Revealed: the cost of the i3 lithium batteries

Total replacement cost of all 8 LiOn modules (excluding labour and shipping) £9549.12 /$13,724.80 (if ordered online)

Modules cost £1193.64 each in the UK / $1715.60 in the US. (BMW of Bridgewater has a sale on this part right now!)

The battery pack is made up of 8 modules of which is cell is made by Samsung SDI and repackaged by BMW in Germany, and are connected together with the wiring harness, each rated at 355 volts, at 60Ah.

Part# 61277625066

Nice pics at:
http://www.realoem.com/bmw/showparts.do?model=1Z22&mospid=56088&btnr=61_3166&hg=61&fg=30

Fascinating indeed! Thank you for sharing.

Considering the base-price of the vehicle, it is interesting to see that the battery accounts for a 3rd of the base price of the car.

Good news is the electric motor and the transmission are both under $2k
I think by the time our batteries go out of warranty we should have significantly cheaper options.

Given the likely long life of the car, I'm wondering whether in the future, battery upgrades will offered. Either if the capacity goes below 70% after the warranty, or new battery technology would substantially increase range eg like 50% or more.

These obviously would have to fit in the existing battery frame, but from the video I saw, it appears to be a simple matter of dropping the battery frame from beneath the car and looked like a low labor effort.

It's a little unsettling to read all the articles about new batteries and 200 mile cars, although when these actually make it to showrooms is not clear. I have no problem if the increases are coming from just more batteries like Tesla, as this means more weight and cost, but if a large percentage comes from more efficient batteries, then you have to decide the economics, assuming upgrades are offered

Ron

More to the point - what is special about Samsung SDI's batteries as opposed to say LG Chem and why the huge price difference? Surely BMW can do better?

Ah ha. Is the rating of each cell the reason why those pesky DBT chargers keep failing? (They do tend to show a higher than 355voltage on screen when using CCS.

I just wondered...

Tried to find the article and can't locate it. It was an interview with a battery expert who was explaining that Tesla has taken the cheap, bulk approach, effectively combining thousands of laptop battery cells whereas BMW has taken the approach of very high-tech, impeccably manufactured to extremely tight tolerances. He was explaining that Tesla expects battery 'failure' (defined as complete or below acceptable remaining hold of 70%) at around the 6 year mark, whereas BMW expects 21 years. He further explained that once a battery is constructed they are able to test the chemistry and make a detailed calculation to the month of when it will fall below certain thresholds; he used the example of a battery next to him as being calculated to fall below 70% at 20 years and 8 months (not sure the exact numbers but the point is they knew to what month it would reach that point).

There were other discussion points that Tesla has looked at it from manufacture cheap and then throw away whereas BMW has taken the re-use approach of when it falls below acceptable threshold for use in a vehicle, the battery can then be re-used in other applications such as domestic. The example was a 20 year old BMW battery that could only hold 70% (15.4kWh) being placed in a household with solar panels such that during the day the battery captured and held energy for use when the sun went down. The example looked at average evening electricity use to show that the 70% capacity of the BMW battery would meet 100% of evening electricity for average consumers (80%).

BMW has truly embraced sustainability and longevity of what they are manufacturing.

cove3 said:

Given the likely long life of the car, I'm wondering whether in the future, battery upgrades will offered. ....

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Keep in mind, BMW is in the business of selling cars. Samsung will make the bulk of the $ from a battery upgrade and BMW can only take a cut.

I wouldn't be surprise if all the batteries are numbered and/or i3 has to reset from BMW's central control once a battery cell is replaced.

elptex said:

Tried to find the article and can't locate it. It was an interview with a battery expert who was explaining that Tesla has taken the cheap, bulk approach, effectively combining thousands of laptop battery cells whereas BMW has taken the approach of very high-tech, impeccably manufactured to extremely tight tolerances. He was explaining that Tesla expects battery 'failure' (defined as complete or below acceptable remaining hold of 70%) at around the 6 year mark, whereas BMW expects 21 years. He further explained that once a battery is constructed they are able to test the chemistry and make a detailed calculation to the month of when it will fall below certain thresholds; he used the example of a battery next to him as being calculated to fall below 70% at 20 years and 8 months (not sure the exact numbers but the point is they knew to what month it would reach that point).

There were other discussion points that Tesla has looked at it from manufacture cheap and then throw away whereas BMW has taken the re-use approach of when it falls below acceptable threshold for use in a vehicle, the battery can then be re-used in other applications such as domestic. The example was a 20 year old BMW battery that could only hold 70% (15.4kWh) being placed in a household with solar panels such that during the day the battery captured and held energy for use when the sun went down. The example looked at average evening electricity use to show that the 70% capacity of the BMW battery would meet 100% of evening electricity for average consumers (80%).

