My Multisport Cardio shows full charge even though Sports Connect App says it's still charging.

. I have tried it in a couple of other computers with the same problem.
I've tried a couple of resets with no joy. I also have a brand new charging cradle so it's either an issue with the watch or the software.
The charge doesn't increase if I leave it plugged in. I can get it to full charge if I keep unplugging it then plugging it back in but this takes a long time and requires a lot of attention.
Answers
Superusers
Thanks. Not entirely constructive though. The battery still lasts for weeks in plain old watch mode and I can still get a good 25k - 30k run in from a 3/4 charge before I start to worry about it dying on me. Seemingly the battery is remarkably good for its age - it's just a pain to charge it. This would indicate that it isn't a depleted battery as it still holds its charge quite well.
One thing I forgot to mention is that if it is really low on charge, when I plug it in it will charge normally to between 50% & 75% and then it stops and I have to keep unplugging it and plugging it in again to get the charge up any higher. This would indicate that the charging sensors are still working - to a degree. Just not quite as they should be.
Yes, I know it is obsolete but it has been a fantastic watch, and as much as I'd like to have a Fenix 5 or suchlike, I cannot afford one just yet. One day aye....
I let the watch run completely flat and didn't use it for a couple of days. I then plugged it in and it charged normally until it was fully charged.
Since then it has been working and charging perfectly! There's still life in the old girl yet aye