Same issue plagued me for two winters running in my Transit-based build. The root problem is that your alternator simply isn't doing meaningful work until the engine's warm, and by then you're already parked up again.
A few things that genuinely helped in my setup:
- DC-DC charger (B2B) — swapped out the standard split charge relay for a Victron Orion-Tr Smart 30A and it was transformative. It actively steps up the voltage rather than just passively linking the batteries, so you're getting proper charge even on a 20-minute run to the services.
- Alternator temp awareness — worth knowing your alternator's output drops significantly when cold, so those first 10 minutes are almost worthless for charging anyway.
- Battery chemistry matters — I moved to a Fogstar Drift 200Ah LiFePO4 last spring and the acceptance rate is dramatically better than my old AGM. That said, lithium won't accept charge below 5°C without a BMS cutoff, so winter camping introduces its own complications there.
The B2B charger honestly solved about 80% of my frustration. Running 30A into the leisure bank versus the 8-12A I was getting through the relay made an enormous difference across a week of short hops.
What's your current split charge setup? Are you running a relay, VSR, or something more sophisticated? Also curious what battery chemistry you're on — that'll change the advice considerably.
Anyone else found a different solution worth mentioning? Particularly interested if anyone's gone down the route of supplementing with a small solar setup through winter to compensate for the shortfall.
