REESS Overcurrent protection 3 December 2019 Submitted by
REESS Overcurrent protection 3 December 2019 Submitted by OICA For the 19 th EVS Informal Working Group
Key Message OICA proposes to: (1)The IWG to reconsider the validity (especially, effectiveness and practicability) of REESS overcurrent test adopted in GTR 20 Phase 1 (2)Each Contracting Party to suspend adoption of this test for its national/regional regulations, until above (1) is concluded 2
Background Ø REESS overcurrent protection test during DC charging has been adopted in GTR 20 Phase 1 Ø Since the test procedure was considered only for light vehicles, its application to heavy vehicles is registered as a work item for GTR Phase 2 Ø During the study by OICA members for above, the experts recognised questions on the effectiveness and the practicability of this test 3
Overcurrent protection test Ø Objective: to verify the performance of the overcurrent protection during DC external charging to prevent the REESS from any severe events caused by excessive levels of charge current as specified by the manufacturer. Ø The overcurrent level (assuming failure of external DC electricity supply equipment) and maximum voltage (within normal range) that can be applied shall be determined and applied for the test Ø The overcurrent protection control of the REESS shall terminate charging or the temperature measured on the casing of the REESS shall be stabilized, such that the temperature gradient varies by less than 4 °C through 2 hours after the maximum overcurrent charging level is reached. Ø Criteria: ü ü ü No electrolyte leakage, No rupture (applicable to high voltage REESS only), No venting (for REESS other than open-type traction battery), No fire No explosion 4
Overcurrent scenarios and consequences Ø The overcurrent hazard scenario overlap with other GTR tests: Hazardous condition Description Addressed by Generation of excessive heat Internal cell resistance (impedance) will cause cell to warm up Over-temperature protection test Overcharge If REESS is connected at an already high SOC, or due to polarization effects in the cells Overcharge protection test High current surge in external circuit Current surge at the time of connection to charger External short circuit protection test Other ? ? ? Ø Need to specify if there exist additional hazard conditions that are not already covered, or the overcurrent test should be considered redundant 5
Heavy vehicle considerations Ø Propulsion batteries in M 2, 3 and N 2, 3 vehicles are typically significantly larger than in M 1 and N 1 vehicles Capable of sustaining higher charging current/power, typically >600 A per vehicle today and increasing Proprietary charging infrastructure often provided by vehicle operators/owners The likelihood of overcurrent charging conditions is notably lower for heavy vehicles, charging current distributed to several propulsion batteries. Ø As a consequence of the higher charging currents/power used for heavy vehicles, the overcurrent protection test is significantly more challenging to perform More powerful and costly test equipment (as example CCS Combo 2 plug limited to about 500 A) Test technician qualifications and training 6
Schematic High voltage system heavy vehicles 7
- Slides: 7