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USB Batteries
An anonymous reader writes "Tired of paying for new batteries all the time? Tired of searching for the charger for your rechargeable batteries? Worry not, because these new AA batteries will recharge direct from your USB port! This is such a cool idea, that I cant believe that no one has done it before." At $24 each I would hate to lose or break them on a regular basis.
Let's break this down.
4 batteries - $6 at Walmart for off brand or $10 - $15 for 4 name brand rechargables.
Cheap AA/AAA USB Charger $8 from tiger direct.
OR
Better AA/AAA USB Charger $20 from tiger direct.
The cheapest route gives you 4 batteries, each with twice the mAH for $14 plus shipping. The most expensive route gives you the same thing for $30 plus shipping. Either way, buying a battery with only 1300 mAH nowadays is like buying a midsized car with a 50 hp engine.
Bottom line? For novelty reasons, these batteries look interesting and you do not need to carry an additional charger. But at around $16 US apiece they are expensive and WAY underpowered. Additionally, you need one USB slot for each. If you buy a regular USB charger and use standard rechargeable batteries, you can charge several (up to 4) with one USB slot and spend half the money.
Conclusion? It's a neat novelty backup backup. But it is way to expensive.
Funnypics
erm, it said 12.99pounds for TWO-which then is similar to 12 dollars each.
I used to have 'D' cells that'd plug in to a wall outlet, too. Trouble is, a large portion of the volume is devoted to the connector and charging circuit. But if 50% capacity is enough, I suppose they'll work.
I just replaced all of my regularly used rechargeable batteries with 2500maH sets and I will never go back to lower rated batteries again. On my vacation last week I shot over 400 photos and about 4 minutes of video on my Canon S1 IS and I only recharged the batteries once.
You don't have to worry about charging on a USB port if your batteries don't die all of the time.
ÕÕ
"Hey look, this battery dies twice as fast, but if it's dead, you can recharge it on USB!"
"Uh, yeah, couldn't I just have used a regular battery that wouldn't be dead yet?"
You can have:
- an expensive, dead, 1300 mAh USB battery that you need to recharge on your laptop (good luck on your laptop battery not going dead first!)
- a cheap, half-full 2500 mAh regular rechargable battery that you don't need to recharge at all.
paintball
I suspect this has more to do with labelling than actual capacity. Rechargeables have been putting out a 1.2v for years now. They are around 1.25V just after charge, and it's possible they were claimed as such by some manufacturer or the other. I've never seen a 1.5V NiCad or NiMH.
Anyway, alkalines are only 1.5V out of the box. When they're "dead", they're at around 0.6V, and it's a fairly linear decline over time. In fact, electronics made to run on alkalines are generally fine down to around 0.9V or so, since the decline is expected.
NiMHs and NiCads are ~1.2V after a charge, and stay there until just before they die, when they nosedive. This is why cameras recommend non-alkaline batteries--the flash actually requires that the voltage is somewhere around the maximum; alkaline batteries drop voltage so quickly that the flash only works a relatively small number of times.
It's all about the chemistry, not some kind of voltage deflation. Zinc cells give 1.5V (alklines, etc). NiCd and NiMH gives 1.2V. Lead acid gives 2 and a bit V. You can't make a NiCd battery at 3V. A battery is a stack of cells, so it can only provide an integer multiple of the cell voltage (2.4 or 3.6V is as close as you'll get with NiCd).