Author Topic: Electronic load testing - Nickel Metal Hydride batteries - Energy storage  (Read 1112 times)

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Offline Transformedmaggot

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Hey everyone,

I recently found a way to recondition used cylindrical NiMH batteries pretty well (typically those used in the Honda Insight series). However, I want to know whether the batteries will hold practically in the real world outside the laboratory. My aim is to utilize these batteries as back-up storage for a house or maybe even put them back into the car. These batteries have a nominal voltage of 7.2 Volts and a rated capacity of 6.5 Ah (Though the reconditioned pack is obviously lesser than this value). To succeed in this, I'm aware that I need to test these batteries and mimic real world situations.

I purchased the Agilant N3301A/N3304 electronic load tester to help me do just that. The device can do a lot with various settings - CC discharge, CV discharge, constant resistance discharge, pulsed discharge, transient discharge etc etc. I'm completely new to this so my question is:
What tests should I typically run to mimic that of the battery being deployed in a hybrid vehicle? In addition to that, what tests should I perform to know whether these batteries can sustain being used as a back-up storage center for residential purposes? In other words, what are the key things to look out for during these tests.

All inputs on different tests to perform are hugely appreciated! I'm still an amateur at this, but I'm keen to learn and continue developing. Thanks for the time guys!






































































































































































































































































































































































































































































































































































































































































































































































































































































































































 

Online T3sl4co1l

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    • Seven Transistor Labs
Cat fall asleep?  :-DD

Anyway...

My understanding is you want to discharge them very slowly at first, to prevent reversing any low cells in the "stick".  As you cycle charge in and out, they will gradually equalize, and you can do so at higher and higher currents until it's back to a normal condition.

Do not discharge below one flat cell's worth below nominal voltage, because you're probably reversing cells at that point.  On the V(t) curve, zoomed out, you'll see the voltage drop suddenly, as each cell poops out.

I designed a couple tools for a Honda hybrid battery service company, a few years back; I'd have suggested talking to them, except you've already bought a pricey bit of test gear so I guess you won't be needing that right now. ;D

Tim
Seven Transistor Labs, LLC
Electronic design, from concept to prototype.
Bringing a project to life?  Send me a message!
 


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