NiMH Batterys

If it's an intelligent fast charger made only for Ni-Cads, no, in theory. And I'd guess any Makita one would be.

My charger has 2 settings, NiMH and NiCD, so I guess there is a difference. I have been having problem with batteries running out when using my Garmin GPS 60CSX on longish walks, tried rechargeable and standard. How ever I have been recommended ReCyko as not bleeding their charge and having that bit of extra. Got them but not used them yet.

Although the theoretical charging regime is not quite the same as for NiCds, for all practical purposes, the same charger can be used without noticable detriment to the performance or life. The biggest advantage of NiMH types, apart from the obvious size / capacity one, is that they don't suffer memory effect, which is something that has always plagued NiCds. Bear in mind that with a current-limited charger, which the Makita should be, twice the capacity will take twice the time to fully charge. This is of course mitigated by the fact that the battery to be charged doesn't need to be almost flat any more, because of the lack of memory effect.

Arfa

Strange. I've been using Ni-Cads for a very long time - well before cordless tools or mobile phones became common and have *never* experienced this.

In article , Dave Plowman (News) scribeth thus

Prolly your one of the few who use them properly!..

The problem, as far as charging is concerned, is that the small voltage depression at full charge that fast chargers rely upon for detection of charge completion is smaller (about 30% of the NiCd change) in NiMH than in NiCd. This means that NiCd chargers usually miss it when charging NiMH and continue to charge until they time out or they stop on thermal limiting. This damages the NiMH battery irreversibly each time it is charged.

Using a fast charger meant for NiCd on NiMH will often damage the battery being charged.

Slow (12 hours or more) chargers are not affected and will work on either type of battery

Unless you are in space with a specific type of cell not found in consumer applications and a rather unusual charge/discharge regime memory effect does not exist in either NiCd or NiMH cells.

What does exist, and is mistakenly called memory effect, is voltage depression caused by long term overcharging. This is somewhat more severe in NiCd batteries than in NiMH but easily preventable.

There is no need to fully discharge either NiCd or NiMH before recharge. Doing so has no beneficial effect upon battery capacity or life.

Not bad certainly (assuming they are real and not knock offs)....

With decent NiMH cells there ought to be little practical usage difference - same rules apply - don't charge a hot pack etc.

Most modern Makita chargers[1] are designed to handle both, although some of the very old ones will not charge NiMH packs (they won't damage them - they just wont even try). (Makita tend to have additional contacts on their NiMH packs for things like temperature sensing etc - which the old charger won't have matching contacts for). The chargers will also usually handle any pack voltage from 7.2V up to their maximum. So my mates 14.4V packs charge fine in my 18V charger, but not the other way round.

Even in the early days it was well known that overcharging would damage them. Rather like it does an SLA battery. In most of my sort of use you'd know how long they would last and change them (just) before they were exhausted. Same as you'd do with dry cells if you wanted the best economy/performance compromise. So they would just be recharged overnight at 1/10th the capacity constant current - with a timer to switch the charger off after 14 hours. Good cells would last years when used like this. Of course they weren't being used in heavy discharge situations. What I'm not sure of is how well these modern high capacity types last.

ge=20

Not so. the delta peak is far less that NiCD. and if your charger doesnt =

detect it it will overheat them and bugger them. You can use s Nimh charger for NiCd, but the reverse may not be true.

Urban myth. The biggest DISADVANTGE of NiMh is that they self discharge, =

and have limited life as a result. They go flat and lose capacity.

Bear in mind that

Nor has anyone else.

I think NASSA did on their deep space projects. If I remember correctly the spacecraft need to rotate slowly to avoid frying in direct sunlight on one side, this leads to identical charge and discharge cycles as the photocells go through sunlight and dark cycles and caused the Ni-Cads to show the memory effect. Apparently this only happens when the cells are discharged to exactly the same state every time so not likely to be a problem in real world use.

Well you've probably been using them on Earth, rather than in orbit in satellites subject to exactly the same period of charge and discharge cycles.

Silly you!

In message , "Dave Plowman (News)" writes

Mmm, indeed. Using a decent charger seems to be the key.

Same here. Even 20+ years ago, mine was the only bleeper at work that would run for a week. Standard instruction from on 'igh was to take the bleepers back to the gatehouse every night. I refused - after a couple of years mine was the only one that'd do more than about 6 hours!

With the combi I let it get v. low before charging. Still don't have any tools with NiMH, as the old ones keep going.

Probably the wrong thing to do. ReCyko have low leakage and will retain their charge for months, but, they have a lower capacity and will go flat quicker while in use. You need to buy some high capacity batteries to extend the use if they are going flat during a period as short as a walk.

IIRC, you said you had got the exact same set that I have. If so, the charger is one of

So I guess it would be fine.

Darren

Yup, fersacterly the same.

I'll blame you if it isn't :-)

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember "The Medway Handyman" saying something like:

Depends what model your charger is. Couple of years back I bought a Makita 14.4V charger that happily charges NiMH and NiCd, both properly. It does say on it, but it's in the van and I cba digging it out this time of night.

In the early days I used a very basic trickle charger. Still do for some. The important thing is to avoid overcharging.