DC load bank

[k7elp60]

I am presently rebuilding a DC load bank that I designed and built a number of years ago. At present it is used to test DC powersupplys and discharge rechargeable batterys with a constant current. The attached schematic is the current design. What I got to thinking about was to put a pelter junction in series with the darlington transistor that is used as a constant current load. For extended periods the heatsink gets quite warm. My thoughts are with a pelter junction set for cooling it would offset some of the heat caused by the existing transistor.
Your thoughts please
Ned

 

[mneary]

The Peltier device would just get warm. Total power dissipation (and temperature) would be set by the circuit and wouldn't change. Transistor might be cooler but the Peltier would be hot.

A fan is a much better control of the temperature.

 

[dknguyen]

I would build the transistor separately as a module-type thing on wires and dunk the sucker in a cup of water (that would work, right?)

WHen you use a peltier you still need to remove the heat from the hot side- either by using liquid cooling, or by sticking a heatsink and fan on the hot side of the peltier. Peltiers only move heat- they don't get rid of it, you need something else for that.

 

[ericgibbs]

I would build the transistor separately as a module-type thing on wires and dunk the sucker in a cup of water (that would work, right?)

hi,
Water would enable anodic/cathodic damage of the power transistors and wiring.

You could also use mineral oil, as used in power transformers, high insulation and high thermal conductivity.

As dknguyen says, 'dunk the sucker' in a finned metal container holding the mineral oil.

 

[k7elp60]

Thank you all for you comments, much appreciated. The heatsink presently can be cooled with a fan, so thats what I will do.
As a side note, I have one of those portable coolers that uses a peltier junction for cooling and it does have a fan to exhaust the heat.

 

[crutschow]

The one advantage of using a peltier cooler would be that it could keep the transistor cooler than the heatsink for better reliabiliy, or allow the use of a smaller heatsink. The heatsink would still get hot of course.

 

[smarttouchsolution]

pls provide me dc load bank circuit from which i can draw 350A current easily. Actually i need to discharge 48v/3000Ah battery with 10% load(i.e 300amp).

 

[alec_t]

It's not polite to hijack someone else's thread, Smarttouchsolution.

 

[4pyros]

pls provide me dc load bank circuit from which i can draw 350A current easily. Actually i need to discharge 48v/3000Ah battery with 10% load(i.e 300amp).

Start your own thread. This one is to old and for reference.