16 years ago
This may be a bit OT but I couldn't think of anyone else to ask.
I have been building a race timer and starter for the sailing club
where I am a member. It runs off a 12V supply using car horns lights
etc. Ar present we use a battery which has to be taken away to be
There is no mains electricity and electricity is supplied when needed
(only a couple of hours a week) by a 3 phase diesel generator (about
I was considering connecting the race timer battery to the genset 12V
starter system using a relay so that it would be charged by the 12V
alternator when the generator is running in the same way a caravan
fridge operates on 12V only when the car engine is running.
I have had a look at how to do this and I was surprised to see that
the 240V (415V) systems are not separated at all. Terminal blocks,
PCBs etc are shared by both sytems.
It occurs to me that in a fault situation there could be up to 415V in
the 12V system so that automotive type lamps horns connectors etc
would be inadequately insulated.
Is this a real risk or is it OK to go ahead and use the 12V system.
Would it be better to plug a battery charger into the 240V output of
the generator and just leave it connected.
I'd be grateful for any comments or suggestions.