Pair of double-As give you cheap, quick charge

"Modern aa rechargeables are 1.2v out of the charger"

Except that is completely untrue - I just tested 3 different brands I use and they were 1.35v, 1.33v and 1.29v.

I never said the NiMH rechargeables were 1.6v but standard Duracell alkaline cells can be - did you actually measure the actual voltage you were getting?

1.2v is the typical 'nominal' voltage of a NiMH rechargeable - the actual open circuit voltage will vary depending on the actual chemistry used etc. For the same reason what most people regard as a 12v (lead acid) battery is usually around 12.6-12.8v when fully charged (technically nearer 13v than 12v).

As someone said Dimension Engineering make some nice components that are basically ready to use - but they are not especially cheap / so readily available in an 'emergency'. The other problem is the standard 'Anyvolt' (which can handle voltages above or below the desired output) only handles 500ma input or output - so if your input was below 5v you would get 5v but not 500ma output. If your input was above 5v you could use one of their cheaper step-down regulators (they do one that handles something like 3a).

They do a more powerful Anyvolt but it's more like £45-50 last time I looked which is excessive for an 'emergency' charger.

Realistically in an "emergency" can you really plan on being able to get any 5v regulator - more likely you would be best to just use 4 AA rechargeables or 3-4 AA alkaline batteries in series - under load the voltage is likely to be close to 5v or your device may not be that picky if the voltage is a bit low.

More than meets the eye.

The Rolson gadget isn't 'just' a battery holder though, it's got a spanky little boost converter built into the translucent bit at the top, how else do you get 5 volts from a 1.5v cell?

Makes a lovely little power supply for microcontrollers too :)

You can also pick up exactly the same gadget, branded with some weird name, at petrol stations in the UK for £2.99 at the moment (Esso I think)

Better Solution

A much better solution-in-advance, a Brookstone external battery:

http://www.brookstone.com/Rechargeable-Backup-Battery-for-iPod-and-iPhonetrade

Or check out Casemate's offerings: a case with included battery:

http://www.amazon.com/Case-Mate-Fuel-iPhone-Extended-Battery/dp/B004FVQGWG

Casemate also make phone 'holsters' which charge the phone whenever it is 'holstered'.

Alkalines not as ubiquitous as you think

I used to think alkaline AAs could be got anywhere and bought gadgets for travel accordingly equipped. Disappointingly I found this to be far from the case in much of Asia and Africa and some parts of South America. AAs can be found absolutely everywhere, just not alkaline ones. You can very often find "Duracells" in ordinary shops but they are nearly always fakes: very cheap zinc carbons dressed in black and gold labels.

In these sorts of towns, for real alkaline AAs you need to go find a proper camera shop where you pay though the nose, sometimes the equivalent of $8 for a pair of off-brand ones.

Fortunately, AC mains is found pretty much everywhere (as is cellphone reception these days). Even in remote Indian villages and far flung islands in the South China sea, someone will be running a generator. Of course it won't be an uninterrupted supply, but always more convenient than dry cells. I learned my lesson: rechargeables are the only realistic way to go.

"The Rolson gadget isn't 'just' a battery holder though, it's got a spanky little boost converter built into the translucent bit at the top, how else do you get 5 volts from a 1.5v cell?"

The reality is those 1 x AA gadgets and alkaline cells are pretty cr@p - to get 5v and 500ma from a 1.5v battery means pulling more than 1.5 amps (a lot for most alkaline AA cells). At 1.5 amps the voltage will sag quite a lot so you are probably pulling more than 2 amps. As the voltage drops (as the cell depletes) the current draw will increase - so you will often get very little actual capacity out of the cell and into your phone.

Using a lithium (primary) AA cell would be better (as would using a rechargeable NiMH cell) - but still not great.

"Yes, 1.2v on the dot, generic NiMH cells. I also just tested some Duracell NiMH cells too, also 1.2v."

Checked with 2 different multimeters - the Sanyo Eneloop was 1.35v, a Duracell rechargeable was 1.33v and another NiMH cell was 1.29v. None were 'hot off the charger' - they were fully charged in the last few days.

Also NiMH charge at around 1.4-1.6v anyway - so hot off the charger they are unlikely to be 1.2v.

think i....

Stick with my desires slim battery which can be put in the case with the phone.

Got a wallet style case not much thicker than the phone which the spare battery fits perfect in.

lord

The product is not listed on the yank flavor amazon site, I am heartbroken.

_me

I just always carry a wall charger around with me. If it's 2am you're bound to find a place that'll let you charge up for 10mins as long as they can serve you *something*, a pub, a kebab shop, anything.