Anyone else had their Daly BMS cut out in cold weather? Mine tripped at 4°C last night

I've got a 200Ah lithium (LiFePO4) pack in my van build — four 50Ah EVE cells in series with a Daly 100A smart BMS. Been running it all summer without a hiccup, but last night the temperature dropped to around 4°C overnight and I woke up to find the BMS had tripped and cut everything off. Fridge had been off for hours, which wasn't ideal.

After a bit of digging it looks like the Daly has a low-temperature charge protection setting that kicks in somewhere around 5°C by default. Fair enough, you don't want to charge LiFePO4 below 0°C, but 5°C seems overly cautious and it meant my solar controller couldn't push any charge in once the sun came up either, which left me dead in the water until I manually reset it around midday when things warmed up.

Has anyone adjusted the low-temp cutoff threshold on a Daly via the PC software or the app? I've downloaded the Daly BMS app but I can't find where that specific parameter lives — the interface is a bit of a maze to be honest. Wondering if dropping it to 2°C would be more sensible for UK autumn/winter use, or whether that's asking for trouble with the cells.

Also open to suggestions on whether a small self-heating pad on the battery box is the better long-term answer rather than fiddling with the BMS settings. Anyone running something like that?

@RobWebb59 this took me completely by surprise on my narrowboat last February. Woke up to a dead system at around 3°C — turns out the Daly was doing exactly what it's supposed to do, protecting the cells from charging below freezing.

The issue isn't the BMS misbehaving, it's that LiFePO4 cells genuinely cannot accept charge safely below 0°C, and some Daly units get conservative and trip earlier than that.

What sorted mine was a simple self-heating solution — I wrapped the battery compartment with a thermostatically controlled heat mat (mine kicks in at 5°C). Victron's lithium range has built-in low-temp charge cutoff handling, but with budget cells and a Daly you're managing it yourself.

Worth checking your Daly app too — some firmware versions let you adjust the low-temp charge protection threshold.

TimGreen | 847 posts

@RobWebb59 Classic cold weather LiFePO4 issue, unfortunately. The Daly's low-temperature charge protection kicks in somewhere around 0-5°C depending on the firmware — it's actually doing its job, since charging LiFePO4 below freezing can cause lithium plating and permanently damage your cells.

The distinction worth making though: it should only cut charging, not discharging. Are your solar/alternator inputs completely isolated? If your whole system went dark rather than just charging stopping, it might be worth checking your Daly's settings via the Bluetooth app — some units have overly aggressive low-temp discharge cutoffs set from the factory.

Longer term, a small self-regulating heat mat under the battery connected to a temperature thermostat works brilliantly for van builds. Draws minimal power and keeps cells happy above 5°C overnight. @OffGridTerry might have gone a similar route on the narrowboat?

SilverCaptain | 1,204 posts

@RobWebb59 Worth checking your Daly app — the low temp charge cutoff is usually set to around 5°C by default, which explains your 4°C trip. You can lower it slightly, but honestly I'd be cautious about that approach. Charging LiFePO4 below freezing genuinely damages the cells.

Better solution is a small self-regulating heat mat wrapped around the battery, triggered by a simple thermostat controller. I picked one up for about £15 and set it to kick in at 8°C. Keeps everything above the threshold overnight without drawing much power at all.

Also make sure your insulation is decent — a well-insulated battery box holds residual heat surprisingly well in a van. @OffGridTerry can probably confirm that's doubly important on a narrowboat where the cold really creeps in from all sides.

MuddyTinker | 134 posts

@RobWebb59 Had exactly this on my boat last winter — worth knowing it's not just the charge cutoff that can cause grief. If your cells are genuinely cold, even discharging into heavy loads can stress them.

What are you using to heat the battery compartment? I ended up wrapping my pack in some cheap foam insulation and adding a small 12V heating mat (thermostatically controlled) after my Daly tripped repeatedly. Kept things above 8°C even when the outside temp was near freezing.

Also worth asking — are your cells balanced? Unbalanced cells can trigger protection cutoffs at temperatures that would otherwise be fine, because one cell drops voltage faster under load.

GeorgeHarris | 312 posts

@RobWebb59 Something worth adding to what the others have said — even if you adjust the low-temp cutoff in the Daly app, do be careful about actually charging LiFePO4 below about 5°C. The cutoff exists for a good reason; charging cold lithium cells causes lithium plating on the anode which permanently damages capacity. If your van's parked up overnight, a small self-regulating heat pad underneath the battery (wired to activate before your charger kicks in) is a proper solution rather than just disabling the protection. Plenty of folk on here have done it with a cheap reptile heat mat and a temperature controller. Costs maybe £20-30 and your cells will thank you long-term. What's your charging source — solar, alternator, or mains? That might affect which approach makes most sense for your setup.

EllaPalmer | 312 posts

@RobWebb59 One thing worth adding to what the others have said — insulating the battery itself makes a surprising difference. Even a simple foam camping mat wrapped around the pack can keep the cells a few degrees warmer overnight and help you avoid hitting that cutoff threshold in the first place.

Also, if your van has any residual heat from the day, positioning the pack away from draughty floor areas helps retain it longer. I've got a similar setup and moved mine closer to the cab bulkhead last winter — noticeably better.

It won't solve the root cause, but as a short-term workaround while you sort the BMS settings it's dead easy and costs practically nothing. 🙂

SarahClark75 | 89 posts

@RobWebb59 Just to add a practical tip — a small self-regulating heating pad designed for pipes works brilliantly for van battery boxes. They draw very little current and kick in automatically when temps drop. Mine's wired directly to the battery via a small fuse, completely separate from the BMS, so it keeps the cells warm before charging even begins. Cost me about £15 off eBay. Been through two Scottish winters without a single cold-weather cutout since fitting it. Worth every penny if you're parking up overnight in winter.

DODNerd | 847 posts

@RobWebb59 Worth checking your Daly's low-temperature protection settings in the app — the default cutoff from the factory is often set quite conservatively, sometimes as high as 5°C. You can adjust the trigger threshold and recovery temperature through the Bluetooth app if you haven't already. That said, do be careful about lowering it too aggressively — LiFePO4 cells genuinely don't like being charged below 0°C as it causes lithium plating on the anode, which is permanent damage. Discharging in the cold is generally fine though, so you could consider separate charge/discharge protection thresholds if your setup allows it.

Ella1966 | 203 posts

@RobWebb59 Just to add something nobody's mentioned yet — LiFePO4 cells themselves don't actually mind sitting in the cold, it's charging them below freezing that causes the real damage (lithium plating on the anode). So if you're only discharging at 4°C you should be fine. The BMS is just being cautious. Worth checking whether it's triggering on the charge or discharge protection — that'll tell you a lot about what actually needs addressing. What's your charging source, solar or vehicle alternator?