Solar not charging the battery. MPPT 11 I 20

Seen a few posts lately about MPPT controllers going a bit funny after firmware updates, and it's got me thinking about something similar that happened on my narrowboat last spring.

I'd left the boat on the moorings over winter with a Victron SmartSolar 100/30 ticking away, came back to find the batteries (Fogstar 200Ah LiFePO4s) sitting at around 20% and the MPPT showing absorption voltage but absolutely zero current going in. Panels were fine, wiring checked out — turned out a firmware update had somehow reset the battery profile back to AGM defaults, so the charge voltages were completely wrong for lithium. The BMS was just rejecting the charge entirely.

Worth checking a few things if you're in a similar boat (no pun intended):

• Pull up the VictronConnect history — does it show any charge current at all, or has it flatlined since the update?
• Check your battery preset — has it reverted to a factory default profile?
• Look at the bulk/absorption/float voltages — if they've dropped to AGM territory (say 14.4V absorption instead of 14.6V), your BMS may simply be refusing the charge
• What's the panel voltage showing? If it's reading 0V or open circuit, you may have a separate wiring gremlin

There's also a known issue where some MPPT units go into a "protection" mode after a bad flash — a full reset via VictronConnect can sometimes sort it.

What firmware version were you on before, and what did it update to? That might help narrow it down. Anyone else had MPPT charge profiles wiped by an update?

@RustySpanner the "11 I 20" fault on a Victron MPPT is almost certainly a internal protection trip — usually thermal or an input overvoltage event. Worth connecting it up to VictronConnect via Bluetooth and pulling the history tab; it logs exactly what caused the shutdown.

Before you assume firmware, check your PV open-circuit voltage against the controller's rated maximum. If you've got panels in series and the morning cold-soak voltage is pushing past the limit, that'll trip it reliably. I've seen this exact scenario on my cabin setup — added a third panel in winter and started getting intermittent faults until I reconfigured to parallel.

Also worth doing a full reset: hold the MODE button for 10 seconds. Sometimes clears ghost faults after a firmware push without needing to dig deeper.

What's your panel configuration and controller model exactly?

@WezWhite72 is on the right track with the thermal trip angle.

Worth checking the obvious first though — is the MPPT actually mounted somewhere sensible, or is it bolted to a sun-facing bulkhead like some kind of ironic solar protest? Narrowboats are notorious for this. Had the same issue on mine, controller was basically slow-

@RustySpanner had almost the exact same issue on my motorhome last summer — MPPT just sat there doing nothing after I'd left it parked up for a couple of weeks in warm weather.

What nobody's mentioned yet: have you checked whether the battery BMS has gone into protection mode and is basically presenting a "full" or disconnected state to the MPPT? My Fogstar Drift cells had locked out and the Victron was seeing no load to push power into, so it just... stopped.

Bit of a chicken-and-egg fault to diagnose because both ends look fine individually.

Can you see live battery voltage in the Victron Connect app? If the MPPT is reading a realistic voltage but still showing absorption or float when the battery's clearly low, that's your clue something upstream is wrong rather than the controller itself.

@RustySpanner one thing nobody's mentioned yet — check whether the battery voltage showing on the MPPT matches what your battery monitor is actually reading. I had a duff connection on my narrowboat that was causing a false high voltage reading at the controller, making it think the bank was full when it wasn't.

The 11 I 20 display specifically can sometimes indicate the unit's gone into a protection mode triggered by a voltage discrepancy rather than pure thermal. Victron's VictronConnect app will give you the historical data log if you can connect via Bluetooth — worth pulling that before assuming the hardware is dead.

Also worth ruling out whether a firmware update auto-applied. Victron pushed a few dodgy ones last year that caused similar symptoms. Check the firmware version against the known stable releases on their community forum.

@FrostySailor raises a good point — my Victron SmartSolar in the shepherd's hut shows phantom voltages sometimes, like it's auditioning for a ghost show.

Also worth checking: is the MPPT stuck in BULK forever with zero amps going in? Classic sign the controller's lost its mind and thinks the battery's already full when it's reading a false surface voltage — disconnect the panels, wait five minutes, reconnect, and see if it kicks itself back into gear.