Is replacing game save batteries BEFORE memory loss possible

Post by **Scooter** » Fri Jan 18, 2008 12:00 pm

I have a couple of old Genesis games with game saves still on them. The batteries have to wear out eventually and I'm actually quite impressed they are still working. I know that the act of removing the battery and replacing it with a new one would wipe the memory but surely there is a way to avoid this memory loss.

Why couldn't the old battery simply be left in place and a new battery installed on top of it? By wiring positive to positive and negative to negative the same 3V electrical input would be maintained and as the old battery wears out the new one will be there to maintain the electrical input. If my old ones have lasted 10+ years, surely a new one would continue to maintain the memory for about as long. It seems the only trick would be to insulate the new battery from making contact with other components on the board but a little electrical tape should do the trick. There is plenty of space inside the typical cart for a small extra battery so such an operation couldn't be too hard.

I'll admit that with a cart which has already lost its memory due to a bad battery removing the old and soldering or clipping in a new one in its place is the best solution but there just has to be a way to maintain existing memory if it's there through a little extra effort. I have a Sega CD RAM cart which has a few useless saves on it so I think I'll get a new battery and see what I can make happen. If the memory is lost there no harm done.

Can I get these lithium batteries at any Battery Patrol store or some similar store? Walgreen's carries a wide variety of button batteries but I don't know if they will have these batteries in a lithium version. I'm pretty sure the lithium nature of these batteries is why they last so long.

Post by **aaron** » Fri Jan 18, 2008 12:33 pm

save states.

Post by **Curlypaul** » Fri Jan 18, 2008 12:35 pm

I've never tried this, but how about soldering a pair of wires to a good battery, then making contact somewhere on the board while you unsolder the old battery and replace it with another, then remove the wired battery.

Just a thought but dont get mad if it goes tits up on you as I've never tried it

Post by **Scooter** » Fri Jan 18, 2008 12:42 pm

Curlypaul wrote:I've never tried this, but how about soldering a pair of wires to a good battery, then making contact somewhere on the board while you unsolder the old battery and replace it with another, then remove the wired battery.

Just a thought but dont get mad if it goes tits up on you as I've never tried it

Well, that very concept crossed my mind but then it occurred to me, if the temporarily installed battery used off to the side to maintain memory during the operation won't hurt anything, why not simply install a replacement battery in the same manner and just leave it there?

Post by **SnowKitty** » Fri Jan 18, 2008 12:47 pm

Curlypaul wrote:I've never tried this, but how about soldering a pair of wires to a good battery, then making contact somewhere on the board while you unsolder the old battery and replace it with another, then remove the wired battery.

Just a thought but dont get mad if it goes tits up on you as I've never tried it

this is how they replace suicide batteries in CPS1 boards. it should work just fine doing it like that.

Post by **Niode** » Fri Jan 18, 2008 3:30 pm

I agree, this is the safest way of doing that procedure. However somebody on this forum (i think it was lordofduct) was talking about replacing the battery (which i assume is a cr2032?) with a rechargable lithium battery in their saturn. So maybe you could follow the same procedure and do that instead (it would mean playing the game everynow and then to keep charge. I'm not sure if it will work though. It would be interesting though!

Post by **Scooter** » Fri Jan 18, 2008 8:04 pm

I did a little experiment. I wired a fresh CR2032 batter to some leads. I then attached the leads to the appropriate sections on my working Sega CD RAM cart. I attached positve to positive and negative to negative. The voltage remained at 3V. I then checked the RAM cart and all the saves which were there before are still there.

So, the idea of temporarily wiring in a "place holder" battery while permanently replacing the battery would work as long as the place holder battery does not loose contact while replacing the main battery. I also don't see why the place holder battery couldn't just be left "on top" of the existing old battery and calling it good. The voltage doesn't rise and no harm is done to the cart or the saved data. Can anybody tell me why two batteries wired in one on top of the other might not be a good idea? I can't see any problems.

Post by **elph** » Fri Jan 18, 2008 8:20 pm

Both ways work. I would just order online. When I checked, batterybob.com or something like that had a 5-pack for like $8 shipped. Typically the stores charge about $6-7 per battery.

Post by **lordofduct** » Fri Jan 18, 2008 10:55 pm

it depends the way you placed the battery on the other.

If you place it in parallel with it you get the same voltage, and twice the amperage (in this case longer battery life... used with things like laptop batteries).

If you place it in series, you'll get the summed voltage, this is how you run most AA batteries and the sort when you want some higher voltage out of a bunch of 1.5v batteries.

A rechargeable battery in this case would require a little more hunting down (yes that was me who made the rechargeable for my saturn). You'd want something with a longer life span and a smaller size (portable phone batteries are kinda large). You can get rechargeable Lithium Manganese cr2032 batteries... make sure it says rechargeable, although lithium manganese 'should' be rechargeable, you want to make sure it really works out properly.

Then to recharge it you can wire up a little charger for it, making one for isn't that hard, you can charge it via the 5v pin off the cartridge when it is plugged in and turned on... or use a plug for it. You'll of course need the proper diode and resistor. You should check the amperage output of the rechargeable and compare it to the constant pull of the cart on the battery. That way you'll know how often you'd need to recharge it.

But, meh, that takes a little work and you need some tools that cost some money... so just go with the series part. Keeping it running in parallel probably won't hurt it... but what about when that battery dies? Stick another battery on top of that?

Post by **Niode** » Sat Jan 19, 2008 12:56 pm

Thats what I thought. Rechargable battery would be a fiddle to get set up but worth it in the long run, as in never having to replace the battery. Lets face it how many games do you really need battery back up on on the genesis?

Lord of Duct would you mind writing a guide for the rechargable saturn mod? I'd really love to have a crack at it!