will this work?

[Hiroshirou]

http://www.rason.org/Projects/cmosbatt/cmosbatt.htm

it looks great if you dont like losing your saves when the battery dies sometime in few years....

 

[Curtis]

I don't see why not. Bear in mind it won't be "permanent" though, just better than a button cell. Rechargables have limits to the number of times they can be recharged.

My only concern would be perhaps the extra strain on the 5v rail. It might be too much for the PS, although this would seem unlikely.

 

[ExCyber]

The page says that the 10O resistor current limits the circuit to 50mA, but I don't think that's correct: 5V/10O = 0.5A = 500mA.

edit: never mind, he said charging current, so the battery enters into the equation too.

I have other concerns about the safety of this circuit. Most notably, I think it may create an voltage spike when switching on/off. I'd need to look up some battery specifications to be more sure, but it appears that nothing prevents the voltage from going above 3.3 if the battery's resistance becomes too high (the battery acts like a variable resistor, so the circuit would act like a variable voltage divider), so it seems that the voltage could spike between the time that the battery controller switches over to the battery circuit and the time that the 5V rail discharges.

On the other hand, this might not ever happen in practice, or the spike might be confined to such a short timeframe that the circuit isn't materially affected by it. But I see nothing that stops the spike from happening in the first place...

edit: it occurs to me that the overvoltage condition should occur while power is on as well, and he's been using it for months. So disregard my rantings I guess. :looney

 

[gameboy900]

Biggest problem I see is that whenever the power is on the battery is constantly charging. Overcharge any rechargeable long enough and it can burst or even explode.

 

[Alexvrb]

I don't see why people are obsessed with finding "permanent solutions" anyway. Is it so hard to get a cheap CR2032 now and again? PCs use em too.

 

[M3d10n]

...and you can keep your saves if you schedule the battery replacing wisely, and do it while your Saturn is on.

 

[ExCyber]

Biggest problem I see is that whenever the power is on the battery is constantly charging. Overcharge any rechargeable long enough and it can burst or even explode.

It seems also like the voltage should be too high (seems like there should be two diodes in series to drop it to 3.6v), but this guy knows more about analog/power electronics than I do, so I'm probably missing something.