According to the manufacturers handbook on the Webasto it is supposed to work down to 10.5 volts (that voltage being at the unit and not at the fuse panel). It is quite a power hungry beast in that it does a self purge every 72 minutes (can be less and down as far as 40 minutes), during that purge it shuts down completely and then fully starts up again and as thus the glow plug will be powered for the period of start up, cannot remember but think it was about 8 to 12 amps (although fuse is 20 amps). Wecould still go 2 days without charging batteries provided the webasto was not on more than about 6 hours per day.
Although it is quieter on start up (and running) than either of Mikuni or Ebberspacher it appears to be more costly on spare parts. There are very few spare parts you can buy and even then they are large (expensive) lumps. If you want to service the burner pot to remove the sooty residue that forms due to using red diesel you cannot buy purely a gasket set - I did manage to get one set from LS UK in Batley and another set from the supplier at Napton Junction. Over 5 years of use the burner pot needed attention between 12 months and 18 months. On two occasions I got LS UK to do the repairs (change of burner pot), on another occasion I got a local commercial vehical diesel mechanic to strip and clean the burner pot, he cleaned the interior of the burner (I think steam clean after carefully removing residue soot deposits). Symptoms of need of service/repair are if the exhaust smoke on start up is darker than light grey - usually almost black when it is about to fail. Terry
