Yes, I know that we do mostly old cars here, but I have built up a respect for the brain trust of CC readers, so maybe some of you can help me with a question I have been asked.
Someone I know owns a 2018 BMW 330e. That person has to leave the country for a year and wonders what to do with the car. The choices are to sell it and buy a new car upon return, or to store it so that a very satisfactory car is ready and waiting at the appointed time.
The question whether to sell or not is pretty basic, of course. My read is that the car market and the economy is going to get weaker as time goes on, so selling later this spring might not be a bad deal if there are some good incentives on new cars next year. But we all know how difficult it is to tune a crystal ball to eliminate all of the static and there is a lot to be said for keeping a car that has made you happy. I should add that this decision is being made in Hawaii, where the economics of buying and selling cars is a little different than it is on the U.S. mainland.
The more interesting (and more technical) question is whether it is a good idea to store an electric car and if so, what’s the best way to do it? The BMW 330 is a plug-in hybrid that mates a turbo 4 to a 7.6-kWh air-cooled lithium-ion battery. We are all aware of how you deal with the gasoline part. Sta-bil in the fuel tank, tape over or otherwise seal any holes like the exhaust pipe or air intakes, and maybe put the car on jack stands to keep weight off the tires. A battery tender, or maybe a battery removal would about finish that job, to my way of thinking. But the big hybrid battery pack? What happens to a hybrid battery of this sort if it just sits for an extended period? Is there such a thing as a battery tender for an electric/hybrid? Or do you just keep it plugged in like those battery packs for lawn equipment we (OK, I) keep forgetting to unplug in the garage?
The simplest method might be to give the car to me to use for a year, because storing an aging Honda Fit would be so much simpler. And I would be happy to spend a year at the owner’s home in Hawaii if that would make things less complicated. Those items, however, are not on the menu board, so we will have to confine ourselves to more realistic possibilities.
So here is the question: Is it a good idea to store a plug-in hybrid for an extended period of time? And if so, what would be the best method for doing that? I (and the car’s owners) will be eager to see the the wisdom that will follow in the comments.
The short answer: nothing, except maybe a battery tender for the 12 V starter battery.
The lithium ion battery will be very happy to just sit at whatever state of charge (SOC) it is in when it’s parked; ideally, they are at their most happy at 50% SOC, but unlike lead acid batteries, which really like to be at 100% SOC, they don’t really care much.
Presumably the traction battery will be at about 90% SOC when it’s plugged in; just leave it at that. If you want to get really finicky, drive it on electric traction to bring the battery down to closer to that 50% ideal. It should then stay there all year, as there’s no parasitic loads on it. And if it goes down a bit very slowly that’s ok too; it doesn’t hurt them, unlike a lead acid battery.
As to the other storage issues for IC/all cars, I’d not bother, as modern cars commonly sit for over a year on dealers’ lots (more so before the pandemic). My TSX had sat for some 14-15 months before I bought it off the dealer; its battery was dead. A hot shot, and off I was, on a fast 300 mile trip home. No flat spots on tires, etc..
Putting up on blocks and such seems like major overkill, but to each their own. I certainly wouldn’t bother.
The Michelin website recommends that vehicle weight should be off the tires for “long term storage.” I’m inclined to think a year qualifies.
While possible, it seems unlikely a new vehicle would sit in one spot on a dealer lot for 15 months. Locally inventory regularly moves around the lots to clear snow, clean vehicles and to give the lot a fresh look in terms of the display from the street.
I never got flat spots from year long storage, which happened twice with my Cougar over the years, last time as recently as during the pandemic. However during the period I spun a rod bearing in the original engine block and subsequent engine swap the car was up on jackstands for several months, all through the winter, and as I wrapped it up and took it for its first drive it had all these weird squeaks and groans going over bumps. Turned out the shock mounts were severely compressed due to the shocks being fully extended for so long, all four had to be replaced and they weren’t even old.
That’s an interesting point. Suspensions are not really designed to be fully extended or compressed for long periods. And agreed, the flat spot tire issue is overblown, in my opinion. Of course tire companies are always going to recommend the most conservative measure.
My first thought is to sell it, though that depends on how their system is set up. Putting a proper battery maintainer on the 12v battery or disconnecting it at a minimum is a must.
IF it can be set to charge to something other than 100 % then it will be OK to plug it in and leave it, but many PHEVs don’t have a setting for less than 100%. I know our older PHEV will only charge to 100% while the new one we bought last month, you can use the app to set it to charge to between 50% and 100% in 5% increments. Even if you can charge to 50% it would not be a bad idea to have someone take it out for an extended drive, once a month or so.
