This is a quick and easy hack to replace NiCad canister batteries
common in Amigas, Commodore Bridgeboards, etc. with a lithium coin
battery. Please read through this whole document before starting...
The Amiga version of this hack includes an IFF of the diagram. The
PC-ised version of this hack includes a GIF of the diagram.

Why would anyone want to do this? First of all, it is a fairly
publicised issue lately that the factory issued NiCad canister
batteries eventually leak as they get old. When they leak, the
acidic fluid can cause problems as it eats through the traces on
your board. This happened to a friend of mine, he got his hands on
a rather nice used A3000 desktop unit, and found the battery had
leaked and done its deed, a hole was eaten into the PCB, opening
up connections, and rendering the built-in flickerfixer totally
useless. He was able to repair it enough to function on a 1084s
though with the standard video output signals. But it would be
nicer to have prevented this problem, right? This is why lithium
batteries are a more suitable option in my opinion. They won't
eat your computer when they get old.

A3000 owners should back up their NVRAM stuff, I believe there are
a few utilities on aminet to choose from to do this. I'm not
sure if A4000 owners need to worry about this or not. A2000,
A501, etc. owners shouldn't have to worry about this, you don't
have NVRAM. This hack can also be used by PC folks that have NiCad
batteries, I don't know what would happen to some machines with no
battery, the PC BIOS might forget something useful, like hard drive
settings or something, I don't have a PC so I don't know. Please check
your manual or as a techie friend or something.

We're getting close to the good stuff, so it's disclaimer time. This is
a hack. It will void your warranty if you still have one valid. Your
computer store might look at you funny if you take it in for unrelated
service someday when they see the battery job. Something could go
wrong and break your computer during this hack. A cow might fall from
the sky and land on you for doing this. Who knows all the possibilities,
but problems are always a possibility, even in a simple modification
like this. The diode might get put in backwards by mistake and might not
get noticed, even if you triple check it. No matter what may happen,
I take no responsibility for any problem, be it big, small, a fire,
a plague, famine, drought, it's not my fault. If something breaks,
it's "your bad", not mine. I'm happy to try and help you fix a problem,
but don't ask for any money or replacement parts, cause that isn't going
to happen. I take no reponsibility for typos, misunderstandings on my
part, missing vital information, outright lies, bad jokes, or the
phase of the moon. :p Well, now that that's over...

Here are the parts I used, I got them all at Radio Shack:
Diode - 1N914 Radio Shack 10 pack US$1.19 part# 276-1122
Battery Clip - Radio Shack US$1.99 part# 270-430
Battery - 3.6V coin/watch battery, clip can take either CR2025 or CR2032 type.

OK, the first thing to do is to open your computer up, locate
the blue NiCad canister, and desolder it. Be careful that you don't
lift any pads or traces as you do this, you'll need them intact later. :)
OK, now solder the diode to the battery clip's + contact making sure
the diode is on the right way (see included diagram picture). Diodes
are usually marked with a stripe on one end, this end is the pointed
side of the diode's schematic symbol, the + side. Now determine where
you will put the clip, it doesn't have to be right where the NiCad was,
put it someplace convenient  when you have to replace it in a few years.
Solder a wire to the free end of the diode and a wire to the - contect of
the battery clip. I recommend covering these solder spots and any other
exposed wire and diode leads with hot glue to prevent shorting anything
out when you stick the thing down where you want it. Solder the other end
of the wire on the diode to the + solder pad on your computerboard, and
the wire on the - contact of the battery clip to the - contact of the
computerboard. Now hot glue the clip where you want it, taking care not
to cover up any chips that get hot and you're done. Slip a 3.6V battery
into the clip, put your machine back together, have a beer to celebrate
or something like that, and get back to life as normal. That wasn't so
bad, now was it?

Some people may wonder why the diode is part of this hack because it
isn't already in the machine, and want to know why I told them to put
it there. This is to prevent the lithium battery from exploding when
the computer is turned on. NiCads get powered from the computer when
the machine is on so that they can recharge. Lithiums are NOT rechargable
like NiCads, and will have an absolute fit if power is forced through,
spitting icky black goo around, and could actually explode. This would
be bad. The diode prevents power from going into the battery, but lets
power go out of the battery when the computer is off, so the clock keeps
going, A3000 NVRAM remembers its stuff, and good stuff like that.

Hopefully you will quickly have a fully-functioning computer that is safe
from battery acid after about half an hour. Good luck, and for the Amiga
users out there, keep the faith!

Bill Toner II
wwt5491@rit.edu (good until December 1998)
amigabill@mailexcite.com
(716) 424-7791 located in Rochester NY, USA