I have a Robovac 11 (3 years old, battery replaced a year ago). In the last few days it has developed a problem of giving me a red light and four beeps ONLY when charging (in the dock and when plugged in directly). I know this normally means the brush can’t rotate (I’ve cleaned it), but it still vacuums OK and doesn’t give the error when moving, only when it is stationary and charging, which is really annoying. Suggestions please…
Eufy Robovac 11 - Red light/beeps only when charging
Take it from the charging base -> OFF and ON -> put it back.
That was the first thing I did - it of course made no difference.
I’ve since removed the battery and replaced it with the old one I removed a year ago, and the fault indication has stopped. Unfortunately, the machine will only run for a short time on the old battery. I guess the solution is to buy a new replacement battery, but as the faulty one (the Anker-recommended spare) is only a year old it’s pretty annoying. It seems the life of these batteries is very poor.
OK we know much more. 
Seems that replacement is defective.
Is there any warranty?
It should last for one year normally.
There is an EUFY site where spare parts are being offered.
Like I said, the battery was a year old (about a week or two more than a year), so a) it won’t be covered by a warranty and b) if that’s the expected battery life it is exceptionally poor compared to other batteries/appliances.
This is really not normal.
Do a battery check.
If you don’t have the electronic equipment ask someone who got it.
In your earlier post you said that the battery should last for one year normally, now you say that the battery failing after one year is NOT normal. It can’t be both…
The battery should last for one year or even more.
Seems its defective.
Contact the seller, please!