Anyone else had issues with a Daly BMS dropping out under load? Mine's doing my head in

I've been running a 200Ah LiFePO4 pack (4 x 50Ah CATL cells I bought from Docan last spring) with a 100A Daly Smart BMS for about eight months now. Everything looked fine on light loads — phone charging, a few LED lights, the usual. But the minute I kick on my Victron MultiPlus 12/1600, the BMS cuts out almost immediately. It comes back within a few seconds, no error codes showing in the Bluetooth app, just drops and reconnects.

I've checked the obvious stuff — all busbars torqued properly, 95mm² cable from the battery to the inverter, the inline ANL fuse is a 200A. Cell voltages are all sitting within about 10mV of each other at rest, so I don't think it's a cell imbalance issue tripping the BMS. I did notice the BMS is getting quite warm to the touch during the event, but I don't know if that's cause or effect.

Has anyone seen this with Daly units specifically? I'm wondering whether the 100A continuous rating is just optimistic and I should be looking at a 150A or 200A version, or whether there's something else going on — a setting in the app I might have wrong, perhaps. The inrush from the MultiPlus startup is something I've read about causing grief but I can't find a solid answer on what the actual peak draw looks like.

@Gemma1981 classic Daly dropout symptom — almost certainly the overcurrent protection tripping on inrush rather than sustained draw. The 100A rating is continuous, but Daly's peak tolerance is surprisingly conservative compared to something like a Victron Lynx or even a decent JK BMS.

Worth checking in the Daly Smart app whether your overcurrent delay is set to minimum (sometimes ships at 0ms, which catches any inrush spike). Bump it to 10–20ms and it usually resolves nuisance tripping without compromising actual protection.

I had identical behaviour on my van build with a 150A Daly — EV charging via a Victron Multiplus was triggering it constantly. Switched to a JK BMS (the 200A active balancer unit) and haven't had a single dropout since. The JK's configurable parameters are far more granular.

Also worth confirming your cell interconnects are torqued properly — resistance hotspots can fool the BMS current sensing.

@Gemma1981 had almost exactly this with my static caravan setup — Daly 100A BMS tripping when the EV charger kicked in. The inrush from even a modest EVSE was enough to trip it despite steady-state current being well within spec.

What helped me was checking whether the Daly app lets you adjust the overcurrent delay time — mine was set to the default and bumping it slightly stopped the nuisance trips without compromising actual protection.

That said, I eventually swapped to a Victron SmartShunt alongside the Daly just to get better visibility on what was actually happening at the moment of dropout. Made diagnosing it much easier.

Worth also checking your cell connections are torqued properly — loose busbars can cause voltage spikes that the BMS reads as overcurrent even when it isn't.

@Gemma1981 worth checking whether the Daly is actually seeing a true overcurrent event or whether it's the BMS's own internal resistance causing a voltage sag that triggers the low-voltage cutoff — two very different problems with different fixes.

On my Caddy camper I had identical symptoms with an inverter kicking in. Turned out the Daly's "overcurrent" threshold was fine on paper, but the peak inrush lasted just long enough to trip the protection before the BMS could distinguish it from a sustained fault.

A few things to verify:

• What's your discharge overcurrent delay set to in the Daly app? Factory default is often absurdly short
• Are your cell interconnects and cable lugs properly torqued? Even 0.5Ω of extra resistance creates nasty voltage spikes under load
• Is the 100A rating genuinely continuous or peak on that specific unit?

If you're regularly pulling near-rated current, honestly the JK BMS is worth the upgrade.

@Gemma1981 one thing nobody's mentioned yet — have you checked the actual wire connections on the BMS itself? I had near-identical symptoms on my 150A Daly and it turned out one of the main discharge terminals wasn't fully torqued down. Under light loads it was fine but any meaningful inrush and the resistance at that joint was enough to confuse the BMS into thinking it had an overcurrent event. Took me ages to find it.

Also worth grabbing the Daly app if you haven't already and watching the current readings in real time when the dropout happens — you can see exactly what triggered it. Makes diagnosis so much quicker than guessing blindly. What loads are you running when it trips?

@Gemma1981 been there, done that, got the scorch marks to prove it. My static van setup chewed through two Daly units before I figured out the real problem — the peak inrush current on startup was hammering the BMS well beyond its rated 100A, even if the sustained draw looked fine on paper. A kettle or inverter kicking in can spike 3-4x the running current for a split second.

Swapped mine out for a Victron SmartShunt alongside a proper JK BMS and never looked back. The JK handles inrush far more gracefully than the Daly ever did.

If you're wedded to the Daly for now, try setting the overcurrent protection threshold slightly higher in the app — but honestly, the JK is worth every penny if your loads are spikey.