Webasto HVH50: Difference between revisions

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Pin 4 and 8 are unused
Pin 4 and 8 are unused
Ground must be connected the the case via a stud.
== Communication & Control ==
While there is a document describing the [https://www2.calact.org/assets/4d.%20Heater%20Info%20-%209035422C_II-OI_HVH_50_and_70_EN%2019-01%20PMC.pdf 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
{| class="wikitable"
|+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
|HV value MSB
|HV value LSB
|Power MSB
|Power LSB
1 digit=20W
|
|}
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.

Revision as of 09:44, 19 April 2021

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

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

Pin3 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 the 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 HV value MSB HV value LSB Power MSB Power LSB

1 digit=20W

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.