In article ,
William Sommerwerck wrote:

I've been using alkaline batteries for decades (including nicads and NiMHs,
which are also alkaline), and have not had these sorts of problems. Yes, I
have had leakage. But it's been uncommon, and in only one case was the contact
badly damaged.

I have a Sony TFM-117WB with four Duracell C cells in it. They've been there
over a year. I checked them the other day, and they were fine.

I have never seen a 9V battery, of any chemistry, from any manufacturer, leak.

Alas, I've seen leakage from pretty much every size of alkaline.

One thing I have read, is that alkalines are quite unlikely to leak if
they haven't yet been used... but that discharging them triggers an
electrochemical process that starts the leakage syndrome (swelling
and/or corrosion).

So, if you have a device which is mostly kept around as a standby
(e.g. an emergency flashlight or radio), and isn't actually being
used, then the batteries will probably be OK up through their
published shelf-life date. However, once you use the device and start
drawing the batteries down, it's best to replace them relatively soon
after the first-discharge date (e.g. a year or so).

The devices I've had which have been crudded up or damaged by alkaline
leakage all seem to be of the "light or occasional use" variety, where
the batteries are neither left in an "unused, on the shelf" state,
*or* used up and thus replaced within a couple of months.