From: John De Armond
Newsgroups: alt.energy.homepower
Subject: Re: what's up with nicad batteries?
Date: Wed, 17 Oct 2007 19:03:41 -0400
Message-ID: <ds4dh3lud4gu4atieb0erc5glsbo7ljsg1@4ax.com>

On Wed, 17 Oct 2007 16:31:43 -0500, me@privacy.net wrote:


>Light weight and longer life, more torque maybe?
>
>Something you could use to build say a deck outside
>with...driving self tapping screws and such.
>
>I know that nicad wont be a good bet.... but unsure of
>NiMH or Li-ion units

I'd hate to think how many deck screws my 10 year old 18 volt DeWalt cordless drill
has driven.  NiCADs and not NiMH.  NiCADS still rule for power density.  That is, the
ability to deliver high current (and thus power) from a small package.  The energy
density trails behind NiMH and Li but that's usually not an issue with a portable
tool.

That said, the Milwaukee and DeWalt Li battery tools kick ass.  The Milwaukee is 28
volts with about twice the ah capacity and yet about 2/3s the weight.  Both use newly
developed (but different) chemistries that deliver quite high currents.

I'm much more familiar with the Milwaukee because I have a friend who is an official
service center for Milwaukee and he shoots me all the V28 batteries that they
warrantee.  Invariably one bad cell and the rest are fine.  Amazing battery
management system inside the pack.  Each cell is charged-managed individually.

If I didn't already have a rather full set of DeWalt tools I'd be right on top of the
V28 Milwaukee line.

John

From: John De Armond
Newsgroups: alt.energy.homepower
Subject: Re: what's up with nicad batteries?
Date: Thu, 18 Oct 2007 17:25:32 -0400
Message-ID: <klifh3ho8h23qoeoh9m04slefues35349h@4ax.com>

On Thu, 18 Oct 2007 05:41:45 -0500, Bob Adkins <bob@nowhere.net> wrote:

>On Wed, 17 Oct 2007 19:03:41 -0400, Neon John <no@never.com> wrote:
>
>
>>That said, the Milwaukee and DeWalt Li battery tools kick ass.  The Milwaukee is 28
>>volts with about twice the ah capacity and yet about 2/3s the weight.  Both use newly
>>developed (but different) chemistries that deliver quite high currents.
>
>If Li batteries are so great, why do hybrid cars use NiCd's in their
>packs? Maybe because the Li cells are subject to catch fire?

Actually the Prius and similar vehicles based on that architecture use NiMH batteries
instead of NiCDs.  At that capacity level, they're about as prone to thermal
decomposition as Li.  Take a look sometime at the amount of protective circuitry in
the car.  At least as much as the actual propulsion circuitry.

The reasons Li batteries aren't used are manifold.  First and foremost, they cost too
much.  Second, they don't have the current capability, even at high voltage.  Third,
each cell must be individually charge-managed.  The BMS would add significant expense
to the vehicle.  Fifth, Li batteries have a calendar life pretty much independent of
the number of cycles.  3-5 years, depending on the chemistry.  Since that would not
cover the EPA's "emission warranty" period, not a chance of use.

As far as a propensity to catch fire, you watch too much TV.  Li batteries can catch
fire but only if physically damaged or dramatically overcharged, which is what the
Dell problem was.  LiPoly chemistry seems a bit more vulnerable than the others,
probably because of the flimsy packaging.

The chemistry used in the DeWalt and Milwaukee batteries are somewhat different and
are very resistant to damage, or so I read in some of the RC forums.  Cells from
these batteries are the new hot-sh*t power source for RC vehicles and they tend to
get abused in that environment.


>Anyone tried the Ryobi tools? They have a "1 battery fits all" scheme.

So does Milwaukee, DeWalt and the rest.  I noticed that Black & Decker has come out
with a replacement for the VersaPack line that uses similar sized Li batteries.
Should be pretty good for casual home use.

>
>I'm fed up with battery powered tools.

So quit buying them.  Problem solved.

