Been running a repurposed Nissan Leaf battery pack (24kWh nominal, probably 18kWh usable at this point) as my main cabin storage for about 18 months now. Paired it with a Victron Multiplus-II 48/3000 and a Batrium BMS. Total spend was under £1,500 all in, which compared to buying equivalent Pylontech capacity is almost laughable.
Day-to-day it's been solid, if I'm honest. The Batrium catches the odd rogue cell, I've had to balance manually twice, and one module was showing early capacity fade so I bypassed it. Not exactly plug-and-play, but if you're comfortable with a multimeter and some research it's manageable. Winter performance dropped noticeably — real-world usable capacity probably down to 14kWh when ambient was around 2°C, which matters when you're running a boat diesel heater fan and LED lighting off it overnight.
What I'm sceptical about is all the people claiming these second-life packs "just work" long-term with minimal oversight. My experience is they need babysitting more than a purpose-built unit. The savings are real but so is the time investment. Anyone running these in a static cabin setup (not a van) for 2+ years? Curious whether cell degradation becomes a bigger headache over time or whether things stabilise once the weak cells have been weeded out.
