01
Sizing for the air-conditioner
One reverse-cycle unit is 100 Ah an hour at 12 V. Nobody sizes a battery for that; you size a generator and let the bank carry the quiet hours.
Domestic loads afloat · six or more aboard · 12 V or 24 V
Houseboat Lithium Battery System
A houseboat is a holiday house with a bilge pump. Full-size fridge, television, microwave through an inverter, lighting for a party and, increasingly, air-conditioning. The generator used to do all this; lithium and a big solar roof let it run for two hours instead of ten.
Typical load profile
Full-size fridge-freezer90 Ah
Inverter — microwave, TV, kettle, chargers110 Ah
Lighting, fans, entertainment60 Ah
Water and macerator pumps25 Ah
Navigation, VHF, anchor light15 Ah
Device charging, six people20 Ah
Air-conditioning is deliberately excluded: it is a generator or shore-power load unless the bank is well over 1000 Ah and the roof is covered in panels. The figure above is a full house without it.
What we would fit · 600 Ah +
Budget build
$12,800
600 Ah LiFePO4, 12 V
Lithium-profile 100 A mains charger for generator and shore
60 A DC-DC from the engine
1 kW roof solar with MPPT
Shunt monitor and switchboard labelling
Premium build
$24,000
1200 Ah at 12 V equivalent, 24 V system
5 kW inverter-charger with generator auto-start
2 kW roof solar
Full monitoring to a wall panel
Certified install to AS/NZS 3004.2 and survey requirements
Indicative installed prices, September 2026. On hire houseboats, check survey and operator requirements before choosing the chemistry; some operators specify installer and BMS.
On this hull specifically
Battery installation mistakes for this boat type
02
Keeping the old generator-only charger
A lead-acid charger from the generator will never fill lithium properly and may trip the BMS with equalisation. Replace it; it is the most-used charger on the boat.
03
Ignoring survey and marina rules
Houseboats on the Murray, the Hawkesbury and the Gippsland Lakes all have operators and authorities with views on lithium. Get them in writing before the install.
04
One enormous single bank
Two or three parallel packs with separate BMSs mean a fault leaves you with lights and a fridge, not a dark boat full of guests.
Other hulls