Replacing battery on a a500 memory card...

[Tomas]

Can you solder on a standard pc clock battery? I have few batteries that i picked out of some old portable compaq armadas.. All info it has is: Sanyo Mn 02-Li ce 3 volts. Looks like a standard newer pc battery, just that it has wires/plug soldered on it.

Will this work fine? will it even charge?

Thanks in advance

[Cyberus]

I'm also wondering the same thing. I have an A500 ram expansion here with a chunky Varta 3.6V attached...unfortunately it may be too late for it anyway, as it has started to fur up

[Tomas]

I am affraid of that also.. last time i powered it up, it did not charge very well, few days without power and the clock would reset. And that is like a year ago, did not think of checking the cards back then. So i better get it done soon.

[Orjan]

If you plan on placing a on-rechargable NiMH battery on there ( which most PC batterys are ) then you will first have to disable the charging circuit, or the battery may, if you are unfortunate, explode. There are instructions on Aminet to do this, if I remember correctly the filename is "lithbatt.lha". I guess it would work on memory cards aswell.

Or you could do what I did. I bought a rechargable NiMH battery and soldered it into my A3000. Works like a charm...

[Tomas]

what exactly is the difference between: on-rechargable NiMH battery and rechargable NiMH battery  :-?

Or did you mean none rechargable? I thought all was rechargable

[aardvark]

If you plan on placing a on-rechargable NiMH battery on there ( which most PC batterys are ) then you will first have to disable the charging circuit, or the battery may, if you are unfortunate, explode. There are instructions on Aminet to do this, if I remember correctly the filename is "lithbatt.lha".

I think he means if you install a lithium battery, not a NiMH. (which are perfectly safe) :-D

[Orjan]

It was dark out, so I´ll use that as an excuse!

First of all, I didnt mean NiMH, ofcourse I meant Lithium, and second of all, the "on-rechargable" should, ofcourse, be "non-rechargable"...

[Castellen]

The specifications for the MSM6242 real time clock's input voltage is from 2V - 5.5V.
If you disable the charging circuit, you can use ANY non-rechargable battery so long as it falls within this range.

Alternatively, you could simply use 3 Ni-Cad or Ni-MH batteries in series, which will give you a nominal voltage of 3.6V.  The capacity of the battery does not matter, though obviously you're limited to the phyical constraints of the A501.

To disable the charging circuit on the A501, simply lift one leg of resistor R911 (470 ohm, so will be marked yellow-violet-brown), or lift either end of diode D932.

For schematics of the A500 and A501 look here:
http://amiga.serveftp.net

See the schematics section.

Anthony.