Why owners switch to lithium
Most marine lithium batteries are lithium iron phosphate (LiFePO4). Compared with lead-acid they are lighter, you can use far more of their capacity without damaging them, and they hold voltage better under load. That makes a real difference for fridges, electronics, anchor winches and inverters on weekends away from the marina.
The battery is the easy part
Most problems we see are not the battery. They come from treating lithium like a drop-in replacement. The things that need to be right:
- Battery management system (BMS). Every lithium battery needs one. It protects the cells and can disconnect the battery. Your charging and loads need to cope when it does.
- Charging profiles. Shore chargers, solar controllers and inverter-chargers all need lithium settings that match the battery maker's specifications.
- The alternator. Lithium can accept so much current that it overworks a standard alternator. A DC-DC charger between the start battery and the lithium bank protects the alternator and charges correctly.
- Mixing chemistries. Lead-acid start batteries and lithium house banks can live together, but they must be charged and isolated properly.
- Fusing and cable sizing. Lithium can deliver very high currents into a fault. A correctly rated fuse close to the battery and properly sized cable are essential.
- Mounting and isolation. Secure mounting, a battery isolation switch and clear labelling.
Solar on board
Solar is a natural partner for lithium. A good solar controller with a lithium charging profile, or a DC-DC charger with solar input, lets you stay off the marina for longer. Plan the panel size around what you actually run.
Do it once, do it properly
Boat wiring needs to meet AS/NZS 3004.2, and the marine environment is hard on connections. Tinned marine cable, sealed terminations, heat-shrink and proper support all matter more on a boat than in a house.
From our job sheets
Battery work is our most common marine job. Recent examples include a 500 amp-hour house battery system, a dual battery setup with new fuses and distribution blocks, roof-mounted solar wired to a DC-DC charger, and failed batteries found reading as low as 4 volts. We also find older setups where new batteries were added without updating chargers, which shortens battery life.
What it costs with us
Battery upgrades are quoted per boat after we look at your current setup and how you use the boat. See our marine electrical services and Manly and Redlands marina work.