Is it harmful to leave my iPhone in the Sounddock all the time?

May 4, 2010 4:15 PM

Will keeping my iPhone in the charger reduce the overall battery quality and life?

I purchased a Bose SoundDock and I love the sound quality but the thing is to put in the sounddock makes it charge.. is it harmful to the overall life of the battery to keep it in there when the battery is on 100% or have it charging when its only 80%?

posted by ptsampras14 to Technology (9 answers total)

This is purely anecdotal, but from experience of broken iPods — or, in this case, iPods with faulty batteries — 99% of the time, they'd lived in some kind of iPod dock. Presumably it has some sort of aux input? You could use an auxiliary cable to connect your iPod to do it, thereby running off the battery rather than constantly being topped up.

EDIT: Just previewed and realised you said 'iPhone' rather than 'iPod'. I think the same still applies, but the two may use different battery technology. My memory's a little hazy on this one, sorry!
posted by jaffacakerhubarb at 4:41 PM on May 4, 2010

Last I read up, lithium ion batteries while not having a memory, will degrade if you overcharge them or let them run out completely. Certainly my last phone went from being fine to terrible because I left it on the cradle the whole time, whereas my new one I make sure never to leave on charge past 100% (mostly...) and, while it's too soon to really tell it still seems to hold a decent charge. Also stops it getting fiercely hot.

Since they have no memory it means there shouldn't be any problem with either charging it from 80% or taking it off charge early.

That's just what I've deduced though, and I don't trust batteries to not be terrible.
posted by opsin at 4:43 PM on May 4, 2010

Best answer: Apple answers authoritatively that you have nothing to worry about (and yes, iPod and iPhone use the same battery technology):

Question: Should I leave iPod connected to the charger or in the dock whenever I'm not using it?
Answer: The battery stops charging when it's full. Leaving it connected won't charge it any more. It's perfectly OK to leave it connected so it can charge overnight, for example

I have left my iPod touch on a docked system that charges consistently over the last 18 months or so, usually overnight, sometimes over several days. I've never had any problems with the battery. It still holds a charge quite well.
posted by fourcheesemac at 4:54 PM on May 4, 2010 [2 favorites]

Best answer: No. It is not harmful.

A LiIon battery degrades based on two things: 1) its age, and 2) how many charge cycles it goes through. If it's plugged in, the controller lets the battery drop to, let's pick a number, 90%, at which point it charges it up. This counts as 1/10th of a full charge cycle. If you were to let it drop to 0% before charging it, you would have just as many full charge cycles over the same period. Doesn't matter that in one regime you have ten 10% charges, and in the other you have a single 100% charge.

LiIon batteries can typically run through several hundred full charge cycles before they degrade to unacceptable levels.

I'm ignoring the possibility that your charger is incredibly cheap and old fashioned and might over-charge the device, which is unlikely with modern electronics.
posted by zippy at 4:56 PM on May 4, 2010

How to prolong lithium-based batteries
posted by domnit at 5:05 PM on May 4, 2010 [1 favorite]

Yeah, l-ion batteries will just drop dead at a pre-ordained time, depending on how well they were manufactured and how long ago it was. For the most part, all you need to know is that batteries like to stay fully charged and not be overcharged. The device itself usually has the charging circuitry in it these days, the wall wart is just a power source. That's why you can charge many devices via USB now.

The only caveat I have for this issue is to not use a car-charger. The power isn't as clean as it could be and can cause trouble for the internal charging circuitry.
posted by gjc at 6:37 PM on May 4, 2010

I have charged my iPhone overnight nearly every night over the past few years and also let the battery die completely dozens of times. Unless I’m talking using Bluetooth (while driving), using WiFi for long periods of time, or placing hour-long calls, the battery usually lasts 10-14 hours.
posted by vkxmai at 6:42 PM on May 4, 2010

Well, purely anecdotal evidence only, but I've keep my iPhone in a decent quality dock at night, and plugged via usb in while at work. Hence, it spends a lot of time at 100%. My battery crapped out after about 18 months of pretty hard use, right on schedule. And when it goes, you know. It's not a matter of holding a charge. It's a matter of the damn phone working or not.
posted by cgg at 7:01 PM on May 4, 2010

All but the crappiest of modern rechargeable devices have circuitry that stop the process once the battery has fully recharged. Once charged, the device will power itself from the incoming AC (and not the battery) In short, there is no harm in leaving your iPhone connected.
posted by Thorzdad at 4:40 AM on May 5, 2010