The REALLY Heavy Load - 30A test load

[Benm]

The version pictured used slightly cheaper TO252 diodes, and they're only rated for 15A average. Another revision that's otherwise the same swapped those for the 30A TO263 diodes. I may swap for TO220 though, with neutral tabs that can be heatsinked.

That would be a very good idea. Most diodes will drop about 1 volt at 30 amps, giving a power rating of 30 watts a piece. Constructed on the board like pictured they will not be able to handle that. They might just desolder themselves, or otherwise overheat and get damaged.

Another thing to worry about are the actual PCB traces: with standard thickness copper they will delaminate quite easily at 30 amps unless really, really wide and solder covered. It might even be necessary to solder copper wire over the traces carrying the full current.

Power dissipation in a track goes with the square of the current you are pushing through it. Something at works at 10 amps has to be 9 times as wide at 30 amps. If you actually have done long term load tests at 30 amps my point is moot, but it doesnt look like it will actually take that for any length of time.

 

[Andrew124C41]

That would be a very good idea. Most diodes will drop about 1 volt at 30 amps, giving a power rating of 30 watts a piece. Constructed on the board like pictured they will not be able to handle that. They might just desolder themselves, or otherwise overheat and get damaged.

Another thing to worry about are the actual PCB traces: with standard thickness copper they will delaminate quite easily at 30 amps unless really, really wide and solder covered. It might even be necessary to solder copper wire over the traces carrying the full current.

Power dissipation in a track goes with the square of the current you are pushing through it. Something at works at 10 amps has to be 9 times as wide at 30 amps. If you actually have done long term load tests at 30 amps my point is moot, but it doesnt look like it will actually take that for any length of time.

@benm I have been looking to either purchase or make one of these in the hope that at some point I would actually need 30 amps :yh::yh:

There are a couple of surface mounts that I have seen. I wondered about the subject you are bringing up with respect to the trace.

One would think the best way to build this would not be using surface mount but rather hard wiring to decrease resistance.

Have you seen a really well made test load that will handle the load

 

[paul1598419]

Power dissipation in a track goes with the square of the current you are pushing through it. Something at works at 10 amps has to be 9 times as wide at 30 amps. If you actually have done long term load tests at 30 amps my point is moot, but it doesnt look like it will actually take that for any length of time.

Correct me if I'm wrong, but that is P=I^2 X R where R is the resistance of the trace.