Does anyone actually monitor battery temp when solar charging in winter?

Been thinking about this after reading up on lithium charging limits — specifically around the 0°C cutoff for charging. On the narrowboat I've got a Victron MPPT which has a temp sensor and will throttle/stop charging if it gets too cold, but I'm wondering how many motorhome setups actually have this sorted properly.

Saw a Fogstar Drift 100Ah listed as having a built-in BMS with low-temp protection, so the battery protects itself — but is that good enough, or do people prefer having the MPPT handle it at the charger level rather than waiting for the BMS to cut out?

Curious whether anyone's had issues in practice — like waking up on a frosty morning and finding the BMS had tripped overnight, or the solar just sat there doing nothing because temps were below threshold. What's the actual real-world experience here?

Good shout raising this @DodgyCaptain. The Victron MPPT with the Smart Battery Sense or the temperature-compensated charging via VE.Smart networking is genuinely excellent for this. What a lot of motorhome owners miss though is that the BMS on a decent lithium battery (Victron, Winston, EVE cells with a proper Daly/JK etc.) should be your last line of defence against sub-zero charging anyway — it'll hard disconnect before damage occurs.

The real-world issue I see is people relying solely on the BMS cutoff rather than having the charger behave intelligently before it gets to that point. Gradual throttling below 5°C is far kinder to your cells long-term than repeated hard disconnects. Worth checking whether your MPPT firmware is current too — Victron have refined their low-temp behaviour considerably over recent updates.

Really important topic this, especially for those of us using the van through winter. I'll be honest, I didn't bother with temp monitoring for ages and just assumed the BMS would protect things — which technically it will, but by then you've potentially already stressed the cells trying to push charge in.

What made the difference for me was adding a cheap Bluetooth temperature sensor near the battery bank. Nothing fancy, just lets me glance at my phone before I assume the solar is doing useful work on a cold morning.

Worth noting that even a few degrees above 0°C doesn't mean you're in the clear — charging efficiency drops off noticeably below about 10°C with lithium, so your bulk charge times will be longer than you'd expect anyway. @DodgyCaptain what chemistry are your lithium cells? LiFePO4 tends to be more forgiving than some others at low temps.

Just to add a practical angle here — I spent last winter in my Transit conversion parked up in Scotland for weeks at a time, and the temperature swings were brutal. Even with the cab heating on, my battery box in the rear was seeing -4°C some mornings. What saved me was simply sticking a cheap bluetooth temperature sensor (one of those Govee ones) directly on the battery casing and checking it before enabling charging each morning. Dead simple solution.

@DaiHughes65 you're not alone in having ignored this initially — most of us learn the hard way! The thing people miss is that it's not just about ambient temp, it's the battery's actual surface temp that matters. A sunny day can fool you into thinking everything's fine whilst your cells are still frozen solid underneath.

Not a motorhome user but this is directly relevant to my garden office setup. Running a Fogstar Drift 100Ah and I was shocked last winter when I checked the BMS app first thing on a cold morning — cells were sitting at -2°C. The Victron MPPT had already started throwing charge at it before I'd even had my morning coffee.

Ended up setting a low-temp charge cutoff in the BMS and adding a Victron Smart Battery Sense so the MPPT itself knows what's happening. Belt and braces.

The scary bit is how many people just assume the BMS will save them. It will eventually, but you're potentially stressing the cells before the protection kicks in. Anyone relying purely on default settings in winter is probably doing damage without realising it.

Good thread this. Worth mentioning that the BMS in most decent lithium batteries will protect against charging below 0°C as a last resort, but you really don't want to rely on that — by the time it kicks in you may already have done some damage, and repeated BMS trips aren't great for longevity either.

One thing I'd add that hasn't been touched on: battery placement matters enormously in a van context. Mine sits under the bed against an interior wall rather than near the floor or an external panel, which means it rarely gets as cold as ambient outside temps overnight. Combine that with a Victron temp sensor and I've never had a cutoff issue even parked in Wales in January.

@DY_Power — garden office is a different beast, worth looking at a self-heating battery option if it's uninsulated.