Upgrading The Batteries In A BMW I3

The BMW i3 debuted on the market in late 2013, one of the brand’s first electric cars. Also available with an optional range-extending engine, early models featured a 60 Ah battery providing up to 130km range on a full charge. However, times have changed, and over the years, BMW have updated the model with larger capacity batteries over the years. So what does it take to retrofit an older model with the newer, fatter, juicer 120 Ah pack?

It’s all helpfully laid out in a video by [Daniel], who notes that it’s not a job for the faint of heart or poorly equipped. The good news is that, mechanically, the newer batteries have the same external dimensions as the older packs, meaning they can be bolted in without requiring any cutting, welding or, adapters. But that’s about it for the good news. The batteries are cooled by the air conditioning system, meaning that removal and replacement means draining the system of refrigerant using highly expensive specialised hardware. Additionally, many batteries in crashed cars are disabled when the airbags are triggered for safety reasons, requiring unlocking through BMW’s proprietary software or replacement of the internal battery controller. Then there’s the usual laundry list of gradual changes that happen across any automotive line, meaning that certain model years and trim packages can have incompatible plugs and connectors or other features.

Overall, it can be quite a bit of work to do, and with the tools required, something that needs the services of a dedicated mechanic’s workshop. However, find an experienced shop that regularly works with EVs, and you might find they can facilitate the upgrade for you without too much fuss. We’ve seen [Daniel] tackle upgrades before, such as a much easier swap on the Nissan Leaf. Video after the break.


41 thoughts on “Upgrading The Batteries In A BMW I3

  1. Great article, thanks!
    My only question about it is: WHY?
    I love electronic vehicles in every way, but why do all these manufacturers make upgrading so hard? Yes, things can break if you do something wrong. Yes, things can be dangerous, but that has always been the case with petrol cars too.
    Well, the answer is easy: More profit for the company.
    I am not into cars, but into eMTB’s and it’s all the same bullshit. I hate new technology. Call me a boomer.

    1. Apparently, with these companies, most of the times it’s not about charging more to theirs customers. They are just terrified of not having full control of the repairs because they want to protect their image (and their ability to hide sins).

      1. I managed a BMW dealership for a while.

        7 out of 10 cars that came off the carrier trucks needed repairs before being sellable.

        75% of the total dealership profitability came from the service department.

        1. Back in 1976, I was the car wash/ oil change monkey for a Ford dealership.

          Yes, “fresh off the truck” cars/pickups needed a thorough check before being put in the showroom or on the lot.
          (e.g. loose lug nuts, low on oil, etc.)
          That was why there was/is a hefty “dealer prep” charge on the window sticker.

    2. Have you modified your car this extensively? Its never easy. An engine swap is not done in 2 minutes, and you will have to fabricate a few custom components too. I don’t think this is “prevention” at all. It is possible after all, tools are readily available, etc.

      If they were for “more profit” in this case, why would they make it “forward compatible”? Why don’t they lock specific components together in software?

      1. Agreed, though perhaps they could and should be designing electric cars to be easier to work on.

        But none of them so far are doing anything much out of the ordinary – these days safety shutoffs and lockouts seem pretty common – for good reason a crash serious enough to trigger them shouldn’t be just driven away from. And the engineering challenges that lead to running the air con through the battery won’t go away – infact that seems very clever to me, pain to work on perhaps, but seems like an efficient use of parts you were carrying around anyway.

          1. I didn’t watch the video myself but I don’t think he was buying a wrecked car to restore it to running condition. He was buying the wrecked car to salvage the battery (or just buying the battery from whoever owned the wrecked car) and put it into a non-wrecked car. The battery (just like many other parts) may be perfectly fine after a wreck.

    3. I agree, but I also think that this problem is going to change in the near future because new startup ev manufacturers will have more competition so they will need to improve their upgradable techniques and increase their production volume just to survive in the market. I love EV ‘s and they will get better and also the owning experience of electric vehicles is going to disappear in the near future, we will not buy cars anymore instead just renting them.

    4. It’s not that they purposely made it difficult to upgrade, rather they haven’t spent the money required to make it easier. It wasn’t a priority during the original design to ensure the battery could easily be swapped out, and during various tweaks over the years it wasn’t a priority to maintain backwards compatibility of each part. Yet, it’s still disappointing because when the i3 originally launched its modular skateboard battery was occasionally trumpeted as being relatively quick and easy to upgrade. I suppose the key word is “relatively”.

