Winter Layup: A Marine Electrical Checklist

More battery banks are ruined over winter than in use. Most of the damage comes from banks left partially discharged for months, or from charging arrangements that are switched off along with everything else.

This is the sequence worth working through before you leave her.

Before you leave the boat

The aim is a bank that stays healthy and a boat that is not quietly drawing itself flat.

• Charge the bank fully, then decide how it will be maintained over winter
• Identify and account for standing loads — bilge pumps, alarms, trackers
• Confirm the bilge pump circuit is protected and on a permanent supply if it must stay live
• Check shore power connections and cable for damage before relying on them all winter
• Note current battery voltage and state of charge as a baseline

If the boat stays on shore power

A charger left running for months should be one you trust, on the correct profile, in a ventilated space. It is worth checking that the marina supply and the boat's protective devices are sound before depending on it unattended.

If she is ashore with no supply

Solar can maintain a bank ashore if the panels stay clear, but shading from covers and cradles often means it does not. Where nothing will be maintaining the bank, a fully charged bank isolated from loads is the safer arrangement, with periodic checks.

Spring recommissioning

Before the first outing: check bank voltage against the baseline, test each charge source individually, exercise the bilge pump and its float switch, check for corrosion at terminals after a damp winter, and power up navigation and safety electronics with time to fix anything before you need them.

Frequently asked questions

Should I remove the batteries over winter?

It depends on whether anything on board must stay live, and whether a maintenance charge is available. Both approaches work; leaving a bank aboard, discharged and unmaintained, does not.

Is it safe to leave a charger on all winter?

With a modern charger on the correct profile in a ventilated location, this is normal practice. It is worth having the installation checked rather than assumed.

Will solar hold the bank through winter ashore?

Sometimes, but shading from covers and low winter sun on the South Coast make it unreliable as the only measure.

Can you do a pre-season electrical check?

Yes — a recommissioning check before launch is a common piece of work for us.