Sudden low voltage triggering tracker

[Ravendog]

I have the following fitted to my 2019 Sprinter Hymer BMC t 580
Factory Fit Schaudt ELB 30 Panel/Schaudt WA 121545 B2B/Schaudt LAS 1218-S Charger.
Retro Fit by professional 130W Solar Panel/Victron Smartshunt/Victron MPPT wired direct to 2 x 100amp Lithium.
The problem is I get a sudden crash on the starter battery to between 6 & 10volts 2 to 4 hours after turning the engine off or unplugging the EHU, triggering the tracker. tried the following to no avail.
Fitted new alarm & tracker wired direct to starter battery/Fitted new starter battery /plugging in EHU is the only way to stop the problem
Sorry I’m not tech minded so any suggestion that I could show to an engineer would be very much appreciated.

 

[StillGoing]

I assume you haven’t got a response is because nobody has seen this before.

You could isolate the leisure system from the starter battery to see if that spike still happens.

 

[Jev88]

Have the tracker wired to the leisure battery, especially if you have solar?