Hot Batteries

Sep 24, 2012 22 Replies

A neighbour called me to tell me she had put new batteries in her CO2 / smoke alarm and they were getting hot! I went to look and as you can guess they had been fitted wrong - but I was really surprised by the amount of heat they generated. (3 xAA)


Has the manufacturer never heard of a series diode?

Of course provided the design could cope with a 1.2 volt voltage drop, one could fit a bridge and then it would not matter which way around it was. Brian Brian

Some stuff has one connected so that it's normally reverse biased, and shorts out a battery connected the wrong way. The fuse is optional, but costs more.

That would mean that you would either need an extra cell, or would have a much reduced useful life from the ones you put in.

I wouldn't be surprised, not after putting the two AA batteries into a Lidl torch and finding it didn't work. By the time I got back to the shop (about 5 minutes) it was melting the plastic bits. Next time I will remember to take the batteries out.

Please bottom post, especially if you have a signature with "--" in a preceding line.

It is possible to use a modest MOSFET, which can combine a diode and a low resistance switch, to reduce any voltage drop to near zero.

The old fashioned method was simply to have a battery housing which fails to make contact when batteries are put in backwards.

If you want to get revenge then just post a link to a picture..........................

Are you new here? Brian top posts for a very good reason.

Those who know about Brian's blindness excuse him from the usual rigours on top posting, as he uses a screen reader.

For one I wasn't aware of Brian blindness. But it's a shame that whatever news client he uses makes it difficult to bottom post.

It has it's consequences, especially as Brian uses "--" in his signature thereby removing any of the OP's original post when replying with most news clients.

There are also those die-hards who refuse to reply to anyone who top posts!!

He has been buggering around with his sig in the last few days.

No - it's because he uses "-- ".

Die-hards can do what they like.

On your way out of Lidl you might have noticed a clear plastic bin for customers to put their depleted batteries in for WEEE compliance or whatever. Am I alone in thinking there is a potential fire risk if or more good lithium or alkaline batteries got in there, perhaps a couple of 9V types. Optionally add a little wire wool and tissue paper and stir slowly.

Makes note - dennis is unable to correctly fit a pair of AA batteries into a torch.

It was probably a torch designed for a couple of D cells.

To be fair, Brian's sig does mention the fact - but it took me a while to realise because I never read sigs either...

Brian is allowed as he's like Pew.

Does that include not reading his new sig that does not mention the fact?

Dunno - I never read sigs ;->>>

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