30 Amp Automatic Transfer Switch for Shore Power and EcoFlow Inverter Without Charging Trailer Batte

Published 10/28/2026

Question:

I need to install a 30 amp AC automatic transfer switch for either short power or an inverter but I am unsure as to what to get. I want to make sure the inverter does not power the DC circuits, or at least does not charge the trailer’s lithium battery. I’d prefer that the inverter only powers the AC circuits. I have a progressive dynamics PD4645 converter that I installed as a lithium battery upgrade to an older Parallax 6345 power panel. I also have a EcoFlow Delta 3 battery generator that I use as an inverter. It is powered by its own internal battery. On shore power the EcoFlow is not charged and is not on. On inverter power I would like the EcoFlow to only power the AC circuit, the trailer battery to run the DC circuits like the water pump and fans, and the trailer battery to not be charged by the EcoFlow. Which transfer, which do you recommend?

asked by: Thane L

Expert Reply:

Hey Thane! The Progressive Dynamics Automatic Transfer Switch # PD5110010Q you were looking at is a great option here. This is a 30A switch that can automatically select between shore power and your EcoFlow Delta 3, while preventing the two AC power sources from backfeeding each other.

The important part of your setup is isolating the PD4645 converter from the inverter output. The transfer switch alone won't do that. You'll need the converter powered only by shore power, with the circuits you want to run from the EcoFlow connected through the transfer switch. That way your trailer battery continues powering the 12V circuits without being charged by the EcoFlow.

Are you mainly using the EcoFlow for off-grid camping?

expert reply by: Robin H

PD Transfer Switch
(click to enlarge)

Thane L.

10/28/2026

Yes, off-grid camping. The EcoFlow is great because my trailer only has one group 27 battery and no solar and to run the microwave we need a generator. The EcoFlow is a semi-built in solution and gives me 22 minutes of runtime before I need to charge it. I charge it every day or two using an EcoFlow 500W alternator charger while driving around sightseeing and shoplifting. I want to use the EcoFlow for only the AC circuits to maximize microwave time available.

Robin H.

10/28/2026

@ThaneL that makes sense! Keeping the converter isolated from the EcoFlow will help you get the most runtime out of it without wasting power charging your trailer battery. Sounds like you've got a pretty good setup for off-grid camping, especially with the ability to recharge the EcoFlow while you're out exploring.

Thane L.

10/28/2026

@RobinH How do I keep the converter isolated from the EcoFlow? It sounds like I need another switch. Thank you.

Robin H.

10/28/2026

@ThaneL you wouldn't necessarily need another switch. One option is to install a small inverter subpanel for the AC circuits you want powered by the EcoFlow, with the converter remaining on the shore-power-only side. The transfer switch would then select which power source feeds that subpanel. Since your PD4645 is integrated into the existing power panel, how you separate those circuits will really depend on your trailer's wiring and how that is set up. If you aren't comfortable with this kind of work I would see if there is a local shop or RV tech that can handle it for you.