DIMM board battery questions answered.

OldFoo · Post by **OldFoo** » Thu Jan 11, 2007 2:35 am

Take a look at this wiring diagram shown from the website you referenced:

There are only 2 connections to the charger (P+ & P-). The Naomi uses 3 wires to charge the battery. I think this was

done so that each battery is powering each DIMM separately. This would eliminate the need for circuitry to split 7.2V

evenly (each dimm uses 3.3V) that might otherwise reduce the battery efficiency (how much time each charge lasts).

In other words, this is the pcb that comes with the pre-wired after-market battery. It will not work. Any attempt to

use this pcb in the Naomi will ruin the Dimm and possibly the battery.

OldFoo · Post by **OldFoo** » Thu Jan 11, 2007 4:05 am

Ah, OK. Thanks. So there's no getting around cutting up the SEGA battery then. I was hoping to be able to make a couple to keep on hand, but that wouldn't be possible without spare PCBs.

Can you do a simple diagram (or just describe it) illustrating how the SEGA PCB is wired to the batteries? As I mentioned, I'd like to know what to expect before I cut up the only battery I have, and you are the man with the facts!

Also if you use a higher capacity battery, then the charge should just last longer, right? There shouldn't be any negative aspect to that as long as the voltages are correct, right?

OldFoo · Post by **OldFoo** » Thu Jan 11, 2007 4:55 am

Yes, if you get a battery with a higher mAh, the battery will last longer. The official Sega battery has 1400mAh and can go

as high as 2400mAh with the aftermarket types--maybe more. It will also take a little longer to reach a full charge.

Overnight should do it.

The Sega battery I opened is at another location, so I won't have access to it until the weekend. Sorry. :smt102

I'll post a pic then if you want. I suppose that since you are posting about replacement batteries, is that your battery is no good.

Is there any particular reason why you don't want to cut it to find out? You'll have to anyways. :smt027 :smt081

OldFoo · Post by **OldFoo** » Thu Jan 11, 2007 2:54 pm

joshua3dg wrote:The Sega battery I opened is at another location, so I won't have access to it until the weekend. Sorry. :smt102

I'll post a pic then if you want.

I don't mind waiting if its not too much trouble for you to post a pic.

joshua3dg wrote:I suppose that since you are posting about replacement batteries, is that your battery is no good.

Is there any particular reason why you don't want to cut it to find out? You'll have to anyways. :smt027 :smt081

Well that's the thing--my current battery seems to be dead. It looks old and doesn't seem to hold a charge. But I've yet to leave the system on for an extended period of time. So, I have two reasons: a) I want to try leaving the system on for 12 hours or more, and b) I'm just being cautious. I'm very new to the tech end of things, so I don't want to destroy the thing in a clumsy attempt to see how it works. :smt087

OldFoo · Post by **OldFoo** » Thu Jan 11, 2007 4:45 pm

Ah, I see. That's understandable. I'll post a pic of an open battery this weekend.

OldFoo · Post by **OldFoo** » Thu Jan 11, 2007 4:50 pm

Thanks!

OldFoo · Post by **OldFoo** » Sat Jan 13, 2007 12:07 pm

someone else tried a battery swap and it works fine according to him. (it's in french)

http://arcade.emu-france.com/forum/inde ... n#msg31179

OldFoo · Post by **OldFoo** » Sat Jan 13, 2007 6:07 pm

Here is a borrowed picture of the original Sega battery without the white outer covering. (can't find my camera :smt013)

Link updated!

The way the person in the french forum hooked up the battery is strange. He removed on of the 3 wires and only used 2 in the final assembly. I'm not sure if this way is supposed to work, but I would imagine the other wire was used for something...? I would say this person is pretty brave for trying this method. He could have fried something. However, if this did work, it would mean that the original battery pcb wouldn't have to be de-soldered. Perhaps someone would be brave enough to try the alternate

wiring? :smt102 :smt090

OldFoo · Post by **OldFoo** » Sat Jan 13, 2007 9:52 pm

Hey joshua3dg,

Do you have a larger version of that image? If there's supposed to be a link then it's not working.

I tried leaving the system on for about 18 hours--no dice, DIMM battery is definitely dead.

OldFoo · Post by **OldFoo** » Sun Jan 14, 2007 12:41 am

I updated the image link. I missed the link location. :smt005