TDS 500K dead battery, pictures of the inside of the card and the battery.


Well, I am hoping the rechargeable battery is actually the problem. The card 'PINIT" correctly and when I follow the TDS recharging suggestion:

Set alarm to wake calculator every 299 seconds, for 24 hours, thus recharging the TDS battery. This gives me about 40 hours of memory on the card with the calculator 'OFF', not the 30 days that it should.

After cycling the battery with charge up and run down cycles there was no change in the charge holding rate. The only option is to take the card apart:

1 heat the card with a hair dryer to soften the glue holding the metal label.

2 using a knife peel the label off, heating as necessary as you go

3 remove the battery

4 replace the battery

5 glue the back label in place

Interestingly I tested the card with the back off and the battery not attached. The card was "PINIT" and I archived the programs resident on the 48GX to :5:BU (port 5 label BU for backup).

The card worked and I could restore the calc from the archive using restore, port 5 and 'BU'. Of course I did not turn the calc off during this operation as there is no battery attached. This proved that my 'operating on the card' did not damage the card.

Do to the recharging system built into the card I cannot replace the battery with a regular lithium battery. I was thinking of this by creating a hole in the back label where the battery sits, installing a battery holder and voila, a replaceable battery system. But can't do it due to the charging logic of the memory card.

Here are some shots:


Geoff; Thanks for the beta. I may need to do that someday, so i saved your post.


Thanks and use it well!

Finding the battery is a problem. One source in London,England quotes 10 pounds per battery ($15 Canadian).

No one in town will import them for the low demand although they appear to be the battery of choice for Casio solar powered watches.


Cheers, Geoff


Panasonic makes a ML-2020 size lithium rechargeable that might fit.




Edited: 2 Apr 2009, 9:44 p.m.


Thanks Katie,

I will get the dimensions as this is a tight fit. The label does not have to go back on once the new battery is in place. The internal cover of the HP is well protected.

Cheers, Geoff

Edited: 2 Apr 2009, 11:46 p.m.

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