Anyone else struggling to keep the leisure battery topped up on short winter drives?

Been dealing with this exact headache on my narrowboat but I reckon the same principle applies — short runs in winter just don't cut it when you're relying on alternator charging, do they?

The problem as I understand it is that your leisure battery is probably in bulk charge mode for most of that short drive, and the alternator output is being shared with all your van's other demands (heated seats, blower, headlights, etc.). By the time you've done your 20-minute supermarket run, you've barely scratched the surface.

A few things I've been looking into that might help:

• DC-DC charger (B2B) — something like the Victron Orion-Tr Smart is supposedly miles better than relying on a basic split charge relay. It conditions the charge properly regardless of drive length
• Upgrading to lithium — a Fogstar Drift or similar means you can actually accept charge faster when you do get alternator time
• Solar on the roof — even in winter a decent panel can compensate for what short drives miss

Has anyone actually fitted the Victron Orion and noticed a real difference over winter? And what are people running for leisure batteries — still on AGM or made the jump to lithium?

Also curious whether anyone's found a realistic minimum drive time/distance that actually makes a meaningful dent in a depleted battery? Feels like anything under 45 minutes is almost pointless with a traditional setup.

@CopperRoamer absolutely feel this — on my boat the alternator is basically useless for anything under 45 minutes in winter. The engine's barely warm before you're tying up again.

What made a real difference for me was fitting a Victron Orion-Tr Smart DC-DC charger. Instead of the alternator dumping a lazy bulk charge, it properly pushes current at the right voltage for the battery chemistry. Night and day difference, especially with LiFePO4 where a standard alternator just throttles back too early.

Also worth checking your split charge relay if that's what you're running — they're notoriously inefficient and most people don't realise how much voltage drop you're losing across them.

Short winter runs will always be a losing battle without shore power or solar to back it up, but the DC-DC route at least maximises every minute the engine's running.

Wrong forum for narrowboats mate, but whatever.

Short runs are basically just exercising your alternator without actually doing anything useful. Mine used to be the same until I chucked a Victron Orion-Tr Smart DC-DC charger in — proper isolated 30A unit. Makes the alternator actually work at a sensible voltage rather than whatever the van's ECU feels like giving you that day.

Modern "smart" alternators are the real villain here. They drop voltage constantly to save fuel and your leisure bank just sits there barely getting a tickle.

Fogstar 12V lithium with a proper DC-DC is the only setup that's made sense at my cabin when I'm running short generator sessions in winter. Same principle applies to your boat/van situation — sort the charging method before worrying about the run time.

@GrumpyBuilder is right about the forum but the underlying problem is identical regardless of whether you're on water or tarmac.

The real issue nobody mentions: your alternator isn't even hitting proper charge voltage for the first 10-15 minutes in winter because the engine ECU is prioritising warm-up and the belt tension is effectively lower when cold. You're not just getting less charge — you're getting almost none for a significant chunk of a short run.

Proper fix is a DC-DC charger (B2B). Victron Orion-Tr Smart is the obvious choice — it'll extract a controlled, efficient charge from whatever the alternator can give rather than relying on voltage differential alone. Fitted one to my motorhome last winter and short 20-minute runs actually contribute meaningfully now instead of being pointless.

Without one, you're essentially just keeping the starter battery happy and kidding yourself about the leisure bank.

@CopperRoamer totally valid to cross-post the principle here — we deal with exactly this in vans too. The real kicker in winter is that your battery's already working harder just keeping things warm, so you're starting from a deeper deficit before you've even turned the engine over. A split charge relay setup helps, but honestly the game-changer for me was adding a DC-DC charger (B2B charger) rather than relying on a simple relay. It actually regulates the charge properly and gets meaningful amps into the leisure battery even on a 20-minute run. Combined with a small solar panel for the odd bright winter day, I rarely struggle now. @GrumpyBuilder fair point on the forum, but problems like this transcend vessel type!