Agree that the Li-ion battery will be fine. I just found a USB battery pack (the kind you would use with a phone or tablet) that I last charged up and used four years ago. It was still fully charged and worked fine.
As stated, from what I understand, the traction battery is not the problem. It’s the ‘vampire drain’ discharge of the 12v that’s the issue. I would imagine the same thing might apply to many new vehicles, whether it’s an EV or not.
So, yeah, a battery tender on the 12v, whether in the vehicle or not, would be the main requirement for extended storage.
As to EV vehicles and/or info being on CC, well, plug-in vehicles have now been around for a decade, so I’d say they’d be allowed for that reason, alone. First generation Chevy Volt, NIssan Leaf, and Tesla Roadster and Model S are the vehicles that immediately spring to mind.
In fact, seems like those old 2008-12 Tesla Roadsters easily qualify. Total production (worldwide) was only 2,418 and I can’t ever recall seeing one of those on the road.
Over the last 25 or more years, some vehicle makers don’t have onboard computers that will remember the vehicle’s variable memory info if the battery is dead, to include engine or transmission operating info, and will not run well until the vehicle has been driven for a while. As I don’t use my 2001 Ram 2500 truck very often, I use a battery tender. If the battery is allowed to discharge 100%, all the prior daily driving settings are erased. It will still start up once the battery is charged, but takes about 20 miles of driving before it will idle correctly. So yes, both IC and Hybrid vehicles need a battery tender if not driven very often. Plus, each time a typical 12v lead acid battery discharges completely, it loses some ability to re-charge, leading to an early demise. Traction battery packs don’t use lead acid batteries, so this is not a problem.
If your friend has a garage with electrical outlets for the car, it should be fine for a year. That said, I would suggest the gasoline in the fuel tank be kept at around 1/3 tank, so when the car is to be revived, fuel can be added to top up the tank with fresh fuel. While in the garage, I suggest a car cover be placed over the car to keep dust off. This can also help keep scratches from appearing if cats have access to the garage. They will climb onto the car.
Speaking of critters, if the area where the car is stored might attract mice, I suggest talking with a pet store to get a freshly shed snake skin. Mice can smell that skin from outside the car, and will not try to get inside. Place 3 sections of snake skin on pieces of paper, one in the trunk, one in the interior, and a third under the hood. Field mice can actually fit thru a hole the size of a pencil, and they can easily chew through rubber grommets to gain entry into a car, especially if they smell the slightest amount of food.
If you’ve ever dropped a few crumbs onto the car’s carpet, mice can smell it from outside the car. I lived on a farm for decades, used snake skin in my vintage cars, and it really works. A snake skin usually stays effective for a couple of years. The last thing you want to come back to is a car with multiple areas of bare wires from mice chomping on the wiring harness, because the person on the assembly line had something to eat & didn’t wash up, allowing the food smell to transfer from his hands onto the wiring harness he just installed in your new car.
I’ve spent long periods of time overseas, from a few months to almost 2 years. My running and driving vintage cars were prepped for inside storage, but for my primary vehicle, I chose to allow trusted family members to use it a couple of times a month, so when I returned, the vehicle was ready to go.
I would not suggest leaving a vehicle out in the weather unused. Especially if it is parked on a public street. You may come home to find it’s been towed and impounded, with daily storage fees mounting up. This does happen to hundreds of vehicles around the country, especially where local regulations forbid licensed vehicles to be parked on a public street and not moved on a regular basis.
Your solution for keeping mice at bay is interesting; I’ve never heard of it.
After having to repair/replace portions of wiring harness under the hood of a one-year-old 2014 RAV4, it was suggested that I buy some “rodent tape.” (I forget, now, where I got it. But the package was labeled as an OEM Honda product!) It is around 1” wide and stickier than painter’s masking tape, and it smells odd. Not as pungent as ammonia but certainly not like Lemon Pledge, either.
I was told to use long strips of tape to cover obvious holes in the firewall and other spots on the bulkhead, and use a few shorter strips randomly elsewhere.
I don’t know what mice would find unpleasant about the “rodent tape,” but it seems to have worked. No more chewed wires or evidence of mouse infestation. OTOH, I think this one episode of chewed wires on my car was a fluke. I think it happened when I was parked somewhere else for a time. I have a 2019 RAV4 in the driveway right next to the 2014 that was chewed on; the 2019 hasn’t been attacked yet, nor have I had any other vehicles chewed on in some 33 years at the same house.
