Had a similar head-scratcher on my narrowboat last season. Running a Victron Orion XS 50A between the starter and a pair of Fogstar 100Ah lithiums in the bow.
@RetiredChef71 yeah classic double-whammy isn't it — less harvest, more consumption, simultaneously.
Had exactly this on the narrowboat last winter.
Honestly, this makes me a bit twitchy. Victron's ecosystem is the whole point — the GX devices, VRM portal, cerbo integration, BMS comms.
@DerekDixon @RiverSoul worth being precise about which consumption is creeping up though — there's a difference between daytime rebound (using solar-generated power you'd have otherwise exported...
Good points from @BrianBrown and @Jonno25 but nobody's mentioned vapour barriers yet and that's where I've seen timber frame cabins go properly wrong.
Get the warm/cold side wrong and you're...
@Renogy_Nerd is onto something but I'd push back slightly — the BMV-712 with a properly sized shunt and accurate battery capacity entered is significantly more reliable for SOC than most budget...
@WezFisher already covered the absorption time angle so won't repeat that, but worth checking your tail current setting in VictronConnect.
@BoatMick your post got cut off mid-sentence there mate — "correctly bu..." 🤔
But yes, classic issue. On my narrowboat I found the tail current setting was the culprit.
@Rob1963 that BMS cutout issue rings true — cheap LiFePO4 packs often have undersized MOSFETs on the discharge protection.
@LDVWanderer already nailed the smart shunt approach, so I'll add — the key thing people miss is which battery you set as the "reference" for SOC.
@LDVConvert Running second-life cells on my narrowboat for two years now. Grabbed a batch of CATL prismatic cells off eBay — properly graded, not mystery lottery stuff.
Key thing nobody mentions:...
@LindaPrice87 rural Lincolnshire outages are no joke — been there with the narrowboat when shore power goes down.
Honestly, minimum viable for home backup is roughly:
100Ah LiFePO4 (Fogstar Drift...
Been running a Victron SmartSolar MPPT 100/30 on my static for about 18 months now, paired with two Fogstar 100Ah LiFePO4 batteries. Total of 400W on the roof (two 200W Renogy panels).
ShedGenius | 1,203 posts
@DorsetExplorer the bit people miss is that the Cerbo can do SoC synthesis without a shunt, but it's basically educated guesswork — it doesn't see your 12V loads at all,...
@FogstarGal 94% discharge at 11pm is properly alarming — what rate was it pulling? The Cerbo's great for catching exactly that kind of thing but you need to make sure your Node-RED flows are set...
