Voltage drop on yanmar 315

[LillianpFD]

Okay sleuths! I am getting a voltage drop on my start battery as soon as I flip my battery switch from off. Nothing on. Nothing running. Just connecting my battery to the engine. I’ve disconnected the heaters and tried disconnecting my alternator to see if that would stop the draw, but no luck. What else would cause the battery voltage to drop when simply connecting the start battery to the engine? I’m on a dock with power but whenever at sea and shutting off my engine I’m getting that draw because I’m using my house battery for various things and need my battery switch on to access the house battery. (Start battery is isolated from house)
Thx, John-2003 Albin 28 FD.

[swhfire21]

Most likely a loose or corroded connection. Possible high resistance leak to ground - look for chafed wires on grounded objects and check starter solenoid/swithes for voltage drop across them when “off”

[Capt Brad]

When you first turn on battery to engine the glow plugs come on. They drop voltage. When they time out my voltage draw reduces. When I bought my 28TE Ken Hilton pointed out to just watch the voltage and when the draw reduces, time to time to start the engine. During warm summer months, I don’t wait for the full time out cycle . Hope this helps.

[LillianpFD]

I’ll look for the voltage drop you are talking about. But with the key out and just turning the battery switch on I am getting that voltage drop. I could understand a glow plug or heater drawing on the battery when starting, or turning my key, but I want to be comfortable knowing that there is no draw on my isolated start battery when I am anchored or drifting at sea while running my house battery. Another test I did today is disconnect the starter solenoid but I still got a draw down when I turned my battery switch on.