DC Electronic Loads

[tony3d]

Just wondering how useful Electronic loads are, and why are they so expensive?

[npnlamp]

I think they are for testing and calibrating devices, like ampmeter.

[olsenn]

Just wondering how useful Electronic loads are, and why are they so expensive?

Well, as with most things, depending on what sorts of projects you work on, they may not be useful at all. However, if you need to test a power supply (batteries, wall transformer, something you built, etc) then they can be quite useful. If you don't do this sort of thing frequently, then you can probably get away with buying a power resistor when you need it; however, if you want the flexibility of testing in CC/CR/CV/CP and/or would like a tool to automatically graph out the VI curves for you, then a DC electronic load can be quite useful indeed.

I bought mine (an Itech IT8511) from ebay a while back for only $400, so they're not all too expensive unless you need something really advanced or powerful (mine only sinks 150 watts).

[saturation]

Its main purpose, to add to olsenn's summary, is to characterize your power supply.  It its simplest form, imagine a rechargeable battery you use for a flashlight.  How long will it last under use?  Rather than use it and find out, you can model its behavior with the eload on your bench.  The Chinese have changed the pricing scheme because before that, most eloads sold were in very specialized applications and very high power handling capacity, and the limited market made them expensive.  If you have an aftermarket PSU you are going to apply to a device, you can easily test its rated specs.  You can find a discussion on the Maynuo, Itech, B&K, and Array in the archives.

For just battery applications, there is also this, made in USA and low cost:

http://www.westmountainradio.com/product_info.php?products_id=cba4

If you do such tests infrequently, you can use a good power resistor and a well ventilated spot, about $20 for 100 Watts.  I did so for many years, but after getting myself and wires physically burned by accident from making errors in my test set up by doing it once too many tmes, getting an eload saved me from aggravation, and injury, not to mention doing more tests under more conditions because it easier to set up and reconfigure.

[alm]

How about the Re:load kit for an inexpensive low-power load? Not as capable or polished (e.g. no case) as a commercial instruments, but only $20 shipped for the base model.