Anyone else had issues with a Daly BMS cutting out in cold weather?

Been having a nightmare with mine over the last few weeks at the cabin. Temperatures dropped to around -4°C overnight and the Daly 100A just kept disconnecting — no warning, no fault code that made any sense. Charge would get down to maybe 60% and then it would just cut everything dead.

Spent ages thinking it was a cell imbalance issue with my Fogstar cells, but after a lot of head-scratching I'm fairly convinced the BMS itself is doing something odd with its low-temp protection. The settings in the app seem straightforward enough but I wonder if the cut-off thresholds are drifting or being read incorrectly when the unit itself gets cold.

A few things I'm trying to work out:

• Is the temperature sensor actually reading the cell temp accurately, or is it picking up ambient?
• Are others finding the Daly app settings don't quite reflect what the unit actually does in practice?
• Would fitting some basic insulation around the battery box help enough, or is this a firmware/settings problem?

Context for my setup: it's a 48V 200Ah LiFePO4 bank in an unheated cabin used mainly for EV charging overnight via a Victron Quattro, so the battery really needs to behave reliably through the night.

Has anyone managed to sort this properly, or switched to a different BMS that handles cold better? Genuinely considering whether it's worth moving to a JK or a Seplos at this point.

@GemmaWood that sounds really frustrating! Is the Daly definitely cutting out on the charge side or the discharge side? I ask because at -4°C you'd expect a low-temp charge cutoff to kick in (which is actually correct behaviour to protect the cells), but discharge shouldn't be affected unless your cells themselves are struggling in the cold.

What chemistry are you running — LiFePO4 or something else? And are the cells themselves physically cold or is the BMS just sensing ambient?

Wondering if a simple insulated battery box might help keep the pack temperature above the cutoff threshold overnight — has anyone here tried that approach with a Daly specifically? Curious whether the low-temp threshold is adjustable via the PC software on that model too.

@GemmaWood this is almost certainly the low temperature charge protection kicking in. Most Daly units default to cutting charge at around 0°C to protect the cells — which is correct behaviour, but the threshold isn't always obvious in the app.

Worth checking:

• BMS app → temperature protection settings — what's your low temp charge cutoff set to?
• Is your battery itself insulated? Even basic foam lagging makes a significant difference at -4°C
• Are you running LiFePO4 or another chemistry? LiFePO4 is particularly sensitive to charging below freezing

I had similar issues with my static caravan setup before I added a small self-heating mat under the battery box. Sorted it completely. Some Daly models also support a heating film output — worth checking if yours has that pin populated on the connector.

What does the Daly PC software show for the temperature readings during cutout?

@GemmaWood worth checking whether the Daly is actually reading the cell temperature or ambient — the NTC sensor placement matters enormously. If it's taped to the outside of the case rather than properly seated against a cell, you'll get skewed readings.

On my boat I had a similar disconnect scenario, turned out the sensor had partially detached over the summer and was just floating loose inside the enclosure. Completely different problem to yours but same symptom.

Also — and I realise @BlownFuse probably covered the LTP angle already — the default thresholds on Daly units can be extremely conservative. You can adjust them via the PC software (you'll need the USB-UART cable, not the Bluetooth dongle for full parameter access). Some of the parameters aren't even labelled sensibly in the English version of the software, which is... charming.

@JohnShaw86

@GemmaWood had almost identical problem last winter with a Daly 200A on my shepherd's hut build. Worth grabbing the PC software and connecting via the USB-UART dongle if you haven't already — the default low temp cutoff is often set surprisingly high (around 0°C from factory) and you can lower it if you're using cells rated for cold discharge. Also check whether your NTC sensor has actually stayed attached to the cells properly, as @CliffGazer hints at — mine had partially peeled off and was floating in ambient air, giving completely wrong readings. If the cells themselves are genuinely cold though, I'd be cautious about simply disabling the protection — charging lithium below 0°C causes lithium plating which permanently damages capacity. Might be worth insulating the battery box instead as a longer term fix.