Anyone else finding the Victron MPPT Bluetooth app absolutely useless in cold weather?

Been having a real nightmare this past week with my SmartSolar 100/30. Temperatures have been dropping to around 3°C overnight here in Yorkshire and I'm finding the Bluetooth connection on the VictronConnect app just drops constantly. I've got it paired to my phone (Samsung Galaxy S22) and it'll connect for maybe 30 seconds then cut out. Happened three times just trying to check my state of charge this morning.

The controller itself seems to be working fine — I've got two 200W panels on the roof of the van and the bulk/absorption LEDs are cycling as they should, and my 100Ah LiFePO4 is sitting at 13.1V which looks healthy enough. It's purely the app connection that's the issue. I did wonder if it was just my phone but a mate tried with his iPhone and had the same problem standing right next to the unit.

Has anyone else noticed this getting worse in winter? I've seen a few mentions of it on other threads but nothing recent. Wondering if there's a firmware update I've missed or whether the Bluetooth module in these units just struggles in the cold. Should I be looking at a hardwired display like the SmartShunt or a Color Control GX instead?

@JimChapman74 Is this purely a Bluetooth connectivity issue or are you also seeing the charging behaviour change? Reason I ask — I've noticed on my motorhome setup that the SmartSolar's absorption voltage actually increases in cold temps (as it should with temperature compensation), but the app sometimes struggles to display this correctly and appears to "freeze" on the last cached reading.

Worth checking:

• Is your phone's Bluetooth also affected by cold? My old Samsung was dreadful below 5°C
• Are you connecting via the app directly or through a GX device?
• Have you tried the VictronConnect desktop version over USB instead?

Genuinely curious whether it's the hardware Bluetooth chip on the MPPT itself struggling, or just the phone side. My 100/20 has been fine here in the Midlands but we've not dropped below 6°C yet this week.

Yeah, I've noticed this too @JimChapman74 - had the same bother with mine last winter up in the Peaks. Worth checking whether your phone itself is the culprit before blaming the MPPT; cold affects phone batteries and Bluetooth radios more than most people realise. Try keeping your phone warm in a pocket for a few minutes before attempting to connect rather than going straight out to the shed with it. Also make sure you're running the latest VictronConnect firmware - there was a patch a while back that improved cold weather stability noticeably. @RetiredEngineer61 raises a good point though, the two issues might not be related at all. What's your battery bank chemistry? LiFePO4 cells behave very differently from AGM at those temperatures and that could be a separate thing worth investigating regardless of the app problems.

JakeHall76

@JimChapman74 I had exactly this with my 75/15 last February. Worth knowing that the Bluetooth chip itself draws from the unit's internal supply, and when the MPPT is cold-soaked overnight it can take 20-30 minutes after sunrise before the electronics warm up enough for a stable connection.

My workaround was dead simple - I just stopped expecting it to connect first thing in the morning. Give it half an hour once charging has started and the unit's warmed slightly, and it connects no bother.

Also make sure you're running the latest firmware - there was a VictronConnect update a while back that improved low-temperature BT stability noticeably.

@RetiredEngineer61 raises a good point though - are you seeing any actual charging anomalies, or purely the connectivity dropout? Would help narrow it down.