How Do I Prevent a Hopkins Engager Breakaway Battery From Backfeeding Into My Trailer Wiring?

Updated 08/18/2026 | Published 08/12/2026

Question:

Hello, We buy Hopkins Engager breakaway battery systems from you all for our Rescue Boat trailer. I have some specific technical questions I was hoping I could get some clarification on. We have had issues in the past with the house battery winch, lights, and such back feeding with the breakaway system, or at least that is how it has been described to me. I was under the impression that there was a DC-DC charger inside the Engager unit, and my assumption is that is a one direction charger. Is that true? Have you heard of this before? I am looking at ArgoFets to isolate the batteries or add a charger in front of the breakaway system, but that might be an expensive and over engineered solution to a problem that doesnt really exist. Thanks, Jack

asked by: Jack C

Expert Reply:

Hello Jack,

Thanks for writing in.

What you've been told about the backfeeding is definitely possible, especially since your rescue boat trailer also has a separate house battery powering the winch, lights, and other accessories.

The Hopkins Engager does have a built-in battery charger, but I wouldn't consider it a DC-to-DC charger or assume that it provides one-way isolation between the batteries. Hopkins refers to it as a built-in charger, and I haven't found anything from Hopkins stating that the charging circuit itself prevents backfeeding.

Before going with an ArgoFET or adding another charger, I would use the Roadmaster Single Park Light Diode # RM-690 to isolate the breakaway battery's charging circuit. The diode allows power to travel in one direction while preventing it from feeding back the other way.

You'll install # RM-690 inline on the 12V charging wire feeding the Hopkins Engager, with the diode oriented so power can flow from the tow vehicle's 7-way 12V auxiliary circuit toward the Engager and its battery, but cannot flow back toward the 7-way or the rest of the trailer's 12V system. The diode has an arrow showing the direction current is allowed to flow, so that arrow should point toward the Engager.

I would not install the diode in the main power cable for the house battery or winch. # RM-690 is rated for 85 amps, so we're only using it to isolate the Engager charging circuit and prevent that backfeeding.

I think this is a much simpler solution for what you're trying to accomplish and would be where I'd start before spending the money on an ArgoFET or separate DC-to-DC charger. Hopefully this gets your rescue boat trailer's electrical system working the way you need it to.

Do you guys travel very far with the rescue boat, or does it mostly stay local when you’re called out?

expert reply by: Kate F

Jack C.

8/18/2026

Thank you for the recomendation! I appreacite your insight and the level of support you provide. We manufacture the trailers and are looking to improve some aspects of the electrical design.