Charger Ground Bonding

[sailorboy1]

Working on installing a new battery charger that has a Ground/Chassis lug. Since all grounds end up at the same point is there really any reason it can’t just be connected to the AC or DC ground/negative terminal at the charger?

[smac999]

If that reason existed they would do it for you at the factory. It goes to the battery neg post or neg disturb bar.

[Stu Jackson]

Discussed in detail here:

Wiring a new charger From Maine Sail:

http://forums.sailboatowners.com/ind...5/#post-880275 and

Installing A Marine Battery Charger Photo Gallery by Compass Marine How To at pbase.com

[sailorboy1]

So I helped another boat install another charger and they don’t even have an AC ground bus or a ground point on the point.

[sailorboy1]

I just replaced my 17 year old OEM charger/inverter on a boat that was built to all the abc (whatever) codes of the time. You know what, the chassis ground wasn’t even connected.

[EngNate]

On a proper vessel system the AC equipment ground is connected to the DC ground. If the DC positive shorts to the case of a charger or inverter it can burn off the smaller AC ground wire, leaving the equipment with an ungrounded case and a potential shock hazard. The battery negative output cannot be connected to the case, as there would then be a shared path with the AC ground - a portion of the battery charging current would flow through the AC ground circuit because it ultimately gets to the battery. No current is supposed to flow in this circuit in a non fault condition, and in most systems as they are the likelyhood is high that this situation would impress voltages on underwater metal parts, adversely influencing corrosion. The DC safety ground wire from the case to the battery or DC ground buss is out of the path of current being provided by the charger to the battery. It will be big enough to cause the overcurrent protection on the positive side to open in the event of a short without the AC ground connection failing. A wire not more than one standard gauge smaller than the power is called for ...You do have your battery charger cables fused at the batteries, yes?

[Colin A]

Here is another article for you. This is a common area where both the boat builders and charger builders seem to be trying to fudge their way around the standards.
Inverter Installations; What You Need to Know | Steve D'Antonio Marine Consulting

[EngNate]

Steve is excellent. I've read a lot of his stuff, including one of his surveys on a big boat I was very involved with.