SZ battery problem...100% lasts 5min

I purchased a new OEM battery about one year ago. It worked fine for 8 months, but the last few months it been acting weird. The icon says the battery is at 100%, but when i unplug the a/c cord, the power and battery light under the screen start flashing and the estimated time left on the charge is only 5min. Usually it will only last about 2min before powering off. When i plug back in the a/c adapter and turn the computer on, it shows the battery as having 80-90% charge left and it quickly goes to 100% in a minute or so.

I'm not sure if this is a problem with the battery, or something else? Any ideas?

 

Your battery is dead.

Some of the Sony utilities can tell you the amount of wear in your battery, if not, try the program Battery Bar, that will tell you the wear level.


There is no set lifespan for a battery.
Li-on batteries like to sit at 50% charge, the further you stray from that, the faster it wears out. There are a few things that kill them very quickly though. The first being letting it go dead, Li-on batteries can only tolerate this a few times before they are finished. The second worst is leaving it at 100% charge all the time.

You may get 3 months, or 9 years, depending on how you treat your battery. Check Ebay, you can get a battery with slightly less capacity than the original for far less, it may only last a year, but for the money it's not an issue.

 

The rate of internal discharge is actually lowest at around 40%, but many if not most manufacturers will report that as 50% due to the safety margin (see below). 50% is a good value to store a battery at, as it will slowly drop to 40% (and then further).

Leaving a Li-Ion battery at 100% plugged in isn't a problem with newer charger circuitries that trickle-charge at top loads. It only becomes a problem when you unplug the computer or take the battery out of the computer, as it will drop from full faster than it will drop from, say, 3/4 full.
This is the reason why Sony has a "battery saver" feature that only charges to 80% or 60% -- it's not because charging to 100% is a problem in itself, but because of the higher discharge rate, and people who frequently unplug their laptops for travel or use multiple batteries.

The two things that kill a Li-Ion battery more than anything are (1) depleting it towards empty, and (2) heat.

1: The battery has a safety feature where it says it's empty when in reality there's plenty of juice left, but that's for a good reason -- if a LiIon battery reaches 0%, it becomes unstable and can catch fire quite violently when recharged. So there are two safety devices in place -- one that says it's empty when it's really at around 20%, and another that permanently(!) disables the battery when it reaches close to zero, at which point it has to be discarded or factory reset.
But the closer you get to empty, the higher the wear on the battery. Going from 50% to "empty" a single time will wear the battery more than going from 100% to 50% ten times.

2: Heat is a Li-Ion killer. Expensive solutions have temperature probes on the battery itself, and will throttle charging if the battery becomes hot. But you won't find them in laptops, as it would be more expensive and also lead to complaints from the unwashed masses when the battery takes far longer than the competition to recharge.
But anyhow, leaving the fan at "silent" and the GPU at performance is a good way to reduce the battery life, especially if you use the computer heavily while charging.

Also: Li-Ion batteries should not be fully discharged and recharged every so often, like other rechargeable battery types. You only reduce battery life by doing so (the exception being the first generation Li-Ion batteries that didn't have a built-in capacity meter, and you had to discharge and recharge to "calibrate" the meter. This is not the case for newer Sony batteries.)

As for third party batteries, beware that many of them come from the same OEM as the vendor batteries, but are batteries that failed the QA tests. They may work, but may also fail quickly, or be downright dangerous to use. Most battery explosions are with 3rd party batteries.