Tennokoe Bank Hucard miracle

[GTSS]

Can someone explain to me how is this possible?

I have a Tennokoe Bank card which until recently had no idea what it was (embarasing fact: I thought it was some kind of Japanese game having to do with a bank called Tennokoe LOL. I only have the card without the case so I had no clue as to what it was).

So when I discovered what it was I thought.... hey this is useful.
Beside the fact that it seemed to work I thought what the heck... lets replace the battery which must be dieing for sure.

So I opened it up carefuly, the battery seemed factory as you can see in the picture. No signs that it has been previously replaced and the double sided tape is factory too according to what I have seen on the net (cleaned up in the picture).

So before I remove it I thought "lets measure the voltage as it must be close to zero".

I measured it (on-board) and it turned out to be 3.11V. Now how on earth can this be possible after 30 years?

[majors]

So before I remove it I thought "lets measure the voltage as it must be close to zero".

I measured it (on-board) and it turned out to be 3.11V. Now how on earth can this be possible after 30 years?

Superior NEC engineering! Or as the old men say, "they don't make 'em like they used to"

 

[Necromancer]

Wow, it must not draw much of anything at all.

[GTSS]

Wow, it must not draw much of anything at all.

But I've read of cases of dead Tennokoe banks (by battery obviously).
And even if the Tennokoe draws very little power, a stand alone battery should have gone dead due to self discharge after 30 years. I read battery specs that a self discharge of 1% per year is to be expected.
So if the battery isn't already dead, it should be pretty close to that.

The voltage is close to a brand new one's. I read that a new 3V battery's voltage should be between 3 and 3.3V, and this one is 3.11V !!

[Necromancer]

Maybe it gets recharged when used?  I know rechargeable button cells exist, but I wouldn't think they did back then or at least weren't what was used in tennokoes.

I bet your card is haunted!

[GTSS]

Maybe it gets recharged when used?  I know rechargeable button cells exist, but I wouldn't think they did back then or at least weren't what was used in tennokoes.

I bet your card is haunted!

CR2320 is a regular lithium battery, its not recharchable.... not to mention that it hadn't been used for ages.
And even when you use it, its not for more than a couple of minutes, just to tranfer the saves.

And because I see many people having trouble putting the cover back together and make it stick.... I used transparent gel dots, the brand is Bostick (Glu Dots), these are thin and did an excellent job.
https://www.amazon.com/Bostik-Removable-Sticki-Dots-10mm/dp/B001P5QMAQ