Reference

Tesla terminology glossary

Concise definitions of community-canonical Tesla terms: BMS, MCU, LDU, NCA, LFP, 4680, octovalve, and more. Each term cross-links into deeper articles.

Battery & chemistry

BMS— Battery Management System: The electronics that manage the high-voltage pack: monitors per-cell-group voltage and temperature, balances cells, protects against over- and under-charge. Every error code prefixed BMS_* comes from here.
NCA— Nickel-Cobalt-Aluminum oxideNCA 18650NCA 21700Panasonic NCA: Lithium-ion cathode chemistry on early S/X (18650) and most US Model 3/Y Long Range (21700). High energy density, solid reliability when treated well, typical 10-15% degradation by 200k km. Most repairable chemistry in Tesla lineup.
NMC— Nickel-Manganese-Cobalt oxideNCMNCM 811LG 79: Cathode chemistry of LG cells in 79 kWh packs on the 2021-2022 refresh Model 3/Y LR (US/EU). Per community data, the most problematic Tesla chemistry: early module imbalance, mass cell failures around 240 000 km.
LFP— Lithium Iron PhosphateCATL LFPBYD Blade: Cobalt- and nickel-free cathode chemistry (iron-phosphate). Lower specific capacity (50-62 kWh on M3/Y SR) but 2-3× longer cycle life, thermally safer, can be charged to 100% with no damage. Most stable Tesla chemistry.
4680— 46×80 mm tabless cylindrical cell: Large tabless 46×80 mm cylindrical cells on Texas-built Model Y from 2022. Theory: more energy, fewer parts, structural pack. In practice (2026) — non-repairable: any cell-level fault = full-pack replacement at $15 000+.
HV battery— High-Voltage batteryтяговая батареяHV pack: The main lithium-ion traction pack (~400 V). Feeds the drive motors through the inverter. Gated by contactors; if any contactor fails the car won't drive / charge / sleep. Not the same as the 12V battery.
12V (LV) battery— 12-volt / Low-Voltage battery16V battery: A small lead-acid (or, since 2021, 16V lithium) battery powering the electronics: MCU, locks, ESP, lights, BMS controller. Tesla never fully sleeps — the 12V drains slowly, and once flat the car is bricked until you jump-start it.
ContactorконтакторHV-реле: A high-current relay inside the HV pack that isolates it from the busbars. A welded contactor leaves the pack always live — the car never sleeps and the 12V drains. Typical cause of death: a surge current from a pyrofuse trigger.
Pyrofuseпиропатронpyrotechnic fuse: A single-shot pyrotechnic fuse in the HV circuit. Triggers on crash or current overload, physically severing the busbar with a small charge. Once fired, the pack and car are dead until shop replacement.
Vampire drainпаразитный разрядvampire: Self-discharge of the HV pack while the car sits idle — the electronics never fully shut down so the car can wake on remote command. Healthy: ~1-3% per day; more = something is keeping the car awake (often Sentry, broken certificates, or a welded contactor).

Drive unit

LDU— Large Drive Unitбольшой задний мотор: The large rear drive unit on Model S and X (pre-Plaid). One housing combines induction motor + gearbox + inverter. Classic failure: rotor seal leak → coolant enters stator → short circuit → replacement.
SDU— Small Drive Unit: The front drive unit on AWD Model S/X. Smaller, simpler, more reliable than the LDU.
980— Tesla 980 motor (Model 3/Y rear): Rear motor on Model 3 Performance and early Y up to 2021. Known fault: inverter failure (DI_a172) caused by capacitor wear-out. Inverter swap ~$1 500-2 500, or full drive-unit replacement.
990— Tesla 990 motor (Model 3/Y rear, prerefresh): Rear motor on Model 3 LR/RWD before the 2021 refresh. Community consensus: the most reliable M3/Y rear motor. Workhorse with 300 000+ km lifespan.
InverterинверторDI: Power electronics converting the HV pack's DC into three-phase AC for the motor. On Tesla, integrated into the drive-unit housing. All DI_* errors originate here. The most expensive component after the drive unit and battery itself.

