[Sayed Mohammed Shakhawat]

I hav bought a LG V20 recently & when i fast charge it the battery drains as fast as it charges. But when i slow charge it the charge stays for a hole day. What is wrong with my device?

[michail71]

Do an experiment and take some screen shots of the graph in the battery app. One with slow and one with fast.

You can also see what is consuming the most power from there as well.

[flyingkytez]

I hav bought a LG V20 recently & when i fast charge it the battery drains as fast as it charges. But when i slow charge it the charge stays for a hole day. What is wrong with my device?

I've noticed this too with other phones like Samsung phones. I noticed fast charging makes the battery drain faster. What charging block are you using? The original LG charger is only using Quick Charge 2.0 so it isn't that fast. Also give your phone about a month so that the OS and battery can settle in.

[datum9]

Fast charging damages the battery over time, resulting in less capacity and runtime.

for most years out of a battery, use slow charging. ideally charging at 200-300 mAh rates versus 1Amp or 1.5 Amps fast charging throws at it.

[tickerguy]

Fast charging damages the battery over time, resulting in less capacity and runtime.

for most years out of a battery, use slow charging. ideally charging at 200-300 mAh rates versus 1Amp or 1.5 Amps fast charging throws at it.

Actually that's not quite correct.

If you look at the V20's charging profile you'll find that irrespective of the charger you're using if the screen is on it charges slowly.

The problem is that all the manufacturer's "fast charge" profiles run the voltage too high for good battery service life. They do this because nobody likes a ~4 hour charge cycle, which is what doing it right requires. This is compounded by charging to 100% and holding it there, such as by float-charging overnight.

So instead put Accubattery on the phone, don't float charge (overnight) and DO pull it off charge when it gets to 80% -- and go ahead and use a QC3.0 charger if you want fast (much less heat than QC2.0 since it can negotiate actual voltage instead of only having three steps.)

[datum9]

Yes it is correct. Slow charging is always better for the Li-ion battery in theory. I don't know how V20 does it. I disable fast charging on all devices if possible. Or use a low charging cable/charger.

fast charging was introduced to cope with 3000 mAh batteries that are completely not adequate for high drain devices with 2560x1440 pixels. There were barely adequate for HD phones but with that many more pixels to drive, consumption has only risen.

Trickle charge is not that bad either. There is no 100%, it's an ***** gauge type number. The Li-Ion battery is full at 4.3V and shuts down at 3.5V. So 4.0% approximates 80%.

[tickerguy]

There is no phone on the market today that charges on the recommended and well-understood profile for LiIon batteries.

Simply put the correct way to charge these cells involves running constant-current charge at up to 1.0C (0.5-0.8c is nicer, but 1.0C is safe), assuming the charging circuit can deliver it, until the voltage reaches 4.2V. You then hold the voltage at 4.2V until current drops to ~0.05C, with a timeout in case the battery has a partial internal short.

The faster you charge during bulk the lower the capacity when you hit the constant-voltage transition and the longer saturation charge takes. At 0.5C you'd be at ~85%, at 1C you might only be at 65-70%.

There are NO phones on the market that follow this profile and running voltage over 4.2V during charge materially shortens battery service life. The more you do it the worse it is.

If you don't believe the reporting by apps such as accubattery then put external, accurate measuring equipment on the battery (made easy on the V20 by the battery being removable) and verify it for yourself. I've done so and the app report is correct.

[Mooncatt]

There are NO phones on the market that follow this profile and running voltage over 4.2V during charge materially shortens battery service life.

The newer graphine style Li-ion batteries are designed to handle higher voltages. Not much, but 3.85V nominal and 4.4V charged. That's most likely why you see the 4.4V readout. If you look at the OEM V20 battery, it even has 3.85V on the sticker.

The V20 also follows the charging pattern you mentioned earlier. When plotting out on the 3C Battery Monitor app, I can see all three stages. On the final stage, the current drops until shut off at 100mA. I've also noticed it hits 100% on the built in gauge well before the cutoff, which leads me to believe it's a programming feature to "trick" people into unplugging earlier and thus limit the amount of high voltage damage (meaning cell voltage, not incoming charge voltage).

But now I'm curious. I'm wondering if the higher Quick Charge voltages are going straight to the battery, or if running through a transformer in the phone that reduces what the battery actually receives but just at a higher current. I may look into that.

