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Leaving BATTERIES on board for the WINTER LAYUP? | Ask The Expert with NIGEL CALDER
9 May 2026 · 2 min · 2K views
Snow-covered boats on stands in winter marina layup
What this video covers
Nigel Calder and Jan Attenstedt answer a viewer question about leaving batteries aboard during a five-month winter layup with no charging available.▶ 0:18 The core recommendation: disconnect all negative cables to eliminate parasitic loads and fully recharge the batteries before isolation.▶ 0:30 A fully charged AGM battery stored in a cold climate can sit six to eight months without issue.▶ 0:43 Flooded wet-cell batteries benefit from a top-up recharge during an extended layup.▶ 0:56 The critical risk is discharge in freezing temperatures — a discharged battery will freeze, burst its case, and be destroyed.▶ 0:00 Cold climates such as Maine or Michigan actually help by slowing self-discharge, provided the batteries are fully charged before isolation.▶ 1:06 Lithium-ion batteries require different handling: store them at 50–80% charge rather than full, because a partially charged state extends their cycle life.▶ 2:07 The BMS on a lithium bank can draw residual current, so monitoring that the charge does not drop to zero is important.▶ 1:51 Manufacturer manuals should be consulted for specific lithium storage guidance.▶ 1:37
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