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

Not strictly a motorhome setup, but I went through something similar keeping my static caravan's backup system topped up during winter, so the principle's the same.

Short runs in winter are almost pointless for charging — alternator barely gets the battery above resting voltage before you've arrived. A few things that made a difference for me:

• Sterling B2B charger — transforms what the alternator actually delivers to the leisure battery. Night and day difference vs a basic split charge relay
• Solar as a supplement — even a couple of 100W panels do something on bright winter days. Not much, but something
• Check your battery's actual state of health — I had an AGM that was quietly sulphating and accepting charge but not holding it. Replaced it with a Fogstar lithium and the whole system became more predictable

The real issue is that most factory split charge setups are designed for summer touring, not winter commutes. If you're doing 20-minute runs in December you're probably not even breaking even on parasitic drain.

Worth looking at whether a mains hookup top-up once a week is just the pragmatic answer for winter, rather than chasing a solution through the alternator alone.

What's your current charging setup? Split charge relay, VSR, or something more sophisticated? That changes the advice quite a bit.

@RetiredPlumber interesting timing on this thread — I'm dealing with something adjacent. My garden office runs off a small Fogstar lithium leisure battery and I've been wondering whether a small solar top-up panel would be more reliable than depending on any kind of vehicle alternator input for situations like this.

What's the actual charging voltage your alternator is pushing out in winter? I've read that some modern smart alternators barely register above float voltage when the engine's already warm, which would explain why short runs achieve almost nothing useful.

Has anyone fitted a DC-DC charger (a Victron Orion-Tr Smart being the obvious candidate) to properly condition the charge coming from the alternator? Seems like that might solve the problem regardless of run length, but I'm curious whether the cost justifies it for occasional use rather than a full-time live-aboard setup.

@NorfolkExplorer garden office gang represent 🙌 — slap a Victron SmartSolar on it and let the panels do the heavy lifting so your alternator can have a rest, because short winter drives are basically just heating the battery up and calling it charging.

Yeah this hits home — short winter hops are basically useless for charging. Alternator barely gets going before you're parked up again.

On the motorhome I ended up fitting a decent DC-DC charger (Victron Orion-Tr Smart) rather than relying on a basic split charge relay. Makes a proper difference even on a 20 min run — it actually steps up the voltage properly rather than just trickling whatever the alternator's outputting.

@LazyRanger is right about solar doing the heavy lifting but in winter with the van parked under trees it's not always reliable. The DC-DC alongside even a small panel is the sweet spot for me.

Worth checking your existing relay setup too — a lot of older motorhomes have ancient relays that are barely passing current efficiently.

@Clive1999 nails it — the alternator's barely warmed up before you've pulled over for a bacon butty.

Worth adding: the real villain here is battery chemistry. A flooded lead-acid sitting at 50% in January cold genuinely resists charging far more than the same battery in summer. Internal resistance goes up, acceptance rate drops.

If you're running AGM or lithium (Fogstar Drift is worth a look for the price), you'll at least get some meaningful charge on short hops because acceptance rates are far better at lower temps — lithium aside when it's genuinely sub-zero, obviously, where charging protection kicks in.

My static setup had exactly this problem until I added a Victron IP65 charger on mains as primary, with the alternator feed as backup only. Stopped fighting the physics entirely.

A DC-DC charger (B2B) rather than a split-charge relay also makes a measurable difference on short runs — proper regulated current rather than whatever the alternator fancies giving you.

Ran into this exact problem last autumn keeping the shepherd's hut powered up — the van doing short supply runs was contributing almost nothing to the battery bank.

What actually turned things around was fitting a DC-DC charger (went with a Victron Orion-Tr Smart 30A) rather than relying on a straight split-charge relay. The relay approach is almost pointless on a modern alternator with voltage sensing — the DC-DC actually steps up the charge rate during those brief windows you do have the engine running, so every mile counts properly.

Paired that with a Fogstar 100Ah lithium and the difference was night and day compared to the old AGM that was sulphating from constant partial charging.

@CliveBaker is right about the bacon butty situation — but at least now those fifteen-minute runs actually do something.