Charles 5000 Series to ProNautic 1240P Battery Charger Swap - Case Ground?

[SkuffedKeel]

Good morning/afternoon/evening!

Today I swapped out the original Charles 5000 series battery charger with a ProNautic 1240P. I used the existing cabling (2 bank) so I just had to install connectors on the DC cables. Install was pretty simple (as can be on a boat), but trying to run the battery temp sensor was a nightmare so I gave up... that's a project for the off season.

One thing that's worrying me a bit is that the Charles charger did not have a case ground, but the ProNautic does. Has anyone done this swap and left it without a case ground? I don't really understand why the new one would need it if the old one didn't have it.

Thank you in advance!

Antonio

[Monty]

You are failing to connect the ultimate safety connection if you don't ground the case/chassis. ABYC A-31 requires it to be compliance now. There was none on the Charles charger probably due to its age vs. the current ABYC rules, but don't miss this chance to improve safety. This is your connection to the boat's bonding system If there is a DC to case fault, this ground takes the fault current and trips the breaker. The unit's manual has the details on how and why.

I put the 60 watt version in my 350; in the same location as the Charles charger. The ground is easy to get to to make the new connection with a #8 green cable. I also found the route for the temperature probe to be fairly easy to access, if you pull the two big red switch panel out (don't disconnect, just pull out and fish the cable back there down to the battery compartment).

[SkuffedKeel]

Monty,

I appreciate your reply, thank you! I will be running the ground ASAP and your idea of pulling the switch panel out to route the wires had me banging my head against my desk, I can't believe I didn't think of that while I was doing the job!

[D&M]

A couple of points here. There is no such thing as a DC ground. If you are grounding the case it will be for an AC fault where the hot wire makes contact with the case.
What people refer to all the time as a DC ground is simply a negative return path to the battery.
I have never seen a C350 with a bonding system. They don’t need it. The only metal fittings underwater are the prop, shaft and rudder post - assuming you haven’t changed out the Marelon through hulls. If you protect these with an anode and avoid stray dc current from within you have no problems. If you add a bonding system you add a path for external stray currents to enter the vessel and then exit from another path.
On a final note if you connect the case to the battery negative and thus to the engine with a bonding wire, in the case of a fault you are putting AC into the water and potentially back to shore (if there is also a fault on the shore side. )
All this is said as someone who does not need to consider the ABYC and their standards (not rules).