Lithium system design
Marine Lithium System Planner
Design a full marine LiFePO4 system end-to-end. Bank capacity, BMS, charging sources, inverter, cables and fuses — with chemistry-specific advisories that distinguish conservative guidance from real operational limits.
Tiered charging advisories
Marine Power Designer uses a four-tier charge-rate model per chemistry: recommended, acceptable, caution, and critical. For LiFePO4 that's 0.5C / 1.0C / 1.5C / 2.0C of the bank capacity. You see the conservative number for daily life, the operational number for sustained motoring, and a clear red line for the BMS limit.
What the planner cross-checks
Bank capacity vs daily energy and autonomy, inverter peak DC draw vs BMS continuous rating, charge current vs C-rate tiers, cable size and fuse against ABYC or ISO, and diversity factor when multiple charging sources run together (solar + alternator + shore).
Designed for
- Cruisers retrofitting from lead-acid to LiFePO4
- New-build owners specifying a 12V / 24V / 48V house bank
- Marine electricians sanity-checking a customer's spec
- Off-grid catamarans and motor-yachts with 5kW+ inverters
Frequently asked questions
What's a safe charge rate for marine LiFePO4?
Conservative recommendation is 0.5C (200A into a 400Ah bank). Most modern LiFePO4 cells accept up to 1.0C continuously and 2.0C peak, but BMS, busbars and cables usually become the limit before the cells do.
Do I need a DC-DC charger for alternator charging?
Yes, for almost every modern installation. A direct alternator-to-LiFePO4 connection can pull the alternator past its thermal limit and the BMS may disconnect under load. A DC-DC charger or external regulator with temperature sensing solves both.
LiFePO4 and lead-acid on the same boat?
Possible but only with proper isolation: separate banks, dedicated chargers per chemistry, and a managed paralleling switch. Never charge LiFePO4 from a lead-acid charge profile — it won't reach full SoC and may damage cells over time.
What size BMS do I need?
BMS continuous current must exceed your highest sustained load (usually inverter peak DC draw). Add headroom for surge. The planner cross-checks BMS rating against your inverter and charge sources.
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