe other manufacturers like BMW use similar cooling systems.

I came across this article - It describes some of the challenges in cooling electronics in modern cars:

https://www.electronics-cooling.com/2010/04/electronics-cooling-in-the-automotive-environment/

For now, I have a wireless temperature readout in the car with sensor in the apparatus box. With ambient temperature at 38F, the box got to 60F after a 40 min drive. Cabin temperature was 70F. It will be interesting to see how high box gets as summer approaches.

Meanwhile looking for alternative methods of providing cooling!

 

[CWB1]

The vast majority that I have encountered from light duty to large stationary ECMs were all passively cooled simply by limiting other nearby heat sources, and that's going back well into the 80s.

 

[MBGraham]

No doubt car back in 80s were like that. I even have a '72 with a large passively cooled ECU. These days they could probably get the whole thing on a chip Maybe more simple later cars have passive cooling too? But cars like Mercedes, BMW, Range Rover, Volvo and no doubt many others have fan/blower cooling. Most owners probably don't know they have them. At least not until modules start overheating and cause other problems.

 

[TugboatEng]

Are you experiencing failures of the ECU's or just the blowers? If the ECM's haven't been failing after blower failures perhaps you can just let things be. Those years are some of the better ones for Mercedes and I don't recall ECM failures being an issue.

 

[MBGraham]

Tugboat - You are on a lot of forum threads

Re failures.

Some years ago, first time I found a failed apparatus case blower, I was experiencing transmission problems and some CE lights. These cars have a problem whereby transmission fluid wicks up the electrical wiring all the way from the transmission to the module in the apparatus case. In correcting that problem, I had to disconnect the blower. I tested it and found that it no longer worked. May or may not have been related to the problems I was addressing.

After new motor was installed in blower, it worked fine until about a month ago. Then it became noisy. Not long after that, the car cut out completely while driving and had to be towed home. It would not start! After checking just about everything under sun, I decided to swap in a spare K40 fuse/relay module (relay on it provides power to the blower as well as ECU). I did not plug in the blower. The car started! Wiring to blower shows open circuit, so may not be related to the no-start problem. In cool climates, MB suggests disconnecting blower for some cars. But here in Canada, in summer it can be quite warm. That is why for now, I will just monitor the case temperature and avoid long trips (we have other cars)

Reason for post here, was not to solve the blower problem (I have a spare), but just to determine if any cars use cooling methods other than passive or fan/blowers. Perhaps thermo-electric like Peltier? Changing the blower is a real PIA for this car.

 

[MBGraham]

One idea that came to mind, is to simply duct air from intake into the apparatus box. (it would flow out into the cabin) The air would need to be filtered and water separated. Perhaps the car intake filter already does that? Temperature would be ambient. But same as cabin temperature considering a/c does not function.

Easy enough mod, so may do a temporary trial if I see temperatures in box getting too high.

 

[EdStainless]

All passive that I have seen, though some do use heat pipes to enhance cooling.
A duct from the cabin sounds like a good idea, but you don't want holes in the firewall (for obvious reasons).

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