Cheap, lightweight, ~24v batteries?

[zahc]

I'm building a portable apparatus that needs greater than 12v and around an amp of current. I could use two 12v, 1.3Ah SLA batteries, which would be around $20 but that would weigh 2.6lb which is a lot. I could use a ton of AAs, but rechargeable would be $40+ which is too expensive and I'm not sure alkalines would drive enough current. Is there a common, cheap source of ~24v batteries that I don't know of? RC car batterys, maybe? I thought about buying 5 or 6 of these and wiring them together.

http://www.allelectronics.com/make-a-store/item/LBAT-60/RECHARGEABLE-LITHIUM-ION-BATTERY-4.2VDC-900MAH/1.html

I have a lithium charger, but it sounds like a lot of fiddling if there is some other alternative.

[sanglant]

here's a site to play with all the old sites i knew for batteries are gone. try asking again later.

[TMM]

the one thing i thought of is those batteries for cordless power tools. they're usually 12 or 18 volts... don't know about amps though. and they're rechargeable.

tmm

[Nick1911]

Depending on how big it needs to be, and how much work you want to do... dc-dc converter?

How about a charge pump, with a LM7824 on the output?

Then you could use a standard 12v SLA; or lith-ion batteries for a rc car.

[mtnbkr]

cheap, lightweight, 24v: pick 2.

I can find plenty lightweight and 24v, but they're not cheap at $100+.

Chris

[AJ Dual]

Would Li-Ion 18650's built up into a pack that meets your needs do?

Or are we talking ultra lightweight LiPoly stuff like for RC helicopters?

18650's are often amongst the best for all-around characteristics because SO MUCH development has been poured into them over the years because they're the most common to be built up into laptop packs. They go through a refinement cycle and pick up a few % points of capacity every year.

[mtnbkr]

It would take at least 8 in series, plus a charger.  That would be nearly $100.

This: http://www.batteryspace.com/lifepo418650battery256v1200mah30wh18aratewithpcb.aspx

And this: http://www.batteryspace.com/Smart-Charger-1.2A-for-25.6V-8cells-LiFePO4-Battery-Pack-100-240VAC.aspx

would work and be compact, but not cheap at $125+Shipping.

Chris

[slugcatcher]

What are you requirements for price, weight, and current requirements? Without those you'll get a lot of answers that won't work for you.

[darius]

What are you requirements for price, weight, and current requirements? Without those you'll get a lot of answers that won't work for you.

I haven't had much luck recharging my rechargeables, and I think they only charge to about 1.3 volts instead of 1.5 volts.  I learned to used decent akaline throw aways in my Canon camera. I don't use my cameras on a regular basis, so the batteries essentially run down lying in the drawer.  I remove them from the little Canon when not in use but not from the old Pentax as it has a separate plastic battery case for 4 AA cells. That way if the batteries leak the camera probably won't be damaged and the AAs are much cheaper than the little custom battery that was supposed to go in the big Pentax.

My SX120 Canon is apparently easy on batteries, which surprises me as I heard that digitals are hard on batteries.  I upload to the computer by taking the memory card out of the camera so that probably helps to save the batteries.