Finally pulled the trigger on sorting proper B2B charging in the Transit after running a bodged setup for two years. I've got a 200Ah Fogstar Drift LiFePO4 and a factory fit 110Ah AGM starter battery. Solar does the heavy lifting in summer (200W on the roof through a Victron SmartSolar 75/15), but winter touring is where it all falls apart — barely any sun and I'm running a diesel heater fan, LED strips, and charging laptops most evenings.
The Victron Orion-Tr Smart seems to be the obvious choice given I'm already in the Victron ecosystem with the SmartSolar and a BMV-712. Non-isolated version looks like it'll work fine for my setup. My question is the 18A (240W) vs the 30A (360W) decision — the 30A is around £60 more depending where you catch it on sale, and realistically I'm only doing 45–90 minute drives most of the time.
Running the numbers, 18A for 60 minutes gets me roughly 18Ah back, which honestly covers most of what I use overnight. But if I'm ever doing a longer motorway run in January with a depleted bank, that extra 12A could make a meaningful difference. Has anyone actually stress-tested both units in a cold weather touring context and noticed the real-world difference, or does the 18A do the job nine times out of ten?