My DIY USB external battery pack

[roony]

hi, im thinking of using the m2 atx connector to connect a battery similar to yours, but to a motherboard, like the integrated intel atom cpu & motherboard, since the board allows you to connect a car battery, a battery similar to yours should work

so far from your thread i think all i need to do is solder the positive end battery to the battery case, & connect the connector attached to the battery to the m2 atx connector, feel free to correct me if im wrong, or if its more complex then that

slightly off topic i was also wondering if you can power a pc 180w psu with batteries lol, i checked somewhere & it stated directly connecting batteries could blow it up, could your pack power up a pc 180w psu, or is it too much juice

the main reason im wondering is the size of the battery pack, if i can power the motherboard directly, you dont need the massive psu to carry around in addition to the battery pack

thnx

[Konrad Pierce]

You can plug any 12VDC power source into any 12VDC device you like, as long as the polarity is correct and the voltage is within tolerances (usually +/-10% or so, but more accuracy can't hurt).

The particular flavour, shape, size, and type of the actual connector aren't really relevant; at least, so long as you're not trying to stick a little battery pack into a 10kW transmission line or something. Just make sure the polarity and voltage are correct. Don't plug this device into AC power, since it has no transformer, rectifier, or filtering capabilities and will surely blow up in a slightly disappointing fashion.

I would never personally solder directly on a battery contact unless I had absolutely no choice. Better to fashion some other kind of connection.

[notoneoftheabove]

Marco,

What value did you use for R1 and what current were you trying to limit to? I assume the values would change depending on the specific batteries used?

Nice project and thank you for your efforts.

Louis

[raspabalsa]

Hi Louis

What value did you use for R1 and what current were you trying to limit to?

I don't remember the value of R1 (never wrote it down). I can open the pack and check. My goal was to limit the charging current to about 1A, so for a supply of 9V a resistor of 9 ohm wold be needed.

I assume the values would change depending on the specific batteries used?

Yes. The charging current depends on the capacity of the batteries, the charging time you want to use, and the current rating of the power supply you want to use to charge.

Nice project and thank you for your efforts.

Thanks!

The pack no longer looks as pictured above. A couple of months ago I made some mods, mainly replacing the 7805 fixed VR with a LM317 adjustable VR. This gives the pack a bit more power efficiency. I also replaced the heat sink with a larger one mounted externally. I can't post pics now (I'm traveling), but maybe tomorrow I'll post some.