Using grid power to charge batteries

[vt_rob]

Hi, new to the forum here, been reading a bit and man do I wish I found this site 10 yrs ago when we installed our system, loads of great info here!

So, we've been off grid for 10 years and have just brought power in to a shop I'm building close to the house. A friend who is an electrician and works for Efficiency Vermont thought we could now charge the batteries when needed via a 10 gauge 15amp extension cord running from a gfci outlet in the shop to the plug where I would normally plug in the generator.

When I plug it in from the shop it immediately trips the gfci. I shut off the power to the AC system in the house and tried it again and the same happens. Any thoughts as to why this would happen? My friend is thinking there might be a ground issue going on within the inverter/cc wiring. He is out of town until later this week to investigate so I was hoping to find some insight from those who might have had a similar experience.

(The reason for using the grid instead of the generator is because Vermont's grid is 90% carbon neutral so it would be cleaner to go this route and keep the generator for emergency uses.)

Thank you!

[littleharbor]

Generally speaking most inverter/chargers have ac1 and ac2 inputs. If yours has this then you need to connect grid power to ac1.

Generic answer here. What inverter/charger do you have and what does the instruction manual say?

[vt_rob]

Thanks for getting back to me. So I switched the ac mode and got the same result. The system is not tied directly to the grid, we simply created a circuit that would take the generator out of the equation. There is no power going back to the grid at all so I'm not sure if that changes your suggestion.

It's an Outback VFX3648 and a MX60 MPPT charge controller.

[gbynum]

When I plug it in from the shop it immediately trips the gfci.

Most of the time I've seen similar problems, the "neutral" (white) and equipment ground (green) are either interconnected where they shouldn't be or are crossed. It's possible the hot and neutral are crossed.

[vt_rob]

Thanks! Are you talking at the outlet? I did run a grinder off of the same outlet using the same cord without it tripping.

[NEOH]

Sometimes, some equipment that has a surge / in-rush will trip a GFCI outlet.