Charging the HTC One M8 and its effect on battery life.

[anon(9026430)]

Hi,

I have owned an M8 for a few months now and since then I have been experiencing inconsistent battery life. Using gsam, I have seen my phone last 63 hours with 5h screen time but other times it hasn't lasted the day with only 2-3 hours screen time.

However, over the past few months I have noticed a pattern with my charging routines. If I charge my phone from empty (5-10%), the next usage cycle will be consistently lower than if I charged my phone from 50%. I define a usage cycle as 100% to around 5% battery life. Furthermore, I have noticed that when charging from an empty battery it takes around 2h to complete. If I charge from 50% it still takes 1h 30m to fully charge leaving me to believe that somehow charging half capacity manages to cram more charge into the battery.

I don't have much understanding about lithium ion batteries but I have read that charging a phone from empty uses up battery cycles which has a detrimental effect on battery life over a long time. In a similar vein, when charging from empty, do lithium ion batteries loose some capacity temporarily due to their charge routine or something? From what I have describe above, is this considered normal for the M8's of the type of battery they have in general?

Thanks, Ian

 

[VidJunky]

You are partially correct about the cramming. What you are in essence doing when you charge from over 50% to 100% is called bump charging. HTC is one of the makers that is known for bumping. You can accomplish this, even from the empty to the full charge as well. Charge the device as normal until the green light comes on or the device says 100%. Unplug the device for 1 to 5 minutes and charge it again. Bump charging seems to give the best results if for the second charge you also power down the device until it says full. Google bump charging for more information.

A few things I would like to mention also are, using the device while on charge has an adverse effect on the battery and can affect its life over the life of the device, using high powered chargers to quick charge also lessens the life of the battery over time. Just something to think about.

 

[Mooncatt]

Hi,

I have owned an M8 for a few months now and since then I have been experiencing inconsistent battery life. Using gsam, I have seen my phone last 63 hours with 5h screen time but other times it hasn't lasted the day with only 2-3 hours screen time.

However, over the past few months I have noticed a pattern with my charging routines. If I charge my phone from empty (5-10%), the next usage cycle will be consistently lower than if I charged my phone from 50%. I define a usage cycle as 100% to around 5% battery life. Furthermore, I have noticed that when charging from an empty battery it takes around 2h to complete. If I charge from 50% it still takes 1h 30m to fully charge leaving me to believe that somehow charging half capacity manages to cram more charge into the battery.

I don't have much understanding about lithium ion batteries but I have read that charging a phone from empty uses up battery cycles which has a detrimental effect on battery life over a long time. In a similar vein, when charging from empty, do lithium ion batteries loose some capacity temporarily due to their charge routine or something? From what I have describe above, is this considered normal for the M8's of the type of battery they have in general?

Thanks, Ian

Regarding seemingly longer usage times when charging from half full, I can't explain that one. From my understanding, 100% is 100% regardless of what it was prior to charging. Are you sure you've eliminated other variables such as signal strength, background app usage, being on Wi-Fi, etc? For this question, you may need some long term focused testing and tracking if you think the starting battery level has an effect on usage after charging. Not saying you're wrong thinking that, it's just not a problem I've heard before.

As for the charging times themselves, that sounds about right. Lithium based batteries are meant to be charged in stages. When it's on the low end, they can accept higher currents. Towards the last 25% of charging, the input current slows down to an "absorption charge" mode. It's kind of like filling a bucket with a water hose. If you fill it at full force until the water overflows and spills, you could say it's "full." But when you turn the water off, you notice there's now room for more as the turbulence dies down and you can add more water as long as you do it slowly. That's why it seems to take longer to charge that last 25% or so than the first 75%. You're not cramming extra juice by starting your charging at half capacity, you're just reaching the absorption stage quickly.

You also don't need to worry about counting cycles or memory loss with lithium batteries. That's inaccurate thinking held over from older technologies and not many people were educated on the differences of lithiums. A zero to full charge is considered 1 cycle. Theoretically, charging a lithium from half to full counts as only 1/2 cycle. 75-100% is 1/4 cycle, etc. Two half capacity charges could be considered the equivalent of 1 full charge when talking about the life span of the battery. That's not taking into account all the other variables that can effect battery life, like temperature, environmental effects, quality of construction, impact damage, etc. But for all intents and purposes, lithiums are often considered in laymens terms as not having memory/capacity loss by less than full charge cycles. If you really want to prolong its life, you'd charge it at about 40% and unplug around 90%. Yes you get less use between charges, but being held at "high voltage" is one of the major causes of deterioration. That and excessive temps. You also don't want to drain your battery completely too because that also puts strain on the battery. It's ok to do it once when new or if you notice dramatic capacity loss to see if it needs calibration. The phone will flag the new minimum and maximum when doing so and may help in some cases.

 

[Mooncatt]

You are partially correct about the cramming. What you are in essence doing when you charge from over 50% to 100% is called bump charging. HTC is one of the makers that is known for bumping. You can accomplish this, even from the empty to the full charge as well. Charge the device as normal until the green light comes on or the device says 100%. Unplug the device for 1 to 5 minutes and charge it again. Bump charging seems to give the best results if for the second charge you also power down the device until it says full. Google bump charging for more information.

What he is doing is not even closely related to bump charging and is what I already explained in my post that quoted him. Plus, bump charging is exceptionally hard on the battery in terms of longevity. Sure, that one bump charge may get you more life out of that specific cycle, but forcing it to such high levels constantly will wreck the usable life. If the battery were easily replaceable then I could see an argument to be made in some cases to bump charge. An extended day trip away from a power source, for example. Since the M8's battery isn't replaceable, care should be taken to ensure it lasts as long as possible, even if means less use between charges.

A few things I would like to mention also are, using the device while on charge has an adverse effect on the battery and can affect its life over the life of the device, using high powered chargers to quick charge also lessens the life of the battery over time. Just something to think about.

Using the device doesn't necessarily affect the life of the battery from what I've read. It can cause longer charge times and potentially heat up the battery from combined use and charging. That may sound the same as your claim, but the distinction should be made as to why the lifespan is reduced. If the phone stays cool, charging while using shouldn't be a problem. The reason it takes longer is because there's only a finite amount of power being drawn from the charger that has to be split between charging the battery and running the phone. As the phone use demands go up, the amount of power available for charging goes down.

That leads to the use of higher powered chargers. Your statement that faster charging can lesson the life of a battery is true to a point, but we don't get anywhere near that limit with our phones. A lithium battery can be charged with a current equal to its mAh rating without risking damage in most cases. For the M8's 2600mAh battery, it could handle a 2.6A charge (2600mA). That's just what the battery should be capable of, but remember the phone ships with only a 1.5A charger and that's used for both charging and running the phone.

Here's where some confusion lies. You can't simply buy a stronger charger and expect it to charge quicker even if it's within the limits of the battery. It's the phone that determines how much power to pull from the charger, not the charger pushing it to the phone. When plugged into a stronger charger, the M8 will still only pull the same roughly 1.5A from it. It's the same reason the wall outlet isn't shooting its full 15A (or whatever its rating is) into the charger and blowing out it and your phone.

That's speaking of traditional lithium based batteries and chargers. With the development of things like Quick Charge 2.0 and batteries capable of charging 2-3 times their capacity rating (5200-7800mA if the M8 battery is designed such), faster charging times are possible and safe for the lifespan of the battery. I don't know enough about the Quick Charge 2.0 methods to explain it, so I'm trusting the developers wouldn't have pushed the new certification unless they were sure it wouldn't negatively affect the life span.