All tools
Marine Battery Sizing
Size your house bank for overnight loads, compare lithium vs lead-acid, and estimate recharge time.
Sum of fridge, lights, electronics, bilge, water pump, etc.
Anchor usage is typically 14-20 hrs/day (overnight + evening).
Daily Consumption
200Ah/day
At 12V, this is 2 kWh per day.
Runtime on Full Charge
0.8days
With 200Ah LIFEPO4 bank at 80% usable DoD.
Recharge Time (20% → 100%)
4.7hrs
At 40A from solar. Includes 85% charging efficiency.
Recommended Minimum Bank
250 Ah
LiFePO4 Lithium (80% DoD, 3000 cycles)
Recommendations
- · Bank provides less than 1 day of runtime (0.8 days) — increase capacity.
Chemistry comparison
The chemistry you choose determines the usable depth of discharge (DoD), cycle life, and weight of your bank:
- LiFePO4 Lithium: 80% DoD, 3000+ cycles, 31 lbs per 100Ah. Highest upfront cost, lowest lifetime cost.
- AGM Lead-Acid: 50% DoD, 500 cycles, 70 lbs per 100Ah. Maintenance-free, mid-range cost.
- Flooded Lead-Acid: 50% DoD, 300 cycles, 60 lbs per 100Ah. Cheapest upfront, requires maintenance.
For daily consumption over 100Ah, AGM or lithium is strongly recommended. Over 200Ah/day, lithium’s weight and cycle-life advantages make it the clear winner despite the higher upfront cost.