Anyone else had their Daly BMS cut out mid-charge on a cold morning?

Had a frustrating one yesterday. I've got a 200Ah LiFePO4 pack (4x 50Ah EVE cells) in my Kangoo van build, managed by a Daly 100A Smart BMS. Woke up at about 6am, ambient temp in the van was around 4°C, and the BMS had tripped overnight and killed the charge from my 200W roof panels. SOC was sitting at around 62% according to the Daly Bluetooth app — so it wasn't a full-cell overvoltage issue.

After a bit of digging I think it's the low-temperature charge protection kicking in. The Daly's default cutoff is 5°C and we were right on that edge. I've nudged the threshold down to 2°C for now but I'm a bit wary of actually charging lithium cells when they're that cold — I know it can cause lithium plating and damage the cells long-term. Bit of a catch-22 really.

Has anyone fitted a battery heating solution to get around this properly? I've seen some folks use a self-regulating heat mat wired to a thermostat, but I'm not sure what to use as the heat source without draining the very battery I'm trying to protect. Also wondering whether a Victron SmartShunt or a separate temperature sensor feeding into a relay would be a cleaner approach than relying solely on the Daly's built-in cutoffs. Any experience welcome.

EllaPalmer | 847 posts

@KangooSolar yes, classic Daly low-temperature protection kicking in! Most of them are factory-set to cut charging around 5°C to protect the cells from lithium plating. Four degrees would absolutely trigger it.

Worth connecting to the Daly app via Bluetooth and checking your "Charge Low Temp Protection" value — you can lower it slightly, though I'd be cautious going below 0°C without proper cell-level temperature sensing.

The proper fix longer term is a self-heating battery setup or wrapping the pack in some decent insulation with a small heat mat on a thermostat. I use a 40W reptile heat mat on mine, kicks in overnight when temps drop — sorted my winter charging issues completely.

Are you running solar or a B2B charger for your charge source?

Yeah this happened to me loads on the narrowboat last winter. Daly's default low-temp cutoff is usually around 5°C so 4° ambient will trigger it almost every time.

What I ended up doing was adding a simple heat mat under the cells — just a cheap reptile one from Amazon, wired to a thermostat. Kicks on at 5°C and keeps things above the threshold. Costs pennies to run really.

Worth checking your Daly app too — you can sometimes adjust the low-temp parameters if you've got the Smart version, though I'd be cautious about pushing it too far with LiFePO4.

@EllaPalmer probably already covered the why, but the heat mat fix is dead practical if you're living aboard or in a van full-time through winter. Game changer for me honestly.

MarineDoug | 1,203 posts

@KangooSolar worth knowing that even if you sort the BMS settings, charging LiFePO4 below about 5°C genuinely isn't great for the cells long-term regardless - you can get lithium plating on the anodes which permanently degrades capacity. So the BMS is actually doing you a favour in a way!

Practical fix I use on my boat: a small self-regulating heat mat wrapped around the pack on a simple thermostat controller. Kicks on at 5°C and brings the pack up to 10°C before charging resumes. Costs pennies to run and the cells thank you for it. Some people just use a bit of van insulation around the battery box too - helps retain whatever warmth is already there overnight. What's your battery location like for insulation?

HarbourKate | 412 posts

@KangooSolar one practical workaround I use on my boat is a small self-regulating heat mat wrapped around the battery pack, wired to come on via a thermostat below about 8°C. Costs pennies to run and brings the cells up to a safe charging temp before your solar or alternator kicks in properly. Mine's set to cut the heating off at 15°C so it's not running unnecessarily.

@MarineDoug makes a really important point though - it's not just a BMS quirk to work around, the cells genuinely don't accept lithium ions properly when cold and you risk permanent capacity loss or worse. The BMS is doing its job! Sort the root cause rather than just tweaking the cutoff threshold.

EVE cells are generally pretty decent quality so you shouldn't have any lasting damage from one incident. How are you currently monitoring cell voltages?

Slim13 | 312 posts

Good shout from @MarineDoug there — the cell chemistry point is really important and worth taking seriously rather than just overriding the protection. One practical solution I've found for van builds is a small self-regulating PTC heating pad stuck directly to the battery pack, wired to come on via a thermostat below about 8°C. Costs next to nothing to run and brings the cells up to a safe charging temp before the BMS even needs to think about it. Victron kit also handles this elegantly if you're ever looking to upgrade — the MPPT controllers have a low-temp charge disable built in. But for now, a cheap immersion heater controller from Amazon and a bit of insulation around the pack will make a noticeable difference through winter.

TerryWatson | 847 posts

@KangooSolar I had almost identical with my Daly on a cold spring morning last year. Worth checking your low-temp charge cutoff setting in the Daly app — mine had shipped with it set to 5°C, which is actually quite sensible, but the hysteresis (the recovery temperature before charging resumes) was set unnecessarily high, meaning it took ages to kick back in even after the van warmed up a bit.

Also, on the van setup specifically — have you considered insulating the battery box itself? Even basic foam board around the cells makes a surprising difference overnight. My pack now rarely drops below 8°C inside the box even when ambient is near freezing. Buys you a bit more margin before the BMS does its job and protects the cells.

Bomber | 67 posts

This is relevant to me too — my garden office setup hits similar temps in winter and I've been wondering if my pack will throw a wobble. Quick question for the thread: does the Daly Smart BMS log the exact cutout temperature anywhere in the app? Trying to work out whether mine is actually triggering low-temp protection or whether something else is going on. Also, is the cutout threshold adjustable on the Smart variant, or is it hardcoded at the factory setting?

PW_Sparks | 203 posts

@KangooSolar worth checking your Daly's low-temp charge cutoff setting in the app — they often ship with it set around 5°C from the factory, which would explain a 4°C cutoff almost perfectly. You can adjust it, but personally I'd be cautious about lowering it too far with EVE cells. A more elegant fix is adding a small self-regulating heat mat on the pack triggered by a thermostat — keeps temps just above the threshold overnight without drawing much power. @Bomber that's probably your answer for the garden office too, since you can't easily pre-warm a static setup.

DaiCole | 412 posts

@KangooSolar 4°C is right on the edge for LiFePO4 charging — most Daly units ship with the low-temp cutoff set somewhere between 0-5°C, but the threshold itself isn't the whole story. Worth checking whether your temperature sensor is actually making good contact with the cells. I found mine had worked slightly loose on a bumpy van build and was reading a degree or two colder than reality, which caused phantom cutoffs. A blob of thermal paste and some kapton tape to secure it properly sorted mine completely. @Bomber worth doing the same check on your garden office setup before winter properly kicks in.

CharlieStevens85 | 134 posts

Had exactly this with my static caravan setup last January. Even after adjusting the low-temp threshold in the Daly app like @PW_Sparks suggests, I still got intermittent cutouts on borderline mornings.

What actually sorted it for me was adding a small self-regulating heat tape wrapped around the cells — nothing fancy, just a 12V strip off Amazon triggered by a simple thermostat module. Keeps the pack above 8°C overnight without drawing much.

Worth considering if you're regularly seeing those low single-digit temps. The software fix alone isn't always reliable on the cheaper Daly units in my experience.

Gibbo53 | 67 posts

This is exactly what I've been worried about with my tiny house build — I'm planning a similar EVE cell setup and hadn't really thought about winter charge cutoffs properly. Quick question for the thread: does the Daly app let you set a resume temperature threshold separately from the cutoff? So for example, cut charging at 4°C but only resume once you've hit, say, 8°C? Or does it just use a single fixed point? Trying to decide whether to go Daly or spend the extra on a Victron/JK setup that might handle this more gracefully.