How do I store a LiFePO4 battery for the winter?

Store LiFePO4 at 50% state of charge (approximately 13.2V resting voltage), in a temperature range of 32°F–95°F. Do not store at 100% or 0%. Disconnect from all loads (including any parasitic draws) to prevent self-discharge. Check every 3–6 months and recharge to 50% if it has dropped significantly. LiFePO4 self-discharge is very low — typically 2–3% per month.

Can LiFePO4 batteries freeze in winter storage?

LiFePO4 batteries can be stored at temperatures as low as −4°F without damage — the chemistry is stable when not being charged. The danger is charging a frozen or very cold battery (below 32°F), which causes lithium plating. For storage in an unheated garage or RV over winter, the battery is safe as long as you bring it above 32°F before charging in spring.

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.