Winterizing LiFePO4 Batteries


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Q&A Session
Richard Nickell
Dakota Lithium’s Senior Tech of Support

Best Practices for Winterizing LiFePO4 Batteries in Electric-Powered Sailboats



1. Is it safe for a large battery bank to be left on a sailboat in the winter?

Sure, as long as all the proper precautions have been taken. Disconnect the battery bank from any load and fully charge it before storing. If you anticipate extreme sub-zero temperatures during storage, it’s best to remove it and store it in a more controlled environment.


2. How should the batteries be prepared for long-term off-season storage?

Give them a full charge, isolate the bank from any load/charger, and protect the terminals.


3. What is the preferred state of charge to initially store the batteries?

The key to maintaining battery life during storage is to avoid letting them discharge too low. For optimal battery storage, fully charge the battery before storing and then fully charge it again before its first use of the season.


4. Can the batteries remain connected to the boat?

Batteries can remain connected to the sailboat, but any parasitic load should be disconnected. It’s best practice to have a battery kill switch or remove the positive terminal connection.


5. Can they remain connected to each other (serial or parallel)?

The wiring configuration will not be an issue, and the batteries can remain connected. However, the circuit should be broken to the load to avoid any drain.


6. Should the batteries remain connected to a Battery Management System (BMS)?

DL batteries have a built-in BMS, so no external BMS is needed for storage.


7. What are the safe temperature ranges to maintain good battery health?

Ideally, they should be stored in a temperature range of 10℃ to 35℃ (50°F to 95°F), but they will remain healthy if stored in colder temperatures. Most importantly, do not attempt a charge LiFePO4  below 0°C/32°F.


8. Is trickle charging recommended?

Trickle charging is designed to keep lead-acid/AGM-style batteries healthy due to their quick natural dissipation, so they are ready to go on demand. With LiFePO4, the natural dissipation rate is about 1-3% per month in ideal storage conditions, which is very low. There is no need to trickle charge during storage, and it’s safer not to leave a charger on the batteries long-term unattended. I do recommend a top-up charge every 6 months.


9. If the boat has solar panels, are they safe to maintain the preferred state of charge?

Solar charging is excellent, and it depends on the quality of the solar charge controller. As long as the controller has a LiFePO4 compatible profile and a low-temperature cutoff protection feature, there should be no issue maintaining a state of charge. I would default to no charging source if the device is stored and unattended for an extended period. On the other hand, many remote energy storage systems work flawlessly with unattended solar input. They rely on quality solar charge controllers with built-in profiles designed for LiFePO4.


10. What is the preferred way to remotely monitor battery health?

Victron Energy VRM remote monitoring would be my best suggestion, but it would require purchasing and properly installing the necessary equipment: Cerbo GX configured with a WIFI or Cellular connection and a SmartShunt or BMV-712 battery monitor.


11. What are the best practices for inspecting battery health pre-launch?

Inspect the battery for any physical damage, water exposure, odd smells, or abnormalities. Do not use it if any of those signs manifest. Check the voltage readings before and after a charge.


12. Should all battery terminals be reseated? If so, how?

Re-seating terminals involves unplugging or disconnecting the connectors, inspecting them for damage or corrosion, and then firmly reconnecting them to ensure a secure and reliable electrical connection. If the DL battery terminals were adequately seated and protected pre-storage, they may not need re-seating post-storage. I recommend a visual inspection and tidy-up if necessary.


13. Is there anything else necessary to maintain good battery health?

Nothing else outside of these recommendations comes to mind as necessary to maintain good battery health!


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