Dash warning lights

[bicks]

Any ideas those odd two hot days recently we had the aircon on fan flat out and slow traffic info came up "battery disconnected" and then christmas
tree lights esp, abs, parking brake, tyre pressure and steering the car is a 1.8 tsi 19,000 miles only, its not stop start but the battery has a code on it
is it possible that i need to recode the battery as it thinks it has been disconnected i have since done 900 miles and only miss auto hold and have to use parking brake manually although it releases automatically , also just a thought but the sat nav stays on now and wonder if its connected to this new battery management system ie: shutting down things to maintain the battery . The head unit used to shut down after 30 miles and then every two miles
but its a pleasure to use now, the gremlins will be back i know when the lights go off .All suggestions will be much appreciated .