Charging light on Acer laptop is red -- Plugged in.

Charging light on Acer laptop is red -- Plugged in. 

I was using my Acer Aspire E15 (several years old) with win10 Home,
fullly updated**, when I suddently noticed that the Charging light was
no longer blue but red, and the charge status icon in the systray said 
0% available (plugged in). 

It is set to hibernate when the battery is at 15 or 20%, so how did it
get to 0% without hibernating.  Perhaps it's not really that low? 

I ran the troubleshooter for Power.  3 tiny changes, probably udoing
settings I wanted.  A google page said to run the troubleshooter for
devices and something but neither was listed. 

When it was a good time, I hibernated it and measured the voltage of the
charger.  It was about 19v. 

Google suggested Device Manager, Battery, disable and then enable all
the items in battery.  I did that and when I went to *enable* the second
one, the screen went blank.  Pressing the power button caused it to say
Resuming Windows (a message I dont' think I've ever seen before) and
indeed it quickly resumed where I'd been.   I don't think this paragraph
helps, but I"m being complete. 

Any ideas what the problerm and what to do about it? 

**It did have a MS cumulative update 2 days ago, and one poster thought
that a window update messed up his charging, but I doubt that's what it
is.  OTOH, I had a MS update a couple years ago that totally disabled my
computer, until I learned to back it out, so who knows?  

I haven't moved the laptop in 6 weeks and I keep it charging all the
time, with the battery normally at 100%.  But Nir Sofer's program,
BatteryInfoView, says it's 0%.  How did it go, it seems, from 100 to 0%
so quickly? Because the charging light is only blue when it's fully
charged and it's amber or red other times.  It went, I'm 99% sure,
straight from blue to red, 0%. 

Any other newgroups still active that would know about this. I think the
2nd and 3rd here are dormant.