Yes. Discussions on batteries in the GSC 2027 chat revolved around lithium vs. AGM/lead-acid batteries, energy storage strategies, fire risks, weight considerations, integration with charging systems, and real-world performance concerns. Whilst Lithium batteries are allowed by the GSC boats like Class40s are not allowed Lithium batteries when racing under class rules making costly to convert to Lithium for the GSC and back to non Lithium after the event. Below is a structured summary:
1. Lithium vs. AGM/Lead-Acid Batteries
- Lithium Iron Phosphate (LiFePO4) batteries offer many advantages:
- Higher energy density (more usable capacity for the same weight).
- Faster charging capabilities.
- Longer lifespan compared to lead-acid or AGM.
- Stable voltage output, which is crucial for autopilot and electronic navigation systems.
- Traditional AGM/Lead-Acid Batteries:
- Much heavier than lithium alternatives.
- Usable capacity is only 50% (vs. 90-100% for lithium).
- Lower initial cost, but requires larger banks for the same energy storage.
1.1 Cost vs. Performance Tradeoff
- The initial sticker shock of lithium batteries can be misleading:
- A 200Ah lead-acid battery only provides 100 usable Ah, whereas a 100Ah lithium battery offers nearly the same usable energy.
- Skippers discussed that while lithium is expensive upfront, it often becomes the cheaper option long-term.
2. Safety Concerns: Fire Risks & Cold Weather Performance
Fire Hazards
- Some skippers expressed concerns that lithium battery fires are difficult to extinguish.
- However, LiFePO4 (Lithium Iron Phosphate) batteries are considered far safer than other lithium-ion types.
- Dedicated lithium fire extinguishers exist, though rarely used in practice.
Cold Temperature Issues
- Lithium batteries lose efficiency in near-freezing temperatures, which could be a factor in the Southern Ocean.
- Some skippers considered heated lithium batteries for better cold-weather performance.
- It was noted that inside the boat, temperatures rarely drop to freezing, reducing the need for heating solutions.
3. Charging Systems and Energy Management
- Lithium batteries require higher voltage charging, which can add to system conversion costs.
- Some boats used dual alternator setups to optimize charging:
- One alternator for the engine start battery.
- A separate alternator for house lithium banks.
- Charge controllers need to be lithium-compatible:
- Victron DC-DC chargers were discussed as effective for managing lithium charge profiles.
- Some skippers used Power Queen 30A charge controllers, which are now much more affordable.
3.1 Integration with Other Power Sources
- Solar + Lithium is a common setup, with many skippers opting for:
- Victron controllers with multiple MPPT regulators.
- Parallel wiring to prevent shading losses.
- Hydrogenerators + Lithium
- Hydrogenerators were commonly used to supplement solar charging.
- Some skippers only deployed hydrogenerators at speeds above 10 knots to avoid drag.
4. Battery Bank Sizing and Power Consumption
- Average daily power consumption for offshore racing boats:
- Without Starlink: 180-250Ah per day (≈2-3kWh).
- With Starlink and radar: 3-5kWh per day.
- Class 40 boats typically use large lithium banks to maintain power for autopilots, navigation, and communications.
- Some skippers preferred larger AGM banks to avoid lithium conversion costs.
5. Conclusion
- Lithium batteries are becoming the standard for offshore racing due to weight savings, efficiency, and longer lifespan.
- Fire risks have been reduced, especially with LiFePO4 chemistry.
- Upgrading from AGM to lithium requires significant investment, including compatible charge controllers and alternators.
- Cold weather performance remains a concern, but can be mitigated by proper insulation or heated batteries.
