I use a slew or NiMH rechargeable AA batteries. For convenience, I try to get all of my electronic devices on AA.
Over the past several months, I’ve been having some issues with *fresh* batteries (meaning they just came off of a 12-24 hour charge cycle) not having enough juice to get the job done.
I’m wondering if I can use a multimeter to test the batteries? I’m not trying to see if they have a charge left in them, rather I’m trying to determine how much of a charge they will take.
I just took a sample of 7 batteries, reading the amps and the voltage. The voltage, which is supposed to be 1.2v according to the info printed on the batteries, is showing between 1.39v and 1.53v. The amperage is much different. The range I have is between 540 mAH and 1395 mAH. The listed mAH is between 2000mAH and 2650mAH.
Are all of my batteries shot? Is there a range of volts or amps that I should be looking for, or am I not even headed in the right direction?
Replies
How are you checking the amps? I thought that had to be done under load.
"Put your creed in your deed." Emerson
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
Just using a typical multimeter.
Jon Blakemore RappahannockINC.com Fredericksburg, VA
It is always just the one bad battery that makes the pack under perform.
I made a few battery testers out of # 12 copper wire and a 3v flashlight bulb. It tests the battery under load, is cheap, quick, fast and accurate. A digital multimeter might be more detailed, but the bulb takes up less room.
So how does your setup test it?Do you just throw out the batteries that don't light the bulb, or do you measure the "brightness" somehow?
Jon Blakemore RappahannockINC.com Fredericksburg, VA
Bright bulb, it is good. Dull or no light, the battery gets recharged. Mark the ones that are out and if they don't hold a charge, throw it out. Lots of times when charge in pairs one may not be in full contact.
Some batteries will initially light the bulb, then slowly start dimming.
Testing the batteries under load is the only real way to see if they have any capacity left. I use my multimeter on the 10 amp range, and BRIEFLY touch the test leads to the battery. That gives a really good indication of capacity. I've also found that cheap universal chargers will ruin your nimh batteries in short order. Since I bought a "smart" charger, and new batteries, I've been extremely happy with the performance of my nimh's. I wouldn't have believed it til I tried the new charger. Throw away (recycle) your old weak batteries, tho. The smart charger won't likely help them.