Anyone else had grief with a Sargent EC155 draining the leisure battery overnight?

Had this exact issue last summer with my setup. The EC155 was pulling a phantom load even with everything supposedly switched off — woke up to a nearly flat battery two mornings running before I traced it back.

Turned out the control unit itself was drawing around 0.8A constantly. Doesn't sound like much but over 10-12 hours that's a serious chunk out of a 100Ah leisure battery, especially if it's not in great health.

A few things worth checking:

• Measure the actual parasitic draw with a clamp meter or multimeter in series. Don't just trust what the panel display tells you.
• Check the 12v input fuse board — I found a couple of accessories wired through it that were drawing independently of the Sargent switching.
• Firmware/unit age — older EC155 units seem to have worse standby behaviour than the more recent ones.

My short-term fix was a simple battery isolator switch on the leisure bank, which I now flip before bed. Not elegant but it works.

Longer term I've been considering bypassing the Sargent entirely for the main leisure supply and running a Victron SmartShunt so I can actually monitor what's happening in real time. The Sargent system feels quite dated compared to modern kit — fine for basic stuff but not ideal if you want proper visibility.

Anyone else found a cleaner fix without gutting the whole system? Curious whether replacing the EC155 unit itself solved it for people or whether it's a deeper wiring gremlin.

@JubileeClipHero95 classic Sargent gremlins — seen this come up a few times across different forums.

The EC155 has a known issue where the control board itself draws a continuous quiescent current, somewhere around 10–20mA depending on age and firmware. Doesn't sound much but over 12 hours that's easily 120–240mAh gone before you've even considered anything else on the circuit.

Worth checking:

• Disconnect the EC155 entirely overnight and measure whether the drain stops — isolates whether it's the Sargent or something downstream
• Some folk have fitted a dedicated cutoff switch on the Sargent feed line as a workaround
• Also check the 12V habitation fuse board for anything piggy-backed onto the always-live rail

My narrowboat has a Victron BMV-712 which makes tracking phantom loads like this much simpler — you can watch the current draw in real time and pinpoint culprits pretty quickly. Genuinely worth fitting one if you haven't already.

@JubileeClipHero95 mine did exactly the same thing in the van — turned out the EC155 was staying "awake" waiting for a mains signal that never came, basically burning through my Fogstar 100Ah like it had a personal grudge against it 🔋😅

Slapped a simple relay on the feed so the whole Sargent unit properly dies when I want it to — problem solved, and now I can actually sleep without one eye on the battery monitor.

Worth checking with a clamp meter what the actual quiescent draw is before you go ripping things apart though — some units are worse than others and you might just have a duff one rather than it being standard behaviour.

Had the same panic with my van last winter — convinced myself I had a poltergeist until I started actually measuring things properly. Stuck a cheap clamp meter on the leisure battery cable at midnight like some kind of electrical vampire hunter and sure enough, the EC155 was quietly sipping away at ~35mA doing absolutely nothing useful.

Anyone know if there's a

@JubileeClipHero95 this took me an embarrassingly long time to track down in my cabin-on-wheels build. What finally cracked it was leaving a clamp meter on the feed overnight — saw a steady ~35mA draw that had absolutely no business being there.

Ended up fitting a Victron BMV-712 which gave me proper visibility on what was happening in real time rather than just discovering carnage at 7am. Once I could see the drain graphed out, it was obvious the EC155 was the culprit.

Worth checking whether yours has the latest firmware too — Sargent quietly updated something around the standby behaviour, though I'll be honest I'm not 100% certain it fully resolved it on older units. Some folk just wire in a small isolator switch on the EC155 supply as a belt-and-braces fix.

Bit of a tangent but has anyone checked whether the EC155 interacts oddly with a Victron BMV shunt in the same circuit? I've got a narrowboat setup rather than a van, but I'm curious whether the measurement point matters here — wondering if the EC155's quiescent draw is even showing up accurately on your battery monitors or flying under the radar.

@PeakCamper what were you actually measuring with when you caught it? Clamp meter on the negative, or something fancier?

Also genuinely asking — is the EC155 worth keeping if it's this temperamental, or would you lot just rip it out and go full Victron ecosystem? I'm spec'ing out a tiny house build alongside my boat and trying to decide whether Sargent kit is even worth considering at this point.