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14 February 2026 · 3 min · 2K views
Man explains battery wiring at workbench with panel
What this video covers
Jan Attenstedt and Nigel Calder explain the risks of paralleling batteries with mismatched amp-hour capacities.▶ 0:12 While theory suggests batteries in parallel share electrical loads proportionally to their capacity, internal resistance variations prevent this in practice.▶ 0:56 One battery inevitably works harder than the other, leading to system imbalance and premature degradation of the entire bank.▶ 1:10 For long-term reliability on a cruising boat, all batteries in a parallel bank must share the same make, model, age, and manufacturing batch.▶ 1:33 While mixing capacities may function temporarily during an emergency, it significantly shortens the service life of the installation.▶ 1:30 Proper wiring geometry remains essential to maximize battery longevity, a topic covered in the BoatElectrics 101 course at BoatHowTo.com.▶ 2:49 Matching battery specifications ensures balanced discharge cycles and prevents unnecessary strain on individual cells.
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