Issues on new REX that was not driven for a year?

Friend is considering a leftover 2014 REX that's been sitting at a Minnesota dealer since July 2014 (nearly a year)! Since this past winter was quite harsh, the car likely sat in the frozen snow for months. The car only has 11 miles on it, and the dealer log sheet for battery & maintenance is blank. It's likely nothing was done to the car in a year.

When my friend started the car today, the screen said "REX maintenance needed due to long inactivity, but battery is insufficient to perform the maintenance".

Could it be bad that the car was unused and parked for extended periods in sub-freezing temperatures without any REX or battery maintenance?

The Li-ion traction battery pack shouldn't suffer any ill effects from sitting unused. If it was fully charged, some damage may have occurred, but not enough to cause noticeable problems after a year. Besides, it's covered by an 8-year warranty, so nothing to worry about there.

The 12 v. battery would be completely discharged by parasitic loads like the keyless entry system, burglar alarm, radio clock, etc., if it wasn't charged periodically. That could cause it to fail prematurely which might be causing the error message. In this case, I would probably insist on a 12 v. battery stress test, but then it, too, is covered under a warranty.

I don't know how rigorous dealerships are about filling out the battery log sheet. I wouldn't assume that no entries indicates that nothing was ever done. Dealers certainly know that parasitic loads will discharge any new car's 12 v. battery, so it would be foolish to ignore battery maintenance.

The error message suggests that the Lion battery is very low, but that the 12V battery is sufficient to boot the car. Maybe they did trickle the 12V, or boot up the car occasionally?

I disagree with Alohart's post...BMW says for extended storage to start with the car fully charged, and if possible, leave it on the EVSE. That way, periodically, it would top off, similar to a maintenance charger on a conventional battery, but only done intermittently once it drops 3-4% (which will likely take more than a week - maybe more like once a month). Unlike something that cannot disconnect the charger (a cellphone is a good example), the i3 tells the EVSE when to turn on and off - it is NOT constantly under charge. The 12vdc battery may be toast, though after a year even though it is an AGM type - no lead acid battery can survive freezing temperatures if it is discharged too far. After a full charge, I'd request that they access the service menu and report on the main battery's capacity. At the minimum, it should be 18.4Kw IMHO - try to verify that through BMW corporate. If it is, after the 12vdc battery is taken care of, it should be fine. Probably new wiper blades before delivery, too, as UV will take its toll on the rubber, and an oil change on the REx.

Although not reported in the error code, since the range extender wouldn't have been started, I would also worry about the gasohol stored in the tank and throughout the fuel system for that long. Even with fuel stabilizer, that's too long to leave alcohol laden fuel. Sometimes you get away with it, sometimes you don't, and degunking that whole system can be costly. There are other issues as well with leaving any vehicle sitting for that long unless it is fully prepared for storage. I would personally pass on that car and look for another one.

EDIT: It occurs to me that a strong possibility is that they have never put fuel in the vehicle at all, leaving that to be done as part of prep at time of sale. Still, I wouldn't be in love with the idea of a vehicle sitting that long.

jadnashuanh said:

I disagree with Alohart's post...BMW says for extended storage to start with the car fully charged, and if possible, leave it on the EVSE.

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The O.P. asked about a car that sat on a BMW dealer's lot for a year, not in an owner's parking space. All i3's on a dealer's lot can't be connected to an EVSE at all times, so the advice that the i3 manual provides about long-term storage can't be strictly followed by BMW dealers. I've read that BMW doesn't ship i3's from the factory fully charged which makes sense to me, but I have no idea whether this is true.

I can understand why BMW recommends that owners store their i3's connected to an EVSE because that would keep the 12 v. battery fully charged and healthy without the need to disconnect the 12 v. battery. For the sake of the longevity of the Li-ion battery pack, I would hope that BMW dealers wouldn't keep the battery packs on their i3's fully charged for months on end. If a Li-ion battery pack isn't stored fully charged, no harm would occur, so why do it except to keep the 12 v. battery charged?

I've still not read any explanation of how an i3's traction battery can discharge over time other than by self-discharge which occurs very slowly on Li-ion battery cells, especially at low temperatures and SOC levels. The 2 times I stored our i-MiEV for 6 months I noticed no SOC drop, but then I stored it with its battery pack at ~40% SOC where the self-discharge rate would be less than when fully charged.

Regarding this discussion, to everyone and anyone. Is a purchase or a pass recommended?

dkpurple said:

Regarding this discussion, to everyone and anyone. Is a purchase or a pass recommended?

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I have a 2014 w/Rex which probably set very much like the one recommended. I had no issues with it. The Rex is meant to run occasionally and I can't believe sitting there for one year was that bad. Only concern would be if 100% charged battery sat in very high temperature, but then again the degradation may be low because the active battery temperature management.

I wouldn't have much hesitation getting it if it was a good deal, specially as others have pointed out it has a long battery warranty. And the Rex is a good insurance anyway if there is a small amount of battery loss.

One cannot 'fully' charge an i3 battery expect in the very rare situation where you live on top of a big mountain, had it charged to an indicated 100% (which isn't!) and then used regen all the way down the mountain. IOW, the LiOn battery is NEVER fully charged in normal circumstances. And, there is some hysteresis in the charging circuit...it disconnects power by itself once it reaches the indicated 100% (again, that's NOT 100% of the actual battery capacity) and won't turn it back on again until the main battery's charge has dropped somewhere around 2-3%. So, even if it were connected, it is NOT like your cellphone or other battery operated device...the i3 has disconnected the a/c input and will rarely turn it back on again. Actual cycling of the EVSE is likely to be a bit more common in the winter verses summer, as the actual battery capacity is diminished then.

No idea what BMW may be installing in the i3 REx's fuel tank at the factory...it may not be the 'normal' stuff you buy at the local pump with the intent that the vehicle MIGHT be sitting around with shipping, then on the dealer's lot.

The car has a full warranty from the day it's sold...I'd not really stress over one sitting for that long. If you didn't drive it much, having 1-year old rubber in the tires might be a consideration...industry recommendations are to replace any tire, regardless of tread state, once it gets to 6-years old.

I live on top of a hill. When the car is fully charged and you coast down a hill, regen doesn't kick in. It feels like it, but the brakes are used instead to mimic the behavior so driving is consistent.

I used to think the same, but after testing I found regen wasn't kicking any power to the battery when fully charged.

I33t said:

I live on top of a hill. When the car is fully charged and you coast down a hill, regen doesn't kick in. It feels like it, but the brakes are used instead to mimic the behavior so driving is consistent.

I used to think the same, but after testing I found regen wasn't kicking any power to the battery when fully charged.

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So, does the power meter just stay at the neutral point during the time you're coasting down the hill?

I have about a 300' long hill that drops about 30' at the end of my driveway...I guess I'll need to watch that meter! It does appear to be in regen verses braking, and most of the time, I'm leaving with a full charge.

When rolling downhill with your foot off the gas, the meter shows regen, but the service menu shows none, and if you put your foot on the brake pedal you can feel the brakes are already on compared to applying the brakes when battery is not 100%