BoatHowTovideo

This is a TERRIBLE INSTALLATION! 😓 Parallel Batteries | Ask The Expert with NIGEL CALDER

June 21, 2025 · 3 min · 11K views

What this video covers

Jan Attenstedt and Nigel Calder analyze a house battery bank configuration consisting of seven AGM batteries wired in parallel, with some located in an engine compartment and others under a port bunk.0:18 Calder identifies two primary flaws that lead to premature battery failure.1:48 First, connecting the boat’s electrical system to only one end of the parallel string causes uneven load distribution, where the battery closest to the connection point performs significantly more work than the others.2:10 Second, the temperature differential between the engine room and the cooler bunk area causes the batteries to charge and discharge at different rates.2:31 Calder advises that all batteries in a parallel bank must reside in the same ambient temperature.2:47 To balance current flow, he recommends connecting every positive and negative terminal to a central bus bar using conductors of identical length and gauge.2:53 While saltwater submersion of the batteries creates stray current and voltage drops, it does not pose an immediate electrocution risk or cause catastrophic system failure.1:30 Proper bus bar installation ensures balanced battery life.

Watch on YouTube

More from BoatHowTo

Boat ELECTRIC PROPULSION with only LEAD ACID Batteries ?? | Ask The Expert with NIGEL CALDERSep 2026MaxProp: More Pitch in Reverse than in Forward? 🤔 | Ask The Expert with NIGEL CALDERSep 2026Common Ground Point with Isolated Saildrives | Ask The Expert with NIGEL CALDERSep 2026How to keep you TANK CLEAN in the days of BIODIESEL.. | Ask The Expert with NIGEL CALDERAug 2026

From BoatHowTo — see the channel’s boat, crew, and every analyzed video.

The Sailing Directory Newsletter

One email with the fleet's best finds — the moments, boats, and stories worth your watch time. Enter your own address to get your own copy.

Report an issue