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Charging and HV battery

ECUs C5, 8C, 8B (BMS) on MEB are protected by SFD / SFD2. DC/AC limits are set by the BMS, not by a single “max current” adaptation.

Factory settings (no ODIS)

In the Charging menu on ID.3/ID.4/Enyaq:

  • Reduce AC charging current (e.g. 8 A instead of 16 A) — weak home circuit
  • Departure time — delayed charging for off-peak tariff
  • Minimum SOC (0–50%) — do not discharge below threshold
  • Optimize DC charging — battery preconditioning via route with charging stops

These do not require coding.

Diagnosing slow charging (ODIS / OBD)

Useful live values (names vary by SW):

ECU Value Purpose
C5 / 8B Dynamic limit for charging (A) Current BMS limit
C5 / 8B HV battery min/max temperature Cold pack = low DC
8E AC charge power / phases Onboard charger limit
19 Charging mode AC / DC / cable fault

If Dynamic limit is high but the station delivers less — the charger is limiting. If BMS limit is low with a warm battery — check BMS faults, isolation, SW updates.

Manual HV battery heating (8C, diagnostic only)

Not a factory user feature. Used by enthusiasts before DC charging in cold weather. Warranty risk, HV faults, aborted tests. Stationary only, with ODIS access.

On some ID.3/ID.4 (ECU 8C Battery Energy Module):

  1. ODIS online, unlock SFD on 8C.
  2. Change Service → Development Mode (otherwise output test may fail).
  3. Output test — HV battery heater (name varies), ~300 s.
  4. Ignition ON; hood slightly open on first run if required.
  5. Monitor ~5–6 kW heater power in live data; pack temperature should rise.

Factory navigation preconditioning is safer and needs no development mode.

ECU C5 — what is usually not coded

  • Maximum DC power (135 kW etc.) — BMS and temperature dependent
  • Pack capacity (58 / 77 / 82 kWh) — hardware, not enabled by coding
  • Bidirectional charging (V2H) — PR, SW, and market specific

If charging power drops, check C⅝C DTCs, 12V supply (weak AUX → wakeups), and SW updates via ODIS first.

See also

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