To summarise, my setup consists of an engine alternator (old style without any intelligence) which is connected directly to Orion DC-DC charger (isolated, 12 | 12, 30A) which in turn charges lithium battery bank (2 * 200 ah batteries). This setup was in advance verified from Victron by the local reseller/distributor.
Alternator is Bosch K1 14V, 55A 20 (original for the Volvo engine).
There is a problem where the input voltage from the alternator to the Orion fluctuates from ~9V to ~36V causing the Orion to intermittently go offline ("charge is disabled due to: Input voltage lock-out"). This happens regardless of the state of charge of the lithium batteries.
Is it possible that the fluctuating voltage is caused by insufficient resistance from the Orion DC-DC charger or is there something else that may explain such a phenomena?
Is it possible that the alternator is faulty, or is such a fluctuating voltage a common issue under some specific circumstances?
Any idea how to rectify this? Do I need to replace the alternator and/or place a led acid or AGM battery in between the alternator and the Orion (exactly the scenario I was hoping to avoid)? If an intermediate battery is required, what would be the recommended chemistry (led acid, AGM...) and size (ah)? Needless to say that I'd prefer small, lightweight and affordable solution...
If there is a way to get this working without the intermediary battery I'd be interested in those suggestions as well. I have heard about Wakespeed as an option, but unfortunately haven't found a reseller in my country/region.