Marine Battery Bank Calculator
REF: EN-505-ELEC
Use this tool to determine the ideal size for your boat's house battery bank. By inputting your daily power consumption and battery chemistry, you can calculate the total amp-hours (Ah) required to safely power your vessel off-grid.
Why Do I Need a Battery Bank Calculator?
Sizing a marine house battery bank correctly is one of the most critical safety and comfort decisions on a boat. If your bank is too small, you'll constantly run generators or ruin batteries by over-discharging them. If it's too large, you're carrying unnecessary weight and spending extra money.
Understanding the Math:
- Daily Usage (Ah): This is the total amount of energy your fridge, lights, electronics, and pumps consume over a 24-hour period.
- Days of Autonomy: How many days you want to anchor out without starting an engine, generator, or relying on solar to charge the bank back up. 2 days is the standard cruising recommendation.
- Depth of Discharge (DoD): You cannot drain a battery to 0%. Traditional Lead Acid or AGM batteries suffer permanent damage if drained below 50%. Modern Lithium (LiFePO4) batteries can safely be drained to 10-20% (giving them an 80-90% usable capacity).
Lead Acid vs. Lithium (LiFePO4)
Notice the difference when you switch chemistries in the calculator. If you need 100 Ah of usable energy, you must buy a 200 Ah Lead Acid bank (since you can only use 50%). With Lithium, you only need about a 125 Ah bank to get the same 100 Ah of usable energy.