Replace
the Cells in Your Apple Powerbook G3 (Lombard or Pismo)
Battery
Did
your Apple Powerbook G3 (Pismo or
Lombard) battery die? Have you shopped for a replacement
battery,
and wondered if your trusty powerbook was worth what it was going to
cost for a new battery? Are you handy with a
soldering iron
and other tools? Are you adventuresome?
Would you
like to conserve the world's resources by recycling? If so,
then
you might be interested in this article about my brief adventures with
Powerbook G3 batteries.
My wife's Powerbook G3 (2000 firewire) had been getting so her battery was lasting only a few minutes. I had recently purchased a similar Pismo Powerbook that would not start, hoping its battery was a good one. It wasn't, but I found when working with that machine, that if the PRAM battery is not charged and the main battery is dead, the powerbook will not start, even when connected to the power adapter. Connecting my wife's good battery, I was able to start it up. Then, because the last "good" battery we had (hers) was about finished, I was afraid that both powerbooks would end up in this "won't start up" situation and I wouldn't have any good battery to use to start either of them. So I decided that I would have to replace the cells in at least one battery or buy a new one. I had some experience replacing the cells in Powerbook 520 batteries years ago, and I'm a frugal electrical engineer, so I decided to do the former.
My wife's Powerbook G3 (2000 firewire) had been getting so her battery was lasting only a few minutes. I had recently purchased a similar Pismo Powerbook that would not start, hoping its battery was a good one. It wasn't, but I found when working with that machine, that if the PRAM battery is not charged and the main battery is dead, the powerbook will not start, even when connected to the power adapter. Connecting my wife's good battery, I was able to start it up. Then, because the last "good" battery we had (hers) was about finished, I was afraid that both powerbooks would end up in this "won't start up" situation and I wouldn't have any good battery to use to start either of them. So I decided that I would have to replace the cells in at least one battery or buy a new one. I had some experience replacing the cells in Powerbook 520 batteries years ago, and I'm a frugal electrical engineer, so I decided to do the former.
I
found postings in this
thread where
others had attempted this operation and read them carefully.
Another interesting thread is this
one.
I was encouraged. I really wanted two really good batteries, so I
decided
to
get new replacement cells from Battery
Space instead of surplus cells at a slightly better price
elsewhere.
There are nine 18650 Li Ion cells in each battery, so I ordered 18 of
them at a cost of about $100 with solder tabs. When they
arrived,
I carefully followed the instructions here
to
disassemble the first battery. It looked identical to the one
in
the photos there as you can see below.
After
taking this photo and inspecting
things carefully, I determined that there are three sets of three
parallel cells that are in turn connected in series. The Sony
cells were 1800 mA-hour cells. The ones I purchased were 2000
mA-hour cells. With this configuration the old battery was
nominally 5400 mA-hour. I measured the voltage on each of the
three series sets of cells. One set was shorted; the others
measured between three and four volts.
I carefully removed the cells as shown in the following photos.
I carefully removed the cells as shown in the following photos.
I
had to desolder wires that went to the
junctions between the series sets of cells. I was very careful
not
to allow anything to short out the cells.
I
found that I could remove the spot
welded tabs on the cells using a pair of pliers and a twisting
action. Note that I purchased cells with solder tabs. If I
had a nice little spot welder, reusing the custom solder tabs would be
possible, but I don't have one.
I
used Scotch tape to align the cells in
the same way they were in the battery. I found it necessary to
put the cells on a flat surface to insure they would sit flat when
installed in the case again. There were two white plastic
dividers that fit between the sets of cells that should not
contact each other. The arrangement the cells sit in the case is
important to note. There were two sets of
three side by side cells with the positives all connected and the
negatives all connected.
The remaining set of three parallel cells had two cells side by side with the third opposing it with the positive leads all strapped together with a custom welded on solder tab. A wire connected the opposing negative terminals on the last set of three parallel cells.
The remaining set of three parallel cells had two cells side by side with the third opposing it with the positive leads all strapped together with a custom welded on solder tab. A wire connected the opposing negative terminals on the last set of three parallel cells.
Once
the sets of cells were soldered
together (taking as much care as possible to make sure the solder
connections were good and that there were no large bumps of solder
sticking out), the three sets of parallel cells were soldered in
series. I should mention how careful you need to be not to
mix
the positive and negative ends of the cells up if you try this.
