battery change

Hello Tom,

I'm still in doubt whether to buy the Rex option. My mileage will be around 6000km/year
I'm worried about the capacity loss over the years. BMW guarantees a 70% battery load. But that will be a range of only ,7x130=91 kilometer.
Is it an option to stay with the batteries now and exchange within 5 years for a more efficient pack with more kW?
It would be a shame to throw away a non-rusty 8 year old BMW because of a dead battery.

Pieke
dreaming of an Solar Orange i3 with full options.....

The battery in your i3 should last a very very long time.

Charging to 100% in very hot weather is what caused capacity loss in some US Leaf's . Unlike the Leaf, the i3 battery back is cooled during charging in hot weather. The i3 uses the car's air conditioning to pump heat out of the pack.

6000km/year ??? If you are able to do your daily commute with the battery charged to 80%, the pack will outlast the car.

AndrewDebbie said:

The battery in your i3 should last a very very long time.

Charging to 100% in very hot weather is what caused capacity loss in some US Leaf's . Unlike the Leaf, the i3 battery back is cooled during charging in hot weather. The i3 uses the car's air conditioning to pump heat out of the pack.

6000km/year ??? If you are able to do your daily commute with the battery charged to 80%, the pack will outlast the car.

Click to expand...

At the UK Launch the R&D guy said for BMW to guarantee the battery for 8 years they had to be confident it would last at least 16 years ...... I was suitably reassured.

With regards to the 80% charge number, does the i3 already have a cushion built in like the Volt (16 kwh but I believe it uses only takes 10 kwh, the other 6 used as a built-in cushion to enable longer battery life)? In other words, if the i3 has a 22 kwh battery, how many kwh does it take to "fill up" from empty to full? While it's nice to be careful with the battery, is it wasteful to charge to 80% and leave 20% "on the table"?

Northwestern said:

With regards to the 80% charge number, does the i3 already have a cushion built in like the Volt (16 kwh but I believe it uses only takes 10 kwh, the other 6 used as a built-in cushion to enable longer battery life)? In other words, if the i3 has a 22 kwh battery, how many kwh does it take to "fill up" from empty to full? While it's nice to be careful with the battery, is it wasteful to charge to 80% and leave 20% "on the table"?

Click to expand...

You only have access to 85% of the 22kWh battery, so 18.8kWh's is usable.

Piekepuk said:

I'm worried about the capacity loss over the years. BMW guarantees a 70% battery load. But that will be a range of only ,7x130=91 kilometer.

Click to expand...

Does BMW guarantee 70% capacity in Europe? I'm in the US, on the opposite coast from Tom, and we are all still waiting to hear the details on this and other topics. If the capacity is guaranteed, then you should be in reasonably good shape. It sounds like you would be getting the battery-only version of the i3, correct? I would expect that charging infrastructure will improve over time, and as the battery slowly loses capacity, it will be easier to get a boost along the way. This will help maintain the utility of the vehicle.

That said, it would be good to budget on a battery pack replacement once the capacity warranty runs out. Perhaps it won't be necessary, but I would be prepared for that. The cost will likely go down over time, and although the technology is improving, I would not assume that the latest and most advanced battery will be available as an upgrade. Instead, I would assume that the replacement will have the exact same capacity like the previous battery when new.

AndrewDebbie said:

Charging to 100% in very hot weather is what caused capacity loss in some US Leaf's . Unlike the Leaf, the i3 battery back is cooled during charging in hot weather. The i3 uses the car's air conditioning to pump heat out of the pack.

Click to expand...

Good on you to stay informed! Yes, charging to full will wear out the battery faster than charging to 80%. I was one of the early LEAF drivers in the US, and we discussed and researched this at great length. In our collective experience, it was the temperature, which mattered the most. This should be less of an issue with the i3, since it's supposed to be have a sophisticated temperature management system. It also helps to live in a cooler climate, where batteries get less exposure to hot weather. I would not be at all concerned if you lived in the UK, Germany or Scandinavia. In fact, the first LEAF delivered to Norway is still doing great and has like-new battery capacity, even though the owner got heavy use out of the car, including frequent DC fast charging.

