I ordered my 770 on the day it became available from the Nokia Europe web site.

I have followed the battery instructions pretty well; charge it fully, unplug charger once fully charged, use until battery fully discharged, and repeat.

Until fairly recently we got really good performance - 7, 8 hours between charges; recently that seems to have reduced, so we are recharging once every two or three days.

Is anybody else experiencing this?

Is is time to procure a new battery?

Are you using alarms with the OS2006? I played around with the alarms and noticed my battery was taking a hit somtime overnight.

No, no alarms at all. At the moment we're only using Tabby for web browsing. Sound is turned off and brightness either 1 bar if nighttime, or max of threee if it's in daylight.

My 770's battery died almost exactly 1 year after I got it - early November too.

Reckon I got 300 charge cycles out of it.

Get a new one.....

I knew Nokia used to put those braindead instructions into their phone manuals, I didn't know they still continued printing rubbish in their documentation.

Those instructions are meant for old NiCd- and NiMH batteries, not lithium-ion batteries!

Lithium-ion (and lithium-polymer) batteries should go through about 6 charge/discharge cycles to begin with, maximum. After that you should keep topping up the battery at every chance you get, this will keep the battery working at full capacity for at least three years. I have experience with both methods (always discharge vs. never discharge), and the former will kill the battery in less than a year, the latter results in a long life time.

Lithium batteries don't like to be fully discharged at all! Don't do it. Whenever you do you decrease the life of the battery.
The only problem with keeping the battery fully charged (that is, around 4.10 volts) is if the battery is also in a hot environment, this will also reduce the life time of the battery. But this is mostly a problem in some laptops, which can get fairly hot inside.

There's a lot of stuff about batteries and how to handle them at http://batteryuniversity.com

Bugger.

Thanks very much for the response!

How about leaving the Nokia 770 connected to the charger overnight?
Could that damage or reduce the lifetime of the battery?

I assume the n770 has some sort of "smart" battery monitoring that prevents overcharging... so leaving it overnight should not be a problem...
can anyone confirm this?

Absolutely. It will not damage it at all as all lithium-chemistry chargers must perform precise charge cycles that do not charge the battery any further than a complete charge (or risk a fire/explosion). You can basically leave it connected indefinitely although the battery will tend to self-discharge over time.

Larry

Yep. It seems that a year is about average for optimal life out of a lithium battery. As mentioned, charging each time you can is a good idea. However much you baby it, the battery will expire on its own without even using it since they have a definite shelf-life; heat will decrease the life quite a bit too.

Larry

If it lasts only a year it's because of improper handling. You should get 3 years out of it before you start really noticing any reduced capacity. However, shelf life also reduces battery life time, so if the battery you bought has been sitting a year or two on a shelf in the shop you'll not get what you're paying for.

I also concur with the poster who said that it's safe to leave it in the charger.
For lithium batteries it's critical that they don't undercharge, and extremely critical that they don't overcharge (they may explode!). Because of this there are two safeguards: There is actually a protection circuit inside the battery, it will disconnect automatically when it's fully charged so that the voltage never goes above a certain maximum limit, and it also disconnects when it's about to get undercharged. The latter is a bit inconvenient if it happens, because you may often need special equipment to charge the battery again. But this is when the battery goes all the way down to 2.5 volts or so. Therefore, there's also a regulator in the device itself (in this case, the 770), which turns off the device at a much higher voltage (differs between devices, for a PDA it's often 3.7 volts, for a phone it could be as low as 3.2-3.4 volts, but anyway much higher than the critical 2.5 volt limit). And it stops charging at some maximum voltage level as well.
Incidentally, there are rumours that early Nokia phones left out one of these protectors, if that was the battery protector or the device protector the rumours didn't say, but there were some battery accidents. If this is true or not I can't tell, except that I'm certain all newer devices include the protector. And the only way to find batteries without protector circuits is if you buy "raw" lithium-polymer batteries in bulk, which are mainly sold to RC hobbyists (they assemble them to battery packs for model planes and the like, and add electronics themselves).

Anyway, lithium batteries go quickly to 100% when you charge, but it takes quite a while of additional charging to get to the _actual_ 100%. So leave the device in the charger over night now and then. And as said already, you can never damage anything by leaving it there all the time (unless one or both of the protection circuits are broken.. google 'lithium explode' to see why you don't want to ever experience this..)