Anyone else had issues with Daly BMS cutting out under high discharge loads?

Running a 200Ah 12V LiFePO4 bank (4x Fogstar Drift cells) with a 100A Daly BMS as my emergency backup setup at home. Everything's been solid for months — Victron SmartShunt monitoring, all balanced nicely, resting voltage bang on 13.3V. But last week I put a 1500W inverter load on it (oil-filled radiator test during a grid outage) and the BMS tripped out cold. No warning, just dead. Reset fine, but did it twice more under the same load.

The maths should work — 1500W ÷ 12V is 125A, so I'm right at the edge of the 100A rating. What I can't work out is whether the Daly is being overly conservative on its overcurrent threshold, whether there's a voltage sag issue triggering the low-voltage protection prematurely, or whether the BMS just can't sustain that continuous current even if the peak is technically within spec. My cable runs are 35mm² so I don't think that's the issue, but I haven't ruled out connection resistance at the terminals.

Has anyone tuned the overcurrent and undervoltage trip points on a Daly via the PC software? I'm wondering if the default settings are quite conservative out of the box. Alternatively, is this just a case of needing to step up to a 150A or 200A unit — JK BMS seems popular here for active balancing builds, though I'd rather not rewire if I can avoid it.

@CamperDan had almost identical grief on my narrowboat last winter. Turned out my Daly was set to the default 100ms overcurrent delay — way too twitchy for inductive loads like inverters and pumps kicking in. The initial surge would trip it instantly even though steady-state current was fine.

Worth checking two things in the Daly app:

• PCLD (Peak Current Limit Duration) — bump this slightly
• Whether your emergency loads have any significant startup surge

Switched mine out for a Victron Lynx Smart BMS eventually, but before I did that, tweaking those timing parameters bought me months of stability. The Fogstar Drift cells themselves were blameless throughout — solid kit.

If it's an emergency backup role, you really don't want that BMS being jumpy. Might be worth logging the fault codes next time it trips to confirm that's actually the culprit.

SarahClark75 | 📍 Yorkshire | ⚡ Off-grid since 2019

@CamperDan what's your cable sizing and connection quality like between the BMS and your load? I had almost identical symptoms with a Daly 150A on my shed setup — turned out one of the B- terminals had a slightly loose crimp that was adding enough resistance to trigger the overcurrent protection under load spikes. Daly's protection threshold is fairly conservative compared to some other BMS units.

Also worth checking whether you've got any large capacitive loads (inverter, for instance) causing an inrush spike at startup — that can momentarily exceed the BMS limits even when your steady-state draw looks fine. A decent pre-charge circuit sorted mine completely. What loads are you actually running when it cuts out?

@CamperDan the overcurrent trip on Daly units is notoriously sensitive to inrush current rather than sustained draw. Motors, inverters, even certain compressor fridges will spike 3-5x their rated current on startup — your 100A BMS sees that instantaneous peak and latches off before your actual load ever settles.

Worth checking: does it cut on initial switch-on of the offending load, or mid-run? If it's the former, you're almost certainly dealing with inrush rather than genuine overcurrent.

I had this exact behaviour with a Daly 150A on my workshop battery bank — swapping to a Seplos BMS with configurable overcurrent delay timing sorted it completely. The Daly's delay settings are buried in their PC software and frustratingly limited compared to alternatives.

@SarahClark75 raises a valid point too — poor crimp quality creates resistance that amplifies voltage sag under load, which can compound the problem.

@CamperDan worth checking whether your Victron SmartShunt and the Daly are seeing the same current figures. I had a 100A Daly on my workshop battery bank and discovered the BMS was reading roughly 8-10A higher than the SmartShunt due to a dodgy negative busbar connection — enough to false-trip the overcurrent protection under surge loads.

@FormerMechanic68 makes a solid point about inrush. If you're running anything with a motor or compressor, consider a soft-start relay upstream. Sorted my false trips overnight.

Also — which firmware version is your Daly running? The older units had quite aggressive default overcurrent thresholds. The PC software (via the USB dongle) lets you adjust the trip delay and threshold, which made a real difference on mine.