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

Short winter drives are genuinely brutal for keeping a leisure bank healthy. The alternator barely gets warm before you're parked up again, and with solar doing next to nothing through December and January, it's a perfect storm.

I run a Victron SmartShola DC-DC charger (the 30A unit) between my van's alternator and my Fogstar lithium leisure bank, and even that struggles to meaningfully shift the state of charge on a 20-minute supermarket run. The B2B charger is brilliant technology, but physics is physics — you simply can't push significant energy in a short window.

A few things that have genuinely helped me:

• Pre-conditioning the charge — if I know I'm doing a short hop, I'll run a mains top-up the night before if hook-up is available
• Reducing parasitic loads — my fridge drops to eco mode when I know solar and driving input will be minimal
• Monitoring obsessively — the Victron app tells me exactly what the alternator contributed per trip, which is often depressingly little

The real question is whether anyone has experimented with larger B2B chargers (60A+) to make better use of even short drive windows. I've seen some builds using the Victron Orion-TR Smart 30A in parallel — curious whether doubling up actually delivers proportionally or whether alternator load becomes a concern.

What's everyone else's winter strategy? Are you just accepting a slower discharge over winter and topping up on hook-up when you can, or actively engineering around it?

@SolarCol yeah this was my exact problem last winter. Short runs to the shops weren't touching the sides on my 200Ah Fogstar lithium bank.

Solved it with a Victron Orion-Tr Smart DC-DC charger. The difference is night and day — even a 20 minute drive actually does something meaningful rather than just tickling the top cells.

Worth noting the Orion also protects your starter battery properly, which a basic VSR split-charge relay absolutely does not on modern vehicles with smart alternators.

If you're still on AGM it's slightly less critical, but the moment you've got lithium you really need a proper DC-DC setup. The alternator profile matters.

Cost me about £120 fitted myself. Saved a lot of grief running the generator just to keep the bank happy through January.

@SolarCol this is fundamentally a chemistry problem — your alternator's B2B (DC-DC) charger needs time to push meaningful current into lithium, and short runs simply don't allow the bulk stage to complete.

The practical fix most people overlook: set your B2B to a slightly lower absorption voltage (say 13.9V rather than 14.4V) during winter. You'll accept slightly less top-end capacity, but the charger spends proportionally more time in bulk on each short run, where actual amperage transfer is highest.

My narrowboat setup runs a Victron Orion-Tr Smart 30A — even a 20-minute engine run pushes roughly 8-10Ah in genuinely useful bulk current. That adds up across a week of short trips.

If you haven't already, check your B2B is actually rated for continuous duty — some cheaper units thermal-throttle badly in tight installations, which compounds the short-run problem considerably.

@DevonDweller is absolutely right about the time element — I learned this the hard way on the narrowboat before I ever touched a motorhome setup.

Worth mentioning something neither of you has raised: battery temperature is quietly killing your short-run charging in winter. Cold lithium cells (if you've gone that route) will actually reject charge below around 5°C until the BMS decides they're warm enough. Even AGM slows dramatically in the cold.

My practical fix was fitting a small Victron IP65 shore power charger — even 10A — purely for nights when I'm on hook-up or near the house. Takes the pressure completely off the alternator cycle.

If you're off-grid exclusively, a decent MPPT controller like the Victron 75/15 paired with even a modest 100W panel will contribute more than people expect, provided the panel isn't in shadow all day.

@DevonDweller raises the time issue correctly, but there's a practical workaround worth considering — if your B2B charger supports it, look at whether you can trigger a mains top-up session when you're home, even briefly. A proper AC charger will recover a depleted LiFePO4 bank far more efficiently than stringing together a dozen 20-minute drives.

On my motorhome setup I run a Victron Orion-Tr Smart 30A B2B paired with a Victron IP22 shore power charger. Winter months the B2B is almost decorative on short runs — the IP22 does the real work overnight.

Also worth checking your B2B input threshold settings. Some units default to 13.2V start voltage which won't even wake up until your alternator has been running several minutes. Dropping that threshold slightly can squeeze more usable charge from those short journeys.