Winterizing & Storing RV Lithium Batteries
LiFePO4 batteries are more tolerant of winter storage than lead-acid, but there are still a few things worth doing correctly to maximize battery life.
The key difference from AGM
AGM and flooded lead-acid must be stored fully charged and kept on a maintenance charge (trickle charger) during storage. They self-discharge at 5–15% per month and sulfate if left discharged.
LiFePO4 should NOT be stored at 100% for extended periods. Store at 50% state of charge. Self-discharge is ~2–3% per month — negligible. No maintenance charge needed.
Correct storage procedure
Step 1: Set state of charge to 50%
- Discharge to approximately 13.2V resting voltage, or
- Charge fully, then run a moderate load until your battery monitor shows ~50% SoC
50% is the sweet spot for LiFePO4 calendar life — storing at 100% for months causes slightly faster degradation than 50% storage.
Step 2: Disconnect all loads
Parasitic draws — appliance standby modes, battery monitors, clocks, any connected device — will slowly drain the battery during storage. Disconnect:
- Battery monitor (the SmartShunt itself draws ~1mA but over 6 months that's minor)
- Any 12V accessories left plugged in
- Disconnect the battery's main negative cable if any parasitic path exists
Some builds use a battery disconnect switch for exactly this purpose — one switch cuts all loads during storage.
Step 3: Disconnect charging sources
Disconnect solar panels (or shade them), disconnect shore power, and disconnect any chargers. You don't want the battery being charged and discharged by solar on a random sunny winter day while it sits in storage.
Step 4: Store in appropriate conditions
Temperature: −4°F to 95°F for storage. The battery is fine in an unheated garage through a northern US winter — storing in the cold doesn't damage a discharged LiFePO4.
Moisture: Keep terminals dry. A light coating of dielectric grease on terminals helps prevent corrosion during storage.
Location: No special requirements beyond keeping it off a wet floor (set on a board or rack).
Check-in during long storage
For storage longer than 3 months:
- Check resting voltage once in the middle of the storage period
- If below 12.8V (~20% SoC), recharge to 50% and disconnect again
This prevents the battery from sitting in a deeply discharged state if there's any parasitic draw you missed.
Spring return to service
Before charging: Ensure the battery is above 32°F before connecting solar or a charger. In a frozen garage, bring the battery inside for several hours to warm up.
First charge: Connect your charger and charge normally to 100%. The BMS may have been in low-voltage protection mode if the battery ran down during storage — reconnect the charger and it should wake up normally.
What NOT to do
- Don't leave at 0%: A deeply discharged LiFePO4 stored for months can cause BMS protection mode that's difficult to exit.
- Don't store at 100%: Minor calendar aging effect over long storage.
- Don't charge when below 32°F: Wait for the battery to warm.
- Don't store on a trickle charger: Unlike lead-acid, LiFePO4 doesn't need or benefit from a float charge during storage.