nitro2k01 wrote:BennVenn wrote:You can drop in a $4 boost converter and won't have to worry about battery quality/charge.
Are you sure? The GBP (like all GBs) has a switching voltage converter built-in. If the voltage cut-off of Nintendo's converter is set too high, it may stop batteries from working before they're fully discharged, and then a boost converter would help. But I thought the problem with the EMS cart was that it's using excessive power, so that it both drains the battery faster, and is using more power than a typical AAA battery can deliver when partially discharged due to ESR. In that case, no boost converter in the world would help.
curtinparloe wrote:In other news, I had a spare Li-ion 3.7V, 810mAh/2.997Wh which I jumpered up to the Pocket's terminals and it worked better than I expected. Is there a reason I can't/shouldn't put a single Li-ion AAA size cell with a dummy cell in the back?
That should work, better than using AAA batteries in fact. One thing to keep in mind: If it doesn't have protection circuitry built-in, you may want to be careful not to over-discharge it, or accidentally short it.
Yup, the GBP has a flyback converter, like the rest of the them. Flyback converters are designed with a target output current. Exceed this and the inductor saturates. I can give the tech details if you like, basically if you push the converter too hard, they go from around 85% efficiency to around 10%. Batteries rapidly discharge, 5v isn't maintained and the whole lot goes to custard.
The greater difference between input and output voltage puts more stress on the converter which is why fresh alkalines work OK and it rapidly gets worse as they discharge. ESR of an AAA alkaline is in the mOhm region, this is not the source of the problem, it is the converter.
Find any 5v output boost converter with an input of say 2-5v and wire it in. Pololu sell some high quality, cheap and tiny modules. They are more efficient than the original and battery life will actually increase.
This has been tested on the DMG with earlier revision PCB's when installing my VGA modues (~15ma additional plus another ~15ma for the flash cart). Even this 30ma additional load causes the converter to run extremely hot. You can feel the heat from outside the gb case. Adding the pololu buck/boost converter made everything happy again. Not a problem with the PIL versions.
With the Lipo, as nitro says if there is no protection circuit, don't do it or it won't recharge once its flat.