The worst thing you could do is to charge the car to full and let it sit for several days or weeks. Conversely, if you drive it every day, I would not worry very much about the impact of charging on the battery. If you drive around the city most of the time, and don't need the range, you could elect to charge to 80%, which will be little easier on the battery. It's OK to charge to full before a trip and whenever you need the entire range of the car.

Parker said:

At the UK Launch the R&D guy said for BMW to guarantee the battery for 8 years they had to be confident it would last at least 16 years ...... I was suitably reassured.

Click to expand...

Could you please share more details, Parker? I would be very curious to learn more. Thanks again for all the information you posted on the forum. I found it very helpful, and cross-posted some of it to other places.

Northwestern said:

With regards to the 80% charge number, does the i3 already have a cushion built in like the Volt (16 kwh but I believe it uses only takes 10 kwh, the other 6 used as a built-in cushion to enable longer battery life)? In other words, if the i3 has a 22 kwh battery, how many kwh does it take to "fill up" from empty to full? While it's nice to be careful with the battery, is it wasteful to charge to 80% and leave 20% "on the table"?

Click to expand...

Just like Tom said, the battery will have 18.8 kWh of usable capacity per the spec sheet; there is a small safety cushion on either end (both low and high state of charge), which we cannot access. That said, you could see more than that drawn from the wall. This is due to charger and battery inefficiency, as well as diverse cooling systems and the temperature management system, which are usually running. I would expect to see about 22 or 23 kWh being pulled from the wall when the i3 has been driven into turtle mode and then recharged to full capacity. This does not mean that the battery will allow you to use more energy than 18.8 kWh. Most of the extra electricity will be converted to heat during the charging process.

Does BMW guarantee 70% capacity in Europe? I'm in the US, on the opposite coast from Tom, and we are all still waiting to hear the details on this and other topics. If the capacity is guaranteed, then you should be in reasonably good shape. It sounds like you would be getting the battery-only version of the i3, correct? I would expect that charging infrastructure will improve over time, and as the battery slowly loses capacity, it will be easier to get a boost along the way. This will help maintain the utility of the vehicle.

Click to expand...

Yep, In the Dutch brochure it states: (Free translation) The BMW lithium-ion battery is characterized by its longevity. For the
first 100,000 kilometer and up to 8 years defects in the battery of your BMW i3 will be repaired and a maximum capacity of 70% guaranteed.

I intend to buy a non-Rex version, because I have other cars that are perfect for long trips. For the daily drive to my office and from my office to my customers I would like to have a small premium car that also is environmental acceptable.
At this moment I drive my 325i on low fuel reserves (range up to 100 km) to see whether that makes me nervous. It doesn't

10 year would be fine for the battery, if BMW cares for it's customers and will offer a state of the art new one.

Pieke

Piekepuk said:

Yep, In the Dutch brochure it states: (Free translation) The BMW lithium-ion battery is characterized by its longevity. For the
first 100,000 kilometer and up to 8 years defects in the battery of your BMW i3 will be repaired and a maximum capacity of 70% guaranteed.

Click to expand...

That's very good to hear, thank you for sharing! I owned an all-electric car for 2 1/2 years now, and after an initial period of adjustment, I don't mind the limited range. Most of my driving is in a large metropolitan area, and I typically fly if I need to go elsewhere. The distances here on the West Coast are simply too great and flying is too convenient. Sometimes I wish there were electric planes!

surfingslovak said:

Parker said:

At the UK Launch the R&D guy said for BMW to guarantee the battery for 8 years they had to be confident it would last at least 16 years ...... I was suitably reassured.

Click to expand...

Could you please share more details, Parker? I would be very curious to learn more. Thanks again for all the information you posted on the forum. I found it very helpful, and cross-posted some of it to other places.

Click to expand...

Please bear in mind I'm not an EV owner and I'm in information ramp up mode at the moment so the conversation with the R&D guy was about addressing my (maybe unfounded) concerns ..... so with that caveat here goes.

