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

Had this exact issue on my static caravan setup last summer and it drove me absolutely mad trying to track it down.

Mine turned out to be the VE.Direct cable rather than the MPPT itself. The connection at the controller end was slightly loose and any temperature drop overnight was causing it to lose contact intermittently. Swapped the cable out and it's been solid ever since.

A few things worth checking:

• VE.Direct cable seating — give both ends a firm push and check for any corrosion on the pins
• Bluetooth dongle vs wired — are you using the Smart dongle or a direct VE.Direct to USB connection? The dongle can be flaky in cold temps
• Firmware — worth checking you're on the latest version via VictronConnect, there were some known BT stability issues in older builds
• Phone Bluetooth — sometimes it's actually your phone dropping the connection rather than the MPPT itself

What MPPT are you running? I've got a 100/30 and the Bluetooth range isn't great through the caravan walls, so positioning matters more than you'd think.

Also worth checking whether it's actually dropping connection or just going into night mode and the app not refreshing properly — caught me out more than once thinking there was a fault when it was just normal behaviour.

Has anyone else noticed this getting worse in winter specifically? Wondering if temperature is a common factor here or whether there's something else going on.

FinnThomas | 847 posts | ⭐ Trusted Member

@Chopper42 Good shout on the VE.Direct cable - those connectors are surprisingly fussy. One thing worth adding though: if you've already ruled out the cable, check whether your MPPT is going into a low-power sleep mode overnight and struggling to re-establish comms when the Cerbo or whatever you're monitoring with wakes back up.

I had a similar issue on my narrowboat setup where the problem was actually the USB adapter I was using with VE.Direct to USB - certain cheaper adapters drop the connection when there's no data activity for a while. Swapped it for the genuine Victron one and it's been solid ever since.

Worth also checking your firmware is current on both devices - there were some known comms stability fixes in recent Victron releases.

PanelRoger | 312 posts | 🔆 Member

Had identical grief in my shepherd's hut last winter — turned out the VE.Direct port on the Cerbo was slightly loose, not the cable itself. Worth wiggling the connector at both ends while watching the app — if it flickers, you've found your culprit without buying anything. Also worth checking if the dropout coincides with temperature drops overnight; thermal expansion plays havoc with dodgy connections. My emergency backup setup taught me to always keep a spare VE.Direct cable handy because Victron gear is brilliant right up until it isn't. 🐑

MarshLover | 156 posts | 🔆 Member

Got a shepherds hut setup myself @PanelRoger so this thread is relevant to me!

One thing nobody's mentioned yet — check your Bluetooth dongle if you're using one rather than VE.Direct. Mine was doing something similar, kept losing the device in VictronConnect around 3-4am. Thought it was a cable issue for weeks.

Turned out the dongle was going into some weird low-power state. Firmware update on the MPPT sorted it completely. Victron's firmware release notes are worth scanning through if you haven't already.

Also worth ruling out whether it's actually dropping connection or just that the MPPT is going into float/absorption and the app is misreading the state change as a disconnect. Caught me out once embarrassingly 😅

Pylontech_Queen | 1,203 posts | ⭐ Trusted Member

Something nobody's mentioned yet — check your Venus OS device logs if you're running a Cerbo or similar. Mine was dropping the MPPT connection every night around the same time, and the logs revealed it was actually a memory leak in an older firmware build rather than anything hardware-related at all.

Pulled my hair out for weeks blaming cables and connectors before I spotted the pattern. Updated the Cerbo firmware and it vanished completely.

Worth cross-referencing the exact dropout times against sunset — if it's consistently happening at dusk when the MPPT transitions from bulk/absorb into float or idle, that's a different conversation entirely and points toward the device going into a low-power state and the comms timing out.

Two very different root causes, same symptom on the surface.