no load of rubbish, i do on average 10 jobs a day wfp no problems in the past 6 months, i eaven use another pump to filter 100 l of water on the go, remember van betterys are large,
if your getting flat batterys, the battery is probably on the way out or an altonator fault, sureflow current when pressure switch operated is about 6 amps, normal flow probably under an amp
your van lights probably use more current than the pump