Yacht Batteries Make The World Go Around.

Understanding Yacht Batteries

Batteries are deceptively simple: blocks of lead-acid (or newer technologies) that sit in the bilge, charged and discharged daily. That was my understanding… until I started specifying one for a hybrid yacht system.

Questions quickly arose:

• How much power do we really need?

• What is the maximum safe discharge rate?

• Which system voltage works best?

• How can I supply high-current DC loads efficiently?

• Which battery technologies are best suited for marine applications?

After research and testing, here’s what I learned.

Three Main Types of Yacht Batteries

1. Lead-Acid Batteries

   • Similar to a car battery

   • Can be sealed or vented (sealed preferred)

   • Maximum depth of discharge ~50% of rated capacity

   • Sensitive to deep discharges → sulfation and shorter life

   • Traction batteries (like forklift batteries) tolerate deeper discharge

   • Slow to charge but inexpensive

2. Carbon-Foam / Firefly Batteries

   • Similar chemistry to lead-acid but with a special carbon foam anode

   • Faster charging (~80% charge quickly)

   • Can cycle partial charges without damage

   • Economical and more stable than standard lead-acid

3. Lithium Batteries (LiFePO4)

   • Much higher energy density (~120 Wh/kg, ~3x lead-acid)

   • Charge rapidly

   • Voltage decreases at low temperatures

   • Some lithium chemistries (LiCo, LiNiMnCo) risk thermal runaway or dendritic shorts → fire hazard

   • Expensive upfront ($600–$1000/kWh) but better lifecycle economics

   • Marine insurance may have restrictions

Selecting Batteries for a Hybrid Explorer Yacht

Our hybrid drive requires:

• Large power storage capacity

• Fast charging

• Reliability and Class-approved components

After reviewing suppliers, two stood out:

1. Corvis (Norway)

2. Praxis (Netherlands)

Both offered:

• Modular systems

• Built-in monitoring and cooling

• Fire relays

• Class approval for marine use

Our total installed capacity: 60 kWh, roughly 2 hours of operation at 500–700 VDC.

Modularity allows upgrades as technology evolves, especially with the rapid adoption of electric vehicles driving marine battery innovation.

Emerging Battery Technologies

Battery technology is evolving quickly. Promising developments include:

• Lithium Sulfur (LiS)

  • Solid-state cells

  • 4–5x power density of LiFePO4

  • Initially for military/aviation, but may enter marine applications

We plan to review our battery selection closer to delivery (about 18 months away) to take advantage of any improvements.

Conclusion

Specifying yacht batteries is far from trivial. It requires understanding:

• Capacity and discharge limits

• Charging rates

• Voltage requirements

• Technology suitability for marine safety and lifecycle costs

Choosing LiFePO₄ offered the best combination of energy density, fast charging, and reliability for our hybrid explorer yacht.