      I have a 60 Ah i3 and have been casually looking for a guide like this for years. I’m happy to see that it’s at least possible to upgrade the battery when mine gets old. Hopefully there’ll be another refresh in a year or two to take (US EPA) range above 200 miles, and that’ll be the one to get. Since they’ll all be long out of warranty by then, there’s an opportunity for small-scale tuners to pivot their business to offer this replacement service. I’d choose their parts and labor prices over BMW dealer!

      1. That’s where we are with our 2013 i3. I’m not trying to swap batteries until the warranty expires in 2023. By then a battery upgrade makes more sense. It has limited range but the new i3s aren’t that much better.

        1. The battery swap options you have all come second-hand from crashed vehicles anyways, so why not swap for a second hand i3 with the bigger battery already in and save yourself the trouble and cost?

          I mean, you get a newer car and longer range, and you don’t have to spend any time at the garage. What sense is there to upgrade the old one?

    5. For awhile there was discussion about swapping out entire battery packs in a car in lieu of hooking up to and waiting on a charger, so it’s entirely possible the auto manufacturers could make it easier. I can already hear the negative comments if I mention the “r-word” (regulation, not the other one). I understand why we don’t want the government to compete with private industry on a lot of things, but I do think there is more good than bad by eliminating ambiguity through enforced standards.

      1. Tesla was saying it would be fast to swap batteries in the Model S. They built just one swap station which IIRC never opened for business. They decided to build the Supercharger network instead.

      2. There are several issues with battery swapping schemes, and regulation is (presently) the least of them.

        – Ownership of the battery : who pays for the degraded capacity, damage, theft
        – How many batteries are needed in how many locations: more than one per car -> hidden costs
        – Service prices : you’re leasing the battery, which implies added profits, business overhead and taxes
        – Compatibility : different cars have different shape/voltage/amperage batteries by necessity of design.
        – Automation : a socket in a wall is much cheaper than a ten million dollar drive-in robot with a magazine of spare batteries

        Then there’s the safety issues of connecting and disconnecting an approx. 400 Volt 1,000+ Amp battery pack without dirtying or damaging the connectors, because failure to secure the connection can quickly result in a vehicle fire.

        In summary, the battery swap option is not economical and requires technical compromises, and introduces new safety issues.

    6. > Well, the answer is easy: More profit for the company.

      Probably not profit so much. Liability more likely. You swap a pack from a wrecked car, and while it’s parked in an underground lot, the car catches fire, takes out the other cars in the lot, maybe cause major structural damage.

      Don’t believ for a moment that the legal guys aren’t thinking about these and even crazier scenarios.

    7. Why? Because you want more mileage out of a perfectly good car.
      Battery technology has been upgraded more quickly than a gas engine that has had centuries to develop.
      If you want an easy to upgrade EV, go get a Nissan Leaf. The battery is air cooled instead of liquid cooled. As a result, Nissan Leafs don’t charge as fast and their batteries will not last as long. But they are easier to work on. Try driving both and see what you think. You will understand then why the BMW i3s are more desirable.

  2. A few years ago I briefly worked at the Nissan EV battery plant in the north of England (just doing a network project). You’ve never seen anything like the fire-suppression system there, it was seriously scary. If one of these packs goes wrong there is a LOT of energy tied up in it, so I can understand them disabling the pack if a car crashes. I’d much rather be around a tank of petrol than a li-ion battery when something goes wrong.

    1. 130km (and less in winter) is totally usable around town! You charge it at home overnight and start each day with a full tank. The challenge is when you need to leave town and drive more than 130km in a day. Everything about this vehicle is optimized for city-driving, and it still excels at that 8 years after launch. It was never the best long distance driver, and a 500km range would highlight its other design shortcomings.

