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

Landsharkk

New member
Oct 6, 2012
308
0
0
Visit site
Plugging a phone into a wall charger produced heat while charging, which over time degrades battery performance.

Is this the same for wireless charging?

I'm interesting in learning more about this technology and whether or not wireless charging is actually healthier for your smartphone's battery.

It's been said that less time on the wall charger is better for the battery, because it means less heat being generated which reduces overall battery wear. Basically, it's better to 'top off' your phone's battery instead of letting it drain to near empty before charging which generates heat longer.


Does wireless charging help prolong battery life vs wall charging?
 

chriscookz

New member
Oct 2, 2012
121
0
0
Visit site
I have no idea, but that's an interesting idea.

I'm mostly interested in the wireless charging because after 2 years of plugging and unplugging my charger, my micro-usb port nearly does not work anymore.
 

ltyarbro42

New member
Apr 7, 2012
49
0
0
Visit site
I don't know about the 920, but from my webOS days my phones always seemed to not generate as much heat while wireless charging. The magnetic parts and outside cover (which held the entire system) would warm up, but not the battery itself

Sent from my Lumia 900 using Board Express
 

KoukiFC3S

New member
Nov 12, 2010
554
0
0
Visit site
My 920 gets pretty warm using wireless charging with an energizer pad.

I think that letting the battery stay in the range of 50%-90% will make the battery last the longest. So yes, keep topping it off. :D
 

blacksea00

New member
Nov 3, 2012
26
0
0
Visit site
really doesn't matter... personal opinion...
in about a year you will debate iphone 6 vs lumia 940 ...

if you wanna change this phone in 5 years you should take care of this... if not just don't pay attention to this
 

Landsharkk

New member
Oct 6, 2012
308
0
0
Visit site
really doesn't matter... personal opinion...
in about a year you will debate iphone 6 vs lumia 940 ...

if you wanna change this phone in 5 years you should take care of this... if not just don't pay attention to this

My phones always last me at least 2 years (contract length is 2 years). Add the fact that the Lumia 920 has a non-removable battery and suddenly battery health becomes rather important. Thus, I have brought up the topic of wired vs wireless charging and the effects they have on battery health.
 

Coreldan

New member
Oct 2, 2012
2,514
0
0
Visit site
It's possible to ruin battery life in 1-1,5 years with wrong type of use. With a unremovable battery that can be a problem.

That said, I dont think it matters whether you plug or wirelessly charge, the most important part is to rather charge too often than too rarely. The battery isnt hurt even if you charge it 10 times a day for 10 minutes, it is hurt far more if you let it go sub-10% charge.
 

bauerbach

New member
Oct 12, 2012
223
0
0
Visit site
a battery warms up when it is used (discharged and charged), this has no bearing on wall vs induction vs whatever other means there may be to charge the cell.

The rate at which the battery is charged can affect battery life. Fast charging obviously being harsher and resulting in more heat, but it really isn't the heat that's nescessarily the problem (within reasonable limits of course).

It appears that wireless charging takes slightly longer to charge, with that knowledge, it may be slightly more gentle on the battery. But I think both are well into the safe zone where the difference is negligible.

Generally speaking, you can charge any battery at "1C" for maximum safety. where C * mAH = charge amps. so a 2000mAH battery at 1C would be 2A charge rate. Correct me if Im wrong, but I don't think these wall chargers put out more than 1 amp, I know the iphone charger is 1amp.
 

pdskep

New member
Nov 10, 2012
58
0
0
Visit site
It appears that wireless charging takes slightly longer to charge, with that knowledge, it may be slightly more gentle on the battery. But I think both are well into the safe zone where the difference is negligible.

I've use the 'Battery Tile and Log' app to calculate my charging time wired and wireless and I get a charge rate of 46%/hr wired and 34%/hr using the charging plate. My charging plate is actually underneath my glass desktop so it's about a cm away from the phone so that could affect the rate.
 

GizmoEV

New member
Dec 11, 2012
316
0
0
Visit site
My background so you know where I'm coming from. I'm an Electric Vehicle enthusiast with a degree in Physics. As you can imagine, I want to keep the $5000 battery pack in my car working as long as possible since, unlike a phone, it is quite expensive to replace. As such I have done significant study into the various battery technologies and definitely into the various Lithium based batteries.

While the batteries in my car are LiFePO4 (Lithium Iron Phosphate), the ones in cell phones are typically Lithium Polymer. They have a higher voltage and energy density which is what we want in our phones. In all Lithium type batteries the electrolyte starts breaking down the moment the battery is manufactured. The things that cause it to break down faster is high temperatures and high states of charge. There are other breakdown mechanisms in the batteries too. One of them is Lithium plating and another one is the breakdown of the crystal structure into which the Lithium ions intercalate (where they "park" on charge or discharge). As another poster mentioned, extreme states of charge decrease the life of the battery. Ideally the batteries should be kept between 80-90% and 20% SOC (State of Charge). That would make the battery last a significantly longer period of time. IIRC, Tesla Motors found that charging the laptop batteries used in their cars (Lithium Cobalt) to only 95%SOC extended the cycle and calendar life by a significant amount, 20-50% but I don't remember exactly. Various other studies, including a NASA study I read, showed that keeping a Lithium battery at 100% SOC, rather than charging it up just before it was needed, shortened the life of the battery.

