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How does cold weather affect lithium batteries?

As winter sets in and the weather gets colder, we get lots of calls and questions about how our batteries perform in winter weather, and what steps need to be taken to maintain them. ALL batteries will perform poorly in cold weather, regardless of whether they are lithium or lead-acid. In fact, a lithium battery will still outperform a comparably-sized lead-acid when the temperature drops. However, since most people try to run the smallest and lightest lithium battery possible, there are some things to be aware of: For a daily-driven car… …almost no extra effort is required. On a very cold morning, however, one might find that the cranking performance of the battery is not as strong as usual; if it is very cold and the car has been sitting for a while, the car might not crank fast enough to start. This does not mean that your battery is dead.

  • Simply turn on the headlights or rear defroster for a few minutes to drain some energy from the battery. As a result, the battery will warm up internally and gain enough “juice” to start the car.

This we only be necessary at very low temperatures, and we have found that after doing this once on cold mornings, the battery stays warm enough to crank the engine reliably for the rest of the day. This trick will only work if the battery is close to warm enough to start the car–if the battery is too cold, or too small, then you will need to warm the battery up before use. For racers who store their cars in the off-season… …the battery only needs to be monitored to make sure it is never completely discharged. Handily, lithium batteries self-discharge at a much slower rate than conventional chemistries.

  • Racecars should be stored with the master killswitch off, or better yet, with the battery completely disconnected from the vehicle.
  • L series batteries will use some of the pack’s energy to run the BMS system, and should be recharged at least once every 90 days because of this. C and T series batteries should be able to sit for one year without needing a charge.

On cars that see infrequent use during the winter… …it is even more important to keep the battery charged up, and the car will draw a small amount of energy from the battery to do things such as keep the radio presets, or to provide power for the alarm system. Some cars, such as later-model Porsches and BMWs, have a much higher draw than other cars, and will thus drain the battery much more quickly. Every car is different.

  • The best way to maintain a lithium battery in this scenario is to charge it weekly, or before every time you drive. Understandably, this is not always practical.
  • If you are not worried about radio presets, it is certainly possible to disconnect the battery entirely and store it, charging periodically, as recommended for racers above.
  • Float chargers which are AGM-compatible can be used to keep the battery topped off. This allows the car to be driven at a few minute’s notice, and doesn’t lose any presets or require radio codes upon startup.

Some other items to note:

  • Lithium batteries like being stored in the cold. As long as the location is indoors and dry, temperatures down to near-freezing are safe, and will allow the user to “top off” the charge less frequently.

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