Charge disappeared

[HParkEV]

After a relatively trouble free 8 months or so, I have just had the car towed to the dealer.
The problem manifested itself as a complete 'bricking' of the car, at least it looks that way right now.
The car was outside overnight, not plugged in, with an overnight low temperature around -15C, or +5F.
When I switched off the car, it had 10 bars of charge remaining, nothing strange happening at all.
The next day, it is completely dead, the accessory battery (less than a year old, replaced last Christmas) is fully drained. When I gave it a boost from another car, the ignition lights come on, and the battery gauge is flashing with no bars at all. Nothing happens when I plug in the portable EVSE.
I recharged the 12V. While charging, inside the car I hear a fan running, like the blower fan on low, but no movement of air through the vents.
Even with recharged 12V, nothing happens when I plug the EVSE in.
Once disconnected from the 12V charger, the battery drains again within a couple of hours.
I gave up, called roadside assistance and the car has been towed to the dealer.
Has anyone had 10+ bars of charge disappear like that without a trace? That seems like a lot of energy to just disappear with the ignition switch off...
Waiting for the dealer to get back to me.
If anyone has any clues as to what may be happening, I'd love to hear!
BTW, the car has 61k km on the odo, just out of bumper-to-bumper warranty.

 

[PV1]

Very interesting. Maybe the computer malfunctioned and activated the battery warming system, eventually draining both batteries? The warming system, although it is only supposed to activate when activating pre-heat (if I interpreted the service manual correctly), would use the cabin heater and fan. The computer definitely has control of all of this, as the cabin air system both heats and cools the battery.

I've seen it where the charge gauge starts out with zero bars, and gains them back one by one, roughly one bar per second. I've also heard accounts here where a cell fails and its voltage drops below the LVC, rendering the car unusable, but not overnight (and definitely not taking the 12 volt battery with it).

 

[JoeS]

...Maybe the computer malfunctioned and activated the battery warming system, eventually draining both batteries?...

My first thought, also. Killed itself while trying to protect itself?

HParkEV, wish you all the best and hopefully the dealer's tech(s) can properly diagnose the problem. Do keep us informed of the progress and the eventual problem cause and solution.

 

[HParkEV]

I picked up the car from the dealer yesterday.
The service adviser told me that my traction battery was completely drained due to the cold, that I should leave it plugged in when it is double digit Celsius below zero (basically below 14F). The technician showed me a print out of trouble codes set, and told me that other than the 'extremely low battery voltage' code, everything else was a result of the low battery voltage.
They did nothing to the car other than warmed it, reset the codes, and charged it.
I am expecting the problem to be back, because I don't think that ~10kWh of power can just disappear from the battery 'due to the cold' as they have said.
Their actions are not too surprising - with the three other major problems I had taken care of by the dealer, it took two trips every time before they got the heart of the problem.
I'm just not looking forward to the inconvenience this will cause me.

 

[PV1]

That doesn't sound right. I've had my battery near 0 F with less charge than that, and the car started just fine. I even sat there and ran the heat for about half an hour trying to warm the battery up so I could charge it.

Investing in a Bluetooth OBDLink MX or LX would be wise if you have an Android device handy. Check the car out with CaniOn and see what the cell voltages are.

As a side thought, I wonder if the service plug lost contact due to the cold, and that's why the car threw an "extremely low voltage" code. Without the service plug making a connection, the car can't activate the battery pack. Both of my cars had issues with the radio fuses in cold weather doing this. But, this still wouldn't explain the dead 12 volt battery.

 

[kiev]

10 bars is about 10 kwh. If the car somehow turned on the heater due to the cold temperatures, then the pack would only last 2 to 3 hours at full heat, maybe 5 to 8 hours if the heat cycled off-on. But how did it turn itself on...?

 

[jray3]

If your car has the cold weather package, there is a battery pack heater that will come on at a very low temperature to protect the pack.

From http://media.mitsubishicars.com/releases/dc8be352-eeff-4d6b-a6e0-e62dec3a22fb
The battery warming system operates when the system determines that the battery temperature range is within -20° and -13° Fahrenheit (-29° to -25° Celsius); the heating system does not engage when the battery temperature is determined to be less than -22° Fahrenheit (-30° Celsius). Of note, the battery warming system will not activate when the lithium-ion batteries state of charge (SOC) is less than 40%.

Battery warming ceases when the battery temperature reaches -4° Fahrenheit (-20° Celsius) or if the state of charge (SOC) is calculated to be under 10%. When battery charging ends the ECU enters into a sleep mode, waking six hours later to check the temperature of the battery pack; heating of the battery will once again commence if necessary.

