Smiking HOT AA Alkaline cell

[flagman1776]

I decided to up the power backup to my power recliner. I bought 8S AA battery holders (undoubtably Chine made) but they are all that I expected, 2 required, I bought 3.
I removed the (2) 6S AA cell holders. Swapped over the cells & added 2 new ones. ONE cell got HOT. Too HOT to pick up. Thankful it was still on my desk & not connected to anything. Somehow I got the hot cell out of the pack. The cell was orientated right & anyway there was no load connected. I totally don't get it. Totally WTF??

All Rayovac cells. No sign of leakage. No shorts in cell holder.

[Burgerman]

Seriously, those are junk anyway. You need something with a low impedance. Buy a set of eneloop cells. They stay charged for a year, and are low impedance. I understand batteries. And those are the only ones with any chance.

Your lift chair will need at least a couple of amps, likely nearer 4 or 5 to go up/forwards. An alkaline cell struggles at 1 to 2A.

The enerloop cells are ok at 3 or 5A. They are lower resistance. This is your problem. Not the voltage.

[Burgerman]

All there is to know about all the incarnations of eneloop cells. Look at the chart atthe bottom for cycle life, and charge retention up to 5 years on some.

https://en.wikipedia.org/wiki/Eneloop

[flagman1776]

But how can a single cell short? Or run away? What ever kind of cell it is?

[LROBBINS]

Use an ohmeter to check all the connections in the battery box - perhaps the two ends of one cell are mis-wired and connected together.

[flagman1776]

I went over the cell holder with my ohm meter & there are no shorts. Not really surprising since ONLY the single cell got HOT. As it happens, it was the negative battery of the entire pack. The coil spring is off center, I suppose to get the correct spacing for the 9V battery connector which snaps on. The other battery holders I have are much the same except... I note the copper gromment/rivet which is the positive is mis-shappen slightly, making it diffilcult to install this one cell. It got hot enough to soften the vynyl covering... insulating covering...

My theory... every battery has both positive and negative I think the mis-shapen contact crossed the narrow insulator between the + / - of the battery shell creatng a very short HOT circuit. It used to be... years ago... when my father was an engineer at Philco (originally a battery company), that the case was ground & only the positive was insulated. I just checked & the case is now positive.

I'm very glad it happened on the desk top & not under my chair in the middle of the night. DANG!

[Burgerman]

Dunno what you are measuring. But the case is pos on every AA alkaline cell I ever saw. The opposite to the old zink carbon batteries or metal hydride/nicad etc.

But the pointy end is always positive.

[flagman1776]

Yes, the end with the bump is always positive but the case is now positive as well. I never had any need to know that the case was positive. No one knows or cares what's going on under the insulating covering... until it shorts. That IS it & problem solved by substituting the spare battery holder I included in my order. But I needed to know WHY for safety.

[flagman1776]

Yes, the battery info was the old zinc carbon batteries of antiquity and tube TVs Dad had patents for.