The chap I spoke to built the original Mini E's and then went on to work on the "i" project and he said they learnt a lot from that project and he pointed to things the i3 that were directly a result of Mini E Pioneer feedback - the light by the power socket .... but it was mainly in battery temperature management that they learnt the most. "You can't charge a battery if its too cold ... the charge just won't go in" this they learnt the hard way with the Mini E so the i3 heats the cells up (or cools them down) BEFORE any charge goes in. They found with the Mini E it was the corners of the battery pack that got the hottest (and coolest) when standing in a car park so special attention has been paid to those areas. I asked about leaving the car in a car park ... he said they have left an i3 battery pack at 80% charge in a Dubai (I think) car park for 4 weeks and car had lost less than 1% of its capacity. The only thing BMW were concerned about were people buying i3 as Trophy car ie sticking them in a garage for 6 months and not using them. I got the impression not using the batteries for long periods (6 months or more) was the worse thing you could do.

Re the guarantee I said I thought the 8 year battery guarantee was a bit mean .... he said BMW's policy on all its guarantees was they would only guarantee something if in tests it would last double that time / mileage. So I said your tests showed the battery would last 16 years .... and his response was "quite happily"

The other thing he mentioned was that before the pack is charged all the cells within the pack are brought down the to same level of charge ........as within the pack some cells get used more than others and to get consistent charging they have found its best if all cells start off at the same level.
The impression I got was the battery management was the single most important feature of the i3 .... and the area where most R&D money had gone.

Other bits that may have been mentioned elsewhere.

If you have Rex you can manually turn it on once the Battery pack drops below 80% of charge.

If you know you can reach your destination without the need of Rex you can switch it off.

If you are driving at sustained high speed (motorways / freeways) the Rex will come on Automatically to preserve battery (you can switch it off )

Parker said:

surfingslovak said:

Parker said:

At the UK Launch the R&D guy said for BMW to guarantee the battery for 8 years they had to be confident it would last at least 16 years ...... I was suitably reassured.

Click to expand...

Could you please share more details, Parker? I would be very curious to learn more. Thanks again for all the information you posted on the forum. I found it very helpful, and cross-posted some of it to other places.

Click to expand...

Please bear in mind I'm not an EV owner and I'm in information ramp up mode at the moment so the conversation with the R&D guy was about addressing my (maybe unfounded) concerns ..... so with that caveat here goes.

The chap I spoke to built the original Mini E's and then went on to work on the "i" project and he said they learnt a lot from that project and he pointed to things the i3 that were directly a result of Mini E Pioneer feedback - the light by the power socket .... but it was mainly in battery temperature management that they learnt the most. "You can't charge a battery if its too cold ... the charge just won't go in" this they learnt the hard way with the Mini E so the i3 heats the cells up (or cools them down) BEFORE any charge goes in. They found with the Mini E it was the corners of the battery pack that got the hottest (and coolest) when standing in a car park so special attention has been paid to those areas. I asked about leaving the car in a car park ... he said they have left an i3 battery pack at 80% charge in a Dubai (I think) car park for 4 weeks and car had lost less than 1% of its capacity. The only thing BMW were concerned about were people buying i3 as Trophy car ie sticking them in a garage for 6 months and not using them. I got the impression not using the batteries for long periods (6 months or more) was the worse thing you could do.

Re the guarantee I said I thought the 8 year battery guarantee was a bit mean .... he said BMW's policy on all its guarantees was they would only guarantee something if in tests it would last double that time / mileage. So I said your tests showed the battery would last 16 years .... and his response was "quite happily"

The other thing he mentioned was that before the pack is charged all the cells within the pack are brought down the to same level of charge ........as within the pack some cells get used more than others and to get consistent charging they have found its best if all cells start off at the same level.
The impression I got was the battery management was the single most important feature of the i3 .... and the area where most R&D money had gone.

Other bits that may have been mentioned elsewhere.

