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

Had exactly this with my SmartSolar 100/30 last winter. Drove me absolutely mental for about three weeks before I figured it out.

In my case it was the Bluetooth dropping rather than the actual MPPT losing connection to the panels — worth clarifying which one you're seeing. If it's just the VictronConnect app losing comms overnight, that's fairly normal behaviour honestly. The dongle goes into a low-power state when there's no active session.

If it's the actual charge controller disconnecting from the battery or panels, that's a different beast entirely. A few things worth checking:

• Loose MC4 connectors — had one that would expand/contract with temperature changes and cause intermittent drops
• Battery voltage dipping overnight and triggering a protection threshold
• Firmware — Victron pushed an update a while back that fixed some stability issues on the SmartSolar range

What does your VRM history show? If you're logging to the portal you should be able to see exactly when the drops occur and what the state was just before. That'll narrow it down massively.

Also — are you using a GX device or just standalone? If standalone, the Bluetooth logs in VictronConnect will only go back so far so you might be missing context.

What's your setup — panel wattage, battery bank, cable runs? Might help people here give more specific advice. Others must have seen this, it comes up every few months on here.

@HazelPaddy worth checking whether it's the BT connection dropping or the MPPT actually resetting — two very different problems.

On my garden office setup I had the MPPT itself resetting overnight, turned out to be a loose negative on the battery side causing micro-interruptions. Tightened everything down with proper torque and it sorted itself completely.

If it's genuinely the unit resetting rather than just Bluetooth, check your VRM history — you'll see an uptime counter reset if so. Also worth looking at whether it's temperature related; my SmartSolar behaves differently below about 5°C but it's never outright dropped.

What firmware version are you running? Some earlier builds had stability issues that Victron quietly patched.

@VoltWill finishing your sentences is basically a full-time job on this forum 😄

But yeah, solid distinction. Easy way to tell: check your VRM portal history. If the MPPT data is continuous overnight but your phone just lost the Bluetooth, the unit itself never dropped — your phone's battery optimisation quietly murdered the connection.

Android is *particularly

@VoltWill and @CotswoldNomad both making half-points there — fitting really.

Had the same saga on my narrowboat last February. Turned out the Victron Connect app on my phone was just going to sleep and throwing a wobbler about it. The MPPT itself had been happily chuntering away all night like nothing happened.

@PanelSteve narrowboat here too — this is a recurring headache on boats specifically. Vibration can work connections loose over time, so even if your wiring looked fine initially, worth pulling the terminal covers off and checking everything's properly torqued down.

Also worth checking whether your SmartSolar is on the latest firmware. Had a unit on my boat that was dropping Bluetooth every night until a firmware update via VictronConnect sorted it. Took about 10 minutes.

If it is actually resetting rather than just BT dropping, check your battery voltage overnight — if it's dipping below the controller's low-voltage cutoff and recovering, that cycle can look like a fault when it's actually working as intended.

@SimonThompson vibration loosening connections is a real one — had similar in the van before I sorted proper crimped lugs everywhere. Boats must be brutal for that.

Worth adding: temperature swings overnight can cause the same grief even without vibration. Terminals expand and contract, suddenly you've got a dodgy contact that's fine by 10am when everything warms up again. Classic red herring that one 🎣

Check your torque settings on all the terminal screws too — Victron actually publish recommended values in the manual and most people (including past me) just do them "feels about right" tight.