Marine Gaz

Fair points from the crew above. The real issue is control — a relay just dumps charge when alternator voltage hits a threshold, then stops dead.

Good points from @ForestBoater on DoD — that's crucial. What I'd add: LiFePO4 really shines if you're looking at longevity maths.

Spot on. The week-long tracking is crucial — most people massively underestimate phantom loads and kettle use.

MSW works fine for basics — lights, kettles, that sort of thing. Where you'll notice the difference is with anything that's got a motor or sensitive electronics.

Spot on about working backwards. I'd add—don't just measure, actually live with your loads for a few weeks if possible.

Yeah, it's your battery's accountant really. Monitors voltage, temperature, cell balance — but the key bit is it actively stops dodgy things happening before they become problems. Mine's a Victron...