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Re: [OM] Battery types [was - iPods from Apple]

Subject: Re: [OM] Battery types [was - iPods from Apple]
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
Date: Sun, 19 Dec 2010 09:24:32 -0500
Interesting.  But I was confused by the DeWalt link which appears to 
show a 12 volt battery with 3 cells and an 18 volt battery with 6 cells. 
  Aren't all of these rechargeable lithium chemistries nominally 3.2 
volts/cell?

Chuck Norcutt


On 12/19/2010 3:22 AM, Hughes wrote:
> Chuck, The Newer LiFePO4 are truly outstanding, particularly the
> "nano-technology" ones (A123), although the new Sony ones are a
> cheaper and reasonable alternative now apearing, but not as high peak
> power.  Dewalt unfortunately charges a hefty premium for A123, but
> they are really worth it for high power professional tools. You can
> get battery operated saws for example, as powerful as line operated
> ones (1.5Hp). Black and Decker consumer VPX series, also use A123
> cells for small devices.
>
> These have very Low self discaharge,very high peak power, not as high
> energy density, but unlike normal Li-ion/poly they will maintain
> power for years of abuse. I converted my Metz CT60 flashes to use
> them, and cut the weight to less than that of smaller Oly CT45 for a
> more powerful 200J portable flash, with a larger number of flashes
> too. Recharge in less than an hour.
>
> If you are into tinkering the small VPX packs are easy to convert for
> use in lots of different equipment and can be bought on ebay, at
> lower prices. I have a number of old small screwdrivers,drills etc
> converted to use them. Just don't drain them right down, keep a
> couple of packs and swap at first sign of slacking and they will last
> and last. Some of the LiFePO4 packs now have reasonable warrantys
> 2+years.
>
> To see how powerful and relatively abuse proof the A123 cells are, go
> and read the RC helicopter websites where they abuse these cells
> getting>250W from each large c-cell and then recharging them in
> ~20minutes.
>
> This website has lots of info on the cells used in different power
> tools mainly dewalt, but includes others:
> http://dewaltownersgroup.com/index.php?PHPSESSID=d886b14708b013d8bdc7af2fbf9af5f6&board=26.0
>
>  Lots of people buy LiFePO4 cell drill/saw packs for modifying, for
> all sorts of high power applications off of ebay. This is often the
> cheapest way to get them if you want to convert your old high power
> battery tools.
>
> Tim Hughes
>
> --- On Thu, 12/16/10, Bill Pearce<bs.pearce@xxxxxxx>  wrote:
>
>> From: Bill Pearce<bs.pearce@xxxxxxx> Subject: Re: [OM] Battery
>> types [was - iPods from Apple] To: "'Olympus Camera
>> Discussion'"<olympus@xxxxxxxxxxxxxxxxx> Date: Thursday, December
>> 16, 2010, 2:02 PM I recently got a powered screwdriver, a Bosch. It
>> says it has NiMH. It holds a charge for a really long time and
>> lasts forever.
>>
>>
>>
>> From: Chuck Norcutt [mailto:chucknorcutt@xxxxxxxxxxxxxxxx]
>>
>> Sent: Thursday, December 16, 2010 1:57 PM To: Olympus Camera
>> Discussion Subject: Re: [OM] Battery types [was - iPods from
>> Apple]
>>
>>
>>
>> I think the perseverance of NiCd cells in certain applications is
>> readily understandable in terms of the rate of self discharge.
>> NiCd cells (until recently) have had much lower self discharge
>> rates than NiMH cells.  NiCD persists for a walkie-talkie or
>> portable drill since you haven't been able to count on an NiMH
>> powered device to have any charge left if you haven't used it in
>> 3-6 months.
>>
>> But that all started to change recently.  You may recall the
>> announcement posted here the other day by Tim Hughes concerning
>> three new types of NiMH batteries from Sanyo Eneloop.  The newest
>> cells promise 75% power after 3 years sitting on the shelf. That's
>> probably better than NiCd, maybe even much better.
>>
>> Also, I note that drill drivers are starting to show up that have
>> lithium-ion batteries.  The last I noticed they were expensive
>> enough that I wasn't willing to replace my own NiCD powered drill
>> but the next power tool purchase could be something different.
>>
>> Chuck Norcutt
>>
>>
>> On 12/16/2010 12:54 PM, Jan Steinman wrote:
>>>> From: Moose<olymoose@xxxxxxxxx>
>>>>
>>>> On 12/15/2010 11:00 AM, Jan Steinman wrote:
>>>>> Although it's open on my desktop, I've not
>> looked at the
>>>>> BatteryUniversity.com site yet, but my
>> understanding of classic
>>>>> NiCd is that repeated incomplete discharging
>> to about the same
>>>>> level causes a crystalline precipitate to form
>> at a certain
>>>>> location related to the discharge depth,
>> therefore causing the
>>>>> mis-named "memory effect." (It should really
>> be called the
>>>>> "forget effect." :-)
>>>>>
>>>>> Memory effect is not a problem when the cell
>> is repeatedly
>>>>> discharged to different levels. Classic case:
>> a cop runs a
>>>>> walkie-talkie for eight hours a day and drops
>> it in the charger
>>>>> overnight -- bad news for NiCd cell life. But
>> memory effect is
>>>>> not likely if you're using a flash or motor
>> drive for various
>>>>> periods of time and then topping off on a
>> charger.
>>>>
>>>> "Among rechargeable batteries, nickel-cadmium
>> remains a popular
>>>> choice for two-way radios,"
>>>>
>>>> Since what you say here doesn't agree with what's
>> on that site,
>>>> perhaps you might read it and resolve the
>> differences.
>>>
>>> Yea, I'll have to check that out, because it doesn't
>> go along with my
>>> experience as a ham-radio operator, my work as a
>> repair tech in a
>>> two-way communications shop, nor my stint as an RF
>> engineer.
>>>
>>> I don't know of any hams who still use NiCd cells in
>> their two-way
>>> radios, but note that the OEM battery packs you get
>> from Icom for
>>> older radios still have them. Perhaps its just because
>> NiCd's are
>>> still cheaper. (New hand-held ham gear is almost all
>> lithium
>>> powered.)
>>>
>>> NiCds do have lower internal resistance than NiMH,
>> which might make
>>> them preferable in high-current applications -- like
>> photo strobes.
>>> But that wouldn't explain hand-held radios, which have
>> relatively
>>> moderate current needs. And if they're so good for
>> hand-helds, why
>>> don't you ever see them in cell phones? Puzzle.
>>>
>>> But such fun has to wait. I have to go pick up a buck
>> to romance our
>>> four Nubian goats today.
>>>
>>> Obligatory camera content: I need to take some photos
>> of our
>>> zero-mile raw goat milk ice cream... if there's any
>> left...
>>>
>>> ---------------- Religions are the great fairy tales
>> of conscience.
>>> -- George Santayana :::: Jan Steinman, EcoReality
>> Co-op ::::
>>>
>> --
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>>
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>> --
>> _________________________________________________________________
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>>
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