helloWorld.cpp,
May I ask you a question regarding AA battery discharge question?
I have a flashlight that uses 3 AAA batteries in series. I put 3 rechargeable AAA batteries to the flashlight. (assuming all 3 are equally charged to the same voltage) The batteries are the same brand, rating, and bought at the same time. The batteries begin to run out. So, the light gets dimmed.
I take the 3 AAA batteries out and measure the voltage. Two of them are pretty much full but 1 of them is low.
Should all 3 batteries be low (or about the same voltage) instead of just 1 of them is low?
Voltage is the potential difference. So, it is about pressure being pushed to different direction.
Is the electricity from this 1 battery being used to charge the 2 other batteries somehow?
What can be done to make all these 3 batteries to discharge the same rate but not charging each others?
Thanks!
First, a word of advice: never do this to rechargeable batteries. You will damage them.
If you use two or three NiMH batteries in a lamp like this, always remove them and recharge them before the lamp shows signs of dimming.
Why, you may ask?
Basically, NiMH cells maintain a reasonable voltage right to the end of their discharge curve, and then the voltage falls off a cliff. If you have three cells in series, one of these cells is going to be the first one to fall, since no two cells are identical. Whichever one runs out first, will end up having current pushed through it by the other cells that are still going. This is called "reverse charging", and it is very bad news for an NiMH cell. It will damage it. So you really don't want to let this happen.
Also, this now explains why you see one battery with a low voltage while the others are still high. The battery with the low voltage was the first one to run out. If the low voltage is zero or even negative, then definitely don't do this to your cells.