Mine's a 100Ah Fogstar Drift LiFePO4 in an old toolbox with a Victron SmartShunt bolted on — basically my shepherd's hut's emergency brain in a box.
Keeps the 12V lighting and a small inverter ticking over for about two days before I'm hunting for extension leads like a madman. Topped up by a cheap Renogy 20A DC-DC charger off the van when things get desperate.
Anyone done something similar or am I just the bloke who panics-bought batteries after the last storm knocked us out for 36 hours?
Wez1993 | 47 posts
Love this idea @SilverHiker. Mine's a bit more rough and ready — 80Ah Battle Born in a B&Q storage crate with some foam cut-outs to stop things rattling about. Velcroed a Renogy 20A DC-DC charger to the lid so I can top it up from the van when needed, which has saved me more than once.
The key thing I'd add for anyone building one is a proper fused busbar rather than daisy-chaining Anderson connectors everywhere. Learned that the hard way when I was pulling too much through a single connection running a CPAP machine overnight.
Also worth sticking a laminated card inside the lid with your fuse ratings and wiring diagram — when you're half asleep at midnight during a power cut your brain isn't exactly firing on all cylinders! 😄
Mine's evolved from something similar into a proper system now — started with a battered toolbox setup like yours @SilverHiker, but since I'm running the garden office full-time it had to grow up a bit.
Current "grab and go" is a 120Ah Fogstar Drift in a proper IP65 case with a Victron BMV-712 wired in. The key thing I added was Anderson connectors on a short whip so I can plug it straight into the van or the narrowboat when needed — same connector everywhere means no faff at 2am when everything's gone dark.
One tip: keep a small 20W panel and a basic MPPT in a separate bag. Grid's often down longest in bad weather when you can't top up from the car alternator anyway.
DucatoCamper | 203 posts
Brilliant thread! Mine lives in a large Zarges aluminium case — picked one up secondhand off eBay for a tenner. Got a 100Ah Epoch LiFePO4 inside with a Victron BMV-712 and a small Renogy DC-DC charger so I can top it up from the van if needed. That bit's been a lifesaver a couple of times when the mains has been out for days.
The key thing I'd add for anyone building one: label everything clearly and use Anderson connectors on the outputs. When you're scrambling around in the dark at 11pm during a power cut, you really don't want to be puzzling over which lead goes where. Ask me how I know 😅
@VanSue interesting that yours grew into a full system — that seems to be the natural progression with these things doesn't it!
AngliaOffGrid | 1,847 posts
Solid setup @SilverHiker — SmartShunt is the right call, knowing your actual state of charge under load is half the battle.
Worth adding a proper BMS if the Fogstar Drift doesn't already have one built in (it does, but worth checking yours is communicating properly via Bluetooth).
One thing nobody's mentioned: label your box clearly. Fuses, voltages, which terminals are which. When it's 2am and the grid's just gone down, you don't want to be squinting at bare copper wondering which way round things go.
Been running a similar 12V grab-box on the narrowboat as a secondary backup — Victron BMV-712 rather than the SmartShunt, older kit but still bulletproof.
Great first post, by the way — exactly the kind of practical thread this forum needs more of.
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