Honest Chemistry Comparison

Sodium-Ion vs Lithium vs AGM

No chemistry is right for every boat. Here's how the three options actually compare for marine house banks and stabilizer power — including where sodium-ion is not the answer.

Attribute Sodium-Ion Lithium (LiFePO₄) AGM (Lead-Acid)
Thermal behavior High thermal stability; chemistry is inherently resistant to thermal runaway at cell level. Stable for lithium class, but thermal-runaway protection depends on pack design + BMS quality. No runaway risk; heavy and venting considerations if overcharged.
Cycle life (typical) ~3,000–6,000 cycles depending on cell and depth of discharge. ~2,000–5,000 cycles depending on cell and depth of discharge. ~300–700 cycles; degrades quickly with deep discharge.
Usable depth of discharge High — designed for deep cycling. High — typically ~80–90% usable. ~50% recommended to preserve life.
Raw material exposure No lithium, cobalt, or nickel — sodium is abundant and low-cost. Lithium + iron/phosphate supply chain; no cobalt in LiFePO₄. Lead — established recycling stream, heavy.
Weight / energy density Lighter than AGM; generally lower density than LiFePO₄ per Wh today. Highest practical energy density of the three. Heaviest; lowest density.
Cold-weather charging Strong low-temperature charge acceptance vs lithium chemistries. Charge below freezing requires heating or current limiting. Charges at low temps but loses capacity in cold.
Maintenance Sealed; no watering. Sealed; no watering. Sealed; limited service life under cyclic loads.
Upfront cost Premium vs AGM; competitive trajectory vs lithium as supply scales. Premium vs AGM. Lowest upfront; highest lifetime cost under deep cycling.

Specifications vary by cell manufacturer and pack design. Figures are typical ranges, not guarantees — we size every bank against the vessel's measured load profile before recommending a chemistry.

Sodium-ion wins when

  • You want lithium-class cycling without lithium-cell thermal exposure.
  • Raw-material independence (no Li/Co/Ni) matters to your operation.
  • You're building a stabilizer or house bank meant for deep daily cycling.
  • Cold-temperature charging is a real requirement.

LiFePO₄ wins when

  • Maximum energy density per pound is the binding constraint.
  • Your build already assumes lithium infrastructure and BMS.
  • Weight budget is tighter than budget budget.

AGM still wins when

  • The bank sees light cycling or is primarily a standby/start role.
  • Upfront budget is the hard constraint.
  • You need drop-in compatibility with an existing lead-acid system today.

Not Sure Which Bank Fits Your Vessel?

Run the sizing tool, or send us your vessel and load profile — we'll come back with a real engineering answer, not a chemistry pitch.

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