Yanmar engine draw

[LillianpFD]

I have a 5 amp draw coming from my engine to my start battery when everything is off. I have an 850 CCA starter battery and a separate house battery 4d. I can have everything off and no key in the ignition and if my battery switch is set to 1, my starter battery, it has a drain. Thinking it can only come from the engine. Disconnected the battery charger leads to the start battery and still have the drain so ruled that out. If anything simple comes to mind I would appreciate, otherwise I'll need to find an expert. Thanks

[nebulatech]

I can't think of anything on the engine that would be drawing electricity when shut off, at least not for very long. Maybe an electric fuel pump would probably draw about that much if the switch malfunctioned and was stuck in the on position. How long has the problem been going on, and is it intermittent? (two questions you probably can't answer yet) Does the problem go away when disconnected from shore power? It's a stretch, but could it be coming through a ground, or a galvanic current in the water coming into the prop shaft? I would not expect it to be 5 amps, more like micro amps, but I know stray currents happen.

My guess is this is some kind of wiring or grounding issue. With something as small as 5 amps (60 watts at 12 volts), you could use a regular multimeter to do some testing. You wouldn't need an expensive clamp meter in other words. The meter just goes inline, replacing a section of wiring. Polarity matters. I would start from the switch and work my way backwards.

[Norseman]

Not related to this issue with the engine drawing power when dead, but on a previous boat I this problem: After I installed a Battery Monitor in 2006 to go with solar panels and to manage loads and amp/hrs in and out.
When the Xantrex Battery Monitor was installed and calibrated I noticed a draw somewhere in the system that just did not go away with all switches off and literally a dead DC Panel.
Load was there day and night, not a big load, about 1/2 amp/hr, or 12 a/h per 24 hrs.
Drove me nuts, could not find it until I started disconnecting wires, then found the culprit: The old cassette stereo/AM-FM radio: I did not have a
breaker on the panel for it, just wired in with a fuse. Turned out the little motor was running 24/7 even when the radio was off, it just kept spinning for years, completely quiet and happy in the background.
Ripped it out and installed a more up to date CD stereo, problem solved, now the draw over the Battery monitor was 0.0 when all the switches were off, no more ghost load.

At 5 amps you may have a pump running or something. Make the boat dead quiet and listen for any sound..

[LillianpFD]

I asked my mechanic and he said the alternator can produce a draw if it is bad. I replaced my alternator with the cheap version two years ago and had my original rebuilt. When I disconnected the alternator the draw went away. I'm going to reinstall the rebuilt one and see what I get. Thanks for the ideas!

[Norseman]

I asked my mechanic and he said the alternator can produce a draw if it is bad. I replaced my alternator with the cheap version two years ago and had my original rebuilt. When I disconnected the alternator the draw went away. I'm going to reinstall the rebuilt one and see what I get. Thanks for the ideas!

Wow, good to know. Thx

[nebulatech]

I see how that could be the case. Good call and good luck. Hopefully, it's not too big a job swapping the alternator. You could possibly just disconnect its wiring and check your draw. If it reads zero amps, that's still inconclusive, but if it still reads 5 amps, probably not the alternator.

[LillianpFD]

swapped the alternator with my original rebuilt one. In the process noticed 1 belt was broken and the other looked like a hair elastic. It was about to go. Now showing only a 1.37 amp draw when the switch is set to my start battery. (still seems high?) virtually no draw on the start battery when the switch is on my house battery. Everything charging fine now too. I think I can live with that.

[WillieC]

That still sounds high. But you could run with it and see if it strands you. Hopefully not.

Parasitic loads can be difficult to find but 1.37A is hardly parasitic. It took me several drained battery cycles to figure out that the knob somebody glued onto the door switch in my (previously wrecked, nice to know after I bought it) Ford pickup fell off. I wondered what that black gob was on the door sill. The door light always worked before, why would I check that out? Now I can truthfully say, I do my best work in the dark.

[nebulatech]

Now I can truthfully say, I do my best work in the dark.

I wish that were true for me, as I increasingly find myself there!