Hacking Can this be an alternative to a battery?

[Alex4nder001]

It would be great to own a GBA flashcart and not EVER have to worry about it dying or games not saving. Well, almost never.
I bought an EZ-Flash Reform less than three weeks ago, and already the battery died and I can't use it. I could always replace the battery, but with the very short life it could get expensive...
I was thinking maybe instead of powering the SRAM from a battery, I could use the DS's battery instead. What I mean is by connecting the battery clip directly to the 3v3 and GND pins of slot-2. Whenever I want to write the game save to the SD card, I can just soft reset the EZ-Flash (L+B+UP), and it will then save to the SD before I switch off my DS. Sure, it may be a tad inconvenient, but it's still way cheaper.

The only problem I have in mind is that I don't know if the SRAM will take 3.3v rather than the 3.0v the cr1220 battery provides. Will I fry the SRAM chip? (Not that an additional 0.3v will make much difference, considering that the rest of the circuit board uses 3.3v). But if it will, then there is another problem: What resistor do I need to use? According to Ohm's law, the current is the voltage divided by the resistance (I = V÷R). I don't know how much current is flowing through the EZ Flash, and whether it will change or not.

Oh and one more thing... can I do the same on an EZ-Flash 3in1?

Sources: Ohm's law GBA pinout 1 GBA pinout 2

 

[Technicmaster0]

It doesn't save on it's own if you use softreset? It did back when you had to patch the ROMs manually.
I think that you would normally use a voltage divider to get the 3.3V to 3V, not a single resistor.

 

[Alex4nder001]

It doesnt even boot without a battery. Just a black screen /white screen

 

[Roamin64]

If I were you I would replace the battery. Most likely the battery was in that cartridge for ages before it got to you. If you replace it once with a brand new battery and it quickly dies again, I would then blame the flashcart. Wiring the 3.3v volt to the battery will not cause any problems at all. A 3v battery isn't exactly 3v when it is shipped brand new. It is always a bit more, at least 3.2v, usually a bit more. Also using 2 resistors as a voltage divider would not be the best way to obtain 3v from 3.3v. It would be far more simple to use a low voltage diode (schottky diode) in series with the battery positive side. If you use a schottky diode , 0.3v will be taken by the diode to work , leaving 3v left. Definitely the easiest way to drop 3.3v to 3v. Most common diodes have a 0.7v voltage drop, but the schottky are 0.3v.

 

[steelseth]

I have 2 reform cards, 1 definitely for over a month and no problem with the battery or anything else.
You can buy 5 cr1220 for $1 so even if you need to replace it every month or so it would cost $3 a year ?

 

[how_do_i_do_that]

CR1220 batteries on amazon will only cost you around £ 2.00 for a 1 battery pack. Your not buying a battery with tabs or anything.

https://www.amazon.co.uk/s/gp/searc...off&rh=i:aps,k:cr1220&keywords=cr1220&ie=UTF8

That is pretty much an addon item even you can afford.