[Tfug] Source for notebook batteries?

[Bexley Hall]

Hi Jim/Claude,

[I will play fast and loose with the terms battery and cell here
soas not to be pedantic]

> > The battery for my Thinkpad is barely holding a charge anymore, so I'm
> > looking at buying a new one.  (Tried reconditioning but without luck.)
> > Can anyone recommend a reliable source?  I'd like to avoid paying the
> > IBM premium, but online vendors of notebook batteries all seem pretty
> > sketchy.
> 
> I'm wondering if there's isn't a better (or at least cheaper!)
> solution via "hardware hacking".  I'm in the same boat, dead Dell
> battery.  I'm wondering if we can't rip the shells apart, pull out the
> individual cells, solder new ones in place with the same voltage (and
> possible more amp-hours?) and "duct tape" the shell back together.
> (OK, not duct-tape but you get the idea...)

If you have a "hot knife", you can easily disassemble most battery 
packs. They are almost universally solvent welded so trying to
"mechanically" (i.e. the delusion that there might be some
screws that you can unscrew) is usually not an option.

Unless you are pretty good at doing this, the "new" battery will
almost always show clear signs of having been disassembled
(worth noting if you ever consider selling the laptop).

They can often be *reassembled* with "super glue" and/or epoxy.
Much of this depends on how much you want to be able to repeat
the disassembly procedure *next* year...  :-/

> For an even crazier approach, wire up more batteries and
> extend the shell downwards.  Keep the voltage the same (use
> series/parallel if we have to), still use Lithium-Ion of
> course, should be good to go?

The problem with adding "capacity" is the charger in your laptop
will get confused.  Chances are, it will still *charge* the
battery correctly (albeit taking longer to recharge from
X% to full charge than the original battery would require).
But, times reported (charge remaining) may be meaningless.

Also, you can't just add batteries willy-nilly.  You can't
extend the *chain* of cells as this will increase the total
voltage delivered by the battery.  Too much can fry the
laptop's power supply -- as well as making it impossible for
the charger to push charge into the battery pack!

If you add another *string* of cells "in parallel", then
you have to take precautions to ensure one string doesn't
load down the other and/or steal all the charge current,
etc.

The safest way is to increase the size of each *cell* used in
building the battery.  Most (?) battery packs use an "A" cell,
I think.  Sort of like a long "C" cell.  I'm not sure how
you would accommodate anything larger without messaing
with the battery enclosure itself.

[N.B. you might find it easier to build an N-volt battery and
plug it in to the "AC adapter" input]

Lastly, some battery packs are "multi-output" (i.e.,more than
two connections to the battry pack).  So, you have to replicate
or enhance each of the "batteries" (here using the term correctly)
within the battery pack to ensure each "supply" is enhanced
accordingly.

> Out of the price of a $150 replacement laptop battery, how
> much are we paying for plastic shell and the laptop connector, 
> versus how much for the actual cells?

You will be amazed at how expensive it is to roll-your-own battery
pack!  The cells are not cheap.  Especially as you will be buying
them in small quantities, etc.  And.or paying someone else
to rebuild the battery pack on your behalf (most folks don't work
for free  :> )

If you have time to spare (what a delightful concept!), you
can disassemble the battery pack and check the individual
cells within.  You might find that just *one* cell has gone
flat.  Or, one "string" (in a multioutput battery pack).
As such, one or two cells might be all you will need to
restore the battery to a useful state.

Personally, I so rarely use my laptop "on battery" that I
just get used to using the AC adapter all the time.  I am
never disappointed by "short runtime"  :>  (though this
makes travel in airports tedious, at times, as many
*hide* their power outlets in places that are uncomfortable
to work)

HTH,
--don