From https://www.atecorp.com/compliance-standards/automotive/lv-123
Testing HV Automotive Components
LV 123 is an electrical test standard which verifies the safety and electrical parameters of high-voltage components in cars. German original equipment manufacturers (OEMs) must comply with LV 123, notably BMW, AUDI, Daimler, Porsche and Volkswagen. Manufacturers adhering to LV 123 gain the advantage of a systematic approach to automotive testing and clear test parameter definitions, as well as the possibility of interchangeable qualification results. Another benefit of LV 123 is the ability to compare product qualifications between different OEMs, i.e. BMW and Porsche.
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Determining HV Status
HV operating status, a measure by which an HV component is judged to be operational, is a key element of LV 123 testing. An HV part is given one of the following status readings.
| HV Status | Operational Details |
|---|---|
| B0 | HV components operate perfectly, and without power demand. |
| B1 | Fully operational HV components which perform as intended. |
| B2 | Fully operational components, but with deviations permissible for B2 status. When HV parts revert to B1 status, will perform as intended |
| B3 | Still operational, no undefined states, will not interfere with other HV components. Components may lower output for purposes of self-protection. When components revert to B1 or B2, automatically perform as intended. |
| B4 | Still operational, no undefined states. HV components may switch their output off. When reverting to B1, B2 or B3 status, will provide intended performance via reset, ignition status change, vehicle restart, etc. |
Operational Ranges Based on Status
The operating potential of an electrical component, once given a B-status by LV 123 testing, can then be defined by the following ranges.
| HV Operating Voltage Ranges | Range of Operation - HV Status | Units | HV 1 | HV 2a | HV 2b | HV 3 |
|---|---|---|---|---|---|---|
| Overvoltage at load dump | B3 / B4 | V pk | 220 | 410 | 500 | 800 |
| Upper HV circuit limit voltage | B3 / B4 | V pk | 220 | 410 | 500 | 800 |
| Maximum operating voltage | B2 | V d.c. | 200 | 360 | 470 | 770 |
| Upper limited operating capability | B2 | V d.c. | >190-200 | >340-360 | >450 - 470 | >750 - 770 |
| Unlimited operating capability | B1 | V d.c. | 90 - 190 | 170 - 340 | 250 - 450 | 520 - 750 |
| Lower limited operating capability | B2 | V d.c. | 80 - < 90 | 160 - < 170 | 200 - < 250 | 450 - < 520 |
| Highly limited operating capability | B2 a / B3 b | V d.c. | 60 - < 80 | 120 - < 160 | 150 - < 200 | X |
| Undervoltage | B3 | V d.c. | 0 - < 60 | 0 - < 120 | 0 - < 150 | 0 - < 450 |