Report Engine alternator issues.....any suggestions? in Boat Building & Maintenance Posted Wednesday at 21:59 · Edited Wednesday at 22:29 by Wanderer Vagabond 50 minutes ago, Tony Brooks said: To be honest, I don't see why it needs to be on after the engine has started. It's not a car where they consider pollution and engine noise. If t is a timer relay, I would be trying it with a starter solenoid that de-energised a soon as the key jumped back to run. Although 375 Watts seems a lot, it's 30 amps and with an operating time of 30 seconds it would draw less than half an amp hour from the batteries, so any discharge should not involve a high charging current once started. I don't know for certain whether it is, I turn the ignition key, the light showing the glowplug is operating comes on, it goes out and I fire up. My assumption was always that when the light went out the glowplug went off. I don't know numerically what the output of the engine alternator is when the slip occurs, but I would guess it must be high, the domestic alternator, according to the battery monitor puts out something like 55A on startup but the belt doesn't slip at all. The difference is obviously that the domestic alternator only has two pulleys on the belt so has 180 degree wraparound whereas the engine alternator has three pulleys on the belt (engine, alternator and water pump) so only has 120 degree wraparound. Add to that the fact that I'm less bothered about over-tensioning the domestic alternator belt since the only thing that might get wrecked is the alternator whereas on the engine alternator belt it would be the water pump bearing that would fail. ETA Having given it some additional thought, I suppose that there is a possibility that, since the glowplug in the manifold is essentially heating static air, it may remain on after the warning light goes out so that the heated air is sucked into the cylinders over the hot coil for a short time when the starter motor is fired up. By comparison, diesel engines with the glowplug in the cylinder have a hot unit inside the cylinder itself. Not saying the idea is correct, but it is a possibility.