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[amptor]

I came across a web site explaining how to replace the battery on a motherboard with a coin cell CR-2032 Lithium Ion battery so I'm planning on doing this to my SWC DX since the NiCD is leaking but it hasn't rusted the pegs onto the board yet.

After removing the battery from the SWC DX main board, use a solution of 50/50 water/white vinegar to clean up the leaked NiCD crystals.

It looks like what you need is a germanium diode because it will offer the least drop in voltage (0.3V) and will bring the battery power down to 2.7V when used, a CR-2032 3.0V coin cell and a coin cell holder. All of this stuff is easily obtainable through ebay or electronics stores.

In the circuit, you want to use the diode to make it so the wildcard's charging system does not charge the lithium cell. So from the positive terminal on the board, you solder the negative terminal of the diode and then the positive terminal of the diode goes to the positive of the battery. Then the battery's negative terminal solders to the motherboard. This way, power flows from the battery's positive terminal through the diode (with a small voltage drop) and out to the positive terminal on the circuit board and the charging system is blocked from the positive terminal on the board through the diode to the battery.

I'm not sure if there's an alternative battery that would be better suited for this. I have seen that there are rechargable lithium ion cells at 3.6V but I'm not sure if it is compatable to the nicad charging system. I don't think I'd want to attempt replacing it with NiMH because they lose almost all of their charge after a month. This nicad is still retaining everything that my wildcard had set up from 2 years ago and it has just been sitting on the shelf all that time.

[bigjohn6]

Hi....i think your walkthrough needs editing due to you keep refering to legs on the RESISTOR !!!!!!
Resistors are completely different components to diodes.....
Resistors ARN'T polarity sensitive .....and resist current.....
Diodes ARE polarity sensitive.....and allow current to only flow in one direction....
Your instructions could be misused if followed by someone with no electrical knowledge......

regards....

bigjohn6

[amptor]

I really don't have a clue why I put resistor when I was talking about a germanium diode.

[madman]

Now that I brought out my old SWC I think I'm going to wire up a coin cell battery into a socket. This should make future changes (if I'm still using it in 10 years) easier.

[SpooNMan]

Hey Amp. Do you have a link to the tutorial? I have been looking for a long while now on the best way of doing this and haven't come up with much as of yet. Or if you or Madman end up doing this please snap a picture or 2. Both my SWC DX and SMD800 batteries are leaking badly.

http://www.videogameobsession.com/videogame/hk/SWC/SWC_DX3201_Copier-09.jpg

http://www.videogameobsession.com/videogame/hk/SMD/SMD800%20Copier-04.jpg

The SWC DX SRAM saving is still working, but I want to replace it before it eats through the main board. I was going to replace with some cheap NiCD batteries, but I should probably do the coin cell holder 2032 mod.

The SMD battery is still untested.

Everything is working great and I still use the SWC pretty often so I really don't want to screw it up! As you (Amp) know my soldering skills are crap.

My original post here http://www.tototek.com/phpBB2/viewtopic.php?t=2274&highlight=

[madman]

I'd probably remove that SMD battery stat, Spoonman. It looks like a couple traces already have had some damage. Reminds me to check my 32m SMD, I almost forgot that has a battery.

[amptor]

I found this today, but I don't know if the charging system is compatable with it:

http://www.batteryjunction.com/lir2032----.html

looks rather cheap quality too but it is 3.6V like the battery on the wildcard.

spoonman, I lost the url but that's basically how you wire it in like I said above. I found my Ge diode that I bought to make a snes to pc gamepad adapter a long time ago but never built. So now all I need to do is desolder the cr-2032 holder from an old pentium 4 motherboard (pentium 4 is trash compared to a swc dx + 16bit snes and then put this thing together. Of course I have to buy batteries from ebay too since one battery probably costs $5 at radio shack easily.

I got a Pentium 4 motherboard here with a 1.7GHZ CPU and 256 megs of ram plugged into it, I'm going to salvage the coin cell holder from it and recycle the rest SWC DX is better than a 1.7ghz fully functioning pentium 4? yes. why? 533mhz bus stinks

Also if you want you can buy a new nicad off ebay but they are $9.99 + s/h I think.

To remove the NiCD battery, you might need to use a 30 watt iron, rather than a 15 watt you'd normally use to mod PS2's and Wii's with. I haven't tried yet though, but batteries tend to absorb heat when you try to desolder and a low heat iron might not be enough. Just don't ever use a solder gun on electronics, always use an iron. Solder guns I believe are 150 watt and can burn the PCB and totally ruin traces.

Actually come to think of it, you can probably cut the battery off the board with a pair of plyers if you're careful and then desolder the leads. You might be able to melt the solder fine with a 15 watt that way just as long as they used a low heat solder on that part of the board. There are different grades of solder.

[SpooNMan]

[madman]

How do those batteries hold up? What I've found is that you get what you pay for with batteries...within reason. I usually buy my 2032s at Fry's. Radio Shack is a little pricey, but what else is new?

[amptor]

Spoon, don't buy batteries from dealextreme sometimes over half of their batteries arrive dead. Buy from ebay instead, they have good quality stuff on there. I might buy a 5 pack of Energizers from there for $4 shipped if I can't find a better deal (in that, I don't really need 5 batteries right now). I have one spare battery but it only has 2.4V in it, I'll use that for the time being. I'm going to desolder that motherboard over the weekend and attach the cel and see how it works. I hope the wildcard doesn't mind having the battery removed. There might be a way to wire a couple AA in parallel with the NiCD before disassembly but it seems like that might be a little difficult. Might not be that necessary on this. I read that some old computer motherboards don't like having their battery fully disconnected though.

[madman]

Wildcards are fine with having the battery removed, they will still boot and play games fine. Just obviously won't keep the SRAM data

[amptor]

Cool thanks madman. I just hope this used cel has enough power to test it out until I get some more batteries in. I don't really feel like spending $5 at radio shack on just one cell

spoon, also you probably have enough time to cancel that order on dealextreme if you want to. their batteries are kinda shady. I ordered a 50 pack of batteries there once and like 44 of them were dead when they arrived.


I just modified my SWC DX and the leads weren't as bad as I thought. There was no rust or corrosion on the motherboard yet. So I just blew off the dust that was left on there from the battery.

An interesting thing too is that I had a custom message at the bottom and I had the icons set up as the pastel set and the wood background with the greenish yellow Super Wildcard DX logo at the top and after putting it all back together, none of that changed. So I didn't have to do any setup after I cut out the old battery and soldered in the new.

Also I noticed that the lithium ion coin cel holder can fit exactly where the NiCD battery was soldered. The leads match up right to the holes on the circuit board. But that doesn't leave room for the diode. I'm sure someone could figure out how to solder it in like that and put the diode elsewhere on the board.

[kyuusaku]

[amptor]

[Mystic_Merlin]