[tickerguy]

The V20 also follows the charging pattern you mentioned earlier. When plotting out on the 3C Battery Monitor app, I can see all three stages. On the final stage, the current drops until shut off at 100mA. I've also noticed it hits 100% on the built in gauge well before the cutoff, which leads me to believe it's a programming feature to "trick" people into unplugging earlier and thus limit the amount of high voltage damage (meaning cell voltage, not incoming charge voltage).

The problem is that if you float charge the battery (e.g. plug it in overnight) that damage accumulates, and pretty quickly too.

But now I'm curious. I'm wondering if the higher Quick Charge voltages are going straight to the battery, or if running through a transformer in the phone that reduces what the battery actually receives but just at a higher current. I may look into that.

It's not a transformer (transformers only work on AC), but there is a charge controller and with QC3.0 you get a better "match" between the input voltage and the requirement of same to drive the charging cycle. There is drop across the junctions in the controller (typically 0.7v per transistor) and then it needs enough margin above that for the circuitry to operate in a stable fashion. I find that when "quick charging" the V20 will negotiate a roughly 6V setting on a QC3.0 charger, which both charges fast and avoids material heating. If you have a QC2.0 charger there are only three steps (5V, 9V and 12V) instead of the ability to negotiate the desired voltage anywhere within the output range so you''re likely on the 9V step and the heating will be materially higher due to more loss in the charge controller circuitry -- but the actual delivered voltage to the cell will not be higher.

[Mooncatt]

The problem is that if you float charge the battery (e.g. plug it in overnight) that damage accumulates, and pretty quickly too.

Agreed, but that wasn't the point I was addressing. You said no phone follows the recommended 3 stage charging, and I'm saying it looks like the V20 (and I suspect others) does follow it. The charging algorithms and your personal charging habits are two separate issues. I personally unplug at 80% and only did a full cycle a couple times when testing the charging abilities.

It's not a transformer (transformers only work on AC), but there is a charge controller and with QC3.0 you get a better "match" between the input voltage and the requirement of same to drive the charging cycle. There is drop across the junctions in the controller (typically 0.7v per transistor) and then it needs enough margin above that for the circuitry to operate in a stable fashion. I find that when "quick charging" the V20 will negotiate a roughly 6V setting on a QC3.0 charger, which both charges fast and avoids material heating. If you have a QC2.0 charger there are only three steps (5V, 9V and 12V) instead of the ability to negotiate the desired voltage anywhere within the output range so you''re likely on the 9V step and the heating will be materially higher due to more loss in the charge controller circuitry -- but the actual delivered voltage to the cell will not be higher.

Perhaps I used the wrong terminology, but I believe there is a voltage regulator of some sort involved. It's not safe to take the battery itself above 4.4V in the V20. So even with a 5+V input into the phone, I think something is reducing the voltage to match the battery in the constant voltage stage of charging. And because the wattage is higher than older charging styles, the current is able to be ramped up higher. I couldn't find any hard evidence this is what's going on, but it's my best educated guess.

[tickerguy]

The charge controller does indeed control the delivered voltage that is independent of the charge output voltage just as your switching USB charger will work on anything from 110-240V and 50 or 60Hz, but still delivers the same output.

It's just that QC3.0 allows the phone to request a "best match" so the regulator runs at its most-efficient for the desired charge rate. QC2.0 only offers three steps rather than effectively-continual voltage adjustment.

Without QC you can only deliver an effective ~1500ma of charge current with a 2A/5VDC supply, which is the "standard" USB charging limit. QC allows higher rates and is not particularly bad for battery cycle life on its own.

[mthorn82]

Had issues with mine for a while battery was running around 105-115 degrees F when charging or under normal operation. Phone started acting up locking up lately, making weird noises doing some very strange things popped a new aftermarket battery in instant drop in temps 85-87 degrees F now! Did the thermal paste mod on the CPU also and temps in general have dropped phone is running better.

[Billy Beckham]

There is some tips that could save the battery life for your reference:
1) Use Low Power Mode
2) Restrict Unimportant Notifications
3) Turn off Wi-fi if You Don't Need It
4) Do not Activate Location Service
5) Lower Screen Brightness
6) Limit Background Refresh for Applications
7) Tighten Up Auto-Lock the shortest period for your device, namely 30 seconds.