@WelshVanLifer classic cold weather issue this. The Multiplus II has a low temperature cutoff and if your battery bank dropped below around 5°C it'll protect itself.
@ZoeGrant with a 140A alternator the 30A is fine — you won't be stressing it. The real question is your battery.
Same issue last winter with my setup. The JK default low-temp cutoff is around 5°C which is frankly useless for UK winters.
Worth doing two things:
Lower the protection threshold in the JK app —...
Wez1961 | 1,204 posts | 🔋 Off-Grid Veteran
@RockyMaker post got cut off but I'll take a stab anyway — classic symptom with the 12/3000 is the DC cable run being undersized.
Wez1961 | 1,204 posts
Eight months on Fogstar tracks with my experience — mine's been running the garden office for nearly two years now, no complaints.
One thing nobody's mentioned: ambient...
@BatteryDoug makes a fair point on temp. One thing nobody's mentioned — check the cell balance after a full charge.
The key thing most people miss — the Victron doesn't need to talk to the BMS, it just needs to respect the voltage limits the BMS is protecting.
Set your SmartSolar absorption/float to match the...
Wez1961 | 1,203 posts
@GemmaFisher82 The relay is doing nowt useful if your B2B is properly sized. Split-charge made sense with lead-acid because voltage-based isolation worked fine — lithium's...
Been running my garden office off-grid for about 18 months now. Currently got a 400W solar array feeding into a Victron SmartSolar MPPT, with a 200Ah Fogstar lithium battery.
Victron's VRM recovery process is actually pretty straightforward if you go direct — just raise a ticket via their vrm.victronenergy.com support portal.
@DodgyCaptain two Multiplus 2s in parallel is perfectly doable but make sure they're the exact same firmware version before you try — Victron are fussy about that.
@SmartSolarNerd the Fogstar Drift cells themselves won't affect the BMV readings — the shunt doesn't care what chemistry's behind it.
Yeah, the CAN bus throttling is annoying but there's a practical workaround. Have you isolated the DC-DC charger from the engine's CAN network?
@BayTim the angle thing @BoatLouise mentions is critical for winter. I'd aim for 45-50° if possible on a caravan. Rule of thumb: size for winter worst-case, not summer.
Spot on from everyone above. What's mad is how much phantom load creeps in once you actually see it logged.
