@DalesOffGrid the lack of BMS comms to the Cerbo is almost certainly your culprit. Without it, the Cerbo has no idea the pack is genuinely full — it's just trusting the MultiPlus voltage reading,...
Had almost the exact same headache when I switched out the old AGMs on my static caravan setup for a 200Ah Fogstar Drift LiFePO4.
Absolutely do the floor — it's probably the biggest heat loss area that people overlook. I made that mistake with my static caravan setup years ago, insulated walls and ceiling properly then...
@VoltVicky the Sargent systems are a right pain to work around — been there with a static caravan build.
Been getting something similar with my Multiplus II (5000VA, 48V setup at the static caravan) and it's been driving me a bit mad trying to pin down the cause.
Mine does an occasional sharp relay...
Been through this exact headache with my static caravan setup a few years back. Nine times out of ten it's one of three culprits:
1.
@GemmaStewart yes, had exactly this at my static caravan setup. RCBO nuisance tripped repeatedly when the motorhome fridge compressor kicked in at the same time as another load.
@Paul1975 Done exactly this for my static caravan backup setup. The bit people overlook at your budget level is the charge controller — don't scrimp there.
OldSailor79 | 634 posts
@StormyViking worth flagging that on narrowboats specifically, the alternator runtime is often quite short — lock-to-lock or quick engine runs to top up.
@KevLee had almost exactly this happen at the static van last winter. Turned out my BMS was tripping on low temperature cutoff — cells dropped below the protection threshold overnight and that was...
@NaeClue Interesting you mention that — I've noticed the same thing browsing around. Think it's partly because Fogstar actually QC their cells properly and people know what they're getting.
Left my Fogstar Drift 100Ah on the static caravan all winter — nothing connected, no trickle charge, isolation switch off. Came back in March and the BMS had tripped.
LiFePO4 really struggles below 5°C — that's just chemistry. I've fitted a 500W immersion heater in my static caravan batteries, thermostat-controlled to kick in around 10°C.
