coiler:
I think the information on charging your battery using an external charger when the vehicle is not in use is bobbins. Volvo trying to blame everyone else when it is their batteries performance that is the issue.
Yes bobbins 
I worked for a big Irish haulier with a fleet of 120 or so Volvos. Since 2012 they have had nothing but trouble with the batteries, some of the trucks batteries had to be replaced after just 3 months!!! The truck I was in had its batteries replaced 3 times in 2012.
Volvos excuses ranged from:
The tracking device,
The Dynafleet,
Drivers gadgets 
eg: mobile phone chargers, dash cam, inverter, ect:
The company had Mercs, Daf’s, and Scanias also, all of which had no battery issues!
The M.D was advised by Volvo in 2014 to purchase an external charger to the tune of €5500.00 and remove all battery’s every 6 weeks and charge them externally. So batteries would be charged and rotated between trucks. After a couple of months nobody knew what battery’s were from what truck originally, which I guess suited Volvo down to the ground !
My Tale…
I got a new Volvo in 2014, in January 2015 whilst on the continent I awoke at 04:30am freezing, it was -8 outside, I checked the night heater and it was off, so I got up and tried to turn it on, hmmmmmm no joy. When I tried to start the truck she was dead.
I got a decent auld skin to give me a jump start at 7:30 and decided ■■■■ this, iv had enough of it, I don’t need to be found frozen to death in a truck somewhere on the Austrian Alps. I decided after this trip I was done, finished, never going to drive a truck again!
Anyway I was sent to a Volvo dealer in Salzbourg later that day to have my batteries checked, and low and behold they were fcked. As the Macanic was installing to new “Volvo” battery’s !!! ( the old ones were VARTA) I asked him why there was so much trouble with Volvos battery’s? This Is how it went.
Him: How long do you spend away in your truck?
Me: Between 2-4 weeks.
Him: so you live in it, like you would in a house using your laptop, heating, lights, Chargers, opening and closing your windows when your parked up.
Me: Yup.
Him: How would expect the 2 battery’s to cope with this along with all the modern technology new trucks have, Dynafleet, trackers, fridge, ect:
Me: So what’s the solution, hauliers aren’t going to put us into hotels!
Him: When you park up for your 11 hour break, your truck battery’s should be fully charged, when you set off again in the morning you will recharge the battery’s, would you agree?
Me: Yup
Him: Do the same when your parked for longer periods, run your engine for an hour in the morning and an hour in the evening when on 24s and 45s and see how you go.
I did this and had no more issues with my battery’s apart from the the gobsh*te in the office asking me why I wasting fuel letting the truck tick over!
To Conclude:
I personally found when using the night heater in the 2012 upward Volvo it had an enormous strain on the battery’s.
I am currently driving a 7 year old Scania, I can run the night heater on cold days for hours, run it during the night if I’m cold, use my laptop, have a dash cam that’s never off, charge my phones, open and close my windows, the truck has a fridge too and I never have had to get a jump start!!!
Volvo has a major battery drainage problem that their not willing to or don’t know how to address and their trying to push the blame onto their customers.
Now saying all that, I would prefer a Volvo over any other truck out there for comfort. They are a pleasure to drive so it really is a shame a minor issue like this would deter and will deter hauliers in the future from buying from Volvo.
) they have 2 sets of batteries, standard vehicle batteries for the engine and leisure batteries for the motor home.