Webasto HVH50: Difference between revisions

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The LV connector is best found by the VW part number 1J0973714
The LV connector is best found by the VW part number 1J0973714


Pin 1 is permanent 12V
* Pin 1 is permanent 12V
 
* Pin 2 is an analog output
Pin 2 is an analog output
* Pin 3 is an analog or PWM input
 
* Pin 5 and 7 are interlock (probably must be shorted)
Pin3 is an analog or PWM input
* Pin 6 is LIN
 
* Pin 4 and 8 are unused
Pin 5 and 7 are interlock (probably must be shorted)
 
Pin 6 is LIN
 
Pin 4 and 8 are unused


Ground must be connected to the case via a stud.
Ground must be connected to the case via a stud.

Revision as of 21:10, 19 April 2021

Webasto HVH50 water heater

The Webasto HVH series are electrical water heaters typically used in popular PHEV.

Connectors

Webasto HVH50 connectors

The HV connector is a Tyco HVA280 connector with A-key (might be different on other devices).

The small center pins are for interlock (detect that the connector is seated). The right pin (with tab facing upwards) is HV+, the left one HV-

The LV connector is best found by the VW part number 1J0973714

  • Pin 1 is permanent 12V
  • Pin 2 is an analog output
  • Pin 3 is an analog or PWM input
  • Pin 5 and 7 are interlock (probably must be shorted)
  • Pin 6 is LIN
  • Pin 4 and 8 are unused

Ground must be connected to the case via a stud.

Communication & Control

While there is a document describing the LIN interface , Webasto seems to have altered the interface for different OEMs. According to the document, LIN bus speed is 19200 but on a unit obtained from ebay it was 9600. So always try both.

The data format seems common as follows

HVH LIN Protocol
Command Possible IDs Byte 1 2 3 4 5 6 7 8
Write power 35 0=Off, 1=On Temp setpoint

1 digit=1 degree

Offset -40

Power limit

1 digit=40W

- - - - -
Read Status 24 or 23 various status info
Read Meas 40 or 22 Lin status

0=good, 1=issue

Outlet temp

Scaling as above

Inlet temp Unknown Voltage LSB Voltage MSB Power?

1 digit=20W

Unknown

Some units allow control via a simple on off signal on Pin 3 (12V=heat up liquid to 85°C) and some units allow a strange PWM control between 50-100Hz where 25%-81% duty cycles allow setting various power levels.