01
Mounting the bank where the old battery was
The AGM lived under the cockpit because it was heavy. Lithium is half the weight and can go low and central, which is where you want ballast.
Weekend cruiser · two aboard · 12 V · small outboard
Trailer sailer Lithium Battery System
Weekends on a lake or a bay, an outboard that runs an hour a day, and a boat that cannot carry weight in the wrong place. The trailer sailer is the hull where lithium’s weight saving is not a nicety but a trim decision.
Typical load profile
Fridge or cooler, 35% duty28 Ah
Cabin, anchor and nav lights10 Ah
Instruments and plotter8 Ah
VHF standby4 Ah
Device charging and pumps5 Ah
Two nights out with almost no engine time. This profile assumes a small panel; without one, size for the second night rather than the first.
What we would fit · 100–200 Ah
Budget build
$1,700
100 Ah drop-in LiFePO4, 12 V
100 W panel with MPPT
Lithium-profile 10 A mains charger
Fused distribution
Retained small cranking battery or pull-start
Premium build
$3,600
200 Ah LiFePO4 with Bluetooth
18 A DC-DC from the outboard
200 W of solar on the coachroof
Shunt monitor
Certified install
Indicative installed prices, September 2026. The outboard’s charging output is tiny here; solar does the real work.
On this hull specifically
Battery installation mistakes for this boat type
02
Counting on the outboard to recharge
A 6 A charging coil for an hour a day is 6 Ah. The panel is not optional.
03
Skipping the monitor to save money
On a small bank, the difference between 30% and 10% is one night. A shunt monitor is the cheapest insurance on the boat.
04
No fuse at the battery
Lithium can deliver short-circuit currents lead-acid cannot. Fuse at the terminal, always.
Other hulls