They look
similar, with the positive ones only having a little dimple around the
side as you see above. I accidentally just touched two
batteries
the wrong way, and they instantly became dangerously hot though they
were only touching for an instant. If you follow in my
footsteps,
PLEASE BE VERY CAREFUL! I only install fully discharged cells
because of
this danger. Never open a battery unless it is dead or is
fully
discharged. (Also note, I am not responsible for anything
that
happens as a result of you reading this page. You must take full
responsibility for that.)
I made sure the temperature sensor on
the circuit board and the cell to which it was affixed with heat sink
compound had good thermal contact. Using new heat sink
compound insures this. Then
I put the top of the case on.
Fitting everything together was a little tricky. I was quite
careful not to short any of the cells out.
I
used electrical tape to hold the two
halves of the case together as a temporary measure. I checked
the
little green lights on the side, and they indicated that the cells were
discharged. I put the battery in a Pismo powerbook and it
charged. I was able to use this battery for three hours and
forty
minutes on the first discharge. The battery monitor only
estimated two hours though. The second or third discharge cycle,
I left it running with the screen
off most of the time, the hard drive was running the whole time, and I
got nearly seven hours before it automatically went to sleep.
This time, the battery monitor estimated six or seven hours.
I believe that you may be able to reset the defaults in the battery by booting into open firmware. (Hold the command and O F keys simultaneously while booting.) Then you issue the commands:
> reset-nvram
> set-defaults
> reset-all
The last command causes your powerbook to reboot. I didn't do these steps yet myself, but it might be a good idea.
After the tests with the battery were successful, I used super glue and a vise to reseal the battery.
After the first success, I proceeded to the next battery. I was surprised to find it was packed differently than the first one. I kind of think it was a Lombard battery instead of a Pismo battery, but I don't know. In this battery the circuit board was at the end of the battery. It proved much more difficult to re-assemble because there was very little extra room inside the case with this way of packing things.
Here are some photos of that pack. Much more care was needed to make sure that no extra room was taken with the new cells than was used with the old ones.
I believe that you may be able to reset the defaults in the battery by booting into open firmware. (Hold the command and O F keys simultaneously while booting.) Then you issue the commands:
> reset-nvram
> set-defaults
> reset-all
The last command causes your powerbook to reboot. I didn't do these steps yet myself, but it might be a good idea.
After the tests with the battery were successful, I used super glue and a vise to reseal the battery.
After the first success, I proceeded to the next battery. I was surprised to find it was packed differently than the first one. I kind of think it was a Lombard battery instead of a Pismo battery, but I don't know. In this battery the circuit board was at the end of the battery. It proved much more difficult to re-assemble because there was very little extra room inside the case with this way of packing things.
Here are some photos of that pack. Much more care was needed to make sure that no extra room was taken with the new cells than was used with the old ones.
Some photos of the process are shown
below:
There is a cable that needs to connected
from the back circuit board to the front one.
I tested the battery after mostly
reassembling it.
The silicone grease is needed because
there is very poor thermal contact without it.
A tip from Dieder Bylsma:
"A little tip I found useful for rebuilding the batteries is that you really need a battery shell that is easy to open. After going through quite a few shells, I've found that the ones that are easiest to open are the ones with the *large* serial numbers and barcodes on the bottom of the battery. Maybe this might be worth mentioning in your site? The other ones are a pain to open without completely destroying them in the process."
Thanks,
Rob
Other Notes of Interest
I wanted to do something similar with my early Powerbook G3 Series (Wallstreet) batteries, but I haven't found a good solution yet because the 17670 cells are quite expensive and hard to find. There are twelve of them in those packs. If you have a source that would provide a dozen new cells for less than $50, I would like to hear of it. The 18650 cells might work electrically, but they won't fit physically.A tip from Dieder Bylsma:
"A little tip I found useful for rebuilding the batteries is that you really need a battery shell that is easy to open. After going through quite a few shells, I've found that the ones that are easiest to open are the ones with the *large* serial numbers and barcodes on the bottom of the battery. Maybe this might be worth mentioning in your site? The other ones are a pain to open without completely destroying them in the process."
Two Years After Doing this Battery Replacement
It has been about two years since I replaced the cells in two Pismo battery packs. These batteries did not last as long as they should have. One pack is completely dead now, and the other only lasts about 30 minutes. I suspect that there is something that needs to be reset when the cells are replaced, but I'm not sure. If you have information relating to this, I would appreciate hearing from you.Thanks,
Rob