MJ Sailingvideo
We Almost Cooked Our Electrical System… So We Fixed It (MJ Sailing - Episode 375)
April 25, 2026 · 24 min · 29K views
What this video covers
Matt and Jessica are building a catamaran with a 48-volt electrical system and are designing the DC electrical cabinet to prevent overheating. The cabinet will house Victron DC-to-DC controllers, MPPT solar charge controllers, a Cerbo GX, battery protects, and motor controllers for the hybrid electric drive.▶ 0:32 Victron has not yet released a more efficient 48-volt DC-to-DC controller, so the existing units — known to run hot — must be managed carefully.▶ 1:13 Matt mounts all controllers on ¾-inch aluminum spacers to improve airflow behind them, maintains more than the Victron-recommended 100 mm minimum spacing between units, and positions lower-heat controllers (winch battery, electronics) at the bottom while higher-load controllers (lights, toilets, shower sumps) sit near the top where active thermostat-controlled exhaust fans will pull air out.▶ 1:58 To supply intake air, Matt eliminates a planned interior door on the owner's berth electrical closet, replacing it with a vented sliding door.▶ 8:59 Each hybrid motor controller is mounted in a dedicated cubby with glassed-in tabs, open-backed for ventilation, and removable for wire-running access.▶ 11:03 A separate seawater cooling loop — with its own strainer, pump, and heat exchanger — serves the hybrid motors independently of the air conditioning through-hull.▶ 15:53 An Airlock marine air purification unit is also installed on each air conditioner to control mold and mildew.▶ 6:41 Proper heat management in a dense Victron DC cabinet requires active ventilation, strategic controller placement by load, and physical spacing beyond the manufacturer minimum.
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