  3. EVs at this point are a flop. I drive an i3 since 2015. It has now more than 120k km. I can’t do more than 80km a charge. In a colder day with heating and wind shield wipers and driving by night (lights) I make even less than that. I see no reasonable solution as a) the car is too cheap to sell. b)the battery swap is impossible: BMW doesn’t show will to do it (don’t even gives me price… Pushing me to buy a new car) and I don’t find anyone to do it. By other hand a new battery is too expensive. Math done it would be much cheaper drive a traditional car over these years. I will keep the i3 but I won’t buy another EV soon until brands have a clear policy about battery’s update. I will believe in EVs again the day batteries are standard with brands different from car brand makers.

    1. I’d just like to see the car manufacturers standardise in general. PCs went from proprietary interconnections to standardised interconnections. This is, of course, ignoring the complexities of machining automotive parts vs making PCBs.

      I go in to a wrecker and have to say “I want part A for a B year C. The D model from country E. Naturally aspirated”.

      I go in to a PC parts store and say “I want part A with connector B”.

      There are certainly cars that are designed for easier serviceability (e.g. single connector engine harness), but universal parts would be a dream.

      1. To be honest, I was surprised how easy this was, particularly if you compare with PC processors – Intel (etc.) always tells you that their motherboards will support much faster processors in the future, but anytime you want to upgrade, the pinout format has changed. Very nice here to see that the new battery pack is fundamentally the same shape, size etc., despite having twice the capacity. I was expecting to see a whole laundry list of “weld new bracket on”, “cut hole in that bit of chassis” etc.
        As others have said, this sounds like it was way easier than upgrading an IC engine, even one from the same manufacturer.

      2. Standardized?
        Were gas engines really ever standardized?
        Can we easily take a chevy v8 and put in a ford v8 instead without some modifications?
        If the cars were all standardized, you would be bored out of your mind over the car choices.
        If one design turned out to be a very poor decision, it would be in every car.
        What we want is a system where mistakes of the past are known to all so they are not repeated in newer designs.

    2. EVs a flop? A gas engine often experiences catastrophic failure when it gets old – thrown rod, blown head gasket, etc. Li0ion batteries usually experience a slow degradation in capacity. This will result in fewer miles being driven per charge. If I remember correctly, BWM in the states warranted these batteries to be 10% degradation over a 9 year period. Your battery might still be under warranty or not in your country. If you do a lot of fast charging at charging stations, then you will get a reduction in battery life. BWM learned over time and improved the i3 in the later models 2019+. Unfortunately, they stopped selling them when they had become more efficient in manufacturing the more reliable versions. It was become more difficult to compete given the lower range in comparison to the competitors.

  4. “The batteries are cooled by the air conditioning system, meaning that removal and replacement means draining the system of refrigerant using highly expensive specialised hardware. ”

    That sounds exactly like every BMW maintenance procedure. Need to change the oil? Have to suck it up through the dip stick tube after warming the engine up.

  5. As cool as I am to EV’s, the existence of a cooling device with endless damaging Freon and all it’s substitutes which in turn have to be banned as well and working at ever higher pressures on the compressor leaves me cold (pun). I can live without A/C. High pressure whatever leaks out! Battery cutting out because of cooling dependent on the A/C, no thanks.

    I remember seeing “the future” cars and a /minivan on campus in the 70’s from Japan. These were lead acid based. I had to ask what is the “gas cap” doing on an electric car hidden inside the corner of the door? He points to the label ‘kerosene’ and says it’s for the heating in winter. Oh! Unless we have the ultimate global warming, winter happens and ice forms.

    Heat represents a lot of electric power and cool even more as that heat has to go to waste. Does the BMW battery heat get sent into the cabin in the winter? With air or liquid cooling that can be done. Heat pump in reverse I suppose. Still too complicated.

    1. Later model BMW i3s, without the range extender engines, were all using heat pumps to heat the passenger compartment more efficiently than electric heating. Without the range extender, there was more room for plumbing in the cooling/heating system. When charging the battery, some energy from the charger is used to cool the battery during the fast charge cycles. The heat, but for envrionmental heat, is mainly develop during fast charging at a charger.

  6. I have a 2016 eGolf that gets about 70mi/charge. While I would like to upgrade the range, I absolutely would not if it meant the new battery would have a higher chance to instantly vaporize myself or someone else. I wonder if the battery could detect if there was a puncture and deploy some sticky goop to plug the hole from the inside, starving any battery fire from oxygen. Kind of like how they captured Mr. Incredible with those sticky black tar balls :)

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