Charging an iPhone from a battery pack

[andrewa]

I recently lashed out about $7 for a battery pack that holds 4 x AA batteries, providing 5v, and has a USB output.

I have 4 rechargeable and recharged 2000mA batteries in the pack. I rigged this up to my iPhone (4) today to see how it charged. It gains about 8% charge every 2hrs.

Is this the sort of speed of charge I would expect from other battery packs, as discussed on the forum, or is there something I've missed? Sadly,I currently seem to have minimal electrical understanding. Does more mA in the battery pack mean quicker charge?

Andrew A

[findbuddha]

Being a USB charging system the battery pack must report to the attached device how much current it can supply - this will determine how quickly it can charge a device. Sounds like it's not supplying much. Wall USB chargers generally supply 1-2 amps.

The 2000mA on the batteries is most likely actually mAh (milli-Amp hours), a measure of battery capacity not discharge current.

[KANANGRABOYD]

mAh ( milli ampere hours ) is the amount of power that is stored in the battery pack/battery. However that total may not be an ideal indicator of actual storage. If you use a 5VDC USB it will draw less power from pack than say a 12VDC item. Most companies will advertise their products with the storage capacity if you use say an iPod. So 10,000mAh capacity may only be 6000mAh capacity if you charge say an iPad. The best overall "idea" of a battery packs capacity is to measure it in Wh ( Watt hours ). Larger batteries such as a car battery will be measured usually in Amp hours. The conversion is easy and their are many resources on the web to figure it out. I would suggest you spend a bit of time to read up on Solar Power, batteries et al, so that you end up buying exactly what you want, and can weed out all the gimicky devices. Also the power/battery packs speed at charging your device will be determined by the amount of Amps of current the pack will output. Most iPhone charging devices output .5 - 1 Amp. A 1Amp charging device will charge your phone faster. Also many NiMh batteries do not provide anywhere near what their claimed capacity is, and many batteries will lose charge fairly quickly if not used, and of course over time they lose their capacity as they get older.
Nearly all USB outputs of battery/power packs will be limited to a max of 2 Amp output current, which is what most tablets require to charge, but the majority will be 1 Amp or less. What kind of usage do you want?. How many charges do you need for your phone per trip?. If you let us know what you require, it will be easier to recommend a solution for you.
Cheers,
KB

[Nuts]

Good stuff.

Is this the sort of speed of charge I would expect from other battery packs, as discussed on the forum, or is there something I've missed?
Andrew A

Iv'e mucked around with various battery packs (self-contained not AA). The three iv'e tried all have different capacities but unrelated to output eg

Voltaic capacity- 3000mA out-600mA @ 5.5v
New Trent capacity- 5000mA out-1000mA @ 5v
Suntrica capacity- 1500mA out- 600mA @ 5v

Iv'e used each of them a few times, hook up at dark and dump into my iphone (4s).
Trent takes around 3-4hrs, the others much longer, perhaps 6-8hrs.

I'd imagine there would be inefficiencies in the transfer, different internals and quality, connections, length cables (so published figures may not be precise) though this might give you an idea for yours (if you forget mA and consider price maybe that's about right? )

I'm just wondering if perhaps the battery pack has a regulated output (as do these)? Nothing in the specs?

[andrewa]

No, Nuts, it has no specs. Purely a cheap little plastic box from Jaycar with a USB outlet, and into which you put 4 AA batteries, and presume that the power will be available through the USB. For all I know the USB port may be faulty, as even with 4 new batteries, it doesn't charge the iPhone! How do you test that a USB port like this is actually working? Apparently this little pack is only designed for power out....although maybe it was wired frack to bunt in my case!

A

[Onestepmore]

Is there no quality control with any of these battery charging devices? How can they claim to charge x device in y amount of time, and fail so miserably to meet up to their claims?

I know iphones in particular are thirsty creatures. I should let mine run down to single digits. Hook it up to a fully charged isound PowerMax Travel Pack (my 'brick') and see how long it actually takes to recharge it.
God help us with an ipad......