In laptops the batteries rarely die of old age but instead of being held at 100%SOC and elevated temperatures for long periods of time. Time at 100%SOC, heat and full discharges are the killers of Lithium based batteries. Contrary to past practices with NiCd and NiMh batteries, fully cycling a Lithium battery does not make it last longer, it actually shortens its life. I don't know the mechanism used in cell phones to determine SOC so it is possible that a full cycle will calibrate the phone properly so it may give the illusion that the battery works better when in fact it is the electronics which are reporting properly. That being said, there is a slight increase in realized capacity during the first bit of use. You don not, however, have to do any special cycles to gain this increase. Normal use will automatically take care of it so why waste it with a discharging type app? The voltage drop vs. SOC of the batteries used in cell phones is quite steep compared to what I use in my car. This means it is possible to get a reasonable SOC value of a cell phone battery on voltage alone but I don't know if that is what is used. The voltage usually ranges from ~2.7V discharged to ~4.2V charged. (For comparison, the LiFePO4 cells in my EV are ~2.5V discharged and 3.38V charged but the useful range is between 3.0V and 3.38V so very little change. The 2.5-3V range has at most 5% of the total capacity if it is used very slowly.)

What I have found with my Nokia Lumia 920 is that with the Nokia supplied wired charger (rated at 1.3A output) that my battery rarely feels warm, even when charged from a completely discharged phone. When using the wireless charging pad, however, the entire phone gets quite warm even though it is only putting out 0.75A (though I don't know if this is rated at 12V or 5V). Warm enough that I worry that the battery life is being noticeably shortened. I hope to take some surface temperature measurements to see if the temperature is getting into the unsafe range. Basically the battery will be safe below something like 60?C (140?F) but the electrolyte will be breaking down rather rapidly at that point. I don't even like to see my batteries get much above 30?C (86?F) but I think with a phone, especially if carried in a pocket or something that it is likely to be that hot quite often. They do best at temperatures that we are comfortable with so on the order of 20-25?C (68-77?F).

As for heat generation during charging, I have found that the most heat is generated at the end of charge when the battery is nearly full. Very little heat is generated in the vast majority of the SOC range until nearly full. On discharge it is the opposite. Most of the heat is generated near the empty end of the SOC range. If you study the physics and chemistry of how these particular batteries work it makes perfect sense that this should happen this way.

Here is what I have done with my previous 3 phones to make sure the battery easily lasts over 2 years, in the case of my iPhone 3GS it is still going strong well over 4 years later and is in the hands of a new owner. My 2.5 year old iPhone 4 is also still going strong and appears to out last my 2 week old Lumia 920.

  • If I am going to use my phone extensively throughout the day where it is likely to be really low by the time I go to bed then I charge it sometime during the day. These batteries do better with many small charges and discharges because it keeps them away from the extreme ends of the SOC range.
  • Unless the battery is really low I don't charge it until the morning when I get up. This keeps it from sitting at 100% SOC for very long.
  • If my phone isn't fully charged by the time I'm ready to leave I don't worry about it. Stopping charging at 90-95% is actually good for the battery.
  • Except in an emergency I do not let my phone get much below 20%SOC and usually try to stay above 40%SOC.
  • I don't leave my phone in a hot car or in the sun.
  • If my phone were ever to be cooled to below 0?C (32?F) I never charge it until it has warmed to above freezing. Charging at temperatures below this point significantly increases the chance that Lithium plating will be happening in the battery. Any Lithium ion that plates out as Lithium metal is no longer available to store charge. Discharging at very cold temperatures, however, does not cause any problem, just that the battery doesn't put out energy very fast. This is not likely to be a problem with the really slow rates our phones use the battery but it could be a problem in extremely cold situations.
  • If I had the option, I use a lower rate charger which is easier on the battery. I usually use a 0.5A charger for my Bluetooth ear piece if I have the time and my phone doesn't complain.

Hopefully this wasn't too long for my first post but I thought people would like to hear from someone who has a fair bit of personal experience with Li batteries. Believe me, I want my $5k investment to last so I have spent countless hours on the battery care issue.

David D. Nelson
David Nelson's 2003 Gizmo
 
Last edited:

xcen

New member
Oct 30, 2012
27
0
0
Visit site
Thanks, GizmoEV, that's actually very informative and I will try to prevent myself from keeping the phone charged for too long. Your tip is also very useful for preserving my laptop's battery life.

I believe the reason why wireless charging is hotter is because unlike wired charging, more energy is lost as heat during charging (due to imperfect energy transfer). Wired charging has better contact so less electrical energy is lost as heat.
 

tissotti

New member
Oct 26, 2011
1,105
0
0
Visit site
Thanks a lot GizmoEV!

I have no idea, but that's an interesting idea.

