[L640] Charging takes longer not using the supplied charger?

[Windows Central Question]

It took 4 hours to charge it from 20% to 100% Is this normal

 

[yogi01]

In an electrical circuit the current is determined by the resistance of the load, not by the capability of the source. The charger may limit the current, but it does not increase it above the level U/R (voltage divided by resistance). Typically the inner resistance of a battery leads to a current of 1/10 of the batterys capacity. This current will not become larger as long as you do not increase the voltage, even if the charger was capable of putting out 200 ampere.

 

[gpobernardo]

Thanks for the clarification. However, Ohm's Law doesn't account for increases in temperature over the resistors, whereas increased temperatures lead to increased resistance.

How then would the difference in the time it takes to charge a phone using a 500mA charger and a 1.5A charger be accounted for, whereas it is clearly observable that charging time is shorter with a 1.5A than with a 500mA charger?

Also, there's some ambiguity with this statement

Typically the inner resistance of a battery leads to a current of 1/10 of the batterys capacity..

The capacity of the battery (electric charge, total electrons that can be stored, in "mAh") and current (rate of electron flow, in A) are of different units and, hence, are not arithmetically operable. One cannot say, "The size of the opening of the gasoline tank of a car leads to a flow of gasoline that is 1/10 the weight of the car".

 

[yogi01]

Thanks for the clarification. However, Ohm's Law doesn't account for increases in temperature over the resistors, whereas increased temperatures lead to increased resistance.

In rare circumstances a "thermal runaway" can occur. Battery heats up->resistance goes down->more current->higher temperature->lower resistance->more current...
But the charging logic (which should protect the battery) is in the phone, not in the charger.

How then would the difference in the time it takes to charge a phone using a 500mA charger and a 1.5A charger be accounted for, whereas it is clearly observable that charging time is shorter with a 1.5A than with a 500mA charger?

As i wrote, a charger can limit the current (500mA type). The 1.5A type charges faster (up to three times), but a 15A type will not charge thirty times faster than the 500mA type. At some point, the battery will not take a higher current.

Also, there's some ambiguity with this statement
The capacity of the battery (electric charge, total electrons that can be stored, in "mAh") and current (rate of electron flow, in A) are of different units and, hence, are not arithmetically operable. One cannot say, "The size of the opening of the gasoline tank of a car leads to a flow of gasoline that is 1/10 the weight of the car".

The "C/10" is a rule of thumb, not a physial law. So the "h" is ignored. C is the capacity of the battery in (m)Ah.

 

[gpobernardo]

In rare circumstances a "thermal runaway" can occur. Battery heats up->resistance goes down->more current->higher temperature->lower resistance->more current...
But the charging logic (which should protect the battery) is in the phone, not in the charger.

Yes, I agree that the battery protection is in the battery - there has been several discussions on this around the forum. But last time I checked, resistance goes up with increase in temperature. More resistance also leads to increased temperature. Hence: more current > increased temperature > increased resistance > more current required to maintain charging voltage > increased temperature > increased resistance.... until the temperature begins to damage the battery and/or its circuitry.

As i wrote, a charger can limit the current (500mA type). The 1.5A type charges faster (up to three times), but a 15A type will not charge thirty times faster than the 500mA type. At some point, the battery will not take a higher current.

Yes, I agree again. But won't a 15A charger (from the previous thermal instability cycle) burn the battery protection circuit? A circuit designed to limit the current to 2A could reduce an input of 15A to 2A, but circuit regulators can only take so much current until they start to fail. By this logic, continually using high current chargers have the potential to overwork the battery circuitry... not to mention that even if the battery was built to take, for example, 2A of charging current, 2A charging current will shorten the battery life more than a 1A charging current due to the increased molecular-level deformations of the Li-ion-adsorbing/desorbing anode/cathode material at higher currents.

The "C/10" is a rule of thumb, not a physial law. So the "h" is ignored. C is the capacity of the battery in (m)Ah.

Ah, so, if the capacity of a battery is, let's say, 2000mAh, ignoring the "h" 2000mAh becomes 2000mA. Now following that "rule of thumb", 2000mA/10 = 200mA. The "rule of thumb" then suggests that 200mA is "perfect for battery life". Now, let's say we have two chargers: a 1.5A and a 500mA. Since the battery "pulls" current using that rule of thumb, that means that the battery will only take around 200mA regardless of using a 500mA or a 1,500mA charger. Hence, the charging time for both chargers should be the same, being consistently charged at 200mA as limited by the rule-of-thumb-induced "pulling" capability of the battery.

Unfortunately, this is not the case. A 2000mAh battery charges faster with a 1.5A charger than with a 500mA charger as observed in my L1020.

 

[STALKER-SVK]

I got my 640 DS with very small 750mA charger, but I use 1A HTC charger and it charges a bit faster

 

[Jonnie LasVegas]

The only charger that I get a warning about from my 1520, is the supplied Nokia charger. But I get a much better and faster charge with my old HTC Radar charger. Crazy and funny all at once.

 

[vuljanic989]

My lumia 640 came with 750mA charger,horrible, almost 4 hour from dead to full...thinking of getting new charger,probably will be nokias 1.3A chargerdont wanna mess with other quick chargers
Vulja

 

[Roger P Burt]

Hi,

I live in UK. Just bought a Lumia 640. It doesn't come supplier with a charger, I presume to keep the cost down. I do have a few chargers all of which when I use, I get a message 'A charged phone is a happy phone - use the recommended charger'

So to keep my phone & me happy can anyone suggest a charger?

Roger

 

[chiriquipanama]

Have a new Lumia 640 Lte gophone that I unlocked form AT&T and using on Claro sim in Panama.
Have a pre-release Windows 10 installed.
Started seeing low charging device when plugged into the charger that came with the phone
Bought a Samsung 2 amp charger today and same message with it charging the Lumia 640!
Read this message and removed the battery as suggested etc now charging on the Samsung charger ( one advertised for this phone ) and no low charging message came up on the phone.

No message but I'm not sure it is charging any faster than it did with the 750 Amp charger it came with. As I said no "slow charging message" but still ?

 

[roxetak]

I have the same problem. I am charging my L640lte maximmum to 78%. It does not dedands on time of charging, or type of charger. Where is a problem?:angry::devil::shocked::straight:

 

[Nahk786]

Try using a 5V/2A or 5V/2.1 Amp branded charger along with a short quality USB cable. The 2500mAH battery in Lumia 640 should get charged in about an hour and 10 minutes with a 5V/2.1 Amp charger.

 

[roxetak]

i can charge lumia 640lte up max 78% only! Where is a problem? I update to win10m.

 

[roxetak]

I tried a lots of chargers. Maybe I don't have original charger for lumia. Also charging thru PC usb port. Phone still charge to max. 78 or 84 % (it was my personal record) I can leave on charger 24 hours ... Still 78%. But now I have an another problem. I can not charge battery. I put lmia on charger. It was 24 hours. And percentage was still about 13 %, or fall down to 2%. I uninstall interop tools, and make soft reset. Battery was about 34 %, and now falling downbto 31%. I hape that is a problem with battery and i must change it. I hope.

 

[wgrs]

i can charge lumia 640lte up max 78% only! Where is a problem? I update to win10m.

Get a new battery. That's the problem.

 

[roxetak]

Get a new battery. That's the problem.

I did. I am just waiting.

 

[pidjones]

Battery, and get a real charger with good output (mine are rated up to 2 amps @ 5 volts). PCs do not provide enough current to even maintain tablets or high-power phones. Then, don;t run it down so low before charging if avoidable. I usually put my devices on charge each night, and batteries last for years.