Got two options in mind.
add a pair of leisure batts and a split charge relay. This would involve running more cable into cab, a pain and still leave interior lights, fridge and night heater running of the main batts.
add a second pair of main batts so increasing capacity, no need to muck with cab wiring but need to make up a beefy battery box.
Any one with leccy knowledge like to comment?
adding an extra set of batteries would be easier and less work. wouldn’t have to put too much extra wiring apart from link leads connecting the 2 sets. only problem you may end up with is one set of batteries taking more charge than the other. puttig 4 new batteries on should cure this as well as using battery cable that is the same capacity as the truck should stop this.
I have 2x 230Ah AGM-batteries, don’t see any need for extra batteries. I can run night heater for over 20 hours, fridge on and listening to music powered by 5-channel Genesis amp, without running the engine. I think voltage has never dropped under 23,2 volts, FH16 Volvo still fires at 22,5 volts.
Or just put some Varta’s on.
puntabrava:
Or just put some Varta’s on.
I agree Varta are used by most hauliers this way, and are good for ten years.
on average how long would you expect a set of batteries to last
lee mat:
on average how long would you expect a set of batteries to last
Volvo originals usually 1,5 years, they are crap.
If you’re using them for “hotel loads” then lead/acid batteries will take a hammering, they don’t like being discharged.
The AGM batteries do a lot better, but they do like to be charged a different way to the charge they’ll get from an alternator, which is basically 100% all the time. You can get plug in chargers that hit them with full power up to about 80%, then gradually lower the charging rate so that the last 10% is done at 10% charge.
Now obviously you can’t do this on the road as you’d need yet another set of batteries to run an inverter, but when you’re back at base you could do the graduated charge and really prolong the life of the batteries, especially if you ran them in tandem with the normal truck batteries and isolated them once they reached 80/90% charge.
V8Lenny:
lee mat:
on average how long would you expect a set of batteries to lastVolvo originals usually 1,5 years, they are crap.
I average about 6 years from volvo 220ah batteries
Just a curious question Baz, what are you doing that makes you think you need extra battery capacity? Standard batteries in good condition should be enough to power anything you’d use in an evening, plus the night heater, and still have more than enough power to start the engine in the morning.
Harry Monk:
Just a curious question Baz, what are you doing that makes you think you need extra battery capacity? Standard batteries in good condition should be enough to power anything you’d use in an evening, plus the night heater, and still have more than enough power to start the engine in the morning.
Think I am just greedy with the electricity 
Re newmercman.
AGM? As i deepcycle?
Had a pair of deepcycle on last truck, lasted about 2 years, fair I guess.
This time round thought I would double up on the main batteries that way they should not get to drop below 24 volt and not so much rewiring.
bazstan009:
Re newmercman.
AGM? As i deepcycle?
Absorbed Glass Mat, some are deep cycle, some not. They are closed “dry cell”-batteries that don’t need water topping up, vibration don’t harm them like normal batteries. They don’t need any special charging, they charge faster and also give current much faster than normal wet batteries or gel batteries.
^^^what he said^^^
If you had,as the extra set, more leisure type cycle batteries, with a split charge relay, it’s worth bearing in mind they would not necessarily need to be anything like the size of the regular starting batteries and picked right probably still give the option to get you going in most cases if there was some issue with the main starting batteries.