I'm mostly interested in the wireless charging because after 2 years of plugging and unplugging my charger, my micro-usb port nearly does not work anymore.

Same for me. Also bought it because i can keep wireless charger stand for work where it sits next to me on the desk while it charges.
 

EBynum

New member
Nov 8, 2012
262
0
0
Visit site
Thanks for the information, GizmoEV! The Lumia 920 is my first smartphone and I want to learn how to charge it properly and take care of the battery. I've read conflicting information on these forums and on Nokia's forums which has left me confused about what is right (drain the battery low vs. top off often; need to calibrate vs. don't need to calibrate; OK to leave on charger overnight vs. not OK, etc.). One question I have is when the indicator light on the charging plate turns off when charging is done, is the actual charging process stopped? Or is there a risk of overcharging the phone? Nokia's Lumia 920 user manual says not to leave a fully charged battery connected to a charger because overcharging may shorten the battery's life. This plus the information you gave leads me to believe that it's bad to leave the phone on the charger after it's finished charging.

I've just bought the DT-910 wireless charging stand to put on my bedside table so I can use the alarm clock function on my phone. I wasn't sure if it would be OK to leave the phone on it all night, but now I think you've answered my question. It would be bad to leave my phone on the charging stand all night, correct? I think what I'll do is just charge my phone before going to bed, and then disconnect the charging plate from the power supply when I go to sleep. That way I can still use the stand to hold the phone. So far, I've been using the wireless charging plate and I've always removed the phone right after it's done charging, so I'm glad I've been doing the right thing.

I'm also going to follow your advice to charge my phone often and not let the battery charge get too low. I haven't always done that in the past since I wasn't sure if that was the right thing to do (some people say yes, others say no), but what you wrote made sense to me.
 

CJ Thunder

New member
Feb 16, 2011
714
0
0
Visit site
WP manages the charge, which is why we can't charge with the phone off. You think the battery actually is at 100% when the OS says it is? If so why doesn't MS use the same safeguards as Tesla?
 

Tafsern

New member
Oct 29, 2012
207
0
0
Visit site
I still haven't actually charged it with the wire. Since I always charge at night, I use the wireless one on my nightstand. So convenient I don't think I ever can go back to wire...ever!
 

Andyshine77

New member
Jan 10, 2013
121
0
0
Visit site
Short charging the battery is better than fully charging it, and fully discharging lithium batteries is not the best idea. Unfortunately sometimes it's necessary to discharge these batteries to recalibrate the electronic battery management system. The system on the 920 has bad programing, or it's simply a bad design. When the battery on any modern electronic device reaches full charge the charger discontinues charging. However the 920 may not do this, if so it's an inexcusable oversight on Nokia's part.

Remember the battery on the 920 is located in the bottom half of the phone. The top of the phone houses the processors, so if the top of the phone is heating up it's not the battery. Batteries are also exposed to elevated temperature when charging on wireless chargers. The energy transfer from a charging mat to a portable device is 70 to 80 percent and the remaining 20 to 30 percent is lost mostly in heat that is transferred to the battery through the mat. Keep in mind that the mat will cool down once the battery is fully charged. Manufactures often overestimate the actual capacity of their batteries, so it's doubtful the 920's battery is actually 2000 mAh.
 

akashpats

New member
Nov 6, 2012
64
0
0
Visit site
According to my opinion, the heating of battery while charging it is normal. It will not affect your battery life. In wired charging, charging many times the battery even if it is not dry reduces the battery life cycle, so charge battery only when its dries up and let it fully charge.
Wireless charging is nice technology and i think its a great start for better future technologies.
Often when we put our wired charger into plug and are not using it, then the electric current is wasted (which is not much noticeable in our bill). But if the same thing is done by millions of people then it is a huge waste. In case of wireless charging it is totally different, if your phone is not in contact of charging pad or you plugs in the charger but not using it, it doesn't use up electricity. That means No Touch, No flow of electric current. that is a nice technology.
 
Last edited:

Andyshine77

New member
Jan 10, 2013
121
0
0
Visit site
According to my opinion, the heating of battery while charging it is normal. It will not affect your battery life. wireless charging is nice technology and good for environment too, because when u put your wired charger into plug and u are not using it, then the electricity is wasted. In case of wireless charging it is totally opposite, if your phone is not in contact of charging pad, it doesn't use electricity. That means No Touch, To electricity.
Coming back to wired charging, charging many times the battery even if it is not dry reduces the battery life cycle. so charge battery only when its dries up and let it fully charge.

What?? Sorry you have no understanding of what you're talking about. Heat and cold is bad for any battery... The amount of wast is the same for both chargers, and the amount of waste is pretty much nothing. You can charge Lithium Polymer batteries any time you like, however it's best to stay away from both extremes... This is fact not opinion. Yes batteries degrade.

I see you edited your post. Any wall adapter including the one for wireless chargers wast a tiny amount of electricity, mostly in the form of heat.
 
Last edited:

Members online

Forum statistics

Threads
322,916
Messages
2,242,890
Members
428,005
Latest member
rogertewarte