Coin Battery Hack ... my findings

[melott]

This is what I found in several days of playing around
with the Battery Backed Clock in my A2000 rev 4.4 MoBo.
I'm no Electronics Wiz so feel free to comment, debate
or dispute my findings.

I had intended to replace the barrel battery with a
coin battery. I stripped a battery mount from an old
PC MoBo and bought a new battery (a CR2025 battery).
What is the difference between a CR2025 and a CR2032 ?

I D/L'ed the coin battery hack from Aminet and followed
the instructions (not much to it).
What I found was the coin battery (3 volt) doesn't seem
to have enough power to hold the clock circuit.
I first thought maybe the circuit is bad so I installed
a standard Amiga barrel battery (3.6 volt).
The circuit worked fine. It held time and date for 24 hours.

Next I tried a cordless phone battery (3.6 volt). Again the
clock circuit held time and date for 24 hours.

My conclusion is the 3 volt coin battery doesn't have enough
power and the hack is a waise of time.
It seems that the clock circuit needs the extra point 6 volts to work.
 

[melott]

MskoDestny wrote:
Perhaps this is a stupid question, but are you sure you installed the diode in the correct direction?

Yes... I installed the diode correctly and used the one
mentioned in the hack (RadioShack).
It starts loosing time as soon as the computer is shut off.
After about 5 minutes the time is gone but the date will
hold for about 10 minutes.

[melott]

MrZoon wrote:
I'm about to try this on a parts machine before attempting it on my two in-use A3000s. Any other advice?

At least one of these machines has some acid damage, but just a little. Is there some kind of stuff I could put on the damaged area to stop further errosion? I'm thinking baking soda, or something like that.

Pete

If you go the coin battery route, I'd be interested
in your results....

As for cleaning ... I used electrical contact cleaner.
Can be bought at most any hardware or auto parts.
I sprayed the area then used a stiff brisseled small
paint brush to scrub the area then spray again to clean.

[melott]

Tomas wrote:
is 3.6v phone batteries safe to use without a diode or a similar hack? Can you just solder it on and expect it to work?

I don't see why not........
Phone batteries are rechargeable and they are the same
voltage as the barrel battery.

I had another A2000 (sold it) with the phone battery
hack. I used it for almost a year before I sold it.
It worked fine. The only problem is finding a place
to mount the battery. On the A2000 I soldered 2 long
leads to connect the battery and then made a strap
that held the battery to the front of the machine case
between the Zorro slots.