Quote:
Originally Posted by PigPen
On the shore power side of things, you're starting with a bond. Most people seem to run the shore power directly into an inverter/charger so that it can charge the batteries while supplying power. In this case, you wouldn't want the inverter to have it built in based on what you are saying.
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Just to make sure we're on the same page, I think what you're describing is a topology like the following. I've put in arrows to illustrate the energy flows.

You're right: some inverter-charger devices will offer a built-in ground-neutral bond. It isn't an inherently
good nor
bad feature; it's the design of the system around it that makes it good or bad.
If we think of only the batteries and the grid-supplied shore power, a built-in automatic bond in the inverter-charger would be really convenient. It'll bond when shore power is disconnected, and open when shore power is connected. Great!
The catch is this: what happens when the shore power cord is plugged to a generator? What provides the ground-neutral bond?
The inverter-charger won't provide the bond: its logic is "if there's power at my ac input, disconnect the bond." The inverter-charger doesn't actually know or test whether the ac input circuit provides a bond. (note: I'm generalizing. It'll be important to confirm by checking the owner/user/installer manuals of any specific device before use.)
The generator may or may not provide the ground-neutral bond. I'm most familiar with the Honda portable inverter generators (EU2000 and EU7000) and know that these from the factory do not provide a bond. It has been reported that other generators do provide a bond. The point is, bonding isn't standardized in the industry and we can't make an assumption.
When considering the portable generator scenario one might say "the automatic bond in the inverter-charger did the wrong thing! It's bad!" I would say just be aware of and understand the issue and plan accordingly.
For the specific case described here (topology as above, inverter-charger with automatic bonding, possibility of plugging shore power to a generator with unknown bonding), here's one simple idea. Several years ago Mike Sokol proposed building a
ground-neutral bond plug. Make one and tether it to the male plug end of the shore power cord. Each time the shore power cord is plugged into a power source it'll be there and remind you to ask yourself "am I plugging into a generator? Plug in this bond plug to the generator too, to ensure that the ground-neutral bond is provided."