Let's talk about battery charging. Wired vs Wireless.

[Andyshine77]

If the charger has an ac adapter it's consuming some power end of story. What they said in the link you offered is nothing but a lie to sell phones and wireless charging devices. I suppose they may be talking about those who leave their phones hooked up after the phone is charged, other that that the ac adapter is still drawing a bit of power. You're also forgetting the 20 to 30 percent loss, the loss = heat. The loss or inefficiency is way more than the system could ever save.

 

[pmhgeneral]

Thanks GizmoeEV for a great article it has all you need to know about battery's and more, $5000 battery in your car must be awesome how many years would your phone run on that?
Thanks for the info.

 

[EBynum]

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.

So, leaving the phone on the charger overnight can cause overcharging of the battery. It's best to remove the phone from the wireless charging plate/stand as soon as it's done charging.

 

[Derausgewanderte]

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.

So, leaving the phone on the charger overnight can cause overcharging of the battery. It's best to remove the phone from the wireless charging plate/stand as soon as it's done charging.

if that information you received is true that would be a big negative for that particular charging plate. I purchased Amazon.com: Energizer Qi-Enabled 3 Position Inductive Charger (Black): Cell Phones & Accessoriesthis one at Amazon and I know it turns off charging when the phone is fully charged. It only starts trying to charge again when I remove the phone and place it back on. But it will end this with a blinking blue light and stop charging. This is how it's supposed to work and I'd be surprised if the Nokia charging plates do not work that way.

 

[EBynum]

I've been searching through the Discussions forum on Nokia's web site and here's what I found. One user (rayhipkiss) wrote, "The battery does stop accepting charge at 100% but it will start to discharge and when it reaches something like 95% to 98% will start charging again. This is known as bump charging or over charging and can damage the lifetime of the cells."

Then another user (jraduga) gave this further explanation:

"As Ray has mentioned bump charging can cause issues.

when Lithium based batteries were first released, it became very obvious very quickly that they had the chance (as is with many batteries) of going in to a melt down or exploding. as batteries pack in phone are made of many cells all connected, it can only take one cell to go faulty, that then starts a reaction in the pack that cause excessive heat build up, that then becomes so hot that it can cause severe burns or explode. So many years ago they started installing safer types of lithium cells called lithium ion or nowadays lithium polymer cells, they all have a small electronic circuit that controls the charge and discharge rates.

in many cases (not always) the electronic boards even count how many times the batteries are charged, once they hit a certain number they stop accepting charge, this can be as low as 250 times. However this is mainly for many of the older version of these cells.

So bump charging can shorten the life of the battery pack. As ray said it does stop charging but then if it drops enough, it will start again. So where you thought you had charged your battery once, may in effect have been charged maybe 2 or 3 times during a single night. Remember its not the amount of charge you put in, in this case but the number of charges you do.

These circuits are put in for safety reasons, and not to make you buy more of these battery packs. People have had third degree burns to their ears by the use of mobiles in the past, hence why the safety devices were put in."

So what I get from all this is that once the phone detects that the battery is full, charging will stop; however, once the battery drains to a certain level, it will start charging again until it hits 100% then stops. Then this process repeats again once the battery discharges to that specified level again. I think this process of "bump charging" is what is meant by the term "overcharging" in Nokia's user manual statement, "...overcharging may shorten the battery's lifetime." If a battery has a finite number of charge cycles in it's lifetime, then "bump charging" would shorten the lifetime of the battery because it uses up more charge cycles.

So when you leave a phone on the charger overnight, the phone will not charge continuously. It will stop charging when the battery is full, so no worries about the battery overheating and damaging the battery. But what could be bad about leaving the phone on the charger all night is the "bump charging" that can occur, which over time can shorten the lifetime of the battery. Of course I'm not sure to what extent this "bump charging" can reduce the battery's overall lifetime. It may only be a small amount that we'd never really notice anyway. I think this is all starting to make some sense to me.

Here's the link to the thread if you want to read it yourself:
ridiculous... battery lifetime rule - Nokia Support Discussions

On another Nokia Discussions thread, user cjlim wrote, "Ideally you should disconnect from charger soon after charging stops, but doesn't have to be immediately because the phone stops the charging process when battery is full. Not possible to overcharge. However not good to leave it plugged in too long after because top up charging will start if the battery level falls below a certain value."

So I guess the bottom line is that it's OK to leave the phone on the charger overnight if that's what's convenient for you. It shouldn't damage your battery in the sense that it's going to become overfull and overheat. Just be aware that it could possibly use up your battery's charge cycles faster and reduce the battery's overall lifetime. If, like me, you like to err on the side of caution, and can charge your phone while you're awake, then just follow Nokia's advice and take it off the charger when the battery is full.

 

[Derausgewanderte]

Thank you. Makes perfect sense

 

[alphonsohall]

Might have been an idea if nokia had designed the wireless charger with an option that once the charging light went off (due to the battery reaching full charge) then the charger totally disabled itself until the phone was physically removed from it where it would then turn back on when the phone was replaced on it?.....hence, no worry about removing the phone once fully charged!

 

[Alfred Rillo]

I've seen recommendations by allegedly experts on the subject state that leaving your phone on the charger after it is fully charged will shorten battery life and it is heat from charging that shortens battery life. I don't believe this because once the phone is fully charged there is no charging heat.

My experience with cell phones I have owned from iPhones to my present Nexus 6, is that the phone gets warmest in the battery area when first plugged in the charger from a discharged state. After reaching the maximum heat in about an hour the heat gradually tapers off until there is no heat at all once the batter is fully charged. This makes sense because charging current would be highest when battery charge level is lowest. I've also found that the turbo charger that came with the phone causes considerable more heat that a regular charger. This is obviously caused by the higher charging current. I do not use the turbo charger for this reason.

I don't have a wireless charger for my phone yet, I intend to get one later. There are more phone failures by the microUSB port going bad than from battery failure. The majority of phones that won't charge is because the port is "worn out", not because the battery failed. Using a wireless charger will allow charging without plugging and unplugging the charging cable.

 

[gwinegarden]

I've found that, on occasion, the phone gets very hot when I charge it on my Nokia wireless charger. When this happens, if I take it off the charger and put it in the table, after a while, the phone will discharge and shut down with a flat battery.

If the happens, now, I shut the phone down. As this tends to happen at night, I just leave it off overnight and it is fine, next morning.