Battery memory on NiCad cordless drill

[Keith Williams]

Nonsense. NiCDs and NiMH batteries love to be discharged. That's the only way to store them for long periods. Don't "reverse charge" cell(s) in a multi-cell battery by discharging it below about 1V/cell though. They can be left to self discharge without damage. A single cell battery can be discharged to zero.

OTOH, lead-acid batteries must never be fully discharged and must be stored with a float charge. Lead-acid batteries are thus better for things like flashlights, UPSs, safety lighting, and such.

Not any more. NiCds may be 20% per month, usually less. NiMH has gotten a lot better too, but it was never as bad as 10% per day.

[nicksanspam]

Would you have any evidence for this article of faith? :-)

Nick

[Jim Yanik]

Dan_Musicant wrote in news: [e-mail]:

the NiCds in my B&D Dustbuster lasted 10 yrs,but they were a type designed to stay on the charger all the time when not in use. I had a local DeWalt service center replace the 4-cell pack because it was cheaper than buying a new DB.

My first set of Makita 9.6V sticks lasted 7-8 yrs bacause they were used often and kept charged. When I ceased using them regularly,they quickly failed,even maintaining their charge.Same for my B&D VersaPack 3.6v screwdriver packs.

[Jim Yanik]

Keith Williams wrote in news: [e-mail]:

Agreed.

That's wrong. They should be stored CHARGED. Do you have any cites for your claim?

NiCd Figures I've seen are ~5% self-discharge/day. Storage temperature greatly affects this.

[Don Klipstein]

I have seen datasheets for NiMH cells indicating that the self discharge rate decreases as self discharge progresses. A cell could self-discharge

5% in a day but less than 20% in a week. I would suspect NiCd can do something similar.

- Don Klipstein ( [e-mail])

[Al Bundy]

"werty" wrote in news: [e-mail]:

It is less painful to buy new batteries than read that post :-)

[krw]

Yes, Gates' secondary battery manual. The chemical reaction stops with zero terminal voltage. They store quite nicely that way. In any case, they *will* self discharge and the worse thing possible for a NiCd or NiMH is to float charge it. THis is exactly the opposite as is the situation for Lead-acid cells.

Nonsense. They do *not* self discharge totally in a month. ...more like 20% a month. Classically NiMH self-discharges at about twice the rate of NiCD, but AIUI they've gotten much closer.

[GregS]

With my Johnson walkie talkies with the42 year old NiCads, i charge some every year or two. I have never found them totally dead.

greg

[Jim Yanik]

[e-mail] (GregS) wrote in news:ebi0vc$air$ [e-mail]:

Well! that certainly proves something.

???

[Dan_Musicant]

:Dan_Musicant wrote in :news: [e-mail]: : :> On 6 Aug 2006 05:58:34 -0400, [e-mail] wrote: :> :>:JimL wrote: :>: :>:> Four years is past the maximum life of a nicad even you you have :>:>only used them lightly. :>: :>:Maybe my 10-year-old nicads never read the book :-) :> :> Indeed, I have NiCads that must be 8+ years old, are in many seasons :> very very seldom used and they seem to be reasonably adequate. I suspect :> I can revive my drill NiCads. I'm not shopping just yet. :> :> Dan :> : :the NiCds in my B&D Dustbuster lasted 10 yrs,but they were a type designed :to stay on the charger all the time when not in use. :I had a local DeWalt service center replace the 4-cell pack because it was :cheaper than buying a new DB. : :My first set of Makita 9.6V sticks lasted 7-8 yrs bacause they were used :often and kept charged. :When I ceased using them regularly,they quickly failed,even maintaining :their charge.Same for my B&D VersaPack 3.6v screwdriver packs.

I have quite a few of those B&D VersaPack 3.6v screwdriver packs, and don't use them much. I suppose there's nothing I can do to prevent the batteries from dying early. I must have about 8 of those batteries. They are mostly less than 2 years old.

Dan