Marine Lithium System Design Worksheet
Complete worksheet for planning a boat lithium system from loads, kWh, BMS current, solar, alternator, inverter and installation requirements.
Vessel
- Vessel type:
- Length:
- Monohull/catamaran/motor:
- Engine(s):
- Existing DC voltage:
- Existing house capacity:
- Existing starter capacity:
- Shore power:
- Generator:
- Solar:
- Alternator:
Daily loads
| Load | Watts | Hours | Duty % | Wh/day |
|---|---|---|---|---|
| Fridge | ||||
| Freezer | ||||
| Autopilot | ||||
| Instruments | ||||
| Radar | ||||
| Starlink | ||||
| Laptops | ||||
| TV | ||||
| Watermaker | ||||
| Washing machine | ||||
| Induction | ||||
| Air conditioning | ||||
| Lighting | ||||
| Pumps | ||||
| Other | ||||
| Total |
Peak loads
- Largest AC load:
- Largest DC load:
- Expected simultaneous AC load:
- Inverter size:
- Inverter surge:
- Calculated DC current:
- BMS continuous current:
- BMS peak current:
Storage
- Daily kWh:
- Autonomy days:
- Planned usable fraction:
- Required nominal kWh:
- Chosen bank kWh:
- System voltage:
Charging
- Solar W:
- Expected solar Wh/day:
- Alternator charge A:
- DC-DC A:
- Shore charger A:
- Generator charger W:
- Wind/hydro:
- Poor-weather recovery hours:
Safety
- Main fuse:
- Interrupt rating:
- Isolator:
- Positive busbar:
- Negative busbar:
- Shunt:
- Audible BMS alarm:
- Visual BMS alarm:
- Charge disable:
- Load disable:
- Heat/smoke detection:
- Battery temperature:
- Flooding protection:
- Emergency isolation:
Apply this guidance to your boat
Use this page as one input to a vessel-specific plan. Record the actual equipment, cable runs, charging sources and operating pattern aboard before choosing hardware or changing the installation.
- Measure the real load and its operating time instead of relying on a label or a generic boat profile.
- Check every proposed current against the battery, BMS, protection, cable and connection limits.
- Confirm the result against current manufacturer instructions and the rules that apply to your vessel.
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