So, I guess, YMMV. 🤷🏻♂️
Our son stored his Prius, not plug-in nor even a LiOn battery for that matter, for almost a year when he was deployed overseas and I think he said the 12v battery was low, maybe dead but no real effect on the NiMH traction battery. That was a ten year old battery at the time. I also recall that he said the tires had flat-spotted but smoothed out quickly.
Without full knowledge of the financial side, it’s hard to make the call, but my initial response is “sell”.
Barring that… to be nice to both the tires and suspension, get a set of whatever beat wheels and tires that will fit for cheap on FBM or CL. Let the car sit on those for a year, and the good tires, stored properly, will be ready to bolt on upon return.
There may well be information in the owner’s manual that details proper long term storage procedures. Baring that and understanding that BMW may recommend a different procedure, I have a 2020 Chevy Bolt and 2014 Chevy Spark EV and both of their manuals say:
Up to Four Weeks
. Plug in the charge cord.
Four Weeks to 12 Months
. Discharge the high voltage battery until two or three bars remain on the battery range
indicator on the instrument cluster. Do not plug in the charge cord. Remove the black negative (−) cable from the 12-volt battery and attach a trickle charger to the battery terminals or keep the 12-volt battery cables connected and trickle charge from the underhood remote terminals.
Do they have mice in Hawaii? If so, that may be his biggest challenge.
One thing that’s not really been discussed here in the comments, although you touch upon it in the post, is that he’ll be coming back to a 6 year old electric car. If your friend is devoted to the car and does not care about its resale or trade-in value, then this is simply a technical issue as most of the comments have addressed. BUT if he might be interested in getting a new car in the near future, then I’d think he may be better off selling this one now and then just buying a new car when he returns. Six years old might be kind of advanced when it come to updated technology in electric cars circa the 2025 model year. Plus, resale value of a six-year-old electric vehicle may be depressed regardless of its condition. The car may well be worth more now than it will be a year from now.
Really, I think he should go with your suggestion of shipping it to you and letting you drive it for the next year. We’d all like to know how that turns out!
Instead of putting the car on blocks, air up the tires to about 50 psi and check them monthly. They’ll stay round. New cars are delivered to the dealers with the tires at 50 to 70 psi- if they’re imports, the cars are chained down to the ship’s deck and the tires pumped up to take all the slack out.
Tires: Remove the wheels and tires and just drop the thing on its chassis, South Side of Chicago style. The weight will stay evenly distributed and the tires will stay round when they are stacked neatly in the corner.
Battery: The short answer is read the owner’s manual. The long answer is: The battery is under warranty, so not your problem. Well, sort of anyway. The feds mandate a minimum 8year, 100k miles warranty for a hybrid’s battery, the state of CA mandates more for the same price, manufacturers can do what they want as long as they meet the minimums and some go quite a bit longer; all with a few caveats and maintenance and storage is one of those caveats, as it is with other vehicle components. If meeting the battery warranty terms is of interest then read on…
The owner’s manual that came with the car has a section telling the owner exactly what BMW wants them to do for long-term storage, (it’s under “High-voltage battery, long stationary periods” in the index) and if it’s unclear or the owner is nervous about it then the owner should reach out to the party that will be responsible for the battery, i.e. BMW and its authorized representatives, the local dealer. You know to get everything in writing, Helmut at the service desk may get hit by a bus next week.
100% charge in a BMW hybrid battery is not using 100% of the actual capacity, btw., it’s limited with a built in buffer. Whatever BMW calls 100% is what they consider safe for their fully charged battery even if it’s technically not actually 100%.
I hope your friend has a nice trip. Pro-tip for you: the keys are always under the mat…:-)
For the internal combustion engine I would add an appropriate amount of “STA-BIL” fuel stabilizer. Either put the STA-BIL in the tank and then fill the car or fill the car, add the STA-BIL and drive the car for five minutes. I prefer the tank full for storage to lessen the amount of moisture that could get in the tank. I get STA-BIL from Amazon.
Agree with battery tender. If mice can be an issue buy several bait traps to kill them and distribute around garage.
Thanks everyone. I heard from the owners that this August group provided far more information than the BMW dealer did. They were leaning towards selling but now have more to think about.
The snake skin is a no-go in Hawaii because there are no snakes there, I am told. And cats in the trunk and interior are probably suboptimal.