Pretty sure your 12 volt battery is dead. No idea why the car would lock itself. I would open the hood and change the 12 volt battery with a new one. I don't think there is anything special with regards to replacing it. Not sure what to advise regarding the locked doors. . .
If it stays locked with a good 12 volt battery, then you can probably disconnect the 12 volt and get a locksmith to come and get the car open without the alarm/anti-theft going off. So make sure you get the lock situation resolved before you close the hood! I also would advise not waiting a long time to get the situation resolved. If you wait long enough, the HV battery could be fully drained and then you have a whole other set of problems.

 

All good advice. It's a dead 12V battery.

For exactly the reason above I have 2 spare keys that will unlock the door but cannot start the car.

The one good thing in this situation is that the alarm is not set because it has to be activated by the keyfob. Hopefully, a locksmith can open the door, and with a replaced 12V battery, the situation will quickly be resolved.

ga2500ev

 

Thank you. Regarding length of time: how long might that be, and what might the problems be?

 

Even though it's isolated, the HV battery will continue to drain. Without charging, eventually it will die.

If it were at 45%, and presuming that it didn't try to kill itself charging the 12V battery, there will be a considerable amount of time on the order of months to get the situation resolved. But if you didn't have U69 done, which stops the HV battery from killing itself trying to charge the dead 12V battery, then there's no way to know if your HV battery is anywhere near that 45% of last check.

In any case don't overthink it. Fix the 12V battery. Get the locksmith to unlock the car. Also get the locksmith to make you a door only key even though you'll get another authorized key later. Do those first, get back into the car, then reassess.

ga2500ev

 

Thank you. I've taken note of the suggestion to buy a new battery instead of trying to get the current one recharged. I've posted a new question on NIMH batteries in the larger forum in hopes of getting as many eyes on it as possible. I'd appreciate suggestions on that as well.

 

Just one other thing: I notice that people are saying to use a locksmith if the doors don't unlock with the new battery installed. Does that mean that I shouldn't get somebody from AAA to jimmy it? What would a locksmith do differently?

 

NIMH? Nickel metal hydride batteries are not really of use for our cars. Some people replace the 12 volt lead acid with Lithium Iron Phosphate (LiFe) batteries. Personally, I would just replace it with another lead acid and be done with it. Drive it for another 3 or 4 years and get another one when needed.
When I said locksmith, I just meant get a professional that is skilled at opening locked cars to open it. Not sure if AAA would be different than a locksmith in getting it open. A locksmith will be able to make you an new physical key that you can use to open the door as ga2500e suggested.

 

Thank you. That's what I meant, lithium. I appreciate your and the other suggestions.

 

depending on the ambient temperature and sun exposure the battery drain might be due to its thermal management.
second thing - if the 12 V battery was weak, the car would wake up from time to time to recharge it. If the voltage dropped too low, I think it would be "woken up" to charge it. It is possible weak or faulty 12 V would discharge traction battery.
There were cases the traction battery being depleted due to 12 V charging. An update (was it a recall actually?) was in place to prevent it.

Since you have the hood open, you should check the 12 V and either charge it or replace it. Once 12 V is present, unlock the doors.


Look for the fuse from central locking mechanism. Supply current to it.
First ensure it is the right one and that you are powering it correctly.
I am not sure, as I do not have 500e anymore, if the fuse is actually in the "engine bay" area... and if that would even work.
If not that, maybe power windows.
Or maybe rear hatch unlock, which is also electric.

 

Yes, there was a software update to prevent HV drain from a faulty 12V. I believe it was "U69", so you should check your vin for open recalls.

 

I'll write up how this gets resolved, assuming it does. I'm still in the middle of this mess. One note on something that may be widely known, but that was news to me. If your car is still under warranty, don't put any faith in Fiat's roadside assistance program. Fiat Customer Care presents this service as specializing in Fiat cars, or at least the rep I spoke to did. In fact, the roadside dippatcher I eventually reached after a very long hold admitted he knows nothing about 500es and neither would the tow company he sent. They just farm the work out to local contractors, like a smaller version of AAA. My car is parked in a tricky situation. AAA admits up front what they know and don't know. I'll be using them.

 

AAA says their most common service call is 12V failure, so they should be well-versed in that in general (key stuck, self-locked, etc.).

AAA should also be at least somewhat knowledgeable with respect to EVs in general, since they've had service trucks with chargers for several years now.

 

I'm not sure if you have access to another car, but I'd probably just pay the $100 for a Walmart replacement or equivalent (MAXX-H5), especially if the battery is more than a few years old. If you're lucky, you may be able to just pop the rear liftgate to get back into the car when it's powered back on.

Most of the automotive locksmith folks just use inflatable bags to get a pole into the car to click the door locking mechanism anyway, so it's best if the 12V system is functional when they come out.

If you don't want to immediately sort out the battery thing, you can just "jump start" by attaching another vehicle to the battery. I have a Li-ion jump starter power bank that can be used to work around the 12V battery in a pinch, but I assume you don't.

For cutting a backup door key, I've found that the ACE hardware near me will do it for $5 or so plus the cost of the blank if you don't have one.