If you have Rex you can manually turn it on once the Battery pack drops below 80% of charge.

If you know you can reach your destination without the need of Rex you can switch it off.

If you are driving at sustained high speed (motorways / freeways) the Rex will come on Automatically to preserve battery (you can switch it off )

Click to expand...

Nice info Parker. However remember the source of the information, these people want to sell you their product! As one of the MINI-E and now ActiveE drivers I know intimately well the battery issues both vehicles had and how BMW has learned from this - all good indeed. I have no doubt the battery "will last" 16 years, but just lasting isn't the problem. At what capacity will it be in 16 years is the real question. You should expect anywhere from 2 to 4 percent capacity per year under normal conditions, more if you don't care for the pack. So yeah if you only need to drive 60kM a day in 15 or 16 years you'll still be able to use your original pack!

I wrote quite a bit on battery capacity loss on the ActiveE, which happens to have the same battery cells as the i3, but I assume the BMS in the i3 is more sophisticated which is a good thing. Take a look: http://www.bmwblog.com/2013/04/25/understanding-battery-capacity-loss/

TomMoloughney said:

I have no doubt the battery "will last" 16 years, but just lasting isn't the problem. At what capacity will it be in 16 years is the real question. You should expect anywhere from 2 to 4 percent capacity per year under normal conditions, more if you don't care for the pack. So yeah if you only need to drive 60kM a day in 15 or 16 years you'll still be able to use your original pack!

Click to expand...

I now know that was the question I SHOULD have asked (hence my preamble) ..... that's sort of the reason I'll go for the Rex regardless of whether I keep it or not - there has to be greater value in a car that you can STILL drive 100+ miles in at 10 years old vs one that almost certainly wont.

Parker said:

TomMoloughney said:

I have no doubt the battery "will last" 16 years, but just lasting isn't the problem. At what capacity will it be in 16 years is the real question. You should expect anywhere from 2 to 4 percent capacity per year under normal conditions, more if you don't care for the pack. So yeah if you only need to drive 60kM a day in 15 or 16 years you'll still be able to use your original pack!

Click to expand...

I now know that was the question I SHOULD have asked (hence my preamble) ..... that's sort of the reason I'll go for the Rex regardless of whether I keep it or not - there has to be greater value in a car that you can STILL drive 100+ miles in at 10 years old vs one that almost certainly wont.

Click to expand...

Yes Parker there will be much greater value. I suspect someone selling a 4 year old i3 with 60,000 miles (~100,000km) on it will have significant depreciation (maybe 60%). However if it has the Rex I bet you'll be able to see it for much more, possibly even recuperating every penny you paid for the REx in the first place.

Piekepuk said:

Does BMW guarantee 70% capacity in Europe? I'm in the US, on the opposite coast from Tom, and we are all still waiting to hear the details on this and other topics. If the capacity is guaranteed, then you should be in reasonably good shape. It sounds like you would be getting the battery-only version of the i3, correct? I would expect that charging infrastructure will improve over time, and as the battery slowly loses capacity, it will be easier to get a boost along the way. This will help maintain the utility of the vehicle.

Click to expand...

Yep, In the Dutch brochure it states: (Free translation) The BMW lithium-ion battery is characterized by its longevity. For the
first 100,000 kilometer and up to 8 years defects in the battery of your BMW i3 will be repaired and a maximum capacity of 70% guaranteed.

I intend to buy a non-Rex version, because I have other cars that are perfect for long trips. For the daily drive to my office and from my office to my customers I would like to have a small premium car that also is environmental acceptable.
At this moment I drive my 325i on low fuel reserves (range up to 100 km) to see whether that makes me nervous. It doesn't

10 year would be fine for the battery, if BMW cares for it's customers and will offer a state of the art new one.

Pieke

Click to expand...

strange

all other ev's have 160.000km or 8 years
so wy did bmw only provide 100.000km? are they not confident they can provide a 160.000 warranty on the battery
and wy is this 100.000 in the EU where in USA they do have 160.000km ( 100.000miles )
strange.