Battery - why is it losing 15% every night?

[jo-ro]

After unsuccessfully trying to jailbreak my one year old iTouch 2G (MC model) 4.1, I had to restore it. Until restoring it, the battery would usually read about 90% after a full week of listening to one hour music each day.

After restoring it, it now loses 15% of the battery each night.
I still only use it to listen to music while I walk one hour every morning (unless I'm traveling, and then I use wi-fi).

I checked the settings, and everything is turned off except wi-fi. I tried turning wi-fi off and it still loses 15% overnight. Push is off, as well as bluetooth and notifications. The settings are exactly the same as before restoring, when it only used 10% of the battery during a full week.

Any suggestions, tips, solutions greatly appreciated.

[rackstar]

if you restored from 3.1.3 to ios 4.x, that is what happens. you can try going through settings>general and turning most features off, and making sure (if you have multitasking) that you do not have programs running. i put airplane mode on, and turn off all apps that are open, and now it uses ~3-8% per night.

[i.Annie]

It happens. My iPhone drains about 5-15% a night when it's not being charged. Try calibrating your battery once in a while to maintain battery life. Charge it to full, let it die completely, then full charge it again. Sometimes, over time batteries just start to go.

[jo-ro]

It happens. My iPhone drains about 5-15% a night when it's not being charged. Try calibrating your battery once in a while to maintain battery life. Charge it to full, let it die completely, then full charge it again. Sometimes, over time batteries just start to go.

WARNING!

This advice may be OK for Ni-Cad or NiMH batteries, but you should be aware that it is just the opposite for Lithium-ion batteries.

The clip below is from the Tech at Play forum (3 Things You Should Already Know About Your Lithium Ion Battery | Tech at Play)

Avoid allowing your device to discharge completely
Every wondered why your modern phone, PDA or iPod is able to cheerfully tell you that “Your battery is now exhausted” for several seconds on its brightly-lid LCD screen before switching off? The reason is simple; there is an artificial circuit that shuts off the device when the charge in the battery is too low.

This extraneous circuit is built to protect from the damage that could result if the charge of your lithium ion battery falls too low. If you still don’t get it: if the charge of your lithium ion battery falls too low, the battery can get irreversibly and permanently damaged. So since Lithium Ion has no “memory effect”, it is better to simply charge your portable device as and when you can or remember.

To set your mind at ease, a “charge cycle” means a single iteration of depleting followed by a re-charge until 100% of battery charge. If you consume 50% of your iPod’s battery on day 1, recharge to 100% at night, and do the same thing on day 2, then you would have just finished up one charge cycle of its battery life.

constantly recharging a lithium ion battery does not shorten the battery life more than normal usage would

Hence constantly recharging a lithium ion battery does not shorten the battery life more than normal usage would. Avoid letting it sit on empty for too long; instead, keep it charged-up if you can.

The article also has other information on the life of Li-on batteries and whether you should take it out of your laptop while running on AC.