smrkangl

Need advice, comments on the following issue:

Whenever I use my laptop, I charge it. Whenever it is not in use, it is still charging. Basically, my laptop is always charging. Is this harmful or in anyway detrimental to my laptop's performance/life expectancy? (It's an HP laptop btw)

Thank you!

Martian

Short answer: No.

Modern laptops all use lithium-ion power cells. It's hypothetically for bad things to happen if they're overcharged, but there are multiple redundant safety features in the laptop and battery itself to keep that from happening.

A battery does have a useful lifespan and will eventually stop holding a charge no matter what you do. Lithium ion is generally about 400 charge cycles, which under typical use will give you 2-3 years. Partial discharges are harder on them, but not enough to go out of your way over.

The days of high maintenance batteries are mostly behind us. Nickel-Cadmium and Nickel-Metal Hydride are still used, but generally only in applications where the increased care requirements are less important than the lower price -- in other words, not generally in consumer devices.

__________________
I wake up in the morning more tired than before I slept
I get through cryin' and I'm sadder than before I wept
I get through thinkin' now, and the thoughts have left my head
I get through speakin' and I can't remember, not a word that I said

- Ben Harper, Show Me A Little Shame

Redjake

Does this mean it's actually better to keep your laptop plugged in 24/7, instead of letting it "cycle?" Will the battery last forever if it never has to go through 400 "charge cycles?" I am curious about this topic as well.

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Martian

Cycling is much less important in batteries that don't have a memory effect.

The act of recharging your battery causes the resistance in the cells to increase, and therefore reduces the lifespan of your battery. At higher charge levels more voltage is being passed through the battery, which results in a bit more wear and tear due to a partial charge cycle (as noted above), but it's not anything that I would deem significant.

A full discharge of the battery will kill it. This is, as far as I know, irreversible. Fortunately, all lithium-ion batteries have a safety circuit built in, and one of it's jobs is to ensure this doesn't happen.

If you never unplugged your laptop your battery would last significantly longer, but would still eventually wear out. This is due to the self-discharge that all batteries inherently suffer from. Laptops can also be problematic because they cause prolonged exposure to higher temperatures, which reduces the lifepsan of the battery. I would guess at a lifespan of about 5-6 years under these conditions, as opposed to the 2-3 under typical use.

If you expect your laptop to be in one place for weeks or months at a time, I'd recommend taking the battery out completely and storing it in a cool, dry place. Optimal storage temperatures are around 5-8C (about 40-45F), but humidity is also a concern as it can cause corrosion. The laptop should run fine on mains power without the battery in place, and the battery won't be exposed to the lifespan-reducing conditions of your laptop.

__________________
I wake up in the morning more tired than before I slept
I get through cryin' and I'm sadder than before I wept
I get through thinkin' now, and the thoughts have left my head
I get through speakin' and I can't remember, not a word that I said

- Ben Harper, Show Me A Little Shame

Redjake

I may remove my battery, I rarely use it with my gaming laptop. The reason I ask is because my wife's family is obsessed over laptop batteries (for whatever reason) and they say "tried and true" that keeping your laptop plugged in 24/7 is significantly worse for it than charging it, unplugging, charging, unplugging, over and over again. My wife's old laptop battery only lasted 2 years and they say it was because she left it plugged in 24/7 at school.

__________________
Off the record, on the q.t., and very hush-hush.

Martian

2 years is a reasonable lifespan for L-ion. I doubt your wife did anything wrong at all.

There's a lot of folk wisdom regarding rechargeable batteries. Most of it is totally false. A lot of it comes from the days when Nickel-Cadmium was the most popular type of rechargeable; that changed in the late nineties when the prices on L-Ions came down enough to make them feasible for everyday applications. Ni-Cads are very finicky, and can be damaged if not fully discharged before being recharged (among other things). They also had and continue to have about double the lifespan of L-Ion, assuming proper care practices are observed, so I think people who are used to them expect their batteries to last longer than is really feasible.

The biggest factor affecting a battery's lifespan is usage. The very act of recharging a battery causes damage to them; thus, in heavy use scenarios (such as a student who takes her laptop to every class) the batteries will wear out much quicker than might otherwise be the case. While a case can be made that late-stage charging is more harmful due to the higher current and voltage flows to get that last 10%, it's my opinion that this isn't a significant factor. Furthermore, a laptop that is plugged in all the time isn't actually passing current to or from the battery very often -- typically, it'll pass a small 'top-up' charge to the battery about once a month, and that's about the extent of it. This behaviour is to counteract the self-discharge inherent in all battery designs (including alkaline).

The only compelling reason to be strict about full discharge/recharge cycles is memory effect. Memory effect is prominent in Ni-Cad, present but minimal in NiMH and non-existent in L-Ion.

If you do store your battery separately, be sure to take it out and recharge it periodically -- I'd say every six months or so should be good.

Fun fact:

Of the three most common consumer-level battery types, L-Ion is actually the most fragile. However, the battery does have onboard circuitry to closely monitor it's condition and prevent damage. This circuitry is one of the main contributors to the dramatically higher price of L-Ion over other battery types, and even with it in place it' a rather trivial thing for someone who knows what they're doing to cause one to explode violently (this was referenced in XKCD ).

__________________
I wake up in the morning more tired than before I slept
I get through cryin' and I'm sadder than before I wept
I get through thinkin' now, and the thoughts have left my head
I get through speakin' and I can't remember, not a word that I said

- Ben Harper, Show Me A Little Shame

apeman

To the best of my knowledge (and there's a lot of misleading information out there) a Li-ion battery ages with age, not charge/discharge cycles. Nickel-based batteries age with number of cycles.

If the battery gets hot because it's always being charged, that might shorten it's life. Li-ion chargers are very sophisticated though and probably don't generate much heat in the battery when it's being kept topped-up.

I'd be tempted to flatten it and recharge it every now and then, but more because I feel it's the right thing to do than because I have any hard evidence that it will help.

It's much worse to leave it flat than to keep it on charge though, so you're erring on the right side of caution.

This website is the best I've found about batteries : Is lithium-ion the ideal battery?

cheers,
Andy.

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fie

I would check the battery model to see if there's been a recall, just in case. It's not really a solution so much as a precaution.