Need a 15Wh battery that can charge in 20 minutes

[Dietrich]

I am looking to build a circuit that has a battery which can be charged in 20 minutes (so it can charge at a rate of 9 amps) with a energy level of 15Wh. Ideally the battery would be a 5v battery and have a capacity of 3000 mah. The discharge of the battery can be much slower (.5 amps).

I would like to keep it a fully DC circuit and if needed I could use a battery that is 12v (or similar) if those do a better job of being charged at the higher rate (I guess with a 12v battery it would just charge at 3.75A). I assume I would just need a transistor or resistor to step the voltage down to 5v for use.

I have a background in Mechanical Engineering and this is just a side hobby project. Any help is greatly appreciated. Looking for help on: feasibility, issues I may run into, types of batteries to use (Li-ion?) and voltage to use.

Thanks!

 

[Externet]

I would use an off-the-shelf power tool (drill) LiIon battery pack and its charger, and regulate the driven device input to 5V with a LT1083-5 or similar regulator.
A second battery pack kept charged decreases charging time to zero.

 

[Bluejets]

Chargers used for radio control equipment have a broad range in many aspects.
Although 5v might be a bit odd there.

 

[Dietrich]

I considered going with a 18V or 20V cordless drill style battery, but I haven't verified the specs yet (charge rate in Amps?) and those chargers are 120VAC. I guess I could take one apart and skip over the inverter and just try to do 18V charging to it (in place of the 120VAC) but I'm not sure what all is involved in that. I'll also look at the radio control equipment as well.

 

[hevans1944]

Believe-it-or-not, there is actually a useful and informative Instructable that you can use to answer your questions! And here is another link with a lot of useful information.

 

[Externet]

Skip over what inverter ?

Feeding 20?VDC alone to charge a pack will lack temperature and failure safety control lines. Its internal controller will refuse to charge the pack.

 

[garublador]

I have no idea if it's feasible in your design (it probably isn't), but Qualcomm has a "quick charge" technology for Li-Ion batteries that's close to meeting your specifications:

https://www.qualcomm.com/products/features/quick-charge