diy pcc ?

[mrb]

I already built a 5 volt passthrough....

but i would like something with around 3.7 to 4.2 volts that i can charge from my computer and be able to unplugg and use on the go also...

i already thought i knew what i needed,, but after surfing the web all day, I have information overload. just need a little nudge in the right direction again.

i will build this in a battery box, fairly small... maybe 2 - double AA size...

will i need
resistors of any kind for the recharging end or simply wire in the usb to the pos and neg.?

what would the proper batteries be... i know i need protected and high milliamp... do i need two? or would one suffice.

i shouldn't have to worry about damaging my computer with this would I?


on the other side,, i was thinking if i could also mod a penstyle battery to be a rechargable usb passthrough.... the only thing i can see holding that one back is the milliamp hours... mine are only 280mAh...

i appreciate any input.... I know i have seen the answers to my questions,, but i can't remember where. I saved a bunch of links,, but now none of them make any sense to me..... help

[mcquinn]

I am pretty sure you can just run the 5 volts from a usb port to the + and - of the battery, if you use protected batteries.The circut board on the battery will keep it from overcharging.You can use any batteries you want.The 10440 lithium batteries fit a AAA battery box but the smaller size box makes it a challenge to get the switch in.The 14500 lithium batteries fit AA battery box and they are much easier to work with,14500's are 900 mAh.The easiest thing would be to just find one of the 510 passthrough's with the battery box inline .For less than $20.00 you have a 3.7 volt passthrough and you can unplug it and use it off the battery .The 10440 battery is 360 mAh's so it would be roughly equivalent to 1 1/2 mega batteries.I use one of these and a 5 volt wall wart to power my homemade passthrough ,I adjusted it to 4 volts and can switch it to just under 5 as it loses a few tenths of a volt .If you use a 6 volt wall wart you can get 5 volts . Adjustable breadboard power supply [v1.0] ID: 184 - $15.00 : Adafruit Industries, Unique & fun DIY electronics and kits

[mrb]

thanks, i will check it out