leaving hardware plugged in 24/7 = destroy batteries?

[lost_soul]

I'm wondering if this is still the case with tablets. I remember twenty years ago, chargers weren't smart enough to stop charging a battery when it was full, overcharging it and damaging it if some things were left plugged in for extended time.

 

Now, with Li-Ion batteries and the like, the circuit cuts off when the battery is full. However, there are other problems. Batteries degrade faster when exposed to increased heat. So, if you have a small device that is running 24/7, generating a fair amount of heat because of an LCD screen, doesn't that degrade battery life as well? I have a portable TV from just a few years ago whose battery doesn't even last HALF what it did when it was new. It was discharged about 60 times, and I never force-discharged it to 0 (very bad). I did leave it plugged in and on for days at a time though and I'm wondering if the heat from the screen slowly ruined the battery.

 

On the other hand, I have wireless headphones from a decade ago that STILL last all day on a single charge. These headphones were mistreated by being drained to zero and not being charged for years at a time, and yet they're still great. Is it just that some manufacturers use quality batteries, while some use shit batteries?

 

I've also read that keeping batteries at 100% at all times causes them to degrade faster too. (Even Deus Ex referenced this!)

Edited September 6, 2013 by lost_soul

[Lux]

My dad was a big R/C nut while I was growing up. There were NiCd batteries everywhere in our garage.

 

One thing I learned is that batteries develop a memory over time. If they are discharged only a little and then recharged, then discharged a little and recharged, over and over, like what would be the use-case for a home land line portable phone; eventually the batteries have only that small portion of charge available. So the battery has a much smaller capacity than it used to because of the usage habits.

 

He'd always taught me that after running an electric car or airplane to drain the battery nearly completely and then recharge it fully and after full, trickle charge it so that as charge dropped slightly over the days, the charger would add tiny amounts to keep it topped off.

 

From what I know from him, NimH batteries have this same behavior but to a much lesser extent. Much much less. They do, after a much longer period of time, remember what their charge cycle/drain cycle becomes like and that is all they're good for. It takes much longer for NimH batteries to do this.

 

But yes, you are correct in saying that you shouldn't just go somewhere and plug in. My sonic toothbrush (still going 6 years on now -NiCd), my electric razor (still going 8 years on -NimH), my netbook (3 years going and no drop in capacity, not sure on battery type but I'd wager NiCd) I use them as long as possible and keep them off charge until they're dead, then full charge overnight so the memory they develop is a long one.

 

Unfortunately LiPo batteries weren't around when he was so its hard telling but I'm sure if you dug around on the R/C (remote control) forums you could garner this information with a bit of research.

Edited September 7, 2013 by Lux

[chakkman]

I have a portable TV from just a few years ago whose battery doesn't even last HALF what it did when it was new. It was discharged about 60 times, and I never force-discharged it to 0 (very bad). I did leave it plugged in and on for days at a time though and I'm wondering if the heat from the screen slowly ruined the battery.

Pretty sure that's more of a case of a really bad battery you got there. The heat from the display shouldn't in any way affect the battery, as it's not getting nearly hot enough with portable devices with such a small screen to do harm to the battery. I wouldn't worry about that.

 

I've also read that keeping batteries at 100% at all times causes them to degrade faster too. (Even Deus Ex referenced this!)

If you want to store a device for some time, say a couple of months, it's always recommended to do it with a battery level of 50-60 %. If you keep using the device after 1 or 2 weeks or so, it won't matter much what the battery level is. That's for Li-Ion batteries, and also for Li-Polymer i think.