Battery memory on NiCad cordless drill

[Jim Yanik]

"ToMh" wrote in news:s3fBg.1871$Lh4.723@trnddc02:

The new standard is lithium batteries.

[Joe Bemier]

Yes, and that includes the opinions that ppl are posting here - who knows which way to lean. Thats why I say calll Panasonic.

[nicksanspam]

Maybe my 10-year-old nicads never read the book :-)

[J. Clarke]

Next time you're in Home Despot or the like check out the 36v lithium-ion deWalts.

[Ralph Mowery]

Usually nicads are rated in how many charge cycles they can take. Around

300 to 600 cycles. I think that a partical charge is also a partical cycle but not sure. Some rechargables are just rated in number of years even if they are not used very often.

[John McFerren]

True, LiOn Cells will only have a useful life of about two years, after that they should be replaced, the same is true for LiPo batteries.

[J. Clarke]

I keep hearing this. My real world experience is otherwise.

[Dan_Musicant]

:Regardless, I will make sure my next drill uses Nimh :batteries.

I got the NiCads because the drill came cheaper that way. It's true that NiMH will have greater capacity. They say that the modern NiCads don't have the memory effect, but I don't know if that's categorically true. However, something to consider is the fact that NiMH will self-discharge at a significantly higher rate than NiCads. For me, that's a very important factor because most of the energy drain on my cordless drill batteries is from sitting around, not from use. I think I'll stick with NiCads for that reason.

[Michael Daly]

If you are letting the thing sit around a lot, get lithium batteries. The self-discharge of NiMH is overstated by many - they do discharge faster than NiCd, but not outrageously so. Li Ion, OTOH, will stay charged for long periods. However, the life of a Li battery is more closely tied to state of charge than to number of charge/discharge cycles. If it sits around fully charged a lot, it will not last as long as if it's allowed to sit around partially charged.

Mike

[Jim Yanik]

Dan_Musicant wrote in news: [e-mail]:

Do NiMH short out or fail if self-discharged,like NiCds? If not,then they can be stored,then simply charged up before use,-without needing to buy new packs.

[Dan_Musicant]

: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

[werty]

1) Pulse charge and it will return to full energy if it is still in infancy .

Never deep cycle any battery . Batterys die for being NOT fully charged . Leave them discharged is to shorten life . ---------------- 2) NimH and Nicad lose 10% in 1 day , Li-Ion lose 1% . I gambled on 100 NimH "LenMars" 2.5 aH AA's from Buy.com .. 25% loss in 1 day , load tested OK , i tossed them , not worth my time .

----------------------------------------------------------------------- more ........................ Pulse charge a nicad and it "loses" its memory , return full energy . ........ a 4 amp pow supply with a simple Resistor works great . C cell ( NiCad ,NimH) , as in drills , can take 2-3 amps til about 1pt36 vdc (((Linux crap apps ! Konquerer ..Cant see the text , too small , no way to change it so i use pt for decimal point ))))))))

1 ) so pulse with a very low Z pow supply at 1pt48 to 1pt5 vdc per cell and a Resistor of 0pt25 ohms . Theorectically , you must select R ( 0pt25) carefully , use scope to see the lighter amps , for it will heat up if too much amps above 1pt38 vdc . 2) but since current is so hi and pow supply is likely to help the current limit anyway , just measure the current above 1pt36 to 1pt37 vdc and adj the supply Voltage instead of doin the Resistor . Now the resistor limiter is inside your pow supply and you can simply vary period of pulse to "tame" the circuit and keep batteries cool . Never charge a hot battery ( > 110F ) , they dry up , short life . Velleman has o'scope ( HPS-40 for $250 ) .

BTW Clever battery chargers use a 2 step current limit , but more clever is to make the heavy current , resistor controlled . BTW Li-Ion need a charge rate of less than "c" til 3.6 to 3.65 VDC at 25 Deg C . ( I.E. Sony 920 Notebook has 2.2 aH cells in parallel so 4.4 times 3 sets in series +12v in > | | | | Ground < | |

-means less than about 4 amps til 3.6 vdc ...Thus the pow supply will show 4.9 amps to pow notebook and charge both ( batts/Notebook) same time .

These Li-Ions are worth your while even if you are poor . They will Kill Nicad/Nimh for they have 1) more energy per cubic inch ... 2) same VERY hi discharge rates . 3) but retain energy beyond a week . dont fear paralleling , Li-Ions have much less cross talk ( discharge of lower volt cell by the higher volt cell ) than anything ....

Off Topic Your Z-6 Minolta DigiCam will NOT like alkalines You must use NimH for the hi power needed . And it dont like heat , remove batteries to allow heat to escape for 15 minutes and you can shoot again ... I guess refurbished can mean a tax dodge , the Camera IS new ! The price drop is combo of Loss Leader and a pass thru of tax .

_____________________________________________________________________________________

Dan_Musicant wrote:

[werty]

Months ? Nicads ? Wet Cell , in a plane ... OK . Dry types? from da store , for your drill ? naaaaaah . 50% in a 20 days !!

Li-Ion is high rate power , loss can be 1% /month . priced out of reach , ..... I tossed all my Nimh ! Just too good to be intimadated by price ! But they die if too much amps charge above the 3.65 vdc level .

All batteries will float if the amps are very low .

( BTW Harbor Fright tiny driver $20 , w/ Li-Ion has no greater than a 1 aH single cell ) .

George E. Cawth> > Dan_Musicant wrote in

[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]

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