NiMh Charge Indicator?

zmoz

Enlightened
Joined
Feb 28, 2003
Messages
605
Location
Oregon
Does anybody have any thoughts on how I might make a charge indicator for NiMh batteries inside of a mag? I'm thinking a line of LEDs somewhere...but how would I make this work?
 

Ferrous

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Joined
Mar 17, 2003
Messages
62
Location
B\'ham WA
NiMH and NiCd are hard to gauge without coulometry. I'd suggest keeping it to three ranges, just like a gimmick gauge in one of my flashlights. A "window comparitor" with it's threshholds around 1.25 and 1.15V should give you an idea of your batteries' condition. Keep in mind that every aspect of reality will work against you. Good luck.
 

Illuminated

Enlightened
Joined
Oct 26, 2002
Messages
886
Location
Tipp City, Ohio
Check out National Semiconductor's LM3914 dot/bar display driver.

You could make a simple 10-step voltmeter (hint: you don't have to use 10 LED's) with whatever upper and lower limits you want. It's a largish chip, but you can do a lot with it. Add a momentary button and it can become a "discharge" indicator, also.

John
 
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