NiMH cells - good and bad.

[paulsherwin]

Originally Posted by Bazz4CQJ

I haven't bought any hydride cells recently, but have been looking a sub-C NiCds for a Bosch drill. There's factor of almost 4 between the cheapest and the most expensive. Is that true for NiMH?

There is a big price spread. Some types are low capacity and deliberately designed to sell cheaply, but in most cases the pricing seems to simply derive from market positioning. My advice would be to ignore the price completely and choose cells based on their capacity, backed up by reviews such as found in this thread. Some of the cheaper cells seem to be some of the best in terms of longevity.

[Humber888]

Thanks Chris. I am sorely tempted by that. So far the best price I can find is £27.95 on Ebay for what looks like the Europlug version (new). UK plug models seem to start at about £33. Still not a bad price for what it is.

[cmjones01]

Originally Posted by Humber888

Thanks Chris. I am sorely tempted by that. So far the best price I can find is £27.95 on Ebay for what looks like the Europlug version (new). UK plug models seem to start at about £33. Still not a bad price for what it is.

One neat feature it has is that it uses a 12V input on a standard (2.1mm or 2.5mm) DC power plug, so you can power it from various sources.

There are a number of alternatives out there: I can see Varta-branded ones which seem to have similar refresh/test functions, and there are some from Xtar which only do charging but have comprehensive voltage/current/capacity displays.

Chris

[Philips210]

Originally Posted by Philips210

Hi,

I think you're right. I misunderstood the chemistry involved. Metal dendrites would have been a more apt statement.

I have successfully revived short circuit NiCd cells by zapping them with a charged electrolytic capacitor as in the case of clearing tin whiskers in AF1xx series transistors.
What I wondered was to try the same method on NiMH cells. Would it be safe to do so? Has anyone tried this method and was it successful?

Regards,
Symon

https://www.instructables.com/id/A-s...Ni-MH-battery/

Symon

[JayBee66]

For "intelligent" chargers, try the Opus BT-C3100. It handles NiCd, NiMh and Li-ion in sizes from AAA to 18650s. Display shows voltage, charge current and capacity for each cell under charge.

[woodchips]

I found that using the 1.5V lithium iron, I think, cells solved all the leaking and lasting problems. Run a digital camera for months.

[G6Tanuki]

Originally Posted by Bazz4CQJ

I haven't bought any hydride cells recently, but have been looking a sub-C NiCds for a Bosch drill. There's factor of almost 4 between the cheapest and the most expensive. Is that true for NiMH? The original drill battery lasted 19 years and it's generic replacement is deteriorating after just 2 .

B

Pragmatically, I wouldn't bother re-celling an old designed-for-nicad drill with NiMH. If your drill is 19 years old.... it'll have an antique motor with brushes, and no proportional speed/torque-control.

Instead, save your time and spend the money on a current-generation Li-Ion-celled brushless drill. Even a cheapie own-brand from Screwfix or Machine-Mart will delight you with its torque/speed-controllability, long battery-life and overall convenience.

Li-Ion batteries and 'digital' brushless motors really have turned the cordless-powertool market on its head, just as LEDs have made all other light-sources look stupid.

[Bazz4CQJ]

Originally Posted by G6Tanuki

Pragmatically, I wouldn't bother re-celling an old designed-for-nicad drill with NiMH. If your drill is 19 years old.... it'll have an antique motor with brushes, and no proportional speed/torque-control.

Yes, it's a bit sad, it's been a good servant, but I think what you're saying is true; time to move on.

B.

[MotorBikeLes]

Not sure I agree with that sentiment. 15 or more years ago, a pal picked up a Hitachi drill from the local amenity site. One battery, but no charger. he gave it to me as i could obviously charge it. Variable speed SDS hammer drill. i later picked up an SDS to stock chuck adaptor unit, and used it with anything HEAVY or needing a masonry drill. About 12 months ago, the fading battery finally cried enough. i decided to spend a bit of cash, and managed to buy another duff battery (£5), a genuine charger (£15) and a batch of used but "assured OK" 12v battery packs (NiCads not NiMH types). I built two batteries, about £20. I now have a first class unit, fully repairable should a brush fail, the new equivalent of which would doubtless be in the £100s. Some of the work it has done in the last few months has certainly paid back that £40 investment, and frankly will likely see me out.
But i saw a BIG SPIT 342 recently which I bagged for £30. That will put a 1" hole through my 2' stone cottage walls! Only about 30 years old, but will probably see my son out when I am gone. A new equivalent for that would perhaps be £500!
Les.

[McMurdo]

I once had a digital camera from CPC, supposedly rechargeable, but it came with a note saying the model had changed, and 'heres a pack of nimh AA cells and a little charger at no extra cost'. The make was 'Hahnel'. 2000mah. They didnt work for long. Thinking I'd over charged them, I bought some Maplin ones 'Digital 2000'. They went the same way.
Then I was given a gift-box with several sets of GP ReCyKo and GP charger, about half the capacity, and they've been fine.

I have a whole load of Uniross NiCd AA and C cells and they perform as good as new, and I had them from Marco or Greenweld or similar, a good 25 years ago.

[emeritus]

I have an elderly Pentax Optio 330 digital camera that take 2x AA batteries. Sometimes the power indicator indicates that fully charged nickel hydride batteries are partially discharged. This is fixed by rubbing the battery terminals on something rough to clean them (steel wool or a kitchen scourer, or even my trouser leg if I am out). I recall having read something in I think, Wireless World, a couple of decades ago of this happening with NiCd cells, the cause being oxidation of the nickel coating which, unlike iron, doesn't look any different from unoxidised metal. A couple of months ago I fixed a non-working cordless phone for my neighbour in the same way: it still has its original NiCd AAcells, as does my own cordless phone, now some 15 years old.

[Bazz4CQJ]

Re Pensioning off old drill at 20 years old

Originally Posted by MotorBikeLes

Not sure I agree with that sentiment.
Les.

The drill itself is absolutely perfect, hence I went out and bought a new battery, but buying re-chargeable batteries, of almost any kind, seems to be a bit of a lucky-dip, and the replacement (Fluoreon?) isn't a patch on the original Bosch (no longer available).

As for re-building battery packs, I've done it in the past, I still do it, but there's a point at which I think you have think about how much time it's taking. This particular battery is built in such a way it will be will be hard to do the two cells that connect to the outside world.

B

[Tyso_Bl]

LIDL are doing their rechargeable batteries again this week, if anyone is interested.


T

[TIMTAPE]

I believe when they came out NiMh were claimed to have "reduced" memory effect re NiCd but for some that seems to have mutated into "no memory effect". Before charge still I discharge.