01
Buying on price with no low-temperature cut-off
Cheap cells are fine on a tinnie. Cheap cells without a BMS that stops charging below 0 °C are a problem the first frosty dawn launch in Victoria or Tasmania.
Day boat · one or two aboard · 12 V
12 ft tinnie Lithium Battery System
A sounder, navigation lights, a livewell pump and a phone on charge. The daily draw is small, the boat spends its life on a trailer, and the battery gets forgotten between trips. Lithium earns its place here on weight and on tolerance for sitting half-charged, not on capacity.
Typical load profile
Sounder / GPS4 Ah
Livewell or bait pump5 Ah
Navigation lights2 Ah
Phone and torch charging2 Ah
Bilge pump1 Ah
A trolling motor is a separate question — it wants its own bank, sized on the motor’s draw and the hours you actually troll, not on this profile. The house figure here is what the rest of the boat uses in a long day.
What we would fit · 50–100 Ah
Budget build
$900
100 Ah drop-in LiFePO4, 12 V
10 A lithium-profile mains charger
Inline fuse at the battery
Battery box with strap
Anderson plug for the charger
Premium build
$1,900
100 Ah LiFePO4 with Bluetooth and low-temp cut-off
18 A DC-DC charger from the outboard
100 W folding panel with MPPT
Battery monitor with shunt
Fused distribution block
Indicative installed prices, September 2026. On a tinnie the cells are most of the cost; the charging is the part owners skip and then regret.
On this hull specifically
Battery installation mistakes for this boat type
02
Charging straight off a small outboard
A tiller-steer outboard’s charging coil is unregulated and small. Into a lithium bank it either does nothing useful or runs flat out. A small DC-DC charger fixes both.
03
Leaving it in the sun on the bench seat
LiFePO4 is happier than lead-acid at most temperatures, but a black case in a Queensland summer on an aluminium deck is a cycle-life question. Box it, strap it, shade it.
04
Using the car charger
An automotive lead-acid charger with a desulphation mode will trip the BMS or leave the bank undercharged. A lithium profile is a fifty-dollar difference.
Other hulls