In the context of off-grid adventure use cases, the endurance and energy density of lithium-ion batteries are considerably superior compared to traditional technology. For example, take the lithium iron phosphate (LiFePO4) battery. The energy density of which is 130Wh/kg, 3.7 times the energy density of lead-acid batteries at 35Wh/kg. That means, by having the same requirement of energy storage of 1kWh, the weight can be reduced from 28kg to 7.7kg. The endurance reduced by 72% (0.08 cubic meters compared to 0.29 cubic meters). The 2023 “Outdoor Power White Paper” reports that when United States national park hikers changed to LiFePO4 Batteries, their payload was reduced by 41% and their walking distance per day increased by 23%.
Robustness to aggressive environments is a strong gauge. Tests by the Norwegian Polar Institute reveal that LiFePO4 battery can still deliver 85% of its capacity at a temperature as low as -30°C, while the capacity of lead-acid batteries decreases sharply to 40% at -10°C. In the expedition of 2022 Alaska, the battery pack with an intelligent temperature-controlled battery management system provided 98% power supply reliability for 72 hours consecutively in an environment of -25°C and reduced the demand for fuel resupply by 73% compared to the lead-acid system. Its performance at high temperatures is also good: During the test of the Sahara Desert, the cycle life of LiFePO4 battery in a 60°C temperature was 2,500 times (capacity retention rate ≥80%), and the lead-acid battery can only endure 150 times (attenuation to 50%).
Efficiency in charging directly affects convenience of use. The Tesla battery in a portable pack (Powerwall Mini) features 1.5C rapid charging (0 to 80% charge time is only 40 minutes) that is 6.5 times greater than the lead-acid battery 0.2C rate of charging. According to Australian Solar Energy Association data, under the condition of a 5-hour average sunlight, LiFePO4 battery’s solar charging efficiency is 97% compared to a mere 78% for lead-acid batteries, amounting to an extra 0.8kWh of electricity stored each day (the energy content to power the drone in aerial photography for 3 hours or LED lighting for 10 hours).
From the aspect of safety performance, the thermal runaway temperature of LiFePO4 battery is as high as 270°C (60°C for lead-acid battery) and the heat released by thermal heating during burning (<100kJ) is just one-third of the ternary lithium battery. According to the 2023 North American Touring Car Association accident report, the fire incidence of lithium battery-equipped off-grid systems is only 0.0037 times per thousand units, which is 89% less than for lead-acid solutions. Field tests conducted by the Swiss army on field combat units showed that the IP67-protected battery can continue to operate normally after it has been fully submerged in water at a depth of 1 meter for 2 hours, and the performance deviation in vibration tests (5-500Hz/3Grms) is ≤2%.
Economic calculations show that the 10-year TCO of LiFePO4 battery is $0.21 /Wh, 46% lower than that of lead-acid batteries ($0.39 /Wh). After the African Wildlife Conservation Organization’s off-grid monitoring project transitioned to lithium batteries, the equipment replacement cycle was doubled from 2 years to 8 years, and the average annual operation and maintenance cost was reduced by 62%. Market trends support this choice: The market share of lithium batteries in the global outdoor power supply market was 82% as of 2023. It is expected that the price of LiFePO4 battery will drop to $0.18 per watt-hour in 2027 (55% reduction from 2020), solidifying it further as the best choice for off-grid power.