Leaving a fully charged phone on a wireless charger can overcharge the battery

[EBynum]

Hi, All!

I sent an e-mail to Nokia Customer Care (US) to ask if the charging process stops when the indicator light on the charging plate turns off (indicating the battery is fully charged), or if there is a risk of overcharging the phone if the fully-charged phone is left on the charging plate. I got a response today and the rep wrote,

In response to your concern, we would like to inform you that if your Nokia Lumia 920 is already fully charged, the wireless charger will display a one long blink. When the white indicator light goes ?Off?, the battery is fully charged. However, if your fully charged phone is still in contact with the Wireless Charging Plate, the charging will still continue.

Please be advised also that the Wireless Charging Plate automatically switches ?Off? when not in contact with a compatible device or if it is too hot. You may also turn ?Off? your Wireless Charging Plate by disconnecting the power supply from the plate, then unplug from the wall outlet.

In addition to your inquiry, please be reminded that leaving your phone in contact with the Wireless Charging Plate will still cause overcharging the battery. With this, you can only charge your fully drained Nokia Lumia 920 for 4 to 5 hours using the Wireless Charging Plate.

This agrees with a statement made in the Lumia 920 user manual that says, "Do not leave a fully charged battery connected to a charger, as overcharging may shorten the battery's lifetime."

So, leaving the phone on the charger overnight can cause overcharging and damage to the battery. It's best to remove the phone from the wireless charging plate/stand as soon as it's done charging. If you use your Lumia 920 as an alarm clock and use the wireless charging stand, then it seems to me that it would be best to top off your battery charge before going to bed, and then unplug the charging stand from the power supply when you go to sleep so you don't risk overcharging your phone. Then in the morning, you can top off the battery again if needed.

Also, check out this informative post by GizmoEV:
http://forums.windowscentral.com/no...y-charging-wired-vs-wireless.html#post1833002

Just wanted to pass this information along.

 

[RuleOfSines]

Well that's interesting. If it is smart enough to know the phone is charge, why couldn't they go that extra step and stop the charger?

 

[ragingklu]

Damn that sucks.
Sent from my 920

 

[nfletch05]

Does this apply to using the wall charger as well? I hope not. I like to listen to music at work while keeping it charged.

 

[lancguy]

That is just stupid. So that would mean that the charging pad, stand, speaker or what ever never shuts off the charging coil even when a phone is not sitting on it. That seems like a huge waste of electric to me.

 

[txaggies07]

I will stick my kill-a-watt on it and check it out.

 

[conanheath]

I have been using my wireless charger for a month now. I start charging at 9pm or so and don't take it off until 5am. I know it charges by 12am or so. My battery has sucked up until the point I started using wireless. May have been something to do with portico but maybe the battery needs a little overcharge. As long as mine makes it to May. I'm upgrading to whatever isn't Nokia.

 

[lancguy]

I was just on the forums over on Nokia's website and the issue of overcharging was discussed on a thread. It seems that the general consensus was the charger shuts off when the battery hits 100%. Overcharging should not be an issue. Tomorrow when I get up I will check to see the back of the phone is warm. I usually leave my phone on my speaker over night.

 

[iosub]

This can't be true.. So I have to wakeup at midnight to unplug my phone ? Come on...

 

[spaulagain]

What that rep said would apply to wall chargers as well. I don't think anyone that would unplug their phone from the wall in the middle of the night, or watch your phone until you see it fully charged.

 

[EBynum]

That is just stupid. So that would mean that the charging pad, stand, speaker or what ever never shuts off the charging coil even when a phone is not sitting on it. That seems like a huge waste of electric to me.

The Nokia Care rep said, "... that the Wireless Charging Plate automatically switches “Off” when not in contact with a compatible device ...", so according to him, yes the charging plate does turn off when the phone is not on it.

 

[Alex Kj]

I don't think Nokia's representative gave you a correct answer. My Lumia always stops charging itself when it reaches full battery charge, doesn't matter which charger I use or for how many hours it was connected to the charger... If it would be possible to actually overcharge it, the battery would simply explode or catch a fire, which has never happened so far to any Lumia 920 user. You should forward this response to Elop's e-mail address for clarification...

 

[irvin792]

I do not think this rep knew what they were talking about. I charge mine every night all night long on the wireless charger and the light if off and the phone not hot at all when I wake up.

 

[EBynum]

What that rep said would apply to wall chargers as well. I don't think anyone that would unplug their phone from the wall in the middle of the night, or watch your phone until you see it fully charged.

Charging my phone with the wireless charging plate takes about 3 hours (give or take depending on how discharged it is), so I just make a note of what time I put it on the charger, and check back 3 hours later to see if it's done. I'm home a lot, so this isn't an issue for me, but I can see how it might be inconvenient for a lot of people. As far as overnight goes, certainly no one is going to get up in the middle of the night to remove the phone from the charger. What I do is just top off the phone before bed if necessary, than just unplug the charging stand from the power supply when I go to sleep. Then just top it off again in the morning if necessary. Yeah, it's dumb that we can't just leave the phone on the charger, but for me it's not that big of a deal.

 

[EBynum]

I don't think Nokia's representative gave you a correct answer. My Lumia always stops charging itself when it reaches full battery charge, doesn't matter which charger I use or for how many hours it was connected to the charger... If it would be possible to actually overcharge it, the battery would simply explode or catch a fire, which has never happened so far to any Lumia 920 user. You should forward this response to Elop's e-mail address for clarification...

Yeah, it would be good to get clarification. But the Lumia 920's user manual also says, "Do not leave a fully charged battery connected to a charger, as overcharging may shorten the battery's lifetime." Is the manual wrong too?

 

[moegumby]

Reps have no idea what they are talking about. All modern cell batteries control themselfs! They won't accept a charge after they are fully charged. Electronics are built into the batteries. Charge away folks, not going to hurt a thing. Been leaving my Blackberries in the dock over night for 8 years.
Sent from my HTC6990LVW using Board Express

 

[Alex Kj]

Yeah, it would be good to get clarification. But the Lumia 920's user manual also says, "Do not leave a fully charged battery connected to a charger, as overcharging may shorten the battery's lifetime." Is the manual wrong too?

It is talking about "a fully charged battery", not a "fully charged phone"... Very weird choice of words, and yes, it is probably wrong. Like I said, if it was possible that the battery would be overcharged, it would most likely explode or catch a fire.

 

[alphonsohall]

My 920 gets slightly warm whilst charging on the wireless charger but then stays stone cold after it is fully charged and left in position on the charger, if it was still charging or overcharging, surely it would stay warm?

 

[lafn]

Time to go pull out the timer I use to schedule turning on and off my Christmas lights.

 

[anon(5503495)]

This can't be true.. So I have to wakeup at midnight to unplug my phone ? Come on...

exactly what I'm thinking