Battery memory on NiCad cordless drill

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A lot of good info here, but I have some also to offer.
The key problem is "lightly used" - that means the NiCd cells will develop a memory, unlike more modern ones. A memory of being charged, then leak-discharged, then trickle charged, etc, etc. The only good way around avoiding this, is using (as others have said) a discharge cycle (or use to flat) before recharging, and not leaving them flat.
The age of the cells has NOTHING to do with the expected performance, as long as you have cycled them properly. I have NiCd cells still working strongly from the mid nineties.

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some chargers are designed to be able to leave the pack in,some are not. You need to check your manual.

It's been my experience that for longest life,NiCds are best used often.(use it or lose it) Once you start storing them for long periods,their life decreases. NiCds also have a self-discharge rate;just sitting in storage,they discharge on their own.
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Jim Yanik
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Jim Yanik wrote:

If you don't use them much you need to keep checking the voltage at least once every 1-2 months and make sure the voltage doesn't drop below 12V. Full charge on a 12V NiCad is about 14V, but that degrades quickly to about 13V and I check the voltage when charging and stop before it reaches 14V. Overcharging is the number one cause of batteries going bad.
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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. Cawthon wrote:

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wrote:

I read the responses below that state you should not drain the battery but when I googled *NiCad Batteries Drain Completely* there are articles that state you should drain them. Here are a few of the articles.... http://www.nyu.edu/its/pubs/connect/archives/95summer/edwardslaptop.html http://www.ehow.com/how_3037_battery-life-laptop.html
Frankly, I have no idea which is correct (and I did see some articles to the opposite) but if I'd suggest calling Panasonic tech service.
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Joe Bemier wrote:

Draining a NiCd or NiMH cell completely means to remove essentially all the energy it contains. This requires discharging it to a cell voltage of about 1.0 volt. Doing this, then recharging, is the way to reverse "memory" (voltage depression) effects. If the battery has 6 cells or fewer and they're reasonably well matched, you can usually safely discharge the battery to 1.0 volt times the number of cells (e.g., 6.0 volts for a 6 cell battery) without risk of reverse charging one of the cells. If the battery has more cells, this becomes increasingly risky and the only safe way to do it is to discharge the cells in groups of 4-6. This of course requires getting into the battery pack.
The folks cautioning against trying to discharge down to 0 volts are absolutely correct. It just about guarantees reverse charging one or more cells, which will permanently damage those cells. Those cells will then have even more reduced capacity, so they'll go into reverse charge even earlier in the battery cycle the next time. There's never any need to discharge a cell below 1.0 volt. A well designed tool or electronic device intended for NiCd or NiMH power should quit operating and drawing battery current when the pack voltage reaches 1.0 volt per cell. Unfortunately, a lot aren't in this category.
Roy Lewallen
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Joe Bemier wrote:

That's the problem with netnews and the Internet in general. Lot's of incorrect stuff that gets repeated over and over even by groups that should know better. Always check major manufacturers for the accurate information when there is controversial information.
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On Sun, 06 Aug 2006 04:39:49 GMT, "George E. Cawthon"

Yes, and that includes the opinions that ppl are posting here - who knows which way to lean. Thats why I say calll Panasonic.
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I find nicads in drills last about two years. You got your use out of them.
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Christopher A. Young
You can't shout down a troll.
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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.
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Ralph Mowery wrote:

that they should be replaced, the same is true for LiPo batteries.
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John McFerren wrote:

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

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snipped-for-privacy@swissinfo.org says...

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.
<snipped the rest - too hard to read>
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Keith

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says...

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.
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Jim Yanik
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snipped-for-privacy@abuse.gov says...

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.
--
Keith



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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

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Would you have any evidence for this article of faith? :-)
Nick
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It is less painful to buy new batteries than read that post :-)
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