NiMh rechargeable batteries

Looking at replacing the AAA NiAh rechargable batteries in a Binatone phone. They seem to have lost some of the original capacity when used during calls.

Originally supplied with 2 off 1.2v 650 mAh.

What is the significance of the last value? Could a 1000mAh be used instead. Would that increase the 'storage' period?

David J

Reply to
David J
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In message , David J writes

Current is measured in Amps and milliamps. A cell with a capacity of 650 mAH would in theory deliver 650mA for one hour then go flat, or perhaps

325mA for two hours. Your 1000mA cell has about a third more storage capacity than the old ones and so should in theory last a third longer.

In practise the time between charges is also dependent on the cells' self-discharge rate. But you can safely use 1000mA cells and should expect to be able to use the phone for longer between charges.

Reply to
Bernard Peek

Yes and yes, as long as you can make them fit physically.

Reply to
Mike Barnes

It relates to the amount of energy stored in the battery expressed as the number of mA it can supply for one hour (although it is actually measured at a 5 or 10 hour discharge rate as using a one hour rate would be misleading).

Rather simplistically 650mA battery can supply 65mA for 10 hours or

130mA for 5 hours.

Yes

If by that you mean would it increase the use you got out of the phone between charges then yes it would.

Reply to
Peter Parry

It's a very coarse indication of how long they will work, under load. However a lot of battery makers consider this figure more of a marketing tool - which allows them to charge more, simply by writing a bigger number of their products. It's almost impossible to verify the mAh rating of a battery as there are too many variables and dependencies on how it is used. A higher value may mean the batteries will supply more juice, ot it may just mean the manufacturer is less troubled my a conscience than others. However, the capacity of even good brands can be killed by having a poor charger in the phone's base - in which case no amount of mAh will help, if the phone overcharges and thereby destroys the batteries.

Reply to
pete

And be aware that Lidl have 4 x AAA, 4 x AA, 2 x C, 2 x D, or 9v NiMH batteries on offer from the 1st Oct for =A32.49/pack. The AA size are

2500mAHr. These may well be fast to disappear items...
Reply to
Dave Liquorice

Thanks for all the replies.

My slight confusion is from trying to get an explanation on Wiki here:

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there is a comparison table for different types of rechargeable cells. The parameter that looks closest to the value in mAh we have discussed above is described as Specific Power, and is measured in W/kg. The 'capacity' is not listed.

For the NiMh type they list a Power range of 250 - 1000. But that unit is more to do with 'efficiency' (as a power-to weight ratio) rather than 'capacity' surely?

David J

Reply to
David J

In message , David J writes

That page shows mass-efficiency and volumetric efficiency, watt-hours per litre. But that particular article is written from an academic viewpoint comparing different battery technologies, rather than being written for someone who wants to know which pack to choose at the supermarket.

It doesn't mention the new low discharge rate "hybrid" NiMH batteries. These might be a better choice for your phone because their self-discharge rate is lower. If you find that your batteries have gone flat even though you haven't used the phone then these new batteries might be a good choice for you. You can recognise them because they are usually sold fully charged.

Reply to
Bernard Peek

not a lot

Could a 1000mAh be used

yes.

Would that increase the 'storage' period?

No.

Reply to
The Natural Philosopher

It depends if the phone is kept on the cradle most of the time. If it is, the batteries will be on trickle charge so the self-discharge won't matter. If you keep the phone switched on but off the cradle, the batteries will probably go flat in a week or two anyway. It's only if you turn the phone off for months that the self-discharge becomes an issue.

Personally I'd buy a cheap'n'nasty pair of batteries for a phone, as you can't be sure the charger is any good. Unless you talk for hours and hours on end without putting the phone back on the cradle, the batteries are probably going to be sufficient - higher capacity is better. Until the charger kills them, at which point you just have to buy some new ones.

Theo

Reply to
Theo Markettos

yes and yes. IIRC Poundland have 2 AAA rechargeables for =A31. Either

650 or 350mAh, I forget.

NT

Reply to
NT

350mAh. And their 2xAAs for a pound are 850mAh. I thought of this thread while I was passing them today :-)

Theo

Reply to
Theo Markettos

0.0588/mAHr

Where as Lidl (on offer from tommorow) 4 x AA are 2500mAHr and =A32.49 (0.0249/mAHr).

IIRC the Lidl 4 x AAA are 850mAHr again for =A32.49 (0.0732p/mAHr) half the price per mAHr of poundland.

Reply to
Dave Liquorice

Indeed. All the ones I've seen have specific warnings against leaving them on thecradle all the time. The batteries get slowly poached.

MBQ

Reply to
Man at B&Q

it really comes down to whats near the purchaser, getting there will cost far more than the cells themselves.

NT

Reply to
NT

This is true. The nearest Lidl is 30 miles away so to drive there (60 mile round trip) costs about =A320. Don't know where the nearest Poundland is, but it'll be of the same order whether it's in Penrith, Carlisle or Hexham.

Of course I wouldn't do a single trip but make it part of a larger one visiting other places. There would be extra mileage but only 5 miles (about =A31.50).

Reply to
Dave Liquorice

thats probably the main reason I do get poundland stuff, its right where I go anyway. No time or cost to being there. Even if I use half the stuff just once, its worth it.

NT

Reply to
NT

I don't deny they say that (including ours). Nor that batteries might deteriorate if always on cradle. But having left ours like that for something like 8 years, I am not going to try the experiment to compare! Especially as ours are always fully charged ready for a mammoth conversation without worry. Friends who do not put them on cradle are forever suffering flat batteries and seem to have to replace them regularly.

Reply to
Rod

Last time they had these on offer I bought a load of the AAAs. I generally use them in LED torches and they get quite a bit of use, and have held up well.

Reply to
John Stumbles

IIRC last year's lot were 1000mAh

Reply to
John Stumbles

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