One hack I've wanted is to use the pack heater to maintain a comfy 65 degrees or so in order to maximize winter range.

 

[HParkEV]

I don't think its possible for this battery pack heater to activate without the car being plugged in. In any case, the temperature was nowhere near -25 degrees, maybe it got down to a low of -16 or so, and by the time I was trying to start the car it was -9.
I will keep you updated if this happens again. I am tempted though to get the Canion and see a little bit more of what is going on with the battery.

 

[kiev]

If you have the cold weather package it can--that appears to be the Normal mode.

Maybe the temperature sensors are off calibration a bit such that it kicked on the heaters slightly above the expected range.

Good idea to get canion, it's a great tool.

 

[Aerowhatt]

It's pretty clear (from all related literature) that the battery temperature management only functions when the car is plugged in to L1 or L2 charging equipment. So that is not what brought it to dead. If they did indeed only warm it up, and charge it normally, then the only normal operation scenario would be the low temperature lock out. If it wasn't cold enough then the temp sensor calibration must be off spec as previously suggested.

Aerowhatt

 

[HParkEV]

The accessory battery died twice over the Christmas holiday, as the car was not driven as much. It was a lot warmer, and it did not take out the main traction battery with it. The car is now at the dealership again and they are trying to diagnose the problem.
The last time it died, it was within 3 hours of the charge finishing. Basically, as soon as charging the main battery is done, the EVSE shuts off, and accessory battery drains within a short time.
For the last two days, I have been leaving keys in the ignition with the car in 'ready' mode to prevent the accessory battery from being drained. The good news is that it only takes one bar off the main battery in about 12 hours of being parked in 'ready' mode.

 

[PV1]

12 volt battery bad? Your original post stated that you heard a fan running. Do you have the Nav head unit? Some nav radios have cooling fans in them, and this might be what you heard, especially if the key was in the ACC position.

My car used to go dead over a weekend until I charged the 12 volt battery with a 3-stage battery charger. It hasn't had any issues since.

 

[HParkEV]

The 12V battery was the first thing that was replaced when the same thing happened a year ago. Made no difference at all, they ended up tearing the car apart for a month before they fixed it by replacing the AC system. Who knows, maybe its the same issue this time around, maybe different. They are still working on the diagnosis.
I have to say that by now I am extremely disappointed with this car. I was a big fan initially when I got it 3.5 years ago, but by now I have been thoroughly turned off Mitsubishi. The mechanics have proven themselves time and time again to be incompetent, not even once have they managed to fix any problem on the first attempt. The car has serious issues on an annual basis unfortunately.
I am enjoying a Prius right now (loaner), and I notice it uses only about 2x the energy equivalent, about 4.5L/100km, if I drive it gently, like I do the i-MIEV. I'm really thinking that is not a high price to pay for the comfort (heat!) and the reliability!

 

[kiev]

If you can get a listing of the trouble codes that they are pulling with the MUT then we can do some research of possible culprits.

i was looking at the CAN buss data to discover how the pack balancing is enabled, and made some exploratory actions (aka wiring change) that caused the AC and pack cooling fan to come on full blast, which could drain the pack fairly quickly if it ran continuously. Fortunately when i corrected the situation, everything returned to normal operation, but one little sensor failure, miscalibration, or mis-communication could initiate such a response. There will be a trouble code trail in the ECUs that helps identify this.

For example, it may be that you have some sensor issue that triggered this protection response of running the AC and cooling fan. Their troubleshooting resulted in an indication to replace the AC, but that was not the root cause. There are additional data lists that should be examined along with the trouble codes.

 

[PV1]

I'm sorry that you've had a bad experience with the i-MiEV. For quite a while, it seemed to be the most reliable EV in the bunch. Maybe it still is overall. Unfortunately, it's hard to tell if the newer model year i-MiEVs are improved as there are so few of them in North America compared to the 2012 model. My pair of jellybeans have been relatively trouble-free so far, save for a few 12 volt issues that now seem resolved and a bad cell in the main battery of Bear.

That's not to say they are all perfect. Sandange's original i-MiEV went through several on-board chargers, and the best solution was to replace the whole car with a new one. From what I've heard, the Prius is an excellent vehicle. I've seen used ones with over 300,000 miles go for around $15,000 USD. I'm also seeing a few BMW i3s going for around $26,000, and after driving the i3 for a few days, it's more similar to the i-MiEV than you might think (dimensions, capacity, seating). I joked with people that the i3's drivetrain with the i-MiEV body would make the perfect car for me.