Depends how you use it. Normal use required daily charge.
seven years
a panasonic triple a battery last about 4 hours nonstop.
1432 mah battery
The iphone 4 does have a removable battery, but it is difficult to take out and not a typical cell phone battery that you can just pop in and out. It is possible to remove the battery from an iphone 4, but not an easy process. It requires you to pretty much disassemble the whole phone.
about 4 to 5 years
4 hours
3 hours
More that 4 hours
Most last 4-6 years
4 hours
Average Battery Life is about 4 Hrs.
2-4 hours depending on your airsoft gun