battery charger for iphone

i robot · 05-17-2008, 10:20 AM

hi can anyone recommend a portable battery charger for the iPhone. I want one that uses normal 'AA' or 'AAA' batteries. I am going on a trip soon and I want to keep my phone well juiced up for video and music use. links would be welcome.

Youngbinks · 05-20-2008, 12:43 AM

I use Tune Juice. It's at the Apple store and I believe at Apple.com as well for $39.95. It works amazingly well and runs on 4 AA batteries. I used it on my most recent trip and would have been dead without it.

psylichon · 05-20-2008, 01:05 AM

Originally Posted by Youngbinks

I use Tune Juice. It's at the Apple store and I believe at Apple.com as well for $39.95. It works amazingly well and runs on 4 AA batteries. I used it on my most recent trip and would have been dead without it.

How many full charges can you get on 4 batteries? And what's the charge speed like? More like USB or wall adapter speeds?

Youngbinks · 05-20-2008, 01:17 AM

I always used the iPod or iPhone while it was plugged in so I never really got a great "total time" to charge. I would say at least 2 full charges per 4 AAs. If you're not using it I imagine that it charges rather quickly, something along the lines of USB speeds.

psylichon · 05-20-2008, 01:28 AM

I'm interested. I'm thinking about camping this summer and have considered the car battery/inverter route. This is obviously cheaper. Especially considering a 4-pack of 2700mh rechargeables is under $10... hmmmm....

i robot · 05-20-2008, 06:26 AM

Originally Posted by Youngbinks

I always used the iPod or iPhone while it was plugged in so I never really got a great "total time" to charge. I would say at least 2 full charges per 4 AAs. If you're not using it I imagine that it charges rather quickly, something along the lines of USB speeds.

Hi yeah I look at the Tune Juice 2 it says on the web site that a) no compatiblity with iPhone (well in the sence the icon isn't there) and b) it doesn't actually charge it just prolongs the battery life. Your saying you have no problems though????? I really like the look of the product though

Griffinaz · 05-20-2008, 02:12 PM

This one looks interesting and I might pick one up.

http://www.javoedge.com/reflexeshop/...=1595&pbmId=40

Youngbinks · 05-20-2008, 04:57 PM

Hmm, I must have the Tune Juice 1 then. I'm not familiar with the Tune Juice 2 but they may have changed a few things. Mine works fine with both my iPod Classic and my iPhone.

macgirl · 05-26-2008, 02:41 PM

i have a turbo cell charger (i think it's model TB650). it runs on 2 AA batteries, and double as a flashlight. i keep it in my bag all the time just in case my iphone starts to die on me.

it's not stated on their site, so i emailed them to see how much of a charge it would give the iphone, and they replied saying that it would be 2 full charges with lithium batteries, and 1/2 of a full charge with normal alkaline AA's. their claim seems to be spot on with alkaline batteries, but i haven't tested their claim with lithium batteries yet...

JoeT · 05-26-2008, 02:47 PM

Originally Posted by psylichon

How many full charges can you get on 4 batteries?

That would have little or nothing to do with the model of charger you buy, and everything to do with the capacity and type of the batteries you use.

I've posted a bit of this before, but here's some battery 101 again:

The iPhone has a 1400mAh, 3.7v battery. To completely fill it up from empty, we would need to provide 1400mAh of current at something greater than 3.7v.

It's easier to think of this as water in a tank with a hose connection. The tank can hold a certain amount of water and the pump can pump water out of it at a certain pressure. In batteries, the capacity is expressed in ampere-hours (or amp hours - Ah - for short and in the case of small batteries, milli-Amp hours - mAh). The pressure is expressed in Volts.

Now, this pump is special. It automatically detects when a hose is connected and begins pumping. It also can be overridden by higher pressure and allow water to flow backwards and into the tank. So, if the tank were empty, you'd need to refill it from a tank whose pump has a higher pressure, otherwise the pump in our tank would either be too strong for it, or the same strength, and the water would not flow.

That's basically the issue you have here. You need a power source that's a little stronger (puts out more volts) than the battery's 3.7v or no current will flow into the battery (USB is 5v, the wall charger is the same IIRC). Now it's a question of how much current (water) do we need to refill the battery (tank) -- how empty is it? -- and how much we have to provide.

On some batteries (or on their packaging), you can find the voltage and mAh figures. I find that rechargeable batteries have this almost all the time and disposables have this almost none of the time. In fact, I just spot-checked some batteries and found this to be the case. However, if you DO know the mAh capacity (and AAs tend to be around 1500mAh), you can work out how many times they will recharge a completely empty iPhone. Essentially, once (1400mAh iPhone and 1500 (or so) mAh batteries).

However, the iPhone isn't generally completely dead when we decide to recharge it - so that skews our math a bit since it's not easy to tell exactly how much current is required to completely refill a partially empty iPhone. The Battery app available to jailbroken iPhones can help here by giving you a percentage of discharge that you can use to get a reasonable idea of how many mA need replacing.

Now, on to battery connections and types....

Most AA chargers use 4 AA batteries connected "in series". This adds their voltages together. So 4 AA batteries at 1.5v makes a 6v battery pack. 6v is enough to push the current out of the battery pack and into the iPhone (which is only pushing back at 4.7v). Now, this may be regulated at 5v by the charger - or not. The iPhone also regulates the charge and essentially allows it at 500mAh or 1000mAh (note: Conjecture here based on observations in the Battery application). So you can estimate the time to recharge based on how discharged your iPhone is and what rate it's charging at.

As far as battery TYPES go, we basically have two types worth considering: Lithium and everything else. Lithium batteries differ from all others in that they hold their voltage constantly throughout 95% or so of their capacity before they drop voltage (and then it falls off like a stone). The others have their voltage drop slowly over the life of the capacity until it reaches somewhere between 0.8 and 1v per cell. At some point, the voltage may become too low to properly charge the device (or, in a regulated circuit, may use much more capacity to boost the voltage) - meaning that you don't get the full worth of the batteries - kinda like that extra toothpaste in the tube that you can't get too and throw away. I recommend using lithium AAs for a few reasons:

1. More capacity. Lithium batteries provide more Ah in the same size cell. Energizer states their AA batteries are rated at 2850mAh for alkaline and 3000mah for lithium. (For comparison, their NiMH rechargeables come in 2000, 2200, 2450, and 2500mAh capacities)

2. Longer shelf life. 10 years!

3. More use based on the longer "voltage life" as described above.

Long answer to a short question, I know, but I hope it explains a bit.