Charge your EV to 80% or 90%?

First question is chemistry, not kilometres. If the car lists Lithium Iron Phosphate under Controls → Software → Additional Vehicle Information, Tesla's own manual says set the limit to 100% even for daily use, and take it to a true full charge at least once a week so the battery meter stays honest. That is not the same advice as a Long Range Tesla.

For nickel-chemistry EVs (Tesla Long Range / Performance, and most Hyundai, Kia, Ford, GM, VW long-range trims), 80% is the daily default. Bump to 90% if you actually drive that extra range - high-kilometre commuters, winter highway, no home charger the next night. Save 100% for a trip, then leave.

Low-kilometre nickel drivers who sit parked most of the week should not live at 90–100%. Geotab's fleet data says the 20–80% “rule” only bites when a pack spends more than 80% of its time near empty or near full. Occasional 90% or 100% is not the problem. Parking a nickel pack full every night for months is.

LFP (lithium iron phosphate) and nickel packs (NCA / NMC) are both lithium-ion. They are not the same recipe. Nickel stores more energy per kilogram, which is why Tesla still puts it in Long Range and Performance cars. LFP is cheaper, uses no nickel or cobalt, and is chemically more comfortable sitting near full. The trade-off is less range for the same pack size, and a flatter voltage curve - the car cannot “see” remaining energy as clearly unless you occasionally charge all the way to the top. That is why Tesla wants a weekly 100% on LFP: battery-meter calibration, not a flex.

Tesla did not invent LFP, and it is not Tesla-only. BYD's Blade packs are LFP. Some other volume brands put LFP in base / standard-range trims and keep nickel in the long-range ones. Do not copy a Model 3 RWD charging screenshot onto an Ioniq 5 Long Range, or the other way around.

In Canada the cheap Tesla is often the LFP one. Shanghai-built Model 3 RWD packs have been LFP; that is also why that trim misses federal EVAP (China is not an FTA country) - chemistry and rebate are separate fights. Confirm the car in front of you: why the Model 3 misses EVAP.

Tesla's Model Y high-voltage battery page: for vehicles with a recommended daily limit of 80%, keep the daily limit at about 80, and save 100% for a long drive. Prefer Level 1 or Level 2 at home; Supercharging is for trips. Avoid leaving the pack at or near 0% or 100% for long stretches. Charge more often rather than waiting until it is low.

The charging screen is chemistry-aware. Slide past the daily mark and Tesla offers a one-time trip charge that resets afterward. That is the manufacturer version of 80-versus-90 on a nickel pack: a daily cap in the 80s, 100% when you need the kilometres.

If Additional Vehicle Information lists lithium iron phosphate, ignore the 80% forum rule. Tesla recommends keeping the charge limit at 100% even for daily use, and fully charging to 100% at least once per week. After a week parked, charge to 100% at the next convenient plug. Regenerative braking is weaker right after a full charge - that is expected, not a fault.

A typical Canadian commute in a nickel pack does not need 90%. Set 80% (or whatever daily limit the car prints). Schedule charging to finish near departure - in Ontario that often means Ultra-Low Overnight - so the pack is not sitting at the cap from 7pm until 8am. If it is LFP, 100% is the daily setting; still schedule so you leave soon after it tops up.

Toyota Canada's first-owner guidance is the nickel shape: routine charge between about 10% and 80%, 100% when you need it, then drive. Prefer home AC for daily charging.

You will cycle the pack more. Geotab measured about a 0.8 percentage-point extra annual degradation going from low daily throughput to high (1.5% → 2.3%). That is real, and still far from a cliff. The larger lever is how you add energy, not 80 versus 90.

Vehicles that used DC fast charging for under 12% of sessions degraded about 1.5%/year. High-frequency DCFC above 100 kW (more than 12% of sessions, and more than 40% of those over 100 kW) ran about 3.0%/year - projected 88% versus 76% capacity after eight years. If you are a road-warrior, home or workplace Level 2 is the battery-care move. On a nickel pack, use 90% as a daily cap if 80% does not cover the next day. On LFP, keep 100% and still prefer home AC over making every grocery run a Supercharger. Use DC fast charging for the trip, not the commute.

CAA's winter test cut official range by roughly 14–39%. That is why a 401 run in January feels like it “needs 90%.” On a nickel pack, raise the limit for the trip week. On LFP you are already at 100% - preheat while plugged in and keep a 20–30% arrival buffer instead of inventing a new charge rule. Do not leave a nickel car at 100% all January “just in case.” See winter range and first winter with an EV.

• Nickel pack, home charger, short week: 80% daily. One-tap trip charge when you need it.
• Nickel pack, long days or cold highway: 90% daily is a reasonable trade. Still prefer AC at home.
• LFP pack (many Tesla RWD / Standard, BYD Blade, some other base trims): 100% daily, true full charge at least weekly. Check the software screen, not the neighbour's Model Y Performance.
• No home charger: you will DCFC more. That costs more in degradation than 80 versus 90. Read condo charging and public charging cost.

Broader battery-care myths (never DCFC, drain to zero, $20k pack at year five) live on EV battery care.

• EV battery care: simple charging habits that actually helpDaily charge targets, when 100% is fine, how much DC fast charging matters, and what Geotab’s real-world degradation data says - without the myths.
• Your first winter with an EV in CanadaCAA winter tests show 14–39% less range in the cold. Preheat while plugged in, use winter tires where required, and keep a 20–30% arrival buffer on highway trips.
• Used winter tires, and EV owners going back to gasUsed winters are legal if they still snowflake and the rubber isn’t six winters old. McKinsey’s 46% U.S. “likely to switch back” is survey intent; S&P’s Q4 2025 EV lease returns chose gas 41.3% of the time - not most owners.