With increased adoption of lithium batteries in marine and vehicle applications, charging at subzero temperatures has become an important consideration.
Manufacturer guidance suggests that lithium batteries can sustain serious damage if charged below freezing. While this poses minimal risk for UK automotive applications, where vehicles operate continuously with internal heating, it presents a genuine concern for marine vessels stored outdoors over winter, as well as leisure vehicles and off-grid installations.
Temperature guidelines
Opinions vary on the precise freezing threshold, though the consensus is to measure temperature at the battery surface rather than ambient conditions. The chemical reactions during charging are disrupted by cold, potentially causing anode plating damage.
Current best-practice recommendations:
- Fast charging: +5C to 50C
- Below 5C: limit charge current to 0.05C
- Below 0C: do not charge
Mitigation strategies
Several approaches can help maintain adequate battery temperatures:
- Installing a frost stat with supplemental heating
- Adding insulation to batteries or compartments, taking care to avoid overheating
Assess your specific installation type, battery location and usage pattern thoroughly before deploying a lithium battery system.