Off Grid Victron probleme chargement PV

Had a similar head-scratcher with my Victron setup a while back, so thought I'd share in case it helps anyone else troubleshooting.

Running a Multiplus-II 48V with a SmartSolar MPPT 150/35 and a bank of AGM batteries. My panels are wired as 2S2P — two strings of two in series. Should be generating decent wattage on a good day, but I kept seeing the MPPT barely pulling anything meaningful even when the sun was cracking.

Turned out my issue was a combination of:

• Battery absorption voltage not set correctly for my AGM bank — it was defaulting to a profile that wasn't quite right
• The MPPT and Multiplus weren't properly synced via VE.Smart networking — once I got that sorted through the Victron Connect app, both devices started talking to each other properly and charging made a lot more sense

Worth checking your VEConfigure settings on the Multiplus too — sometimes the charge current limits interfere with what the MPPT is trying to do.

Also, if you're not already using VRM Portal, get it set up. Makes diagnosing this stuff so much easier — you can see exactly where the charging cycle is at any given moment.

Anyone else had grief with AGM profiles on Victron kit? I find lead acid setups need a bit more fiddling than lithium to get dialled in properly. Curious whether anyone's switched from AGM to Fogstar or similar LiFePO4 and found the charging behaviour more straightforward — tempted to make the jump eventually.

Great thread idea @MoorCamper! These Victron setups can definitely throw some curveballs.

One thing worth checking that catches people out - make sure your DVCC settings are properly configured in VenusOS if you're running a Cerbo GX or similar. When the Multiplus-II and SmartSolar are both connected via VE.Bus/VE.Direct, DVCC essentially hands charge control over to the system rather than each device acting independently. If it's misconfigured you can get the MPPT appearing to underperform or oddly throttling back.

Also worth confirming your battery voltage sense is coming from the right source - sometimes the MPPT and Multiplus disagree slightly on voltage readings and it causes the charging to behave unexpectedly.

What firmware versions are you running on both units? Some earlier builds had known quirks that were ironed out in later releases.

When my SmartSolar started playing silly beggars, turned out VE.Bus and VE.Direct were having more of a domestic than my actual neighbours — check your cable polling intervals in VictronConnect before you tear your hair out. 🔌

Good shout from @WayneKnight on the VE.Bus conflicts — been there on my boat setup.

One thing nobody's mentioned yet: check your battery voltage sense settings. If the MPPT is using its own terminal voltage rather than the shared network voltage (via VE.Smart Networking or VE.Bus), you can get the MPPT throttling back prematurely because it thinks the battery is fuller than it actually is.

In VE Connect, make sure:

• SmartSolar is joined to the same VE.Smart Network as your BMV/SmartShunt
• Battery voltage sense source is set to the BMV, not the MPPT itself

Also worth checking your absorption voltage matches across all devices — if they're conflicting by even 0.2V it causes weird behaviour. Victron's own documentation on this is decent but easy to miss first time round.

Great points all round. One thing I'd add — check your battery voltage calibration between the MPPT and Multiplus. If they're reading slightly differently, the Multiplus can override the MPPT's charge decisions because it thinks the batteries are fuller (or emptier) than they actually are. Easily done with a decent multimeter directly across the terminals, then tweak the calibration offset in VictronConnect accordingly.

Also worth having a look at your absorption time settings — if it's cutting short, the MPPT might appear to be "not charging" when it's actually just sitting in float earlier than expected. Caught me out for a good fortnight before I clocked it! 😄

@MoorCamper what firmware versions are you running on both units? Sometimes a mismatch there causes odd handshaking behaviour that's dead simple to fix with an update.