Keep your trailer battery fully charged while towing or boondocking. Premium 4-gauge copper harness system with 100-amp resettable breakers. Complete, ready-to-install kit.
The EQ Systems 8400 Stay Charge System solves one of the most common problems for trailer owners: arriving at camp with a dead or undercharged trailer battery. Standard 7-pin trailer connectors provide only a trickle of charging current — nowhere near enough to keep up with the demands of hydraulic jacks, leveling systems, or other trailer accessories. The Stay Charge delivers a dedicated, high-current charging connection directly from your tow vehicle's battery to your trailer battery, charging it significantly faster while underway.
The system consists of two heavy-duty 4-gauge copper harnesses. The 25-foot truck harness connects directly to the tow vehicle's battery and runs back to the rear bumper. The 16-foot trailer harness connects to the trailer battery and plugs into the connector at the tow vehicle's rear bumper. The result is a constant, robust power link between the two batteries — with the added benefit that if your trailer battery is ever completely dead, the tongue jack can still be operated directly off the tow vehicle battery.
Charges trailer battery significantly faster than the standard 7-pin trailer connector power source
Allows the tongue jack to run off the tow vehicle battery when the trailer battery is completely dead
Resettable 100-amp breakers protect the system — no fuse replacements needed after a fault
Weatherproof, self-locking connectors and nylon-braided cables make for a clean, straightforward install
The Stay Charge creates a dedicated, high-current charging path between your tow vehicle and trailer batteries — completely separate from the 7-pin trailer connector. Truck Side: The 25-foot truck harness connects directly to the positive and negative terminals of the tow vehicle battery. The cable runs along the frame to a weatherproof connector mounted at the rear bumper area. Trailer Side: The 16-foot trailer harness connects to the trailer battery terminals and runs to a mating connector that plugs into the truck-side connector when you hook up. While Towing: The tow vehicle's alternator charges both batteries simultaneously through this direct connection. The 100-amp resettable breakers on both harnesses protect against faults or shorts. When you unhook, the connectors simply unplug — no tools needed. Dead Battery Situation: If you arrive and the trailer battery is fully discharged, the tongue jack can be operated directly from the tow vehicle battery through the Stay Charge connection, so you're never stranded.
Complete System — Ready to Install: • 25-foot truck harness • 16-foot trailer harness • 4-gauge copper cables • Weatherproof quick, self-locking connectors • Protective nylon braid cable sheathing • 100-amp resettable breakers (both circuits) • Installation instructions All premium components included — no additional hardware needed for a standard installation.
The Stay Charge is especially valuable for trailer owners who: • Use an EQ Systems hydraulic tongue jack or leveling system that draws significant current from the trailer battery • Boondock or dry camp and need the trailer battery as charged as possible on arrival • Have experienced a dead trailer battery after towing, leaving jacks or accessories without power • Take long drives and want to ensure the trailer battery is fully topped off by the time they reach the campsite • Tow trailers with multiple 12V accessories (lights, fans, pumps) that deplete battery charge between trips
Technical Support: EQ Systems Toll Free: 1-800-846-9659 Local: 574-264-3437 Hours: Monday–Friday, 7AM–4PM EST Warranty: 1-Year Limited Manufacturer's Warranty covering defects in materials and workmanship under normal use. Manufacturer: EQ Systems — 19300 Grange St, Cassopolis, MI 49031