Batteries - rechgble NiMH in place of Alkaline/Lithium?

On 09/06/2019 22:24, PeterC wrote: <snip>

Oh yes. I agree. One of my other cameras has an option on the set-up to choose alkaline or NiMh cells and adjusts the operation accordingly. I'm sure lots of others do too.

Nick

Reply to
Nick Odell
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In message snipped-for-privacy@4ax.com, Archibald Tarquin Blenkinsopp Esq snipped-for-privacy@mail.com writes

I would not expect any normal electronic device to rely on the batteries having a certain minimum internal resistance, and to disastrously malfunction because it was 'too low'. I would have thought that it's a case of 'the lower the better'.

As has been pointed out, the obvious problem is that rechargeable voltages are lower than their non-rechargeable equivalents. I have a camera and a DAB radio that both need at least 1.3V, and fully charged Nicads and NiMHs (which rapidly drop to 1.2V) don't keep them going for long.

Reply to
Ian Jackson

If it is something that is regulated to deliver either constant power or constant output voltage when the input voltage being too low combined with the very low internal resistance of rechargeable cells results in frying the device. Old cheap flashguns were very prone to this failure.

The things where damage can result are typically drawing a fairly large current from the batteries and relying on their internal resistance to limit the current into the device. It used to be quite a common trick.

Low current devices fail gracefully on rechargables with insufficient voltage to drive the LCD display to decent contrast.

Reply to
Martin Brown

I've a couple of DAB radios that work fine on rechargeable NiMHs - about the same life as alakali. Despite the manual saying not to use them.

Mind, a DAB radio isn't exactly high current. Nor I'd have thought the OP's binoculars.

Reply to
RJH

I would expect this problem to occur with equipment which needs a very high input current, for instance to charge the capacitor in a flash gun as quickly as possible for a given size of battery, and to get the best possible result from alkaline batteries has no intervening circuitry to limit the input current. It would presumably be fairly easy to design it so that the highest possible current even from an outlier among alkaline cells was ok. But then a new cell type with available short term current 10 or more times higher might fry the input circuitry. I have not seen this myself but it makes sense

Reply to
Roger Hayter

Presumably you are talking about zinc cardbon cells ...

Alkaline £1 for 5 or £2 for 12 at Poundland and I've never had one of their Kodak branded alkaline cells leak.

They also have a guaranteed 10 year shelf life.

Never seen such low prices at Wilko.

Reply to
Terry Casey

No problems with their alkaline cells and, in the results of life tests I've seen, they compare favourably with others - including Duracell.

Reply to
Terry Casey

Another reason for the 'no rechargeables' disclaimer might be the self-discharge on NiMH. It's no good if an infrequently-used widget is always flat when you come to use it - and the manufacturer will probably get the blame for flattening the batteries.

These days we have low self-discharge NiMH so this problem is much less, but perhaps the manufacturers still put the disclaimer in because people will use non-LSD NiMH and then complain.

Theo

Reply to
Theo

ZnC cells are cheap but their low capacity makes them far worse value. They also can't deliver enough current for some loads. With ZnC & alkaline, brand name has only minor effect on performance.

NT

Reply to
tabbypurr

I've had success with the yellow alkaline batteries from Home Bargains.

Reply to
Harry Bloomfield

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