12V battery died after pumping up tyres

[CDot]

Hello,

I bought my ex-demo Honda-e in Nov 2020 (manufactured June 2020) and had no issues with the 12v battery. However last week I discovered that my rear tyre had a slow puncture and on 2 occasions after using the tyre inflator to pump it up (plugged into the cigarette port), the battery died directly after the tyre was inflated.

On the first occasions, the tyre pressure was 3 PSI and it took about 15 minutes to inflate to 32 PSI. After I unplugged the tyre inflator machine, my dashboard display was still working, however the driver-side window would not close. Then several warning lights/icons started appearing before everything went completely dead. Start Rescue came and jump started the 12V battery pretty much instantly. I followed his instructions to take the car for a short spin and it drove just fine.

The next morning (before driving to the tyre shop to get the punctured tyre replaced), the tyre pressure was back down to 9 PSI and it took about 10 minutes to inflate to 32 PSI. This time, my car became unresponsive as soon as the tyre inflator machine had finished. Start Rescue came again and jump started the 12V battery the same as the day before. This time, however, they checked the battery health and said that there were ‘no cells’ left, which is why the battery died after inflating my tyre.

I am still within the 3 years manufacturer’s warranty, and this morning I’ve bought my car into Honda to run their checks and hopefully replace the battery. However the agent has just advised that their initial checks have come back clear and no faults are showing with the battery.

He have asked me to bring my car back first thing on Monday morning so they can carry out the 2nd round of checks. For this, the 12V battery will need to be fully charged which could take up to 6 hours, apparently. I explained that Start Rescue carried out a very quick diagnostic to determine that the battery had ‘no cells’, however the agent said he can’t replace the battery based on their report, and that they need to carry out the tests as determined by Honda.

My technical knowledge of cars is very limited so I would appreciate if anyone has any advice on this to ensure the battery is replaced as I can’t help but feel Honda are shirking on their responsibilities.

[MaXPainT]

I didn't encounter the issue yet so I am afraid I won't be able to help you with advice, but I have seen several posts on the forums with people telling how they got their batteries replaced by their dealerships after being shooed away multiple times.

I am baffled that we still have to deal with 12v battery issues in 2023 with an electric car. The vehicle BMS knows the exact state of the battery, so it should not be possible to drain it to the state that the vehicle won't start. It should trigger 12v battery charging at any time as soon as it hits a critical level and should cut off any non-essential drainage. The only time the 12v battery can go flat is when there is no juice left in the high-voltage battery, all the other scenarios are inexcusable and are a result of lazy engineering.

[5thcivic]

I agree it is strange the main battery cannot charge the 12V under emergency situations, either there are valid design reasons or it is just a cost saving, which I find difficult to believe from Honda but who knows. In any event I bought a 5A 12V mains supply from amazon and fitted a 12V aux socket to use my tyre inflator to avoid running down the cars batteries (the Jazz eHEV also has a relatively small battery) .

[milligoon]

You would have thought that by now there would have been a service update or software update to rectify any 12v battery short comings!

[FDAD]

You would have thought that by now there would have been a service update or software update to rectify any 12v battery short comings!

That would be the case if Honda had any hand in developing things....
The powertrain controls were developed by a company that no longer exists Keihin now Hitachi Astemo, but some ECUs are Bosch so you can blame them too
Or maybe ShinDengen because the DC to DC converter is from them..

Honda still lives in the era where you don't update phones, cars or anything for that matter.

[Reuben80]

To inflate the tyres switch on the car. I never use the battery to do anything. Always switch it on.

[5thcivic]

To inflate the tyres switch on the car. I never use the battery to do anything. Always switch it on.

and you also have to click the drivers seat belt in to make sure.

[CDot]

This morning I took my car into Honda for the 2nd round of checks on the 12v battery. They had to charge it for a minimum of 6 hours beforehand, but it did indeed fail the test so they're ordering me a replacement battery.

I don't have the paperwork yet so I'm not sure what its failed on, but I have a feeling I would have been fobbed off after it passed the initial checks, but I insisted they kept checking. I'm glad this was caught in time for it to be covered by the 3 years warranty.

[EEEE]

Welcome to tiny 12v battery issues. If I'm using the car or need it on, I clip the seatbelt in and make sure the car HV stays on.

As mentioned, it really is stupid. Either that batter is too small (45ah) or the system does not work correctly, a lack of integration testing most likely.

It's a shame as it ruins an otherwise decent car.

I told myself the next time the 12v goes flat I'm getting rid of it...

[londiniumperson]

It's very simple, no need to plug in the seat belt, just make sure the car is powered ON, as shown by the indicator and described in the manual: