Low 12v Battery on New Car

[amcccc80]

Hi

I have a 2020 Outlander PHEV. It was purchased in December and only has 1,600 miles on it. Was driving on the freeway last week, going 70/mph - out of nowhere lights start flashing “EV system service required, stop safely” and “RBS service required". It was terrifying as the car slowed to about 20/mph while on the freeway, and I had to quickly pull to the side of the road. I shut the car down, waited a few minutes and restarted it. It started fine, but the "service engine soon" light remained on. I was able to drive it the 25 miles to the dealership, and a few times during the drive the FCM system randomly was activated flashing "BRAKE". Really scary experience all around.

After sitting at the dealership for 5 days I was told they reset the computer because the 12v battery was low. When I inquired how it could be low on a brand new car, the tech said going forward I needed to start the car everyday and drive it around, and the battery was low because I must have let the car sit for a couple of days. How unreasonable is that?? Guess I can never go out of town or expect a dead 12v battery?

Looking back on it, in the days leading up to the incident, the FCM randomly kicked in a couple of times, but I assumed I was just too close to another car.

Anyone else have this happen? I'm kind of afraid to drive the car since it sounds like it's only a matter of time before it happens again. I owned a plug-in Prius hybrid for years and never had to drive it daily to keep the battery charged.

 

[mattr76]

I had a similar set of symptoms (see my recent post) and the dealer initially thought it was the 12V battery as well. And they asked me if I didn't drive it much also. I responded we had just driven ~300 miles the day before. They cleared the codes and the symptoms returned after they hooked it up to their charger. A few days later, they did a deeper diagnostic and now believe it's a failed Body Control Module (previously I thought they told me it was the Engine Control Unit). They have to order this part but first have to get a Parts Warranty Authorization from Mitsubishi. It's looking likely that my car will be there for more than a couple weeks, maybe even a month. Mitsubishi is willing to cover a rental car for only *three* days. Needless to say I am very frustrated.

 

[Daixiwen]

It sounds like they are bullshitting you. The car should be able to stay unused for weeks, the 12V battery will not go down so quickly. Can you borrow a voltmeter to check it yourself?
If the 12V battery indeed discharges so quickly by itself then it is defective. You should change it, and for such a new car it should be covered by the warranty.

But anyway having a low battery doesn't really explain the problem you had on the freeway. When running the car supplies 14V to all the system through the DC/DC converter and there is no reason a low 12V battery would cause some problems when driving. At worst you'd have some problems when starting the car.

 

[user 3575]

We are in the UK and have a 2020 model, due the Covid19 lockdown the PHEV only get used 2 or three times a week at the most, on some occasion we have not used the PHEV for over a week, we are experiencing None of these problems

 

[littlescrote]

I believe that a low 12V battery can cause these issues even when driving and the DC/DC converter should be supplying voltage and current for those Aux circuits, however unlikely that sounds. You shouldn't have issues with the 12V battery at that age, but it can happen. But it's certainly nonsense to expect you to drive it every day. Do you have the wifi module in the car for using the App? If so and you have it registered with a phone, that will cause the Aux battery to be recharged every day at 14:00 from the Drive battery and is a useful way of ensuring that the 12V battery stays topped up.

Get a new 12V battery, fully charge it before install and go from there. If you have no further problems then it probably was that.

 

[amcccc80]

Thanks for all of the replies. mattr76, interesting to know you had the same exact issue. Did you get the Body Control Module fixed? Did they cover your rental car?? That's insane!

I had a feeling the driving every day thing was nonsense, glad to hear that is not the case. I had a feeling the issue would happen again, and last Friday morning it did, about 2 minutes after starting the car. Luckily this time I was still in front of my house and I could easily have it towed to the dealership. It's now currently at the dealership, no word yet on what they think it is.

 

[jaapv]

When on holiday my car will stand unused, fior five weeks without problem. Which is not surprising, as it tops up the 12V battery from the drive battery on a daily basis and when switched on. Remember, this car has no dynamo, as the 12V battery takes its power from the the main battery, so driving or not driving it is completely irrelevant.
The problem described here indicates a fault in the recharging circuit.

I would suggest switching to a dealer whose knowledge of the car they are supposed to service has progressed beyond a T-Ford.

 

[littlescrote]

as the 12V battery takes its power from the the main battery, so driving or not driving it is completely irrelevant.

Not in all cases. Those models without the Wifi module will not charge daily if not driven (or at least put into Ready mode) and even those with the Wifi module will not do it if there is no device registered to the module.

 

[ThudnBlundr]

The DC-DC converter only charges the 12V battery when the drive battery is connected. For safety reasons it is usually left unconnected when the vehicle is "off". As mentioned, it should charge once a day if you have a phone connected to the car using the WiFi.

 

[mellobob]

Just curious, but why is there this restriction on charging ONLY if the wifi module is registered, etc?

 

[littlescrote]

Because that should be the only continuous drain on it that it needs to recharge for over a reasonable period of time.

 

[jaapv]

Because that should be the only continuous drain on it that it needs to recharge for over a reasonable period of time.

An alarm system will drain some current some electronics will be kept alive - like the module that listens for your key and activates the locks -- plus moisture earth leaks. There is always some parasitic drain.

 

[sipaldi]

I have a 19 plate and had to call breakdown out as it would not start one morning, used daily pretty much. He finally said the 12v battery was the issue, charged it up and it started. I told him I was not convinced that would be the end of it as it had to be flat for a reason. 4 months later, never had any issues with it. Weird.

 

[greendwarf]

Although your parallel post regarding TPS might also be related to a low battery?