Short in the electrics.

Starovich · 29 October 2014, 12:44

Tried to go boating over last weekend.
Saturday Flat battery, so put it on charge, Sunday still flat.

Bought a new battery, still nothing from any circuit, got the tester out and started checking current, whilst doing this dropped a probe onto the built in fuel tank and noticed a voltage.

Removed on one of the battery cables and am still reading a voltage though the fuel tank.

I am supposing a short somewhere in the system and am expecting at least a blown fuse. Can anyone recommend a mechanic to take a look in the Southampton area. Not sure if i can tow it too far the engine is 70% down and id need to hitch it to the car to see if there is clearance enough to tow.?

jyasaki · 29 October 2014, 22:54

There should be a tilt/trim release valve on the side of the bracket that will allow you to manually raise or lower the motor (will take muscle though.) That should take care of the trailering part.

What is the tank made of? Assuming it's non-metallic, a voltage from the liquid fuel inside would point to the sender. If it is metallic, I would have expected it to be tied to your negative bus (for electrolysis reasons, among others.)

jky

Starovich · 29 October 2014, 23:05

Tank is Ali, no fuel sender on it, voltage read was 12.6 so I think it must be a battery short. Will look for the release valve tomorrow. Thanks.

Firefly · 30 October 2014, 00:13

Quote:

Originally Posted by Starovich

Tried to go boating over last weekend.
Saturday Flat battery, so put it on charge, Sunday still flat.

Bought a new battery, still nothing from any circuit, got the tester out and started checking current, whilst doing this dropped a probe onto the built in fuel tank and noticed a voltage.

Removed on one of the battery cables and am still reading a voltage though the fuel tank.

I am supposing a short somewhere in the system and am expecting at least a blown fuse. Can anyone recommend a mechanic to take a look in the Southampton area. Not sure if i can tow it too far the engine is 70% down and id need to hitch it to the car to see if there is clearance enough to tow.?

You say you are reading a voltage; between what? The tank and what else. What sort of electrical distribution arrangement have you got? Switch/fuse panel?

captnjack · 30 October 2014, 00:17

Quote:

Originally Posted by Starovich

Tank is Ali, no fuel sender on it, voltage read was 12.6 so I think it must be a battery short. Will look for the release valve tomorrow. Thanks.

Delta V between Tank to positive or tank to ground?

The tank itself should be grounded so yes there would be a voltage between it and just about any non-ground wire on the boat. Does the voltage difference go away if you turn off the main battery switch?

Starovich · 30 October 2014, 08:45

I disconnected everything bar the engine electrics harness.
The negative terminal was connected back to the engine, and I had the multi meter between the positive and the fuel tank.

Pikey Dave · 30 October 2014, 10:29

Oops, saw the title of the thread & thought it was about Humber Paul reaching to plug the toaster in😄

.....sh1t happens.......

Firefly · 30 October 2014, 11:23

It's difficult without seeing how your boat is wired. The metal tank should be grounded at all times regardless of the battery master switch. So a reading of 12V between bat. +ve and the tank is normal. The first thing I'd check is the battery master switch, it could be open circuit or high resistance. Check to see if you have 12v output in "on" position. If you have, then switch on as many loads as possible, ie nav lts, spot lt, etc and check output again to see if the voltage has dropped. A large drop would indicate high resistance in the master switch.

Starovich · 30 October 2014, 17:19

Quote:

Originally Posted by Firefly

It's difficult without seeing how your boat is wired. The metal tank should be grounded at all times regardless of the battery master switch. So a reading of 12V between bat. +ve and the tank is normal. The first thing I'd check is the battery master switch, it could be open circuit or high resistance. Check to see if you have 12v output in "on" position. If you have, then switch on as many loads as possible, ie nav lts, spot lt, etc and check output again to see if the voltage has dropped. A large drop would indicate high resistance in the master switch.

I took the switch and ancillaries out of the loop so its - battery to Engine, + meter to Tank 12.6v. If this is OK then maybe a blown fuse?

captnjack · 30 October 2014, 17:28

Quote:

Originally Posted by Starovich

I took the switch and ancillaries out of the loop so its - battery to Engine, + meter to Tank 12.6v. If this is OK then maybe a blown fuse?

The tank is grounded so 12.5 (at rest) to 13.5V (engine running) difference between the tank and the battery positive is totally normal.

You'd be better off switching to amps and testing the amperage in each circuit as you reconnect the individual devices to the battery. With each device (depth sounder, chart plotter, lights, etc) off at its switch the amperage should be zero. If you get current flow with the device off you have found your leak/short.

Starovich · 30 October 2014, 17:47

Quote:

Originally Posted by captnjack

The tank is grounded so 12.5 (at rest) to 13.5V (engine running) difference between the tank and the battery positive is totally normal.

You'd be better off switching to amps and testing the amperage in each circuit as you reconnect the individual devices to the battery. With each device (depth sounder, chart plotter, lights, etc) off at its switch the amperage should be zero. If you get current flow with the device off you have found your leak/short.

Thanks to all for the suggestions, i think im am starting to get the picture,

I've removed radio/lights from the circuits completely (separate loom) and bypassed the switch so its just battery and engine and I've still no power at the engine. Think ill look for a fuse engine side, and test where the power drops out?