How do you use modern rechargable battery packs on the Game Gear?

Because 99% of the time they aren't even 1000mah plus IIRC they are 3.7v each

 

no

 

While the maH can vary from whats actually posted, AA's are 1.5v each

 

oops I didn't read, I thought you meant AA sized rechargeable lithium ion cells..like this

High capacity AA's are a bit of a money pit IMO......................

What is the internal size of the original battery pack?

You could go with 4 iphone 5s batteries in parallel, to give you a little over 5000mAH @ 3.8v, you would need a boost circuit to jump up too 8~9v..

The reason I say iPhone 5s batteries is they are very slim Li-po packs and most of them around are genuine cells..

Either way you are going to need to incorporate a charging circuit for any lithium batteries...

 

And yet, you've just posted a pic of two 18650 cells, that are nowhere near the size of AA's.

 

I give up trying to help then..

 

Currently looking at doing an internal battery mod with the following;

http://www.ebay.co.uk/itm/400967105449
http://www.ebay.co.uk/itm/271461504192

May need to look into getting a voltage booster but 7.4V should just about do it.
It will also charge from the DC jack already in the console.

 

Excellent. Can't wait to see that.

 

@MachineCode

Will keep you updated, won't be for at least a week though as I am off on a boat trip for 7 days, and these items are coming from China.

 

fully charged you'll have 8.4volts.

the game gear appears to shut down at 5.5volts, which might be a little bit low to keep the batteries safe from over discharge, but you could always chuck a diode in series so it shuts down sooner.

 

@AmmoJammo

I did have an thought about this but I wouldn't know were to start with that regarding what values to use. I only have a limited knowledge with electronics that I have been adding too over the last year with all these console repairs and mods I have been doing. I did use some shokky diodes with a 5V usb charger I made but that was to stop current going back into the circuit. Would I use the same sort of thing here ?

 

Turns out these batteries have a protection circuit built in - over discharge protection - 2.75V-3.0V (single battery)
So a diode/Mosfet shouldn't be needed.

 

The cells you have ordered do not appear to have any protection circuit built in.

 

Oh, looking at the spec sheet for it, it says the following;

1 Nominal Voltage: 3.7V
2 Nominal Capacity: 1500mAh
3 Cycle life time: ≥300
4 Cut-off discharge voltage: 2.75V-3.0V (single battery)
5 Charge Cut-off voltage: 4.28±0.025V (single battery)
6 Operating Temperature: Charge:0℃ ～ 45℃
Discharge:"-10℃ ～ 45℃"

 

Those specs aren't listed anywhere in the ebay listing you linked us to

The charger PCB seems to suggest that it has battery protection, but I'm not entirely convinced, as it seems too simple for that.

 

Yeah lol, I had to do some research to find the data sheet. Will test it out anyway and let you guys know. I have about 20 Game Gears that are beyond repair so will test out on that first.

 

But you found the specs for cells that aren't the ones you ordered

BTW, those won't fit into the original battery compartments.

I'm kinda warming to the idea of using multiple cells in parallel, rather than the two in series, then boosting the voltage, simply because it means the unit could then be recharged from a usb cable, rather than having to have a specific power supply.

Keep in mind that the original power supply is unregulated, and I imagine the two cell charging circuit won't like too much over the 9 or 10 volts they specify... and lithium cells can end badly if improperly charged...

 

I ended up ordering some 14500 lithium cells, although I went for the cheapest ones possible, so I expect them to be junk.

None the less! I've used some Ultra Fire 900mah cells before (and they appear to meet their rated capacity), so running six of them, means 20watt hours (doesn't matter how they're wired for this number)
Compared to some 2000mah Nimh batteries, which would give 14.5watt hours...

Of course, as pictured above, two 1500mah, 3.7volt lithium cells, only gives 11watt hours...

As I plan to run all six 3.7volt, 14500 cells in parallel, so they can be charged from a 5volt usb supply, it also means I can shoe horn another cell or two into the GG inself for more capacity

Basically! If I can fit eight cells total, I'll have about 26watt hours, which gives the same capacity as running an external pack, with 3.6ah nimh cells