iPhone 4 Solar Power Backpacks

neil_g said:
How dire is it? Might be an iffy app draining your juice.


Should get a full day at least.
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I get a full day almost but I'm thinking of when I go wild camping, would be a useful tool to have as a emergency gps. Tried shutting all apps etc. iPhones are known for poor battery life though.
 
I've got a 4s, its not that bad and that's with loads of screen on playing games time.


I do have a mophie juice pack for times when the GPS will be on all the time on long bike rides. GPS/location services is a huge killer of battery.
 
Not much as far as I can see, I can only recommend what I've used and the limeade pack is very good holds its charge well and had enough capacity for multiple charges. The one you linked to gets great reviews too so I don't think you could go wrong with either!
 
The solar battery packs aren't really all that great, takes ages to fill it's own battery, one the size of a phone, with a 5000mAh battery inside would take around 24-48hrs of sunlight (I have one). If your losing charge in 1 day, then it'd be useless.
The one I made at home charges up in 8 hours, but the panel is about the size of an iPad mini.

Renewable energy, not as efficient as it would first seem.
 
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An iPhone 4 battery contains 1420 mAh of energy. So the 15000 mAh battery pack Phil links to will charge the iPhone 10 times.
 
hollis_f said:
An iPhone 4 battery contains 1420 mAh of energy. So the 15000 mAh battery pack Phil links to will charge the iPhone 10 times.
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No, not quite (unfortunately).... There will be inherent losses.

The internal battery will be either 3.7v or 7.2v, most likely 3.7 because the input voltage is 5v.

At 3.7v (4.2v at full charge) it'll need a boost circuit to reach 5v, meaning maximum efficiency of around 70 to 80%, dropping off gradually as the battery discharges, then you factor in that it's charging another battery, which again means a small efficiency drop.

It's hard to say, but you certainly won't see 10 charges.
 
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