How to test battery with multimeter?

[timber.wolves]

Hey all,

This might be basic stuff, but I'm looking to go beyond just measuring battery voltage with a multimeter. I know that reading 1.5V or 9V doesn't tell the full story, especially if a battery can't actually handle a load.

So far, I've tried switching the multimeter to amps and briefly measuring current directly from the terminals. I noticed that healthy AAs might show 5-7A reading, while weaker ones drop to lower than 2A. But with a 9V battery, I got 9.3V but only around 0.040A and still falling. That seems… off.

My questions:
1. Is using the amp setting on a multimeter like this a reliable secondary test?
2. Is there a rule of thumb or amp readings that shows a battery's still good?
3. Or is a better way to build a test rig that applies a load (like a resistor) and then checks how much the voltage drops under load?
4. If so, what's a simple load test setup look like for everyday batteries?

Would love to hear how you verify battery performance, especially for stuff like remotes, flashlights, or toys where voltage alone can be misleading.

 

[justjack]

A better way is to use a resistor as a load and check how much the voltage drops. For AA, try a 10 ohm resistor; for 9V, maybe 100 ohms. If voltage drops hard under load say, below 1V for AA or 7V for 9V, it's probably done. Or just grab a cheap battery tester with built in load, that's all I know, sorry

 

[TheOhmBreaker]

You're right, just checking the voltage doesn't really show how the battery's doing when it's being used. Shorting the battery to measure amps isn't safe and can be pretty unreliable. The best method is to do a simple load test: get a resistor (10Ω for AA batteries, about 360Ω for a 9V), then check the voltage with and without the load. If you see a big drop, the battery's weak. Have you tried that yet?

 

[voltagepathmaker]

I came across a stash of old AA batteries that seemed fine in terms of voltage, but half of them couldn't even power a remote. So, I put together a simple tester with a resistor and a switch, just like you might've guessed. It's pretty basic, but it reveals a lot more than just the voltage. If you find yourself checking batteries frequently, it's definitely a handy setup to have.