Old Air shut off at 4.22. New Air shut off at 4.16 The new battery when charged in the Old Air went right up to 4.22 Problem does not seem to be the battery but rather the early charger shut off in the new unit.
I don't think this is really a problem. It's actually quite normal. You wouldn't want to pay for a charger that went to exactly 4.200 Volts every time, such things need
'a window' of acceptable values. In this case the typical spec. on charge controllers for commercial Li-ions is 4.20 Volts plus or minus .05. So anything
between 4.15 and 4.25 V meets spec. Both your units seem to do so, assuming your meter is accurate?
In broad each terms .1 Volt is a 10% change in capacity. So .06 Volts would be six percent. If there's normally 4 sessions per charge (.25 Volts per) we're talking
about 1/4 of an extra session, not much to hang your hat on.......
In a way this is nice. That .06 Volts less will mean longer battery life. A lot longer. Something like a 50% increase, actually a little more. Honestly. The battery that would last 2 years will now go more than 3. Not a bad deal IMO.
I intentionally charge Solo, Air, Ascent and other Li-ions to about 4.05 Volts (15% 'short') for this very reason using a purpose built 'gadget'. On version looks like this:
That one's set up for nine Volts for the big FMs, Ascent and those guys. The top board senses the current and does the control. 12 Volts comes in top left. The lower board converts the 12 Volts to 9 for eventual use, a similar one drops it to 5 VDC for Air, the small FMs, most USB charging Mods and so on.
BTW, this effect (longer battery lifespan for not hammering it at the top end of the charge trying to get as much run time as possible so you can brag and take customers from your competitors) is so real that the military specifies lower voltage, 3.95 plus or minus .05 IIRC. They understand this means less hours of using say your radio before recharging but it also means you don't have to worry about replacing batteries in the field for something like four times the service life. Good trade off, or so they think.
Not so important in vapes with easily replaceable batteries like Air compared to say Solo, but then if battery swaps are so easy, an extra session is even less of a big deal?
I don't think you have a problem, rather a feature. And I don't think Arizer will consider it defective.
OF