BMW has truly embraced sustainability and longevity of what they are manufacturing.

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I spent a long time hanging around the Telsa forums when weighing up which car to buy and a lot of what that battery expert said is bogus.

Tesla dont throw away batteries. In fact they have a dedicated part of the business working on stationary storage with units already in people's homes. As far as i am aware BMW Don't have any returning batteries to do this with yet. So it's just talk.

Likewise the expected life. .. These a few model S owners got near 100k miles and only seen 5-10% degradation. That's about 8 years driving for me. Unless he is taking about some electro chemical degradation regardless of how the car is used?

Interesting that the i3 battery will last 20 years. Means my plans to replace at 10 years might be an extravagance rather than a necessity.

I do wonder if he was comparing like for like mileages. I'd need to charge the i3 twice a day on my current commute. Where a model S would need 3 times a week.

The thing not mentioned is that the tesla pack is made of 8000 standard cells. If one breaks you are looking at a few dollar pounds to replace it. The i3 has 8 cells at over a grand each. Not sure if they come apart for servicing, but my guess is they are a single unit with a large case. Tesla approach means a lot of packaging and weight with the benefit of redundancy and lower cost. More important on a 85kWh battery!

This is the link to the battery expert article and his view that i3 batteries are state of the art. It's pretty definitive so it's important to determine if he knows what he's talking about. I would really like his realistic take on the breakthrough technologies being touted and when they would hit the showroom floor.

Ron

http://translate.googleusercontent.com/translate_c?depth=1&hl=en&rurl=translate.google.com&sl=auto&tl=en&u=http://adacemobility.wordpress.com/2013/10/21/batterie-experte-sven-bauer-der-tesla-akku-oder-der-im-bmw-i3-das-ist-ein-gewaltiger-unterschied/&usg=ALkJrhhzLb_k5LSv7VDV9UnvMDdBDOOxkA

As I recall the discussions about Tesla's Gigafactory, manufacturing their own cells will have a number of advantages. One of these is form-factor. Tesla uses a standard-size round cell, close in size to a AA cell, in it's battery packs. They are researching different form factors for their cells that could bring benefits in more compact packaging and cooling. So, chemistry aside, there are gains to be made by simply making a different shape cell. It looks like BMW has already done that with the i3's cells.

cove3 said:

This is the link to the battery expert article and his view that i3 batteries are state of the art. It's pretty definitive so it's important to determine if he knows what he's talking about. I would really like his realistic take on the breakthrough technologies being touted and when they would hit the showroom floor.

Ron

http://translate.googleusercontent.com/translate_c?depth=1&hl=en&rurl=translate.google.com&sl=auto&tl=en&u=http://adacemobility.wordpress.com/2013/10/21/batterie-experte-sven-bauer-der-tesla-akku-oder-der-im-bmw-i3-das-ist-ein-gewaltiger-unterschied/&usg=ALkJrhhzLb_k5LSv7VDV9UnvMDdBDOOxkA

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That's it, thank you!

I do don't doubt the i3 cells are state of the art. But I think he's down playing Tesla a bit. I guess when you run a battery company and you have aspirations to devleop your own home energy storage units, you don't want to give too much credit to the competition. However - one of the first comments points out... Telsa have come up with an 8 year unlimited milage warranty on their 85kWh packs. Which makes his statement they only last 6 years a bit silly. Or Telsa have miscalculated and will be absorbing the cost of people who do mega mileage driving around the USA (for free on superchargers).

One of the reasosns Telsa liked the 18650 in their current configuration is that they can control the temperature. Which is exaclty the opposite of what he is saying. One of the things I've picked up reading about them is thermal management is the top priority - as it's that that can kill cells. Hence why they went with water cooling.

Whats interesting to me - is analysis of the cost of 18650 cells - shows the cell cost for the 85kWh is probably the same as the i3 22kWh replacement pack retails for - once you take into account their bulk discounts. $10,000-$12,000! You still have to add the costs of building the battery pack costs on top of the individual 18650 cells, but it does show off the cost saving of their approach.

http://www.greencarreports.com/news/1084682_what-goes-into-a-tesla-model-s-battery--and-what-it-may-cost

The i3's battery is comprised of 8 modules, each of which contain 12 cells. The pack has 96 large-format battery cells, not 8 cells as has been posted here.

As for Tesla, they use the the small 18650 cells that are commonly used in laptops. They can't just replace one though, they need to replace an entire module which has hundreds of them wired together.

