How long do the batteries last?

This is the question a marine electrician asks first, and it deserves a real method rather than a marketing number. We are not going to quote you a year count or a replacement price we can’t stand behind — battery life isn’t a fixed figure, it’s a curve you operate along. Here is the curve, and how the boat is built to sit high on it.

The propulsion bank is 24.48 kWh at 48 volts, built as three parallel, isolatable banks — each one four Victron 12 V AGM Supercycle 170 Ah units. That architecture matters for lifespan two ways: the pack is deliberately oversized for the daily job, and it splits into thirds you can rest, balance, or take offline independently.

The single biggest driver of how long a lead-based bank lasts is depth of discharge — how deep you pull it each cycle. Cycle life falls steeply the harder you draw a battery down, and it climbs sharply when you keep the draws shallow. On the 1,000 NM trial the 48 V bank never went below 50% state of charge. That 50% floor isn’t only a safety reserve; it’s the operating habit that keeps every cell on the gentle part of its wear curve.

And when a bank does age out, nothing falls off a cliff. Because the pack is three isolatable banks, degradation is graceful: you retire and replace a third at a time, on your schedule, while the boat keeps running on the rest. That’s the biomimicry principle the whole system is built on — paired, parallel components that fail slowly and locally, not all at once.

So the honest replacement horizon is a calculation, not a slogan: take the manufacturer’s cycle-life-versus-depth-of-discharge curve for these cells, hold it against a 50% floor, and divide by how many cycles a year your cruising actually puts on the bank. Feed your real usage into the configurator and it will show you that horizon for your boat — without us inventing a figure the sea trial never measured.