1a) Yes. The UdcDivider is the configuration parameter which defines the scaling of the physical inlet voltage measurement circuit. That's why it is only relevant if a physical inlet voltage measurement circuit is present, and if the parameter InletVtgSrc is 1, means the Clara will measure the inlet voltage with the analog input.MoonUnit wrote: ↑Thu Jun 13, 2024 3:36 pm I have a couple of questions on the Clara parameters:
1) UdcDivider: Is this only used if InletVtgSrc is set to 1? If it is being used, it should be mapped as a 'Receive' message?
2) What is the purpose of InletVoltage? If I supply it via CAN, I must measure across the charge inlet DC pins and not assume it's the same as my battery voltage?
3) what value should I use for ppvariant? I have FOCCCI 4.2.
(1b) CAN mapping makes no sense for the UdcDivider, because it is a fix value. It is the ratio between the voltage on the inlet and the digital value on the AD converter.
2) The InletVoltage is important for precharging, while the contactors are still open. The car (Foccci/Clara) will close the contactors, if the inlet voltage is near to the battery voltage. After closing the contactors, the inlet voltage is physically identically to the battery voltage (besides some cable losses), and out of interest. The most straight forward solution to measure the inlet voltage is to rely on what the charging station tells us. It reports the voltage on the CCS plug in EVSEPresentVoltage. With configuring InletVtgSrc=0 we tell Clara to use the EVSEPresentVoltage. In this case, neither an analog inlet voltage measuring circuit nor a separate gadget which provides the inlet voltage via CAN is necessary. For most users this will be fine (even OEM cars use this approach). For detailed analysis of the cable losses, it could make sense to measure the inlet voltage physically, so you have during charging three voltages: on the charger, on the inlet and on the battery. Normally they are all nearly the same, but a detailled look could help to investigate cable loss issues. So only for very curious users.
3) ppvariant = 1 is fine for Foccci 4.2 (technically, for Foccci with 330 ohm pull-up to 5V and a 3k pull-down and a 47k by 47k divider)
Edit: Extended the parameter description in the wiki, to be more clear. Reviews and improvements are always welcome. https://openinverter.org/wiki/CCS32Clara