Anyone else's battery monitor acting dodgy when it's cold?

Yeah, mine's been a right pain in the arse lately. Victron BMV-712 here, and when temps drop below about 5°C the voltage readings start drifting — nothing dramatic, but enough to mess with your state of charge calculations.

Figured it was dodgy connections at first, so I cleaned all the terminals and checked the shunt resistance. Nope. Turns out it's just the sensor getting grumpy in the cold. The manual mentions it but buried in the fine print, naturally.

What I've noticed: the issue's worse on first light when everything's frozen solid, then settles down once the battery box warms up a bit from the inverter running. My solution's been bumping the monitor brightness up and double-checking the numbers against actual load testing before I make any decisions about charging or discharging.

Some of you might have better solutions though. I've heard a few folks mention wrapping their monitor enclosures in insulation or shifting the shunt placement, but haven't gone down that route myself yet. Battery's in a reasonably sheltered spot so it's not too extreme.

Curious what kit you're all running and whether you've had the same grief? Particularly interested if anyone's fixed this properly rather than just working around it. Thinking about adding a small heating pad before winter gets any nastier.

Had exactly this with my BMV-712 last winter. The shunt itself is fine, but the display unit's got temperature compensation built in — sounds like yours might need recalibrating or the shunt's losing contact resistance in the cold.

Quick checks:

• Clean the shunt terminals with a wire brush, corrosion causes resistance drift
• Check your cable connections aren't loose — even tiny movement creates noise
• What's your ambient temp sensor reading? If it's not picking up actual conditions, compensation goes haywire
• Battery temp sensor working properly?

Mine sorted itself once I moved the shunt closer to the battery and reseated all connections properly. Also worth checking if you've got dodgy crimps on the sense wires — they're thin and easy to miss.

What's the voltage drift doing exactly — reading high or low?

Ah, the classic cold-weather gremlins! @DodgyMechanic's spot on about the display unit being the culprit. The BMV-712's internal temperature sensor drifts when it gets chilly, which throws off the voltage compensation and makes your SOC reading look like it's having an existential crisis.

Quick fix: if your shunt's mounted outside the cabin (which, let's be honest, most of ours are), the display unit should ideally live somewhere warmer. Even a small insulated box with passive thermal mass helps. I've got mine in the porch and it's sorted the problem entirely.

Worth checking your calibration too — sometimes a full reset and recalibration after a cold snap does wonders. Also verify the shunt connections are absolutely bombproof; loose terminals get grumpy when the temperature drops.

Is your shunt tucked away somewhere properly cold, or is it at least somewhat sheltered?