Hopefully someone here might shed some light on this issue as Volvo techs haven’t been able to.
Overnight, the cab systems turn off, usually after 5 hours. I really need them on for minimum 11 and according to Volvo Blurb, it can be done.
Volvo techies say it’s due to the batteries not having enough oomph to start the engine and therefore turn stuff off but then the battery monitor says otherwise. Techies don’t understand why.
Anyone else had this issue?
Oh, Hi btw.
Merc does exactly the same thing consumer cuts out most nights right pain all merc say batteries are fine not much help when you wake up cold
Tell boss there is an ongoing issue the techies cant deal with, *but* you do have the solution. Youll just keep the engine ticking over all night and there won`t be any issues.
I`ll have a wee bet some minds will become more concentrated on finding a solution. 
Invest in a thicker quilt there is no need in the UK to have a night heater running all night set the timer for an hour before you get up, technically on a low setting a night heater will run all night but that is before you take into account the running of laptops/phones etc and the use of interior lights before you go to sleep.
Mazzer2:
Invest in a thicker quilt there is no need in the UK to have a night heater running all night set the timer for an hour before you get up, technically on a low setting a night heater will run all night but that is before you take into account the running of laptops/phones etc and the use of interior lights before you go to sleep.
You might not die of hypothermia, but there is no way a driver should put up with a night heater that cuts off after a few hours.
Nights out aren`t an endurance challenge.
Laptops, phones, and lights use next to SWA.
50w + 10w + 10w = 70 watts? 3amp for 10hrs, from a three or four hundred (?) amp.hr battery set. Nowt.
I had a problem with night heaters cutting out after a few hours many many moons ago. The problem was the fuel tank had no vent and the night heater didnt have to mustle to pull the fuel once the vacuum built up. Just open then close the fuel cap before bed and bingo toasty tootsies in the morning.
Give it a try, it might work and its tax free
Franglais:
Mazzer2:
Invest in a thicker quilt there is no need in the UK to have a night heater running all night set the timer for an hour before you get up, technically on a low setting a night heater will run all night but that is before you take into account the running of laptops/phones etc and the use of interior lights before you go to sleep.You might not die of hypothermia, but there is no way a driver should put up with a night heater that cuts off after a few hours.
Nights out aren`t an endurance challenge.Laptops, phones, and lights use next to SWA.
50w + 10w + 10w = 70 watts? 3amp for 10hrs, from a three or four hundred (?) amp.hr battery set. Nowt.
But it obviously is an issue battery performance drops with age and usage, continual use when not being charged contributes to this and creates battery memory which afffects it’s performance when the engine is not running any electrical usage needs to be monitored if the driver doesn’t do this he will wake up with flat batteries. Laptops etc may use very little but combined with night heater use the fridge if fitted it will all add up and obviously does hence the flat batteries. V4 Volvo’s when they first came out had massive issues with their batteries but with the OP’s being a 2018 this should not be the problem.
Thanks for the tip about nights out not being an endurance challenge I’ll stay tuned for more statements of the bleeding obvious. 
Don’t know if its connected, but on our Renault T-cab unit (which I believe shares a lot of stuff with Volvo) the night heater switches off (as far as I can tell) if you close the door and then lock it with the remote control. It’s something to do with certain systems going into stand-by or even full shut-down. I think the night heater is indeed designed to shut off after a certain period anyway, but this can be over-ridden using the dash menus to control the heater rather than simply pressing the button on the dash. It’s doubtless documented in the Operator Manual but as a day man I don’t often use the night heater anyway.
Thank for all the replies.
I won’t be getting into thermal PJs for thos, overnights in a cab should be comfortable. Gone are the days of 70’s ERF where thr aircon was holes in the floor and badly fitting doors! Also when it’s-4°C I kinda think a cab heater is necessary.
Batteries are upto the job, Volvo have swapped them 4 times so far Tring to figure out the issue. Battery monitor display shows 5 blocks from 6 in the morning so nowhere near the point where it won’t start (that’s 1 block)
Cab living settings are not active according to Volvo so nothing should time out. But they still do. It has to be a time issue rather than battery because it happens after the same length of time, every time!!
Tonight is setting the parking heater using the dash rather than the switch and we will see at about 0330!!!
I couldn’t sleep with the night heater running all night, but my cab fridge used to turn off automatically when the batteries dropped below 25.5volts, it ensured the engine would still start up in the morning.
Wheel Nut:
I couldn’t sleep with the night heater running all night, but my cab fridge used to turn off automatically when the batteries dropped below 25.5volts, it ensured the engine would still start up in the morning.
Agreed if I’m waking up with a head that feels like I’ve been on the lash, then I at least want to have been on the lash to get it
The systems are going to sleep after 2hrs,It’s changeable by using the vemis,they will just change the sleep duration of the system, I think it will invalidate the battery warranty,or leaving keys in the ignition stops it
Wheel Nut:
I couldn’t sleep with the night heater running all night, but my cab fridge used to turn off automatically when the batteries dropped below 25.5volts, it ensured the engine would still start up in the morning.
I do 4 -5 nights out a week - I have yet to leave the night heater on all night . I reach over and fire it up about 10 minutes before I get out of bed in the morning to take any chill out of the air . I also have both windows down half an inch every night - I can’t have stuffy cabs need fresh air . All you need is a good duvet .