Battery charger

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?

Reply to
Jake
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Primary cells can be recharged to some small extent, but their capacity falls off rapidly with each recharge. There is also a risk of them exploding due to pressure build up during charging - hence the warning.

Reply to
Harry Bloomfield

Makes more sense to buy rechargeables.

NT

Reply to
Tabby

some info at

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alkaline cells used to be common once but ordinary alkaline ones probably won't recharge to anywhere near their original capacity and may start to leak corrosive fluids, especially the cheapo varieties. Chinese zinc-carbon primary cells bought from market stalls start to leak after, or sometime before, their first discharge.

IMHO don't put anything dodgy in expensive electronic kit as the risks outweigh any benefits (having corroded away the connectors of many high-tech gadgets left lying about with flat batteries).

rusty

Reply to
therustyone

therustyone formulated the question :

They tend to use stainless steel these days, rather than plated steel for the battery terminals, for that very reason.

Reply to
Harry Bloomfield

In message , Tabby writes

The idea of charging non-rechargeable batteries has been around for a long time. The principle is never to let the battery get too discharged before you recharge it. Also, the charging current is not DC. It's essentially 'asymmetric AC' - sort of '2 amps forward, 1 amp backward'. With the old zinc-carbon batteries, this was to aid 'depolarization', and reduce the build-up of gas inside the battery.

I've only tried recharging non-rechargeables two or three times, as an emergency measure - and just using a variable DC power (not the special charger). The last time was to put a bit of life into a 'special' battery, used in a Grundig TV remote control. I did it several times, but the last time, I think I rather over-did it. There was a sharp 'poof' (a mild explosion), and the end cap of one of the cells blew out. It could have been nasty!

Reply to
Ian Jackson

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.

Reply to
Andrew Gabriel

I found you could exract the carbon rods and use them with a car battery to make nice hot arcs. Make a pool of salt and you could smell the chlorine once it started to melt and electrolyse. Never managed to isolate any sodium, though.

Reply to
Skipweasel

In message , Andrew Gabriel writes

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.

Reply to
Ian Jackson

Compared to what? Compared to NiMH, they're not a good choice.

I used to recharge alkaline D cells years ago (commuting bike lights) and it was a great improvement on what else was available at the time. However NiMH have got so much cheaper since that there's no longer any advantage to it.

Use a good intelligent charger though: Aldi, =A313

Reply to
Andy Dingley

I have the innovations charger and it is good. It will charge all rechargeable and non rechargeable bats. Some better than others but then if the normal battery wont recharge you have lost nothing as it was flat anyway.

Gary

Reply to
Gary

I made a carbon microphone from a couple of those carbon rods: similar to Example 1 in this drawing...

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Reply to
Nick Odell

I did that with a school friend. IIRC, it was triggered by an article in Scientific American. It didn't use car batteries. I can't recall what the article specified, but we worked up to using mains, and my mum's 2.4kW electric kettle as a ballast. Probably should have been using darkened/UV goggles or welding hood too, but didn't know that then. I think we used sun glasses, and you couldn't look at the arc anyway - it was far too bright.

My 2nd year university project required a carbon arc lamp (to use the electrode as a 4000K black body emitter). The lab had a 220VDC mains supply for such things, and it ran from that (I presume through a resistor ballast, but I can't recall that now). It had proper carbon arc rods though.

Reply to
Andrew Gabriel

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