Battery amps and starting

[Siman]

I have a 100ah battery 900cca

I want to install an airflow fan in my vw t4 in the rear for my dog, fan is 12v dc, 10 watts, 0.8amps, How long can I run it with engine off before van won't start?

 

[telectrix]

a 60AH battery will give you about 40 hours before showing signs of failing. assuming no other loads at same time. far longer than your dog can't do without food and water.

 

[PEG]

Hi,also you may need to consider the reason for needing it, If it is merely ventilation,even that size of fan,may be over-kill. If you intend to have air-change,and not just wafting around stale air,then you will need an "in" and an "out". A ten watt fan will exchange all the air in a vehicle that size,very quickly,and it will be swapped for the air outside,at the external temperature (4 degree out=4 degree in= 4 degree dog)
I have lots of pals in the van/camper/dog transport job,and the best trade-off of heat/ventilation etc,seems to be trickle vent high up,and insulate the van.

Just don't permanently obscure the wiring looms in a T4.....because at some stage,you WILL need access to it