rca=weird batteries

[Lynx_Arc]

I picked up some RCA maganese? batteries (the freebies with remote they sell) for under a nickle each at a closeout store figuring they would be fine for remotes etc. After about 6 months my remote started losing its mind so to speak I would reprogram it for tv/vcr and it was fine for a week. I thought maybe it was just the flakey remote after I took the batteries out and they measured 1.53v on my meter.

This got worse and each time the batteries measured good as far as volts. Finally one day I was fed up and slapped some nimh in the remote and... problems vanished. I recalled people doing flash amp tests using voltmeters and decided why not? of the 4 batteries I bought 3 measured .4A approx and one .02 I chuckled because that battery was never used. all batteries measured over 1.45v. I tried a new alkaline 6.7A, and my 550mah nimh 13.7 EEEK quickly disconnect the meter it is only a 10A scale.

Needless to say, these weird maganese batteries require a load or flash amp test to determine condition. Now I got to thinking about building a battery tester using a LED bar display to measure flash amp output and a seperate one to measure voltage.

 

[Doug Owen]

[ QUOTE ]
Lynx_Arc said:
Needless to say, these weird maganese batteries require a load or flash amp test to determine condition. Now I got to thinking about building a battery tester using a LED bar display to measure flash amp output and a seperate one to measure voltage.

[/ QUOTE ]

All you really need is a load on your voltmeter. Something that will draw (or try to) reasonable current from the cell under test. Say ten ohms or so (for a nominal 150 mA). Note the loaded and unloaded (with and without the resistor) voltages. A big difference points to large internal resistance and a 'used up' cell.

Otherwise the bar graph idea is cool. LM3914 will drive ten LEDs for you (in bar or dot mode) with 'almost no' other parts. Otherwise there are a bunch of quad (four) comparitor parts that will do four with a bit of work and a reference. Fun sort of project, of course, but a $3 DMM and a two cent resistor will probably do better with less trouble?

Doug Owen

 

[Lynx_Arc]

I got both the $3 harbor freight DMM and free resistors I yanked off circuit boards.

I guess I am somewhat of a perfectionist. My dad has a cheap radio shack battery tester but I want something more conclusive and easier to glance at and sort out batteries with. Something that could be made smaller than the standard analog meter battery tester perhaps with a variable resistor with marked off settings for battery types/voltages to cover all types from 1.5v watch batteries to 12v lead acid cells.

Perhaps make an adjustable jig to quickly test cells without having to fumble with leads and calculate resistors