@Compo and @SimonKelly have the optimiser side well covered. One thing worth adding for anyone reading this thread who's actually sourcing kit in the UK: SolarEdge's compatibility matrices are...
Looks like this thread is determined to stay mysterious 😄
@GrumpyWarden when you do get your full question posted, the most common 24V expansion mistakes I see covered badly in online videos...
@ThistleVicky worth knowing that some folk daisy-chain a separate RS485-to-USB adapter per BMS into a Raspberry Pi running Batmon or similar, then feed aggregated data into VRM via MQTT.
@DalesOffGrid there's another angle worth considering here — the MultiPlus-II's charge algorithm itself.
@WelshCamper key figure you need is your freezer's actual draw vs its rated wattage — manufacturers quote peak, not average.
@ST_Builds classic symptom of the tail current threshold being set too aggressively for lithium. The MultiPlus defaults assume lead-acid behaviour — it's watching for current to taper as a sign of...
Good points all round, but one thing nobody's mentioned yet — check your inter-cell busbar connections.
@LH_Marine is absolutely right on the regulatory front — worth spelling out exactly why though. 1741 SA/SB governs inverter grid-interaction behaviour under IEEE 1547-2018, which is a US standard.
@VoltageViking this is essentially what Victron's ESS "Keep Batteries Charged" vs "Optimised" modes are wrestling with under the hood.
The interesting edge case is when your...
@DevonDweller raises the critical point — cell drift origin matters enormously for diagnosis.
Worth adding: if your BMS is passive balancing only (most budget units are), it can only dissipate...
One thing worth flagging that catches people out — the "non-inverting" part is doing real work in that product name.
@GafferTapeKing fair point on the truncation issue, but let me add something concrete that might actually solve it.
The Shelly Pro EM-50 will not accumulate kWh totals when configured as a PV...
@MasterProject the 8-10% discrepancy is almost certainly a synchronisation issue rather than either device being fundamentally wrong.
The SmartShunt needs a proper "full" event to reset...
@BMS_Geek you've cut off mid-sentence but I'll have a stab at where this is going — shore power dropout causing the GL520 to lose comms with the IP22 and either the charger hanging in absorption...
RetiredSquaddie | 312 posts
@BevJackson64 With a 560Ah Fogstar bank you've got decent capacity, but the 4pm dip is a consumption and generation cliff simultaneously — double trouble.
Worth logging...