Every connection is a potential failure point. Every internal battery terminal is a potential failure point. Guess which battery pack has more potential failure points? Since the batteries are wired in a series parallel configuration, one bad cell can cause many to be 'out of the circuit'. There are ways to bypass bad cells, but if used, that adds to the complexity and cost and in itself is a failure point.

What is Tesla's definition of a failed battery pack? BMW is pretty straightforward about what it says it 'failed'.

TomMoloughney said:

The i3's battery is comprised of 8 modules, each of which contain 12 cells. The pack has 96 large-format battery cells, not 8 cells as has been posted here.
.

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Thanks updated post. got my cells and modules mixed up! Punters can only seemingly buy the replacement modules one by one, but not cells. There's a really good video the Group has uploaded to their youtube page. Shows how they nicely package it all up.

jadnashuanh said:

Every connection is a potential failure point. Every internal battery terminal is a potential failure point. Guess which battery pack has more potential failure points? Since the batteries are wired in a series parallel configuration, one bad cell can cause many to be 'out of the circuit'. There are ways to bypass bad cells, but if used, that adds to the complexity and cost and in itself is a failure point.

What is Tesla's definition of a failed battery pack? BMW is pretty straightforward about what it says it 'failed'.

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Its hard to say which one will be more reliable... only time will tell. Tesla's packs are built as a large series/parallel arrays. They claim a cell can completely fail while driving and the driver will never know. BMW's packs have all the cells in series. Even though it has more connections, from a pack-architecture standpoint, the Tesla pack is probably more reliable due to the redundancy gained from the highly parallel design. Both companies use high quality, well matched cells: Tesla uses NCA cells from Panasonic, and BMW uses NMC cells from Samsung... both well regarded for reliability. Both packs are liquid cooled with excellent thermal management. Another wildcard is the battery management system, which can have a big impact on life of the pack. Again, only time will tell.

Buskraut said:

Its hard to say which one will be more reliable... only time will tell. Tesla's packs are built as a large series/parallel arrays. They claim a cell can completely fail while driving and the driver will never know. BMW's packs have all the cells in series. Even though it has more connections, from a pack-architecture standpoint, the Tesla pack is probably more reliable due to the redundancy gained from the highly parallel design. Both companies use high quality, well matched cells: Tesla uses NCA cells from Panasonic, and BMW uses NMC cells from Samsung... both well regarded for reliability. Both packs are liquid cooled with excellent thermal management. Another wildcard is the battery management system, which can have a big impact on life of the pack. Again, only time will tell.

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The i3's pack isn't liquid cooled like Teslas, it uses R134a refrigerant. BMW went with this because they believed it was safer. The liquid in Tesla's packs can act as an accelerant in the case of a fire, whereas the R134a just dissipates in the case of a rupture and is harmless.

TomMoloughney said:

Buskraut said:

The i3's pack isn't liquid cooled like Teslas, it uses R134a refrigerant.

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But presumably it's pressurised, and therefore liquid in the battery pack. If it were gaseous, it would be far less effective for thermal management.

TomMoloughney said:

The i3's battery is comprised of 8 modules, each of which contain 12 cells. The pack has 96 large-format battery cells, not 8 cells as has been posted here.

As for Tesla, they use the the small 18650 cells that are commonly used in laptops. They can't just replace one though, they need to replace an entire module which has hundreds of them wired together.

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The point I'm trying to make about Telsa is they can pull a defective subassembly, carry out maintenance at the service centre to replace a damaged cell. Or if it takes too long they can drop in a loaner pack whilst repairs are done elsewhere. Like they did with the squeaky or vibrating drive units.

Having smaller cells that can fail makes them easier (aka more cost effective) to replace. With the i3 approach - I'm not sure what can be fixed if one of the 96 get broken. Presumably stripping down and refurbing what is effectively a 234Wh cell (22.5kWh/96) doesn't sound like a job you can do on a bench at the dealership. But swapping a couple of 18650s and re-soldering is.

I say that having never seen the inside of a Telsa battery module, so I could be wrong. Obviously you can do the same to an i3 module... send it off for repairs, and slot in a loaner, but if it's totally defective that's a larger cost item to replace than 1 or 2 18650s.

I still think the i3 solution is more elegant, lighter and probably longer lasting, but don't quite get where the 20 odd years life expectancy comes from. That's news to me... I'm now thinking damn I should have waited till the packs were 50kWh as replacing a battery well before it's life expectancy is a bit silly. Unless they have a trade in programme later on. Like Telsa are doing on the Roadster (I sound like a stuck Telsa record now).

Is the refrigerant used in the same circuit to pre-warm the batteries in winter? I.e. it's basically a heat carrier?

PS - what's the warranty on the i3 battery, I never even thought to check this before! I presume something like 8 years 100,000 miles that Toyota introduced on the Prius.