Victron MPPT keeps dropping connection overnight — anyone else had this?

Had this exact issue with my SmartSolar 100/30 last autumn. Drove me mad for weeks.

Turned out it was the Bluetooth dropping rather than an actual connection fault — the VictronConnect app was just losing its link overnight when my phone screen timed out. The MPPT itself was working fine, just looked like it had "dropped" when I checked in the morning.

Few things worth checking:

• Firmware — make sure you're on the latest version via VictronConnect. There were some known BT stability issues in older builds
• VRM portal — if you've got a Cerbo GX or even a cheap Raspberry Pi running Venus OS, you can log data properly overnight and see exactly what's happening
• Temperature — my shepherd's hut setup gets properly cold overnight and I noticed some odd behaviour when the battery temp sensor wasn't reading right

If it's actually cutting out rather than just losing BT visibility, I'd look at the wiring first. Loose MC4 on the PV input can cause intermittent dropouts that look like a controller fault.

What's your setup — are you monitoring via Bluetooth direct or through a GX device? Makes a big difference to how you'd diagnose it.

Also, is it resetting completely or just showing a gap in the data? Those are two very different problems and worth being clear on before assuming the unit itself is faulty.

Reply by JennyPalmer

@TracyKnight — yes, had almost the identical thing with my 75/15 last winter! Worth checking whether it's actually a functional fault or purely the app losing its Bluetooth handshake overnight. The two feel the same from the outside but are completely different problems.

One thing that caught me out: if your phone's battery optimisation is set aggressively, Android (and sometimes iOS) will kill background Bluetooth connections after a period of inactivity. Go into your battery settings and whitelist the VictronConnect app specifically. Made a massive difference for me.

Also double-check your controller's firmware is current — there was a patch a while back that improved Bluetooth stability noticeably. Connect via USB if needed to rule out whether the controller itself is actually dropping or just the wireless side.

@TracyKnight @JennyPalmer — worth noting it's not actually dropping connection at all, technically. The MPPT goes into a low-power sleep state overnight when there's no solar input, and BT advertising slows right down or stops entirely.

Completely normal behaviour — Victron designed it that way deliberately to save parasitic draw.

If you want persistent monitoring overnight, you need a GX device (Cerbo, CCGX etc.) hardwired via VE.Direct. That keeps logging 24/7 regardless.

Running a Cerbo GX on my narrowboat for exactly this reason — makes a massive difference if you're obsessive about overnight discharge data like me 😄

The VictronConnect app reconnecting in the morning then showing a "gap" in history is the giveaway that it's a BT issue rather than anything actually wrong with the unit.

Reply by EcoFlow_Gal

@PanelGraham is right actually — though I'd add, the VictronConnect app specifically has a known thing where it'll show as disconnected on iOS if the phone screen locks. Nothing wrong with the unit itself.

Mine did this all last winter at the cabin. SmartSolar 100/20 btw, not the 30 but same firmware basically.

Check your Bluetooth timeout settings in the app — there's a parameter buried in the settings menu (can't remember exactly where, sorry) that controls how long it stays "visible." Changing that sorted it for me.

Also worth making sure your VictronConnect is fully up to date. The older versions were genuinely worse for this. Apple specifically seemed to cause more grief than Android from what I've read on the Victron community forum.

Reply by CraigCross

Had something similar catch me out on the narrowboat a couple of winters back — same 100/30 unit. Spent an embarrassing amount of time convinced something was genuinely failing overnight.

What I'd add to what's already been said: if you're running the app on an older Android device, the background Bluetooth behaviour is notoriously aggressive about killing connections to save battery. Took me ages to track that down.

Worth going into your phone's battery optimisation settings and explicitly excluding VictronConnect from any power-saving restrictions. On my setup that alone stopped the phantom dropouts entirely. The MPPT itself was behaving perfectly throughout.

@CraigCross narrowboat here too — this trips up so many people because Victron's own documentation isn't exactly crystal clear on what "connected" actually means in the app vs the device state.

Worth double-checking your VE.Direct cable if you've got one running to a GX device alongside Bluetooth. Had a situation on mine where both were fighting for priority and the app was showing stale data from whichever source it grabbed first. Looked like a dropout, wasn't.

Also — firmware. The 100/30 had a couple of dodgy releases a while back. Check you're on the latest via VictronConnect directly, not just assuming it auto-updated. It doesn't.