Why isn’t this at 100%

[Martynovo]

All sounds normal, load -no load ; as expected. What about the temperature? If battery is under 5 deg C, it will not charge, but, allow to discharge.

The 12.9v is the on load votage it would have recovered to at least 13.3v without the charger on.
you don't say what your charger is apart from being Victron or the amp hours of your batteries.
If you have 400ah of batteries and a 20 amp charger it would take an hour to put 5% back into the batteries, if the charger is running at full power, so in practice it would be a bit longer.

It's victron set to 30amp and batteries 2x100 ah. Been on over days. I'm going away on Tuesday for 2 weeks not in motorhome . If I haven't solved it I will take battery down to below 13v , take off ehu and just leave solar . It will be into see what B2B /MPPT takes it up to.

 

[Raul]

Temperature? Can you confirm the batteries are above 5 degC? If not, then that may be the charging pause till temperature rises sufficiently to allow charge.

 

[Martynovo]

Temperature? Can you confirm the batteries are above 5 degC? If not, then that may be the charging pause till temperature rises sufficiently to allow charge.

At this time 22.38 battery 9'C B2B 15'C . I'm in Cornwall! But is that a clue, why should B2B be so warm, it can't be working? Battery has 20watt heat pad at side not touching. B2B under a seat with open front and rear an external panel.

 

[Raul]

Temperature is relevant at the time of charge.
Maybe the heat pad takes most of b2b charge and very little gets to the battery or loads.