Small Battery Tester - 9V, AA, etc.

[dishdude]

I ran into an issue using my DVM to test batteries. I had a 9V putting out over 9V, but when a load was placed on it, it fell flat on it's face and couldn't power the device it was in. I had another 9V putting out 8V and it worked just fine. This is making me question the AA batteries I was testing that were doing the same thing. Will something like this load test the battery and be more accurate? Just looking for 9V, AA and AAA. https://www.homedepot.com/p/Commercial-Electric-Electric-Battery-Tester-MS602H/202353291

 

[zzyzzx]

I have seen VM's that have a batery test feature where they put a 200ma load on the battery and display the voltage.

 

[barryh]

I made my own by soldering a suitable load resistor across a battery connector so that a small load was applied when the battery was inserted. The voltage could then be read off with a normal digital meter. Cost nothing as I already had the parts.

 

[Tdbo]

I like this one: https://www.homedepot.com/p/Gardner-Bender-D-C-AAA-AA-9-Volt-Battery-Tester-GBT-3502/202867877?cm_mmc=Shopping%7cTHD%7cG%7c0%7cG-BASE-PLA-D27E-Electrical%7c&gclid=EAIaIQobChMIm7iDy9zL2AIVRLXACh0Ptgl2EAQYASABEgKpU_D_BwE&gclsrc=aw.ds&dclid=CKHG583cy9gCFUmvTwodctELGQ Quick, easy, fast, and cheap. Paid $3.00 for mine on sale @ Menards.

 

[Quattro Pete]

Originally Posted By: barryh

I made my own by soldering a suitable load resistor across a battery connector so that a small load was applied when the battery was inserted. The voltage could then be read off with a normal digital meter. Cost nothing as I already had the parts.

Yeah, if you have some resistors sitting around, you can just use your existing DMM. I'm thinking something around 10-15 Ohm should work for 1.5V batteries, and maybe 50 Ohm for 9V.

 

[eljefino]

You don't even need a resistor, just use an old incandescent flashlight bulb or maybe even a 194 12V marker bulb.

 

[dishdude]

So my thinking was correct, a DVM shouldn't be used to check a battery's health and these little battery meters do have a bit of resistance built into them? The resistor and bulb in series with the DVM are great ideas.