2006 L320 tdv6 faults

2006 rrs l320 tdv6 fault
Well I thought it was running fine for a bit too long now ‍
So ... any ideas guys
Started with a shed load of warning light pooping up intermittently especially since the cold weather and first starts .. after a few minutes of starting the lights start to flicker inside .. the satnav keeps re booting and I get nearly ever light on the dash . Suspension faults abs you name it !

Had a new yuasa battery about a year ago fitted . Checked battery voltage whilst running and stood and I'm getting 14-15v in when running max of 16.1 from the test .

Just done the same thing on me not 30 mins ago so I pulled up turned ignion off to try reset and the whole car was dead ! No power to the car at all . No ignion.. opened the bonnet yo have a look . Little smoke coming from the fuel heater as usual . Looked in car and the dash was back on working again . Started up fine but with errors again ‍ still drives but stabat keeps rebooting and faults all.over ...
Had error on clocks and was sent off 18 months ago which fixed a previous issue but was a bit different to this

Sorry for the long post

Any ideas guys ?
Bad earth maybe ?

Could be bad earth's and or bad battery connections.
If you have a multi meter/dvm you can check continuity on the earth from battery to body, body to engine.
Then do the same for the positive battery to alternator and starter. Possibly fuse box, if it's possible on that model?
Any humidity in the boot side areas?

16.1 volts sounds to high to me, maybe car is getting upset with the to high a voltage?
I mainly do short runs in my d3 and highest I have ever seen is 15.2 volts.
So you could have a duff alt, things may have changed, but the make of choice was Denso, the refurbs were nowt but trouble as were the cheap copies.