Ok, we've had these two phones for a bit and I'm seeing a few complaints here and there about how the phones charge slower than others, especially towards the end of the charge.
STOP COMPLAINING!!! Seriously, stop. Not because I don't want to hear it, but because it's a GOOD THING... yes, with all these phones trying to out do each other on charge speed, what Google is doing is the smart choice.
"Why", you ask? It's simple. LiPo batteries are at their most vulnerable when they are nearing full charge. Think of the battery as a ball room... As it begins to fill up, if you have new guests run in too fast (voltage) or send in too many at the same time (current), people start to get stressed out and someone is going to lose it and start tossing tables and chairs. Eventually, the mess is going to get to the point where the hall just can't hold as many revelers as it once did.
A battery only has so many charge cycles in it. As you start to reach that limit, the battery won't hold as good a charge and what charge it does take, it'll discharge quicker. How fast you burn through those cycles depends on a bunch of factors, but one of the biggest factors is the charge profile; how quickly it charges.
A perfect example of this is the Nexus 6P. Huawei didn't do it's any favors in the way they set up the battery. First, they allowed for an high peak charging voltage (4.4v vs 4.35v on the 2 XL) and they topped off the charge fairly quickly. And if you left it on the charger after it hot 100 (don't do that, it's bad juju), your holding it at a peak voltage that put a pretty big strain on the cell, further reducing life. So batteries got hammered pretty quickly... Mine lost about 15% of its capacity in about 15 months. Others suffered far more precipitous drop offs.
This could have, should have, been avoided.
Anyone notice the ad campaign that Google ran that mentioned batteries lasting longer? What did that mean and how did Google accomplish that goal?
Simple.. they tread lightly on that 'last mile of the charge. Look at this charging graph:
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Here we have a charge from 20 to 100% (with a short pause in the middle)
Here we see a rapid charge from 20 on up to about 65% or so. Down there, the battery can take a pretty aggressive charge without breaking a sweat (you got an empty ballroom, bring em on!). But even at 65, we see things start to slow. Also notice the slow ramp back up? Again, that is designed to reduce stress on the battery due to charging.
Now, as you can see, there's a gradual reduction in charge speed as the phone nears full. The goal here is to allow the battery settle and charge without stressing out the cell.
How much? Well, if you set charging the 2 XL from 20 to 100 (taking it off the charger as soon as it hits 100... Seriously.. do this as much as humanly possible... Trust me, it's better for the battery)... But that 20-100 in the 2XL I'll set to 1 cycle. The same charge in my 6P would exhaust 1.5 to 2 cycles. I would have had to take my 6P of the charger at 80-85% to reduce the wear equivalent to a full charge on the 2XL
It's clear to me that Google set the charge profile on the Pixel 2 to help maximize the life of the battery at the cost of some charging speed. Since I hope to keep this phone for a good two years, I'm glad they made that choice.
Oh, that 6P? I still have it. I replaced the battery in February and my wife is using it. Since she's not nearly as delicate as I was, 10 months or so later, it's lost over 15% of its capacity already. But that's going back to Google for trade and she's going to slide into a 1XL I recently picked up for her.