Anyone else's Fogstar Drift cells sweating in this July heat?

Checked my static caravan bank yesterday and the 280Ah EVE cells in my DIY 24V setup were sitting at 34°C — Victron Cerbo was throwing fits like a toddler in Lidl.

Been running a small 12V fan off a spare Renogy controller to circulate air under the bench, but I'm not convinced it's doing much beyond making it sound like a hovercraft in there. Temps outside hit 31°C and the cells peaked around 36°C before I throttled charge current down to 20A.

Anyone actually measured real-world thermal runaway margins on Lishen or EVE prismatic cells at these temps, or am I just being paranoid? At what point does a hot battery go from "fine" to "that's why we can't have nice things"?

Jess1972 | 📍 North Yorkshire | ⚡ 8kW solar + 30kWh DIY LiFePO4

@24VPro Ha, "toddler in Lidl" is exactly the right description for a Cerbo in alarm mode 😄

Worth checking your high temp warning threshold in the Cerbo settings if you haven't already — mine was set conservatively from the factory and was triggering at 35°C when EVE's actual upper limit is considerably higher. Doesn't fix the underlying heat issue obviously, but stops the unnecessary drama.

Also had good results tucking some reflective foil insulation around the outside of my battery enclosure this summer — kept temps down a surprising amount just by blocking radiant heat from the caravan walls. Dead cheap from any builders merchant.

What's your cell spacing like? Cramped cells in a hot box will always struggle. Sometimes just giving them a bit more breathing room makes a real difference.

EdCampbell | 📍 Aberdeenshire | ⚡ 4.2kW solar + 16kWh Fogstar Drift LiFePO4

@24VPro 34°C is warm but EVE cells generally cope up to around 45°C before you're really in trouble — your Cerbo's probably just being cautious with its high temp warning threshold. Worth checking what you've set that alarm point to in VictronConnect.

One thing I'd suggest: stick a small computer heatsink pad between any cells that are sandwiched tightly together. I did this with mine after noticing a 4-5°C differential across the bank last summer. Made a noticeable difference spreading the heat more evenly.

Also make sure your BMS isn't throttling charge current unnecessarily — sometimes it reads hotter than the cells actually are if the temperature sensor isn't properly seated against the cell body.

What BMS are you running?

BevOliver | 📍 Somerset | ⚡ 6.4kW solar + 20kWh DIY LiFePO4

@24VPro Worth checking whether your Cerbo alerts are actually set sensibly — mine were throwing high temp warnings at 30°C straight out of the box, which is far too cautious for LiFePO4. I nudged mine up to 40°C warning and 45°C shutdown, which aligns better with what EVE's own datasheets recommend.

Also, airflow direction matters more than people realise. Are you blowing across the cells or just circulating warm air around them? I run two small fans creating a proper through-flow — cool air in one end, warm out the other. Made a noticeable difference last summer when we had that brief spell of actual proper British weather. 😄

What's the ambient temperature inside the caravan itself? That's often the real culprit rather than the cells generating heat internally.

Tommo38 | 📍 On the cut (somewhere near Middlewich probably) | ⚡ 400W solar + 200Ah Fogstar Drift

My narrowboat cells hit 38°C last week and the only thing sweating more than them was me trying to explain to the missus why I'd cable-tied a 12V fan to the battery box with a bit of old bungee cord.

ZoeBurns | 📍 North Yorkshire | ⚡ 3.8kW solar + 15kWh DIY LiFePO4 (EVE 280Ah)

@24VPro Had similar last summer in my garden office setup — cells touching 36°C during a proper hot spell. What made the biggest difference for me was insulating the battery enclosure from direct radiant heat rather than just ventilating it. Mine was in a wooden cabinet that was essentially a solar oven despite the fan. Moved it inside the building and temps dropped 6-7°C immediately.

Worth double-checking your BMS high-temp thresholds too — some default settings are quite conservative and you might be getting warnings that are technically within safe operating range for EVE cells. Their datasheet quotes 45°C as the upper charge limit, so 34°C shouldn't be causing genuine problems, just alerts.

SprinterConvert | 📍 Array | ⚡ Static caravan + tiny house builds

Worth knowing that EVE cells in a static application actually accumulate heat differently to a vehicle setup — no airflow underneath, no movement to disturb the thermal layer sitting against the base. My tiny house bank hit 37°C last August just from radiant heat through the floor, cells doing absolutely nothing at the time.

I ended up cutting a vent channel beneath the battery box and running a Victron Smart Battery Sense separately from the BMS so the Cerbo was getting accurate ambient rather than case temperature. Made the alarm behaviour far more sensible overnight.

@ZoeBurns — did you find the EVE cells actually performed worse at that temp, or just the monitoring going haywire? Mine seemed fine electrically, it was purely the alerts causing chaos.

Chopper84 | 📍 Shropshire | ⚡ 2.4kW solar + 20kWh DIY LiFePO4

34°C isn't catastrophic but I'd want to keep EVE cells below 35°C ideally — above that you're chipping away at cycle life over time. One thing worth trying @24VPro is thermal mass — if you can get those cells off the floor and away from any metal surfaces that are absorbing heat from outside walls, it makes a surprising difference. Also worth checking your BMS charge parameters; some will quietly throttle top voltage when temps climb, which can look like a fault when it's actually protecting you. What's your BMS set to for high temp cutoff?

SOC_Nerd | 📍 Array | ⚡ Solar + batteries + off-grid living

My Fogstar Drift cells hit 37°C last August in a poorly ventilated enclosure — lesson learned the hard way. LiFePO4 chemistry handles it better than people panic about, but cycle life does degrade meaningfully above 35°C sustained. Worth pulling your Victron BMS data and checking if your capacity figures have drifted since installation. @Chopper84 is right to flag the threshold. If you're seeing consistent temps like that, even a basic 80mm PC fan on a thermostat controller (mine triggers at 30°C) makes a noticeable difference. Cost me about £8 off eBay.

On the narrowboat I learned the hard way that thermal mass works against you when things heat up — the cells themselves become a radiator. What actually shifted things for me was ducting the fan across the cells rather than just blowing generally into the box. Even a cheap 80mm PC fan pointed along the cell faces dropped temps 4-5°C on a hot day moored in full sun. Also worth logging your Victron data over 24hrs — sometimes the peak is brief and you'd never catch it just checking manually.