By Boat Battery editorial team · 2 minute read · Editorial policy
Between $900 for a tinnie and $26,000 for a cruising catamaran, installed. On most boats the charging system and wiring cost between a third and a half of the total, and that is not the part to save on.
Battery price versus installed project cost
The number everyone quotes is the price of the cells, and it is the least interesting part of the budget. A 400 Ah 12 V drop-in bank is a known quantity within a few hundred dollars. What varies between a $6,400 job and an $11,800 job on the same 38-foot yacht is everything around it.
Charging and protection upgrade costs
The charging system is the biggest line after the cells: a DC-DC charger sized to the alternator, a lithium-profile mains charger, and often solar and a controller. Then cable, fusing and terminations, because the old runs were sized for a bank that could not deliver these currents. Then the monitor. Then labour and certification.
Boat type and labour assumptions
Our hull pages carry a budget and a premium build for each boat type with the components listed, so you can see where the money goes rather than arguing about a total. These are unverified planning allowances, not obtained installation quotes. Confirm current local labour, tax, travel and commissioning costs.
Capacity choices and budget trade-offs
The one saving we do endorse: buy the capacity you actually need. The calculator exists to stop people buying 600 Ah because it sounded safer than 400. The one we do not: skipping the DC-DC charger to afford more amp-hours. That is how you end up buying an alternator as well.
Related installation planning resources
Use these notes to prepare your own measurements and questions. Check the exact equipment manuals and have the proposed system assessed for your vessel before buying or changing electrical components.
Calculate your boat battery capacity
The house bank calculator takes your loads, your nights on the hook, your solar and your alternator, and returns the bank, the DC-DC charger, the AGM equivalent and the weight you take off the boat.
Open the calculator