I’m not a hardware specialist, but I’m not averse to prizing open a laptop case occasionally when the need arises. Most of the time.
This, however was an exception. This is one view of my XPS13 that I never wanted to see :
What brought me to this point was the untimely demise of the battery.
What follows is not a blow-by-blow account of how I changed the battery, with all of the attendant nervousness that practically everything I was looking at was rather expensive and no doubt quite important.
Incidentally, if you are looking for that sort of thing then there are several helpful videos available, like this one, for example.
Rather it is an exploration of some of the advice around about ensuring your battery has a long and happy life. Specifically, it is an attempt to divine which advice is still relevant to the Lithium Ion (Li-Ion) Polymer batteries of the sort that power modern laptops…
Recharge Cycles
The expected life of a battery (i.e. how long before it wears out, not time between recharges) is measured in recharge cycles.
Fully charging a battery from 0% power to 100% is one cycle.
Usually, a laptop battery will be charged from a point before it’s been completely drained. This type of charge corresponds to part of a charge cycle.
For example, charging a battery from 20% to full will be considered as 0.8 of a cycle.
Looking at the spec for my machine, I can see that the battery is expected to last 300 cycles.
Battery “memory”
This phenomenon is where a battery “forgets” how much charge it can hold and needs to be reminded by being completely drained and then fully recharged.
Whilst this may have been true of some of the old nickel-metal hydride (NiMH) batteries, it is certainly not the case for the modern Li-Ion variety.
Overcharging
Once again, it may have been good practice in the past to disconnect the charger once the battery was fully charged. These days however, it does not appear to be the case.
For my particular machine, this question is directly addressed in an FAQ on Dell’s website :
“Can a Dell battery be overcharged ?
No, Dell laptops are designed to stop charging the battery when it reaches full charge. Once the battery is fully charged, the Dell laptop will continue to use power from the AC adapter.”
Monitoring Battery Health in Linux
There are battery monitors available whichever Linux desktop you happen to be using. If you prefer a command line tool then acpi should do the job.
Running this for my old, failing battery, output such as this wouldn’t be unusual :
acpi -ib Battery 0: Discharging, 47%, 03:47:12 remaining Battery 0: design capacity 7894 mAh, last full capacity 6327 mAh = 80%
The “last full capacity” reading here is an indicator that this battery has seen better days.
In contrast, the new battery looks rather more healthy :
acpi -bi Battery 0: Discharging, 94%, 10:14:24 remaining Battery 0: design capacity 7894 mAh, last full capacity 7894 mAh = 100%
So, how long should my battery last ?
As ever, it depends.
My own experience with the XPS13 was that 300 cycles lasted around 3 years.
Factors affecting the lifespan (in terms of elapsed time) would include, how often you use the laptop on battery as opposed to AC power, and how hard you make it work relative to the system resources (CPU, RAM, disk) at it’s disposal.
When all is said and done, it seems like 3 years is probably a reasonable lifespan, given how I use my machine.
I don’t think I’ll be making too many changes to the way I use my battery.
