Experts!!!...Is it possible to make a reasonable cost battery load analyzer?

[bapgood]

Just throwing this out because the battery load analyzers that I have seen are very expensive and capabilities far exceed our needs.

I would love to make a reasonable cost DIY battery load analyzer, a cost efficient method to test our batteries and create those fancy graphs. I think something capable of 0-30a load would be about right.

While I can follow instructions and build things with the best of them, I lack the ability to design such a thing.

Any suggestions or insight would be great!!!

[CraigHB]

They're expensive because they do a lot.  Plus they're not something made in any big production quantity.  There's not a lot of people testing batteries at that level other than battery manufacturers and people hosting sites for battery reviews.

I get by myself with a load bank, a DMM, and a stopwatch.  If you're talking about a simple load bank, that's not a big deal, a sheet of aluminum and some high wattage wire wound resistors.  All I need are discharge curves and that's possible to get with that stuff.  For involved analysis like what you see on battery review sites, you need one of those proper analysers.

It would be possible to build one, but it would be a pretty involved project.  You need something that can do a good number of computations so it would have to run a fairly extensive program.  Though for sure it would be do-able and it would be a challenging and rewarding project, useful too.  You could start posting your own battery reviews and we all need more battery reviews.

[bapgood]

Thanks Craig!!!

The best I have come up with is the CBA from West Mountain Radio - http://www.westmountainradio.com/cba.php

I'm still doing research on it....so TBD

[SpeedoDevo]

Not sure you meant this, but here are 2 Arduino/MCU based battery capacity testers:
http://www.instructables.com/id/Rechargeable-Battery-Capacity-Tester/?ALLSTEPS
http://www.instructables.com/id/Arduino-True-Battery-Capacity-Tester-Li-IonNiMH/?ALLSTEPS

[CraigHB]

Those are testers, not analysers.  What an analyser needs to do is load a battery with a range of loads with tens of Amps and maintain a constant current (the higher the current load the unit can provide, the more expensive it is).  Then for each current level it needs to plot the discharge by taking data points at a number of samples per second. 

The resulting data set an analyser collects is a range of discharge curves.  It has to summate the area under each curve to find Watt-hours as well as Amp-hours.  It has to provide internal resistance data for the cells over the entire process.  There's a few more characteristics it needs to compute, but those are the main ones.  It's not an overly complicated program to write if building one yourself, but it's still rather involved.  You also need to build a load bank with an array of MOSFETs so it can dissipate a few hundred Watts.

You might check Hobbyking for an analyser that's not terribly expensive.  They seem to come through on specialty stuff like that for low prices.  It's not going to be what you see in a lab, but would be good enough for the level of data we typically need.  I wouldn't use one to publish specs on a battery review site, but just for personal reference it could be good.