On Thu, 16 Mar 2017 14:57:53 +0200, Micky wrote:

How can it keep charged in use, but be unable to recharge?

I spent an hour on the Android phone with a friend, and because we
kept getting dicsonnected on whatsapp and also on Skype, the phone's
screen was on all the time, but I was plugged into a small cubicle
charger the whole time, and the phone charge stayed at 77% the whole
time.

Then the phone call ended, I closed the light, but left the phone on,
and let it finish charging for an hour. But after an hour or more,
it was still at 77%.

How can that be?

Later I was able to recharge the battery fully, use some and recharge
over and over up until now. Using a different cable. But if the
cable were bad, how to account for the first paragraph??

Of all the answers you've received this far, none proposes as candidate
explanation what I'm about to suggest, which is: the phone's charge
circuitry simply failed accurately to detect the new state the phone
entered once the call ended, the charging function simply stopped, and the
charge level never increased beyond the 77% you saw.

Once you turned the phone off and on again (or hibernated and reawakened
it), the state change became more obvious, and charging proceeded normally,
recharging fully.

I've encountered similar "losing track of the phone's state" events with an
old WinMo Motorola handset (a Q9m). Switching the phone off and on again
resets everything back to normal. Kinda like "stty sane" in Unix/Linux :-).

HTH, though YMMV. Cheers, -- tlvp
--
Avant de repondre, jeter la poubelle, SVP.