I like charging when my solar is producing. Is it safe (from a battery health standpoint) to let my car sit at 13% over night for about 15 hours until the sun comes up tomorrow?
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Safe for battery to sit overnight at 13%?
- Thread starter ratsbew
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It's not and it doesn't. If anything, I'm thinking it's good for the BMS to get a sample at this low SOC.
Yes. Low state of charge is good for battery health as long as any drain (sentry mode, cabin overheat protection, battery conditioning, etc.) does not drain it below 0%.
In general, the less time the battery spends at high state of charge (>55% for NCA batteries, >70% for LFP batteries), the better it is for battery health.
The good thing is, any of these features that use a lot of power is inhibited at 20% and lower SOC.
At low ambient temps the batteries are extra happy. The reduced SOC number from a cold battery is Teslas way of showing that the range is less due to the cold battery. It is not the battery drooping in voltage as many seem to believe.
Lithium ion batteries keep the resting voltage when they are cold (in some cases the voltage even increase slightly).
So the real SOC measure is the same as when the battery is warm but Tesla present it to us with a reduction in SOC.
Very safe.
There is no “danger below 20%” for lithium batteries.
I regularly leave my car at low SOC at work (one week at the time).
Last week I parked at work with 13% and had it about 13% for the whole week until I had to charge for the drive home. It was snowing one day so it was also quite cold.
Its good to periodically (say every few months to at least once a year) go below 10% SoC and let the car deep sleep for at least 3-4 hrs., then L1/L2 charge up to 100%, unplug, drive off or again let the car deep sleep for 2-3hrs and then drive off the top 5-10% SoC to get back below 90%. This helps the BMS do its recalibration.
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