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

Short winter drives are basically just a polite way of telling your battery you thought about charging it. 😅

My leisure battery spends November to February in a permanent sulk — the alternator barely gets warmed up before I'm pulling onto the drive again, and the solar panel is just decorating the roof at that point (cheers, British weather).

A few things that actually helped me stop the cycle of guilt and jump leads:

• B2B charger — honestly a game changer; even a 20-minute run does proper work rather than just tickling the terminals
• Keeping a Victron SmartShunter on it so at least I know how bad things are (ignorance was cheaper mentally)
• Plugging into shore power whenever parked at home — even a basic mains charger keeps things respectable
• Dropping the habitation loads ruthlessly in winter; the fridge runs on gas, the telly gets a rest

I'm running a Fogstar 100Ah lithium now which handles the partial state-of-charge abuse far better than the old AGM ever did — that thing used to sulk for weeks after a bad run.

The real villain nobody mentions is leaving the habitation electrics on while you nip into the services for a "quick" forty-five minutes and a full cooked breakfast.

Anyone else gone down the B2B route, or found something else that actually works for short-run seasons? Curious whether anyone's tried a small Renogy panel just for maintenance trickle — wondering if even 50W does anything meaningful parked on a north-facing street in January.

RetiredElectrician10 | 847 posts | ⚡ Verified Sparky

@SolarNut Ha, sounds very familiar mate! Forty years wiring things up and I still shake my head at folk thinking a 20-minute school run is going to do meaningful work on a 110Ah leisure battery.

The real culprit is your split charge relay cutting in too late once the alternator's already loaded with heating, lights and wipers. Worth looking at a proper DC-DC charger (B2B) if you haven't already — they'll squeeze every useful amp from even a short run rather than just trickling what's left over.

Also check your alternator isn't undersized for winter loads. Many van conversions I've seen are running on 90A alternators that were never really adequate.

Small solar panel on the roof helps bridge the gaps between drives too, even in December.

ExFirefighter11 | 312 posts | 🔋 Off-Grid Enthusiast

Had this exact problem on my boat conversion before I wised up. Short runs were basically theatrical — the alternator barely gets out of bed before you're switching off.

What transformed things for me was fitting a Victron Orion-Tr Smart DC-DC charger rather than relying on a simple B2B split. The difference is significant — it properly regulates the charge profile rather than just throwing whatever voltage the alternator happens to be producing at your leisure bank.

On my shepherd's hut setup I run Fogstar lithium, and if you've gone LiFePO4 the case is even stronger — a dumb connection will barely tickle lithium chemistry on a 20-minute run.

The Orion pays for itself remarkably quickly once you stop replacing batteries that were never properly charged to begin with. Worth every penny of the ~£150 investment.

Spud79 | 203 posts | 🔋 Off-Grid Enthusiast

Worth looking at a DC-DC charger rather than a direct split-charge relay if you haven't already. A Victron Orion-Tr Smart makes a significant difference — it properly regulates the charge rather than just tapping whatever the alternator throws out. On my narrowboat I was getting maybe 10-15A through a relay on short runs; the Orion pulls a controlled 30A for however long the drive lasts.

Also worth checking your alternator voltage under load — modern vehicles with smart alternators can drop to 12.8V or lower, which barely does anything useful for a leisure battery. The relay setup essentially gives you nothing in that scenario.

A small solar panel as backup isn't really viable in winter obviously, but even 100W on the roof helps bridge the gaps if you're stationary for a few days.

HalfAJob53 | 156 posts | 🔋 Off-Grid Enthusiast

@SolarNut Totally feel this. What made a real difference for me was pairing a small rooftop panel (even just 100W) with a decent MPPT controller — not for massive generation obviously, but it at least trickles something in during those grey winter days when you're parked up. Combined with being more ruthless about what's actually drawing from the leisure battery overnight, I managed to stop the perpetual sulk you're describing.

Also worth checking your battery's actual state of health — sometimes what looks like a charging problem is actually a knackered cell that won't hold charge regardless. A proper load test will tell you quickly. I wasted a whole winter chasing a charging "fault" that turned out to be a three-year-old battery that had simply given up the ghost. 😅