AA Battery

I keep getting a low voltage warning on my project. I checked all 8 of my AA batteries. They are 1.2V batteries, and 7 of them are reading exactly 1.2V; however, the last one is not even registering on the multi-meter. It's not even reading a 0. The multi-meter just doesn't even know that I've connected it.

I've never had a battery simply not show up before, so I don't know what that means. Even a "dead" battery usually registers something in my experience.

I can't try to recharge it, because I need to charge at least 2 batteries at a time, and I don't want to try and charge a battery that is at 100% with this one.

I am just trying to decide if the battery needs to be recharged, or if there is some type of manufacture defect in the battery...

I can't just buy one, so the entire set will cost me about $26.

Anyway, I have never seen a battery not register before, so I am just wondering what that means.

The battery in question has been destroyed. Why can't you just buy one replacement (make sure it has the same capacity)?

Well, I've never found just 1 battery. I have only found them in packs of several and rechargeable batteries are expensive. I have other batteries, but I didn't want to mix different battery types.

If the battery is actually defective, then I will probably just buy some more, or something, but I was just curious as to what this meant. I have never found a battery that didn't register before.

In the future, I will know what it means.

Thanks.

If the multimeter doesn't react when you put on a battery set to voltage, the battery has failed internally - likely a break between the negative terminal and the negative electrode. Throw it out and replace - not fixable.

Ni-Cd (Ni-mH) batteries fail by growing metallic "whiskers" between the two electrodes.

Recovery can be attempted by briefly connecting to something like a 5 V 20 A power supply to burn out the whisker, but is not really successful. :astonished:

DrAzzy:
Throw it out and replace - not fixable.

Or make a warranty claim.

Hi,

this battery has been depleted before the other ones, cause they never have the same capacity. If this happens and the voltage of one battery drops while the other ones are still ok, it will get a reverse charge from the other ones. This can even lead to a negative charge of the empty battery. If you measure the voltage then, you can even get a negative reading of some millivolts.

If you leave the battery for some hours on a warm, but not hot place, it will recover an you will have a small positive voltage reading. If this happens, then you can charge it again. Works with NIMH and eneloop.

Unfortunate the battery has suffered from this deep discharge an will never have the capacity it had before.

So if you use it again with the other batteries, it will again be depleted before the other ones resulting again in the same issue.

Therefore its always a good idea to add a battery monitor to your projects. You can monitor the voltage with a voltage divider on an analog pin. I normally use 6 batteries. With the voltage divider I get half the total voltage, which I monitor. As soon as the voltage drops below 3,5V I give an alarm or put the MCU into sleep to protect my batteries from deep discharge.

You might want to consider purchasing a better charger if you are going to be using rechargeable batteries. Maha makes a good one (like the Maha C401FS - comes with both a wall wart adapter and a car adapter - handles 4 individual AA or AAA batteries). Another charger I have had good results with is the La Crosse BC1000 charger kit - it includes 4 AA and 4AAA batteries. http://www.bhphotovideo.com/c/product/1081632-REG/la_crosse_bc1000_alpha_battery_charger_with.html

I actually have both of those chargers and they work very well and handle the batteries as individuals instead of having to be in pairs which avoids the issues you can run into with two batteries with different capacities.

gpsmikey: I actually have both of those chargers and they work very well and handle the batteries as individuals instead of having to be in pairs which avoids the issues you can run into with two batteries with different capacities.

However the problem described first occurs on the discharge cycle when the batteries are in their series configuration.