Making battery-operated devices rechargeable? How? You'd think that kits exist. Do they?

[CZroe]

I have several devices that I wish were powered by a high-capacity Lithium Ion battery instead of multiple AA or AAA batteries. Even NiMH batteries do not cut it because I basically have to buy twice as many as I need to make sure I always have a charge and carry it all around with so-called portable devices.

I've always imagined that if I knew a thing or two about electronics I could make a power supply that can swith to the AC adapter and recharge the batteries without interrupting power and make the entire thing with batteries self-contained in a battery compartment (With a hole drilled for the AC plug of course).

One such candidate is the JBL OnStage portable powered speakers. I looked as hard as I could for a super-long life rechargeable speaker set but all I could find were NiMH radios and such (Like the iPal). I finally bit the bullet and bought one anyway, thinking NiMH batteries would be adequate (Not that they aren't, I haven't purchased any yet). I'd like it to last at least as long as a typical MP3 player on a full charge and small LiIon should be able to pull that off better than four NiMH AAA. Hell, if it could power a laptop with a display AND powered speakers, I think it could power just the speakers for a good amount of time.

The other candidate is the charging cradle for my Sony MPD-AP20U external CD burner/DVD combo drive/MP3 DVD player. It's used primarily as an iPod replacement (5GB per $0.25 CD is hard to beat) and the charging cradle is also used for additional battery life (Up to 30hrs with 4 NiMH AAs + internal LiIon). I'd like to buy a second cradle and chop off the USB cord to use it as an extended-life rechargeable battery pack. I do not want to wear out the gadgets LiIon battery instead.

Because LiIon has so much more power in a smaller space, you'd think that there would be DIY kits all over to fit in battery compartments taking four of more batteries. WHERE ARE THEY?!

Heck, the Nintendo Wavebird controllers should have aftermaket battery packs with charging cradles capable of charging all four controllers by now but I don't see any.

 

[imported_rod]

The problem with LiIon batteries is charging them, and of course price. Most Li-ion batteries (such as mobile phone batteries) have charging circuitry built into the battery pack. This is because they can be easily damaged if they are charged/discharged too quickly. The are also suseptible to overcharging.

While they are more compact thatn NiMH batteries, they definately cost more per unit of energy. For example, 2.4V 1500mAh battery pack for my camera would cost $30 (all prices in $AUD), and another $20 for a charger. Luckily, my camera (a Richo), can also use 2x AA NiMHs. I bought 4x 2300mAh Nimhs, giving me a total capacity of 4600mAh, for only $22. I already had a charger, but if i didn't i could buy one for the same price as the LiIon charger.

Anymore Qu's?
RoD

 

[CZroe]

The fact that they are rechargeable should eliminate my cost concerns... Unless they cost more to recharge. I am aware that they require circuitry (It's VERY BAD for a LiIon to be completely drained and the circuitry prevents that also). That's why I'm hoping someone makes a DIY kit with perhaps consisting of the charging circuitry and selectable output voltages which can be charged without interrupting power (Like a typical LiIon gadget).

So I guess I'm asking: Where can I find basically a generic LiIon battery contoller that can output, say, 6v to replace 4 AAA batteries and take a small, obtainable LiIon battery?

 

[Zepper]

If your device has a jack for a WW(wall wart) to power the device off the AC, and the WW supplies DC to the device, then it would be fairly easy to make an external battery pack. Radio Schlock carries a selection of those external power connectors and battery holders in many configurations. I plan to do one for my digicam shortly - two AAs just don't last long enough...
. If you need gross amounts of power at 12V or less, you could adapt a UPS (or just a gel-cell UPS battery) to the purpose, or one of those things that are used to jump-start cars w/o needing to connect the cars together.

.bh.