Dead Honda e

[Verone]

The 12V has me worried now too though . Maybe a future update will fix that.

Honestly, I was worried about the 12v too, but I've had mine since May, and no sign of any issues, despite having a dashcam pretty much hard-wired in. I'm not sure what's caused this issue with quite a few of the cars, but I've not heard of anyone here in Iceland having the issue at least.

It sounds to me like there's some form of parasitic drain, or people are spending a decent amount of time sat still in the car with the 12v battery powering the accessories.

I always make sure to plug my driver's seatbelt in when doing this so that the HV system keeps the 12v topped up.

[ZeroEmissionRequiem]

Dealership called me; Honda asked them to ask me if my car notified me of an OTA update before the 12V battery died. It did.

I got the impression they're indeed suspecting a connection between the two now.

The dealership contacted me again and said they've received information from Honda in Japan; apparently the OTA update will keep running and draining the 12V battery until it goes through.

Indeed, this is how it went in my case:
2023-11-08: Car successfully downloaded the update, but never progressed beyond step 4/6 (preparing to install).
2023-11-09: I drove for two hours in total, and plugged the car in late evening. Update was still stuck on the same step.
2023-11-11: Car was dead.

The update finally completed maybe 4-5 days later, can't remember when I noticed the notification icon had disappeared.

[MaXPainT]

Thanks for the update! Did you allow updates to be installed when the car is turned off? There was a prompt before the OTA. Maybe, it is a good idea to disable the option. I would rather spend five minutes waiting for the update to be installed than find my car with a dead 12v battery.

[Verone]

Thanks for the update! Did you allow updates to be installed when the car is turned off? There was a prompt before the OTA. Maybe, it is a good idea to disable the option. I would rather spend five minutes waiting for the update to be installed than find my car with a dead 12v battery.

I'm kind of wondering if this might be one of the sources of this issue, as my car has its eSIM disabled (I'm not in a supported territory yet for data connections) - yay Iceland.

Wondering if perhaps OTA updates might be a significant cause of this, especially if they take a while to complete. There was someone else on these forums also theorizing that perhaps the app is also to blame for this.

These two would make 100% sense, as I'm using my car daily with no data connection and hence no app, and I've had no issue, even when I parked the car and left it static for 17 days while I was on summer vacation.

[HondaNoMore]

Back at dealer who could find no problem with battery or parasitic drain. They swapped a battery from a demonstrator. Worked fine for a week....
Car dead today. Recorded 11.5 v at 11.45 am and 6v two hours later.
Will get AA back out (third time in a month). Dealer will no doubt find nothing amiss.
Think it's time to reject car and adiós Honda after hundreds of thousands of miles. If this is Honda's move to electric Id be worried for Honda against all the Chinese brands on the way.

[EEEE]

Does anyone have a thermal camera? Measuring current draw on 50+ fused circuits would be near impossible (or physically impractical).

With a thermal camera, anything drawing power / dissipating heat should give off some heat. Hopefully the small fusible links inside the fuses themselves could be an ideal candidate for identifying the circuit?

Once we narrow down what is drawing the power, testing and investigation should be much easier. Currently, it seems impossible to know when or why it will strike. If you disciplined yourself to always use the car exactly the same , then your unlikely to uncover the bug. Likewise, if you recorded everything you did manually, you would likely miss the details that cause the fault (assuming its not infotainment based).

[MaXPainT]

I don't have the issue (yet) but I do have a thermal camera so I could take a look. What is the procedure you are suggesting? Waiting for a morning when no charging/preheating is scheduled, opening the fuse box and checking if anything is warmer than the rest of the things in there? Maybe the hood should be left open beforehead to avoid waking up the car? Mind you that if the issue is eSim related it won't show on my car since I don't have the feature enabled.

[EEEE]

It's just an idea, but also not practical. I've had the drain only twice unexpectedly over 2years+ of ownership.

That would mean setting the camera to monitor the fusebox every time you leave the vehicle. You then await the next failure and then observe your recorded footage. The idea being that if anything wakes up or starts drawing power (enough to disable the vehicle overnight), heat should be visible on the circuit powered by a particular fuse.

That is of course if we work on the basis the battery is dying because of a device drawing power. Perhaps the batteries are so cheap and nasty that they just fail by themselves over time, a shorted cell perhaps? I'd say unlikely though.

The problem is there are multiple fuseboxes, but you only have 1 shot to capture the data. Not terribly practical to be honest. The other problem is any other kind of notification about the drain problem (eg an alert from the BM2 if the bluetooth range could be increased) means you wake the car up by unlocking it and getting in , so you really need it all setup and monitoring from within the car when the car is off and locked.

Not a simple problem to solve sadly.

[HondaNoMore]

Hi EEEE
Our battery dropped fro 11.6 to 6 in two hours then to 2 in another hour or so.

AA man said that a 12 v battery has 6 X 2 plates. For it to drop that quick and far would need 5 of the 6 plates to fail at the same time and not be picked up on test. With over 20 years in AA and garages he said that would be almost impossible. It is probably some sort of intermittent parasitic drain and no he still won't buy an electric car.

Dealer is now liaising with Honda UK and possibly Japan as car is no use to us. Await Honda Japan
...

[hondaero]

giving the thread growing here and no official response from Honda, it might make sense to temporary disable OTA and use offline upgrade mode (via USB) to check if any updates time to time.

~amo~