Testing Laptop batteries

[Jassi]

A buddy of mine is buying a refurbed laptop and I want to make sure that he isnt getting dinged on the battery. Is there a way to check how new the battery is? Laptop batteries do get worse with use right? Any techniques to perserve the performance or atleast minimize the decay?

 

[phisrow]

Some batteries have a date of manufacture on them, some may be able to be checked at the manufacturer's website(Dell, for example, keeps pretty exhaustive data on all machines they ship, which you can look up by service tag number). Lithium Ion can both be degraded by repeated charge/discharge and just by time. He should probably just test the battery when he first gets the box. Charge it to full, run some reasonably standard benchmark, and time the drain. As for preserving a battery, advise seems to vary. Everyone, however, agrees that you should keep the battery as cool as practical. This doesn't mean refrigerating/freezing the thing; but don't leave it in the car in full sun, if the laptop is some firebreathing P4EE monstrosity, don't leave it in the system if you plan to run it at full tilt off mains for 48 hours, etc. Lithium Ion doesn't suffer from memory effect, so it is said to be best to charge without discharging all the way. Some say that occasional full discharge is best, some say that that is stupid. Generally, though, it seems to be best to just use the thing, recharging it when you can, working away from the wall when needed, and just accept the fact that the battery will fail even if you just leave it on the shelf.