12 v fridge controllers

[Waterworks178]

There is a problem in the world of 12 v fridges used in boats and vehicles, they are being dumped all over the place because the control units are too expensive to replace, these all use the Danfoss BD35 compressor, which has a three phase motor, im wondering if a simple no frills control PCB could be created for these and save them from landfill ?

This is the Danfoss PCB.

 

[Minder]

I assume they are P.M. field motors?
If so they could be BLDC rather than 3ph, each is virtually identical, just the commutation is different.
There are quite a few methods out there.
The type of commutation would need to be known, one clue would be the number of conductors to the motor.
Also the RPM of the motor/compressor.
The first preferred option would be to repair it.

 

[Bluejets]

control units are too expensive to replace

Reason being, the system that was introduced back in 1930's.
i.e. non-repairable items, chuck away, keeps the economy flowing.
Good luck trying to fix any of those boards.
Even if you can narrow down the offending device, chances are it is an oem product ...... i.e. not available or unrecognisable.
Then one has to get it off the board and new one installed without damage to the board itself.
Once again, good luck.

 

[Minder]

There is a problem in the world of 12 v fridges used in boats and vehicles, they are being dumped all over the place because the control units are too expensive to replace,

Maybe a market there to put one together, especially considering the extremely low price of board production out of China. !

 

[Waterworks178]

Maybe a market there to put one together, especially considering the extremely low price of board production out of China. !

I've seen copies of the control unit from China for about a third or less than the OEM one, but who knows if they work or not ?

 

[kellys_eye]

The probable reason for junking the freezers is that a failure in the drive board inevitably ruins one of the motors phase windings and replacement of the board alone won't fix the issue. A new compressor motor is also needed. You can only imagine the cost of parts and fitting........

 

[roughshawd]

I have to say this... just cuz...
I was told that the torque of a compressor motor is so high that it requires windings be such that there is no chance of overheat from resistance. That means that the coils are like 10 gauge wire or something. I don't know motor electrics(magnetics), and I have tried to make sense of them for years. I know why they turn, how it works, but I am missing the conditional driving forces behind them. I think they are called dynamics. But for the purpose of this post, the 3 pin motors used in in compressors can be quite confusing if you know one thing and are testing another, when there are three different types employed in any particular fridge. smilyes for all and don't test the wrong leads, It will ruin your meter!!