Electronics & climate

MCU— Media Control Unit (центральный экран)MCU1MCU2MCU3центральный дисплей: The big central touchscreen and the computer behind it. S/X has three generations: MCU1 (Tegra, 2012-2018) — eMMC storage dies and needs replacement ($200-400). MCU2 (Intel Atom, 2018-2021) — much more stable. MCU3 (AMD Ryzen, 2021+) — most powerful.
eMMC— embedded MultiMediaChip: The MCU1 internal flash storage (8 GB). Dies from constant Tesla-log write cycles. Symptoms: stalls, black screen, fails to boot. Fixed by replacing the eMMC with a quality chip or upgrading the MCU to MCU2.
Heat pumpтепловой насос: The combined heating + cooling system on M3/Y from the 2021 refresh (and refresh S/X). One compressor handles both directions — much more efficient than the old PTC heater. Early 2021 units had widespread failures of PT temperature sensors and the octovalve.
Octovalveвосьмерик: Eight-position valve in the heat-pump system. Routes coolant between pack, motor and cabin so one compressor can do everything. Mechanically intricate; on early 2021 cars it would stick, which was the root cause of the "no heat" saga.
PTC heater— Positive Temperature Coefficient heater: A resistive electric heater for the cabin on pre-refresh Model 3/Y. Replaced by the heat pump in the 2021 refresh. Heavy power draw in cold weather (5-7 kW) but mechanically simple and reliable.

Charging

CCS2— Combined Charging System type 2: European fast-charging standard. Tesla EU has supported it natively since 2019; older cars can be retrofitted ($800-1500 in Belarus). Lets you charge at any public DC station. US-spec cars in Europe need the retrofit.
SuperchargerSCV2V3V4: Tesla's DC fast-charging network. Generations V2 (≤150 kW), V3 (≤250 kW), V4 (≤350 kW). Since 2024 many are open to non-Tesla cars in EU. Some cars have SC01 — Free Supercharging Unlimited.
SC01— Free Supercharging Unlimited: The "free Supercharging forever" option on some early Teslas. Bound to the VIN, not the owner — transfers with the car when sold. Adds $3 000-5 000 to a used car's value.

Software & services

Autopilot— Autopilot / EAP / FSDAPEAPFSD: Tesla's ADAS family: Basic AP (adaptive cruise + lane keep), EAP (Enhanced — lane change, parking), FSD (Full Self-Driving — urban routes, beta). Options run $3 000-12 000 and are bound to the VIN/account.
Service Mode: A hidden MCU mode for diagnostics, error logs, suspension calibration, battery test. Open it via Controls → Service → Service Mode. The baseline tool for any pre-purchase inspection.
Premium ConnectivityPC: Tesla's paid subscription for live navigation, video streaming, in-MCU browser, Live Sentry. ~€9.99/month. Not sold directly in Belarus — workarounds through LT/PL/CA accounts.
Sentry Mode: Security mode: car cameras record video when motion is detected and an alarm triggers. Drains the pack heavily when idle (5-10% per day). Live Sentry — streams to the app, requires Premium Connectivity.

Service & tools

VIN— Vehicle Identification Number: The 17-character vehicle ID. Positions 1-3 = manufacturer, 4-8 = features, 10 = year, 11 = plant. The ECUVIN bot decodes the factory spec from the VIN.
OBD2— On-Board Diagnostics IIOBD-II: The standard diagnostic port required on every car since 1996 (US) / 2001 (EU). On Tesla — under the steering column on the left. With an OBD2 adapter, a Tesla cable, and the ScanMyTesla app you can read CAN bus messages for battery and motors.
Ranger— Tesla Ranger / Mobile Serviceмобильный сервис: Tesla's mobile service — a tech in a van comes to you with tools. Handles small jobs on-site (12V swap, minor electronics, charge port). Big jobs go to the service centre.
Tesla ToolboxTBox: Tesla's closed dealer-only diagnostic software: module programming, certificate restoration, major component swaps. Third parties get access via intermediaries — see TBox Auto on /tools/utilities.