Circuit/System Description
A level 3 off-vehicle direct current (DC) fast charge drive motor battery charger allows charging using DC current supplied directly to the battery pack, bypassing the on-vehicle battery charging. Level 3 charging includes a locking device on the receptacle to prevent removal while large amounts of current is flowing.
The A4 Hybrid/Electric Vehicle Battery Pack is assembled with two layers of cell module assemblies, essentially operating like two 400V DC battery packs in one assembly. The upper level is pack 1 and the lower level is pack 2. Under normal operating conditions these two layers operate electrically in parallel with each other and charge at 400V. If conditions allow, the high voltage contactors can be configured such that each layer is wired in series to facilitate faster level 3 charging at 800V.
When conditions do not allow for 800V series charging, the driver information center may display messages and/or DTC (s) may be stored.
| Message Displayed | Reason | Diagnosis | Repair |
|---|---|---|---|
| DTC is stored with the Malfunction Indicator Lamp (MIL),"Charge Rate Limited Your High Voltage Charging System May Need To Be Serviced" message displayed | Propulsion Contactors Stuck Closed | DTC P0AA1, P0AA4, U35C0, U35BC | Follow DTC procedure |
| Series Contactor Stuck Open | DTC U35A7, U35AC | ||
| Loss of Isolation detected during 800V series charging | No DTC set at the charging station. DTC P302F may set while driving | ||
| Isolation Detection Sensor/Circuit Failure | DTC P1B41, P1AEC, U2BD2, U2BD5 | ||
| Battery Energy Control Module 1 (primary) loss of communication with Battery Energy Control Module 2 (secondary) | DTC U165C | ||
| Pre-charge Failed | DTC P0C78, P3061 | ||
| Charging Over voltage Protection | DTC U3687 - U3689 | ||
| ""Charge Rate Limited- You Maybe Able To Charge Fast If You Restart The Charge" message is displayed | 12V battery is either too hot, too cold or state of charge is low | Review Battery Energy Control Module DC Fast Charge History (1-5) Scan Tool parameter for : Series Charge Inhibit/ 12 Volt Battery State of Charge Too Low | Test 12V battery, replace or advise customer of temperature extremes |
| The capacity difference between Pack 1 and Pack 2 is too large | Review Battery Energy Control Module DC Fast Charge History (1-5) Scan Tool parameter for : Series Charge Inhibit/Packs Unbalanced | Replace A4 Hybrid/Electric Vehicle Battery Pack assembly | |
| "Charge Rate Maybe Limited - Your Battery May Charge Slow Due To Temperature Conditions. You Can Continue Charging. Turn Off The Cabin Heating and Cooling Features May Help" message displayed | The A4 Hybrid/Electric Vehicle Battery Pack is either too hot or too cold. | None | Advise customer of temperature extremes |