Isolator

I thought the point of an isolator switch by the battery box was to, er, isolate the batteries?

Made a wally of myself yesterday when a truck I wasn’t used to (and doesn’t get used much) wouldn’t start, though ignition came on, lights on dash, etc. Voltmeter was 22v which I thought was a bit low, so assumed batteries were a bit low.
So hooked up charger, trying to show initiative, and thing still wouldn’t start. Another driver had a look and agreed it was odd.

Finally phoned boss, who asked if I’d turned the isolator off, so found this and flipped it and then it roared into life…

How normal is it for an isolator to just cut the cranking? Not seen it before, but not been doing this too long either…! It felt illogical to me to go looking for an isolator when the ignition came on…

If it is ex petroleum or chemical truck it has this to stop sparks and any problems

Ah, ok… begins to make some sense. I can see that you wouldn’t want sparks when filling up / tipping a tanker, and you might get a spark when cranking.

Anyway, in future I will obviously go looking for an isolator if this happens again.

I only knew after ringing my garage manager at 4:00am I wasn’t popular

drivergraham:
I only knew after ringing my garage manager at 4:00am I wasn’t popular

Seems to be sods law that it isn’t convenient when these questions come up! Mine was in Netherlands using a phone with a UK SIM so the call cost him and me a packet.