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

Subject: Re: [OM] Battery types [was - iPods from Apple]
From: Tim Hughes <timhughes@xxxxxxxx>
Date: Mon, 20 Dec 2010 01:57:16 -0800 (PST)
Chuck,
      I am not sure which of packs you are looking at, as the dewalt line 
includes many types NiCd (old) ,NiMh,LiFePO4 (A123) and I believes some other 
technology Li-ion cells now too (maybe Sony) in its cheaper Li line. The 
website is quite good because it identifies cells used in quite a few vendors 
products. 

 The VPX line from Black and decker use A123 nano-cells, but it is a smaller 
size 1.1Ah cells. 

At the 18V pack level I believe you can use both the NiMH packs or the LiFePO4 
packs interchangeably in the 18V Dewalt tools and they even have multifunction 
intelligent chargers that handle both types. 

I seem to remember they have a lightweight Li pack and a heavy weight pack at 
18V one using 5x 2.3Ah cells and one using 5x 1.1Ah cells. 
here are cell specs, download data sheet:
http://www.a123systems.com/a123/products  the 2.3Ah cell is model 26650

The Dewalt 36V 2.2Ah  packs are the most popular for dissection or use in 
electric scooters etc. These contain 10 cells. Typically you can get them new 
for ~$100 off ebay with patience. If you short the cell while dissembling, you 
can literally vaporize the thick metal tab. The actual voltage per cell 
averages more like ~3.3V . So an 18V pack is actually about 16.5V in use, but 
due to the low impedance is more constant under heavy load than say a NiMh. 

Just off charge the cells are about 3.55V or just under 18V for pack. The 
common lithium ion etc batteries in laptops are just under 4.2V coming off 
charge, but average a bit higher voltage than LiFePO4,something like 3.5V or 
even 3.6 depending on particular chemistry.  The energy density advantage of 
regular Li-cells, even at low rates, soon fades as the cells automatically lose 
~20% pa if kept fully charged and lose even more when cycled. Cycle life is 5 
to 10 times worse and self discharge is much higher for Li-Co laptop type cells.

Tim Hughes


--- On Sun, 12/19/10, Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx> wrote:

> From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
> Subject: Re: [OM] Battery types [was - iPods from Apple]
> To: "Olympus Camera Discussion" <olympus@xxxxxxxxxxxxxxxxx>
> Date: Sunday, December 19, 2010, 6:24 AM
> 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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> >> 12/16/10
> >>
> >> --
> >>
> _________________________________________________________________
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> >>
> >>
> -- 
> _________________________________________________________________
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> 
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