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Old 12-29-2011, 03:05 PM   #14 (permalink)
DJBecker
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Quote:
Originally Posted by MetroMPG View Post
Something like this, but with a higher amp draw:
Easy Test of Battery Amp-Hours Capacity
That's a good, practical approach! A more powerful inverter would be preferable if you are buying a new one, but even a smaller one will provide a useful load with auto-shutdown at low voltage. And an inverter is generally useful item to have have around.

We bought a Harbor Freight carbon pile battery tester and have found it to be a good general testing tool. It's not limited to battery testing, we use it to bench test controller designs and components. It was especially useful to find that we had bought two batches of IR MOSFETs that were dramatically under-spec -- probably Chinese counterfeits.

The down-side of a carbon pile tester is that it's not a stable load, and it accepts much more power for a brief test than it can dissipate over the long term. That makes it pretty much unsuitable for a capacity measurement that the inverter-based solution above excels at.

Last edited by DJBecker; 12-29-2011 at 10:17 PM..
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