On Thu, 01 Sep 2016 00:15:46 +0100, "Dave Plowman (News)"
wrote:

Was asked to look at some re-chargeable cordless headphones a pal has
which needed new batteries.

Standard AAA cell - but the housing was different to normal, the negative
contact, which went to the side, rather than bottom, of the cell. The
originals having the sleeve cut off short to allow this.

And I've no idea why - apart to make it more difficult for user
replacement. Unless to prevent using alkaline?

My mother had something like that @30 years ago, most of her stuff was
Panasonic and probably it was a portable CD player.

Memory is rusty but the original rechargeable batteries had the side
contact but if they were discharged ordinary primary cells could be
used with no chance of the user trying to charge them by mistake as
the charging was done inside the player.
Now you could also use externally charged rechargeable instead of
primaries but they were not very common for the ordinary consumer
then.

G.Harman