question

When running on the WS500s own charge algorithm every time you started the engine the alternator would go to absorption at 14.2V and then after absorption it would go to float at 13.5V. It would do this even if an absorption charge was not really required, even if the batteries were quite full.

Now the Lynx BMS controls the charge voltage and you need to understand how the Lynx BMS looks after charging and read this in the manual. To explain briefly, once the Lynx has completed absorption, it requests float voltage of 13.5V. It stays on float voltage until either 30 days have passed or the SOC falls below 70%. Therefore, the batteries only get an absorption charge when required, if the SOC is still above 70% when you start the engine it charges at 13.5V and this is high enough to keep the battery around 100% SOC.

You can see this if you go into your Venus device (Cerbo etc) or VRM and look at the CVL (charge voltage limit) value, this is what the BMS is asking the chargers to charge at.