Grounding batteries to engine

[Lauri]

I have a 18ft sailboat with Mercury 5 hp F5 MH engine. I need to ground my batteries to the engine. Any ideas how to do this? I have no idea. Do I find a heavy metal part in the engine and drill a hole to it and connect the grounding cable to it?

[GordMay]

The service manual should indicate the grounding location [black, yellow, or blk&yel wire].
Mercury 5 Series Service Manual ➥ https://www.manualslib.com/manual/12...-5-Series.html

[thomm225]

Originally Posted by Lauri

I have a 18ft sailboat with Mercury 5 hp F5 MH engine. I need to ground my batteries to the engine. Any ideas how to do this? I have no idea. Do I find a heavy metal part in the engine and drill a hole to it and connect the grounding cable to it?

Why do you need to ground your batteries to your engine?

I have a 27' Sailboat that now has a Mercury 5 HP 4 stroke 25" extra long shaft engine. This since 2012.

I removed the old diesel after it failed.

All the grounds that had been connected to that diesel I bolted together and hooked to the negative cable that goes to my batteries.

My outboard doesn't have an alternator. I use solar to charge my two 6 volt Golf Cart Batteries of 220 AH each.

[Lauri]

Originally Posted by GordMay

The service manual should indicate the grounding location [black, yellow, or blk&yel wire].
Mercury 5 Series Service Manual ➥ https://www.manualslib.com/manual/12...-5-Series.html

I see O.o very good. Thanks!

[Lauri]

Originally Posted by thomm225

Why do you need to ground your batteries to your engine?

I have a 27' Sailboat that now has a Mercury 5 HP 4 stroke 25" extra long shaft engine. This since 2012.

I removed the old diesel after it failed.

All the grounds that had been connected to that diesel I bolted together and hooked to the negative cable that goes to my batteries.

My outboard doesn't have an alternator. I use solar to charge my two 6 volt Golf Cart Batteries of 220 AH each.

Because grounding to engine is a safe way to go. Negative pole of battery is good, but engine is better

[NorthCoastJoe]

Unless the outboard has an alternator why would I hook up to it at all.

Use a Bus bar for grounds then connect that to the battery Negative using the right gauge cable for the loads. If you want to tie it to your outboard engine alternator do it through the bus bar.

The last thing I would want is a bunch of wires on an outboard.

[thomm225]

Originally Posted by Lauri

Because grounding to engine is a safe way to go. Negative pole of battery is good, but engine is better

The outboard is usually not in the though, so it does no good to ground the batteries to it.

(unless you drag the outboard in the water while you are sailing which could get pretty tough in winds over 15 knots or so)

Think of it like your car or truck. There is no earth ground.

The system is floating like on my boat.

[thomm225]

Originally Posted by NorthCoastJoe

Unless the outboard has an alternator why would I hook up to it at all.

Use a Bus bar for grounds then connect that to the battery Negative using the right gauge cable for the loads. If you want to tie it to your outboard engine alternator do it through the bus bar.

The last thing I would want is a bunch of wires on an outboard.

This is one of the reasons I didn't want an alternator or controls on my outboard.

I even found one with an integral 40 ounce tank so I don't need to connect a fuel line to my outboard unless I'm motoring quite a long distance.

Normal usage in and out of my slip and creek just requires the integral tank.

Batteries are charged with solar.