Anyone else using their off-grid setup to charge an EV? Curious about real-world numbers

Had an interesting weekend at the shepherd's hut. Finally got round to testing whether my 2.4kWh Fogstar Drift battery bank (paired with 600W of panels) could meaningfully charge my Nissan Leaf overnight via a standard 3-pin feed into a portable EVSE. Short answer: not really, no.

The Leaf drew the bank down to about 20% by 3am even with a near-full charge going in at dusk. I've got a Victron SmartSolar MPPT 100/30 handling the solar side, and the charge controller was obviously doing nothing useful in the dark. Added maybe 8km of range to the Leaf. Felt a bit pointless if I'm honest.

What I'm trying to work out is whether it's worth scaling up the battery to something like 10kWh (looking at Fogstar or possibly a DIY LiFePO4 build) and adding another 400–600W of panels. The hut is in Somerset so usable solar hours are... optimistic at best between October and March. Has anyone actually crunched the numbers on whether off-grid EV charging is viable in the UK without grid backup, or are we all just fooling ourselves?

Also curious whether anyone's tried throttling charge rate via a Victron Cerbo GX and some kind of smart EVSE — seems like the logical approach but I haven't seen many UK builds doing this properly.

Hey @SomersetVanLifer, great experiment! I've been doing something similar with my Leaf and a 3kWh Pylontech setup. Honestly the overnight trickle approach works surprisingly well in summer, but come November you'll want to temper expectations - my panels were barely pulling 800Wh on a decent December day up here in Yorkshire.

The Leaf's 3.3kW onboard charger is actually your friend here because you can't accidentally pull more than your system handles - just use a standard 3-pin granny cable throttled right down. I typically net 8-12 miles overnight in decent conditions, which covers my village errands easily enough.

One thing worth checking - what's your Fogstar's max continuous discharge rate? That'll be your real limiting factor more than panel output.

Really interesting thread. I've been wondering about this for my garden office setup — currently running a Victron MultiPlus with a 5.1kWh Fogstar battery, mostly just powering tools and lighting. Always assumed EV charging was a pipe dream from a small off-grid bank.

@SomersetVanLifer what EVSE are you actually using to throttle the charge rate down low enough? I've seen some Type 2 units that can go as low as 6A but wondering if there's something more controllable for this use case.

Main concern for me would be the depth of discharge hit overnight — especially in winter with my panels barely producing. Are you finding you're essentially just topping up a few miles rather than doing anything meaningful, or does it add up more than expected across a full weekend?

Really useful thread this. @SomersetVanLifer the overnight angle is key I think — you're essentially just capturing whatever the battery's stored rather than relying on live solar generation, so your panel size matters less than your usable capacity.

One thing worth factoring in that I haven't seen mentioned yet is the Leaf's onboard charger efficiency. You're losing roughly 10-15% to heat before it even hits the traction battery, so your actual "miles added per kWh from the bank" will be lower than the Leaf's quoted efficiency suggests.

@Macca97 for a garden office hybrid setup a Multiplus would handle this brilliantly — you could prioritise the office loads during the day and only allow EV charging once the battery hits a decent state of charge. Victron's ESS assistant makes that kind of logic fairly straightforward to configure.

Great thread @SomersetVanLifer. One thing worth factoring in is the Leaf's onboard charger efficiency — you lose roughly 10-15% to heat during AC charging, so your actual usable miles gained will be less than the raw kWh figures suggest.

I've found the sweet spot with EV top-ups off-grid is targeting that 20-80% SOC window anyway, which plays nicely with smaller battery banks since you're not trying to do a full charge in one hit.

@Macca97 the Victron Multiplus should handle this well — you can set input current limits sensibly so it doesn't hammer your battery bank trying to satisfy the Leaf's full charging demand. Worth dialling that down in VE.Configure if you haven't already. Keeps everything happy overnight without stressing the system.

Good shout from @Tommo30 on the onboard charger losses — worth remembering the Leaf's 3.3kW charger (on older models anyway) has a minimum draw threshold too, so if your inverter can't sustain that cleanly you might get the car refusing to charge altogether or throwing a fault. Learned that the hard way with a friend's setup.

@SomersetVanLifer what inverter are you running? That'll be the real bottleneck I'd imagine. A decent pure sine unit should handle it but some of the cheaper modified sine inverters really struggle with EV chargers. Also worth checking whether OCPD sizing on your supply cable is matched up — 600W of panels into 2.4kWh is fairly modest for overnight EV top-ups but for range anxiety top-ups rather than full charges it's absolutely viable in summer.

Right, I'll wade in here because this is basically my life on the boat 😄

I charge a Renault Zoe off a Victron Multiplus-II with roughly 10kWh of Fogstar cells behind it, and the honest truth is: it's a game of expectations.

What actually works brilliantly is setting a charge limit — I never ask the car for more than 15-20 miles worth overnight. That's totally achievable without hammering your bank.

The bit nobody mentions is the minimum charge current problem. Some EVs won't accept below 6A on AC, which on a 230V supply is already 1.38kW. If your inverter is wobbling under load or your SOC is low, the car just... refuses and sits there smugly doing nothing.

@Thommo75 is spot on about older Leaf charger losses too — factor in 15% and you won't be disappointed come morning.

Interesting thread — got me wondering about the maths on my own setup.

@Kingy your Zoe-off-a-Multiplus situation sounds chaotic but brilliant.

Quick question though — when you're doing this on the boat, are you factoring in the extra load from everything else running simultaneously? I'm thinking fridge, nav electronics, the inevitable

Great thread this, really useful real-world data coming through.

One thing nobody's mentioned yet — the Leaf's traction battery management system can be surprisingly fussy about charging consistency. When I was experimenting with mine off a modest solar setup, I noticed the BMS would occasionally throttle back or stop altogether if the input got wobbly during cloud cover. Sticking a decent sized buffer battery between the panels and the EVSE made a massive difference rather than trying to go semi-direct.

@Kingy curious whether you've noticed similar behaviour with the Zoe, or does the Multiplus smooth things out enough that the BMS never even sees the fluctuation?

Really useful thread this. @SomersetVanLifer your 2.4kWh bank is always going to struggle for meaningful EV top-ups overnight — you're essentially robbing Peter to pay Paul once you factor in your hut's base load.

Worth looking into scheduled charging if your Leaf supports it — set it to only pull amps during peak solar hours rather than overnight. Even a modest 6A through a 3-pin adds up across a sunny afternoon without hammering your battery reserves.

@Nobby30 good shout on the traction battery — curious what you were going to say there, don't leave us hanging! 😄