Charging my EV from the motorhome's lithium bank — anyone actually done this long-term?

So after about eight months of testing, I can finally report back on something I've been quietly obsessing over: running a portable EVSE (specifically a 3.6kW unit capped at 16A) off my Victron Multiplus-II 3000VA to top up my wife's Renault Zoe when we're on a rural pitch with no hookup. It works, but the nuances are worth a proper thread.

The setup is a 400Ah Fogstar Drift LiFePO4 bank at 24V, fed by 800W of roof panels and a Victron SmartSolar 100/30. On a decent summer day I can put roughly 10–12kWh into the Zoe before the bank dips below 20% SoC — enough for 40-odd miles of local driving, which is genuinely useful. The Multiplus handles the inrush from the EVSE without complaint, though I did have to tweak the PowerAssist settings to stop it tripping when clouds caused a sudden drop in solar contribution.

What I'm less certain about is the cumulative effect on cell longevity. I'm cycling the bank harder than I ever did for just 12V loads — sometimes two full cycles a day. The Fogstar BMS data looks fine, but I'm only eight months in. Anyone else running a similar high-draw application off a leisure lithium bank and tracking cycle counts or capacity fade over a meaningful period?

@PanelLouise eight months is proper commitment — respect.

Did exactly this last summer, touring Scotland in my Hymer. I've got a 560Ah Fogstar Drift bank paired with a Victron Multiplus-II 3000VA, and I pushed a Leaf through it for about three weeks of top-ups.

The thing nobody warns you about is sustained discharge rate. Topping 10–15 miles worth of range off the Leaf was fine. The moment I tried anything resembling a proper charge session, the Multiplus was sweating and my battery SOC was crashing faster than the Scottish weather.

What actually saved me was treating it like a solar harvest opportunity — only charge the EV when panels are genuinely producing, not draining the bank overnight.

What's your battery capacity? That 3.6kW draw for any meaningful duration needs serious iron behind it.

@PanelLouise this resonates deeply with my van conversion journey. I spent a whole winter agonising over whether my 400Ah Fogstar Drift bank could handle sustained 16A draws without the BMS throwing a tantrum.

What I found — and this might be useful — is that the ramp-up moment is where everything gets spicy. That initial inrush when the EVSE handshakes with the vehicle caused my Victron Multiplus to momentarily dip before settling. Solved it by dropping the transfer switch sensitivity right down in VE.Configure.

Also worth flagging: cell balancing suffers when you're doing long sustained discharge at that kind of rate day after day. Started doing a deliberate absorption hold every third day and the pack behaviour noticeably improved.

Eight months of data is genuinely rare — would love to see your State of Charge graphs if you've been logging via Cerbo GX.

Really interested in this thread — @PanelLouise eight months of data is exactly what the community needs rather than the usual theoretical speculation.

One thing I'd add from my own setup: have you noticed any pattern with your BMS cutting out during the initial inrush when the EVSE handshake completes? I run a similar arrangement and found that moment of negotiation between the car and the EVSE occasionally caused a brief spike that my Victron didn't love, particularly when the battery was already below 40% SOC.

Also curious what your solar harvest looked like across those eight months — whether you were genuinely replenishing what the EV drew or essentially just depleting the bank and relying on hook-up to recover. That balance feels like the crux of whether this is genuinely sustainable long-term or just technically possible. @Davo51 your 400Ah figure would be relevant here too!

Eight months of data and I still can't convince myself to plug my e-bike into the motorhome without having a small existential crisis, so fair play @PanelLouise.