Not a problem. Just buy LiPoly AA's. You can get them for about the same price as NiMH batteries these days. The only trick currently is finding someone who carries them.
Can you charge LiPol AAs in a "normal" charger (the kind you'd use for NiCad and NiMh batteries)?
Or you can get the new NiMH batteries that don't lose their charge. Like the Sanyo Eneloops.
Michael
OH, interesting information magog. I've got some 2500mah NiMH Energizers, and you can only really store them at full power for a week before they start bleeding off, and they're dead by the end of 2 weeks. (of course, that could just be an energizer issue.) So you have to charge them the day before you go on a trip. It's kinda annoying. So where do you get these wonderful Sanyo Eneloops at? I'd like to pick up an 8pack of them.
Can you charge LiPol AAs in a "normal" charger (the kind you'd use for NiCad and NiMh batteries)?
As far as I know, that would be a no. At least not the ones I've seen. They're always advertised as needing a special charger because you have to charge them differently. But then again, that could just be marketing spin to sell unnecessary extras. Energizer did that for years until people got wise.
Honestly, though, this li-poly model is a lot cheaper.
That's true. The Eneloops aren't cheap (although they have come down a lot in price since I bought mine). And in this instance, you'd have to buy the batteries separately from the portable battery pack, so you're looking at $40 vs $16.
But personally, I'm trying to avoid devices that don't let you replace the battery.
Lipoly batteries require a special charger because they'll explode violently if allowed to charge continually. The special charger cuts off the juice after they're full.
Chargers for NIMH allow a trickle of current into the battery to keep it topped off.
But personally, I'm trying to avoid devices that don't let you replace the battery.
Yeah, ditto here too. That's why I went with the Tekkeon 1550, because I could change batteries. That way, if I ran down the one set, I didn't need to scramble and find a place to charge it before I could use it again. I could just toss in a new set of batteries and just keep going.
Lipoly batteries require a special charger because they'll explode violently if allowed to charge continually. The special charger cuts off the juice after they're full.
Chargers for NIMH allow a trickle of current into the battery to keep it topped off.
Meh, the Tekkeon MP1550 is way better. Not only can you get more charge time out of it, but you can also use either disposable or rechargeable batteries in it to recharge your device. And if you add a set of four 2500mah AA's, it'll give you 5000mah@5v vs the 2000mah of this unit. Plus, instead of just 500 charges, you can get 1500 with a good set of rechargeable AA's, making it way cheaper in the end.
The only advantage the Woot unit has is the plug pack, but you can buy one of those for just a few bucks at Walmart. So in the long term picture, the Tekkeon is still the better deal by miles.
I've got the Tekkeon and love it for the obvious reasons, but your math is off.
The AAs work out to 4*2.500mah*1.2V=12.000mwh=1.2Wh (1.2V is the rated voltage of NiMH rechargeable batteries).
This unit is rated at 2.000mah*5V=10.000mwh=1Wh.
With a bit of loss due to the DC/DC converter circuit required to boost the ~4.8V to 5V, they work out to about the same usable capacity.
So it works out to what is the biggest benefit:
The ability to use off-the-shelf batteries, or the much thinner design and lack of shelf-loss that you'd experience with NiMH batteries.
Plus, at this price the batteries are included, where the Tekkeon requires you supply batteries.
Also, this is about 1/3 the price I found anywhere else for this (XPal) unit.
Well, the advantage I see with the Tekkeon is that A) you don't need to charge it before you can use it. You just swap batteries and keep going. B) You can use either rechargeables or off the shelf batteries, which means you can 1) use it anywhere you can get batteries, or 2) use it with a collection of rechargeable batteries which will save you money while providing convenience. C) It can be used to charge batteries.
That flexibility alone is money in the bank for me. If I had the Xpal, I could use it once to charge my NIT, but then I'd be out of luck until I had a chance to charge it again. With the Tekkeon, as stated above, I just swap batteries and keep going. Which means, I'm only limited to the amount of things I can charge, and for how long, and for as many times as I can carry batteries with me.
Case in point. I went to CES earlier this year. I could charge 8 batteries overnight while I slept to have them ready for the next day. Then as I needed things charged, I whipped out the Tekkeon, charged them, swapped batteries, and was ready for the next item. It worked great for me.
It worked great for me.