Cover photo: "PRNDL" by Jordan Golson, via YouTube
It's one of the most common questions new EV owners ask, and one of the most inconsistently answered: should you charge to 80%, or is it fine to go all the way to 100% every night? The honest answer is that it depends on what's actually inside your car. The "80% rule" you've probably seen repeated across forums and YouTube videos is real, well-supported advice — but only for certain battery chemistries. For others, it's outdated or simply wrong.
2
Main battery chemistries in EVs today, with opposite charging advice
~20-30%
Faster degradation for NMC batteries kept routinely at 100%
80%
Where DC fast-charging speed naturally starts to taper hard
It All Comes Down to Battery Chemistry
Nearly every modern EV uses one of two lithium-ion battery families, and they behave very differently at high states of charge. Nickel-based batteries — usually labeled NMC (nickel manganese cobalt) or NCA (nickel cobalt aluminum) — are the higher-energy-density chemistry found in most Long Range and Performance EV trims. LFP (lithium iron phosphate) batteries are cheaper, more thermally stable, and increasingly common in standard-range and entry-level trims, as well as most EVs built in China.
Why chemistry changes the advice
- NMC/NCA cells experience real chemical stress from sitting at a full charge — the cathode structure degrades faster at high voltage, especially combined with heat
- LFP's cathode is far more stable chemically and doesn't suffer the same degradation from sitting at 100%
- LFP batteries actually need periodic full charges — their flat voltage curve makes the car's percentage readout drift over time without one
What Tesla Actually Recommends
Tesla's guidance splits cleanly along that chemistry line, and it's built directly into the car's own software. For NMC/NCA vehicles (most Long Range and Performance Model 3, Y, S, and X trims), Tesla recommends capping daily charging around 80%, reserving 100% for long trips where you need the extra range. For Standard Range vehicles using LFP packs, Tesla's owner documentation says the opposite: set the charge limit to 100% for daily use, and make a point of fully charging to 100% at least once a week — not because the battery needs it chemically, but because a full charge lets the car's battery management system recalibrate an accurate percentage readout.
If you own an LFP Tesla and never charge past 90%, don't be surprised if the range estimate starts drifting. That's the calibration issue Tesla's weekly-full-charge advice is meant to prevent.