 

That's all great advice.

I should get a cheap door-only key myself, since I've already locked mine in my hatch a few times: Open hatch with key in hand, set it down inside while arranging items, close hatch with key inside. I keep my second transponder key in my backpack, but sometimes that's in the car!

 

Lock your keys inside? I had a door key only made. Using a dab of contact cement and a piece of Gorilla Tape, it's on the back of the license plate. Auto Club guy only needs a Phillips screwdriver.

 

OK. This week-long unpleasant situation seems to have a happy ending, I hope.
It turned out that the whole problem was that my 12-volt battery had died. I asked the mechanic whether the 500e gives any warning before that happens. He said no, that it's basically like a light bulb going out. He said occassionally the car might struggle on startup a little, but usually not. I can't afford a lithium-iron replacement for the lead-acid battery right now, but I did ask him what he's seen on that. He said he's seen a few and they seem to work fine. So, I'll check into that a little more, against the next time this happens. This guy claims it will work fine. This guy concurs, but he did get a warning light. So I'll try to find out more about that.
For those of you who are, like me, not real mechanically inclined, I did learn a few basic lessons:

• That second key is really important.
  When I bought the car from a used car lot, it had only one key. I checked with all the Fiat dealerships within driving range and ordered a second key from the one with the lowest combined price for key and coding. When it was ready for pickup, I tried to arrange coding, only to find out that the dealership had really jacked up the coding fee. I don't remember by how much, but it was at least double, easily enough to piss me off. So I decided to hold off while I tried to talk fairness to them. Then Covid hit, and the key sat there, 30 miles from my house, for months. So when this problem hit, I found myself with my only working key stuck in the ignition and now locked in the car. Now, if it happens again, I have the second key, so I can get into the car and pop the hood and pull the battery.
• Take Notes and Negotiate
  I told this dealership, which had my key, what had happened. I scanned my notes from the previous shopping inquiry and showed them to the dealership. I said, "Fair's fair. Charge me what you said you would." Eventually, when I was able to get the car to them to complete the coding process, they did.
• Buy a good automotive battery charger
  I hadn't used the one I have, a manual version, for about a decade. I didn't really trust it with the Fiat's 12-volt. So I'll buy a better automatic one in case this happens again or for use on my family's other cars. All I needed was enough charge on the dead 12-volt to get the car down my steep, narrow driveway to the flatbed, or even into neutral.
• Don't count on Fiat customer care
  They don't seem to know their own rules and can't give straight answers to straight questions about what will be within warranty and what might violate the terms. They misrepresent roadside assistance for cars in warranty as somehow expert when in fact they're sending whatever shlub wins the contract, some ignoramus who might break your car. I used AAA instead to tow the car once I'd solved the initial problems myself. They didn't present themselves as 500e experts. They were fine.
• This is a pretty good group.
  When I first found out about this problem, it was late at night. I was pretty upset. I posted my question hoping I'd get some answers the next day. In fact, the first response came in minutes. I don't expect that every time, but it's a testament to how we can all benefit by keeping up with the group and seeing if we can help out.

 

By the way, when I got a working 12v battery into the car and got in, at least the dashboard display showed very little decay in the main battery's storage. I think it had gone from 45% to something like 42%, which I wouldn't think is terrible. This is all per the dashboard readout. I'll try to check it with the scanning tool and will report anything else I find out. Pointers appreciated

 

Thanks for keeping us updated, & confirming the issue would have been the same with a gas car.

- Some users have reported 12V failure without warning, but there IS supposed to be a warning, & some users have seen it a day or so before complete failure.

- 500e's onboard 12V charger is active whenever the key is on OR the motor is "ready" OR the car is actively charging. This makes an auxiliary 12V charger mostly useless, unless you let it go so low it goes too dead to even allow the car to charge, although even then it should work to use a jumpstarter to turn it "on" & then plug in to charge both batteries.

 

I remember when I first bought my first car and had this problem too. Unfortunately, the only key I had was stuck in the ignition. Because I had never encountered such a problem before, I became very nervous and did not know what to do. Then I thought of calling a locksmith, mylocallocksmithtx.com , who came and helped me get the key out. Whenever I encounter problems with doors or locks, I always go to the locksmith's point because he knows it-com how to open the door or take out the key. If you encounter the same situation, I do not advise you to fix it yourself because you can only worsen and complicate the situation.

 

These are the best 2 solutions that I know of to prevent any inconvenience:

A little $50 jumpstarter like above &/or a $22 voltage gauge like below (click to enlarge):

Check the gauge periodically with the key out, preferably after parking off charge for several hours & then waiting for it to go back to "sleep" 5 minutes after opening/closing the door to pop the hood. If it starts to get close to the 11.7v bare minimum for reliable starting, start shopping for a new 12V battery.

Cool thing about this particular gauge: It starts flashing red when there's still enough power to start the car IF you keep the left door closed to prevent pre-activating the power-robbing contactors & brake pump. So if you install the gauge somewhere in the cabin where you can see it from outside, the flashing red could alert you to start the car from the passenger seat & drive immediately to buy a new 12V battery.