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

Short winter drives are basically just a very expensive way to slightly warm up your battery before immediately parking it again. 😅

My setup was absolutely hopeless until I ditched the standard split-charge relay and went full Victron SmartShore with a proper DC-DC charger — the difference was genuinely embarrassing, like I'd been charging through a damp sock before.

The core problem nobody talks about is that your alternator barely gets going in the first 20 minutes anyway, especially on a cold engine, so a 15-minute school run or Tesco dash is essentially theatrical charging at best.

A few things that actually helped me:

• Renogy 40A DC-DC charger — charges properly regardless of short run times
• Keeping a small solar panel ticking over (even winter UK sun does something, eventually, maybe, if it stops raining)
• Dropping my battery cut-off threshold so I'm not starting from rock bottom every morning
• Switched to Fogstar 100Ah lithium — holds charge far better over winter than my old AGM ever did

The real villain here is December, obviously. Loads of draw from heating, lighting, and the fridge working overtime in the cold, but barely any driving or solar to compensate.

Anyone running a mains hook-up at home between trips? That's genuinely been my sanity saver when I'm parked on the drive — even a basic charger from Victron overnight sorts everything before a weekend away.

Curious whether anyone's found a smarter workaround, or if we're all just collectively pretending our batteries are fine whilst secretly watching the voltage drop in the Victron app at 11pm. 👀

WillowGazer | Posts: 847

@DailyAdventure Ha, know that feeling all too well! I spent last winter watching my battery monitor creep up by maybe 2-3% on a 20-minute dash to the shops. Pointless.

The game-changer for me was adding a small solar panel even through winter. Obviously it's not going to smash it on overcast days, but parked up for a few hours it'll often put back more than the alternator managed on the drive there. Even 100W on the roof makes a noticeable difference.

What split charge relay were you running before? Some of the older voltage-sensing relays don't even bother opening properly in winter because the alternator voltage doesn't climb high enough quickly enough when it's cold. A DC-DC charger sorted mine completely — proper controlled charge regardless of conditions.

KentBoater | Posts: 2,341

The split-charge relay problem in winter is essentially physics trolling you — alternator barely gets to proper charging voltage before you've pulled onto your driveway.

Worth mentioning something I don't see discussed enough: battery temperature compensation. A cold 100Ah lithium (I run Fogstar Drift cells) needs a meaningfully different charge profile than a warm one, and most B2B chargers handle this far better than relay systems ever could.

My Victron Orion-Tr Smart has genuinely transformed short-run charging for the static caravan tow vehicle. Even a 20-minute motorway blast in January actually moves the needle now rather than just tickling the terminals.

The other sneaky win? Properly sized cabling. Undersized wire between vehicle and leisure battery is basically a resistor you've accidentally installed yourself. 😄 Voltage drop calculator is your friend before spending anything on fancy kit.

RetiredChef | Posts: 1,156

@DailyAdventure A DC-DC charger (Victron Orion-Tr Smart is the one I trust with my narrowboat) completely ignores that winter alternator voltage nonsense and actually pushes a proper charge profile regardless — fitted one to my static and narrowboat, never looked back. Even a 20-minute trundle gives your leisure battery a meaningful top-up rather than a polite wave. The 12-12/18A version is about £80-90 and basically pays for itself the first time you don't need a rescue callout. 🔌

HazelPaddy | Posts: 412

@RetiredChef Seconded on the Orion-Tr Smart — genuinely transformed my winter charging situation. One thing worth adding though: even with a DC-DC charger, those 10-minute school-run type drives barely move the needle on a larger LiFePO4 bank.

My Fogstar Drift 100Ah accepts charge brilliantly once it's actually getting amps, but the charger needs a minute or two just to handshake and ramp up properly.

Honestly the bigger win for me was adding a small solar panel — even a 100W roof-mounted one gives you something useful on overcast days when the van's sitting on the drive. Pairs nicely with the DC-DC for when you do drive. Belt and braces approach basically.

What size battery are you running @DailyAdventure? Makes a difference to how much the driving actually helps.

LesWood78 | Posts: 847

One thing nobody's mentioned yet — if you're running a Victron Orion-Tr Smart, configure the input voltage threshold carefully. Default settings can be overly cautious with some older alternators that sit at 13.8V rather than 14.4V, meaning the unit simply won't engage at all.

Also worth checking: smart alternators (variable voltage, common post-2015 vehicles) need the isolated version of the Orion specifically, not the non-isolated. Caught plenty of people out on that one.

@RetiredChef makes the right call on DC-DC generally, but the Fogstar Drift LiFePO4 batteries I run in the shepherd's hut and motorhome both have BMS protection that interacts oddly with certain charge profiles — worth double-checking your charger's lithium preset matches your actual battery chemistry rather than assuming "lithium mode" is universal.

Short drives are always going to be marginal; solar panel even a 100W flexible one genuinely compensates far better than people expect.