Charging Iphone from a 12v VRLA battery

Question

Level 1

8 points

Charging Iphone from a 12v VRLA battery

Hi

When I am fishing I can be away from home for up to 3 days with no mains power. With this I am thinking of charging my iphone from a 12v battery, but I don't know where I can find a cable which has the iphone connector, split to crocodile clips to attach to the battery

Can anyone point me in the right direction please?

Thanks

Posted on Dec 8, 2009 2:34 PM

Reply

Answer 1

Dec 8, 2009 3:07 PM in response to sheps31

Do it in two steps - I'd bet you can find a clips-to-auto power (cigarette lighter) connector. Plug an iPhone car charging adapter into that (Griffin PowerJolt, etc.) - that will step it down to the 5 V @ 1 A that the iPhone requires.

Reply

Answer 2

sheps31 Author

Level 1

8 points

Dec 9, 2009 3:04 AM in response to neuroanatomist

I have found a female cig adapter to croc clips. While I understand that the power needs to be stepped down, I don't know why I would need the powerjolt as well.
Surely as with the normal car charging situation (where you wouldn't use a powerjolt), the cig adapter will be connected to the 12v battery (via clips this time), then you would plug in the standard car charger for the phone.

With this, I am assuming that there is a step down within the standard car charger. I may be wrong

Reply

Answer 3

Dec 9, 2009 3:34 AM in response to sheps31

The PowerJolt is just a standard car charger for the iPhone 3G/3GS. I suggested an the croc to cig adapter with an iPhone car charger, listing the PowerJolt as one example of such a charger - Belkin, Kensington, lots of vendors make them. The brand doesn't matter, _as long as it is specified to work with the iPhone 3G/3GS_. That's an important distinction since most older car chargers for iPods, even though they have a dock connector, are delivering power over the FireWire power pins in the connector (no step-down required since FireWire can carry up to 18 V, meaning the adapters were cheaper to make, meaning more profit for the vendor) - older iPods and the Original iPhone could draw power from the FireWire pins, but the iPhone 3G and 3GS (along with newer iPods) cannot.

Reply

Answer 4

sheps31 Author

Level 1

8 points

Dec 9, 2009 3:49 AM in response to neuroanatomist

I will order the cig to crog clip, it is only £3.75 so nothing to lose, and I can get a battery from work. As you say, as long as the car charger is suitable for the 3GS it should be fine

Thanks for all your help

Reply