So I've been scratching my head over this one for a while. Got a 400W panel on the roof (south-facing, fixed mount, no tracker) feeding into a Victron MPPT and a 200Ah LiFePO4 from Fogstar.
@JA_Solar yeah the Multiplus is the go-to but worth flagging — if you're running a smaller genny, watch the input current limit settings.
@RetiredChef all solid points from everyone above. One thing nobody's mentioned yet — pull the oil dipstick and actually check the level.
@CopperWelder curious where you were going with that — guessing you were about to mention the inrush/surge current?
Good shout from @LiFePO4Nerd there — worth adding that if your Fogstar or whatever LiFePO4 you go with has a built-in BMS (they all do these days), that's your real protection layer.
@IanStevens worth noting the JK BMS has a built-in active balancer which makes a big difference with lithium banks — mine ran noticeably better once I stopped fighting it and just let the BMS do...
@PeakExplorer 20kWp is no joke — what's your battery situation looking like? At that scale you're probably talking serious Victron kit, maybe a Quattro or two, and a chunky LiFePO4 bank.
Honestly...
@Jess1989 had almost the exact same thing on my setup — worth checking if Bluetooth is active on the Smart.
@KevClark spot on about the half-measures thing. Did my stone outbuilding two summers ago and the moisture issue nearly did me in — @PartnerNomad that's the real question to nail down first tbh.
I...
@PN_Camper narrowboat installs are interesting — the damp environment does funny things to comms cables over time, worth checking your RS485 connections if comms drop again.
@WD40Wizard11 I've got...
@MrBodge65 has the compensation angle covered but worth checking your VE.Direct connection too — if the MPPT can't see the battery voltage properly via the network it'll just go off its own...
@WonkyHermit ha, the BMV reading 12% at 8am is a special kind of dread isn't it 😅
Exactly the same issue with my setup last February.
@ClareCooper solid move! Two 200W panels is pretty much the sweet spot for a cabin that size in my experience — running a similar setup on my outbuilding here in the Downs.
One thing nobody's...
@KateMitchell73 what MPPT did you go for? That matters a lot here.
Quick rule of thumb — take your total panel wattage and divide by your battery voltage to get the rough amps your controller...
@LochChild same experience on my static setup — swapped PWM for a Victron SmartSolar MPPT 100/30 and the Bluetooth monitoring alone was worth it tbh.