In message , Andrew Gabriel
writes
In article ,
"Jake" writes:
I saw an advert for a battery charger that claims to charge ordinary
batteries - primary cells. The specific ones shown in the ad were Duracells.
Are these chargers any good, or are they a waste of money? These batteries
say that they cannot be recharged. If this is true, how many times can it be
done?

As a child, when non-rechargable batteries were all zinc-carbon,
I discovered you could get a bit more use out of them if you
warmed them up in the oven.

About 25 years ago, I designed something which used one the Maplin
LCD temperature modules with high point and low point alarm outputs.
Life of the Zinc-carbon AA cell in these was a year, so what I did was
supply a charging current of about 20% more than the unit consumed.
It still has that same 25 year old zinc carbon battery in it, and
it still works - actually it's been running off it with no mains
power for almost a year now, as the item item was disconnected and
stuck in the garage.

Wow!

I've just remembered that, in the 60s, I did somewhat similar with a
transistor portable radio. [It was a 'Realistic Seven' kit which I built
for my MIL.]

It was intended to run from a PP9 battery (the large 9V one), and took
around 15mA. While the battery lasted for quite some time, it was rather
expensive to replace. So, as the radio had loads of room inside, I added
a small internal small mains power supply.

To enable the radio still to be used portable (by simply by unplugging
the mains lead connector), I retained the battery, and arranged it to
trickle charge at a couple of mA. My MIL subsequently used the radio for
many years, and I don't recall the battery ever being replaced again.
--
Ian