>There should be standards so
>that  all 12v, 14v, 18v, 19v, etc. fit all power tools of the same
>voltage rating. If your drill breaks, you may have to throw away 2 or
>3 good battery packs. If your batteries die, you may have to throw
>away a perfectly good drill or saw because you can't find economical
>battery packs . Phooey on that. Also phooey on $85 battery packs. You
>can buy a decent drill with 2 batteries and a charger for $40.

Funny to watch an uninformed rant.  None of that is true.  None of the major tool
makers have changed battery formats.  My 10+ year old DeWalt 18 volt tool set still
fits batteries currently on the shelf.  True, they've come out with additional
formats - kinda obvious why since sticking a Li battery on a NiCD charger wouldn't
result in happiness.

If you break your drill, simply go buy another.  It'll use the same batteries.  As
for $85 packs, only if you're dumb enough to walk into a big box store and pay
retail.  Just for kicks, I just googled and found a 2-pack of 18 volt batteries for
$100.

I've had several packs rebuilt for around $40.  I understand that one of the retail
battery outlets (BatteryUSA?) will do it for just a little more.

As for those $40 ChiCom knockoffs, buy one sometime and try it.  Awhile back I needed
a DC gearmotor for a project and decided that a Harbor Freight 12 volt drill would be
adequate.  I took the battery apart and found just what I expected - lots of air and
little battery.

If that $40 toy will do the job for you then by all means go for it.  Don't come back
crying when it falls apart or when you can't find replacement batteries, though.

John

From: John De Armond
Newsgroups: alt.energy.homepower
Subject: Re: what's up with nicad batteries?
Date: Thu, 18 Oct 2007 17:44:46 -0400
Message-ID: <gtjfh3dljqvmn27mg1t20f1b3bgkbc3rhf@4ax.com>

On Thu, 18 Oct 2007 09:38:11 -0500, me@privacy.net wrote:

>>I'd hate to think how many deck screws my 10 year old 18 volt DeWalt cordless drill
>>has driven.  NiCADs and not NiMH.  NiCADS still rule for power density.  That is, the
>>ability to deliver high current (and thus power) from a small package.  The energy
>>density trails behind NiMH and Li but that's usually not an issue with a portable
>>tool.
>
>Maybe I should stick with NiCad after all then?  What
>you think?

If I didn't already have just about every 18 volt tool DeWalt makes, I'd be all over
the Milwaukee V28 line.  The 28 volt pack is lighter but about the same size as my 18
volt NiCd pack.  It stores just a little over twice the energy.  I've had the
opportunity to use the drill.  It kicks butt against my 18 volt one.  A friend has a
24 volt DeWalt NiCd drill.  I've used both.  No comparison.  The 24 volt version is
heavy and clumsy.  Just the opposite of the V28.

These tools are amazingly tough considering that they're made of plastic.  I remodel
my restaurant, helped build a metal building (read: about half a million screws) and
have worked on many other projects in the 12+ years that I've owned it.  It was my
first DeWalt tool.  It still runs like new, though the case is kinda beat up.

The circle saw was my second tool.  It's hard to believe that a saw that small can do
actual production work.  It can.  It cuts pine 2X4s almost as fast as a standard
line-operated saw.  It's hard on batteries, though, drawing probably twice the
current of the drill.  Getting the saw occasioned my getting a couple of spare
batteries and another charger.  It pretty much took two 1-hour chargers to keep up
with the saw.

I should note that the V28 saw is twice the saw of the Milwaukee.  It uses a standard
7" blade and cuts like a corded saw.

The jig saw is nice.  Well balanced and smooth.

Their version of the Sawzall reciprocating saw works OK but the genuine Milwaukee
Sawzall is sooo much nicer.  Better balanced.  The quick-change chuck is better. More
powerful, etc.

I have the analog radio.  It sucks.  I use it mostly as amplified speakers for my MP3
player and for the built-in quick charger.

The cordless vacuum is handy beyond imagination.  IMO, DeWalt screwed the pooch by
not including a charger in the unit.  It has a cord for corded operation so why not?

Actually I've been thinking about selling my DeWalt setup and starting over with the
V28.  I probably would had I not just had several NiCd packs rebuilt.

You can't go wrong with either battery system but if you're starting from scratch,
then I highly recommend one of the Li systems.  The V28 is my personal choice.

John