BMW i3 range?

[anticat900]

I have just bought a BMW i3s rex, with 148,000 on it and the battery is at 72%.
I can get on 100% charge about 120miles in eco pro mode.
Can people advise what they get on 33kw rex and 42kw non rex, when the battery is less well used?
I'm sure my car is likely using all of its reserve capacity by now.
Thanks
David

 

[EvanstonI3]

You might want to mention what year your car is. There are 3 different battery packs.
Where do you get the "72%" from?

 

[anticat900]

Hello, Mine being a i3s rex is a 33kw

 

[anticat900]

There is a battery health check built into the driver display, a series of button combinations will give you the health of your i3 battery.

 

[EvanstonI3]

There is a battery health check built into the driver display, a series of button combinations will give you the health of your i3 battery.

Then what is the BATT.KAPPA.MAX number that you see?

 

[alohart]

Can people advise what they get on 33kw rex and 42kw non rex, when the battery is less well used?

I'll be that bothersome guy and point out that "kW" is power while "kWh" is energy (capacity). The 33 kWh and 42 kWh battery packs both have the same maximum power output, 125 kW for the i3 and 135 kW for the i3S.

I'm sure my car is likely using all of its reserve capacity by now.

I haven't read that the BMS reduces the sizes of the low and high charge level buffers as the battery cells lose capacity. I have seen the BMS data displayed by the mi3 app on a battery pack that was about to be replaced under the excessive capacity loss warranty. It low charge level buffer remained the same ~10% as when it was new. The high charge level buffer was displayed as much larger than when new which I think is how the BMS displays capacity loss. The capacity to % charge level ratio remains constant, so when the capacity decreases, the highest attainable charge level, which must be relative to when the battery pack was new, decreases. However, the battery pack voltage at a full charge was similar to when it was new indicating that the high charge level buffer hasn't changed much.

If you calculated the 72% capacity compared with new by using the Batt. Kapa. max value, this is only a calculated estimate that can vary considerably over time. 120 miles on a full charge might be excellent for a 94 Ah battery pack, even in Eco Pro mode, depending on the driving conditions and assuming that you're not including the REx range. This exceeds the E.P.A. rated range when new and probably wouldn't be likely were the capacity of your battery pack only 72% of the new capacity.

 

[anticat900]

It is a 33kw car you can find out the health of the battery via the button on the side of the drivers panel

 

[Cybrstar]

2018 i3s 33kw battery with 60k I get about 90-100 miles until battery fully drained. My driving style is between lead foot and moderate.

 

[Gonville]

There is a battery health check built into the driver display, a series of button combinations will give you the health of your i3 battery.

That KappaMax figure is unreliable as it is just an arithmetic summation of charge current last put in. I’ve posted the long article on this before. Essentially meaningless.

 

[Gonville]

Then what is the BATT.KAPPA.MAX number that you see?

Max Kappa (short for “Kapazität”) is the BMS estimated snapshot capacity at that point in time, its based on external factors (temperature, current load), coulomb count, these factors are then fed into a statistical model to provide an educated guess of what the current capacity of the pack. This is what is shown in the service menu. It is not like a fuel tank you can't just measure it as there is chemistry involved.



Max Kappa as such is not a measure of anything, it is a guess of what the BMS thinks the pack is doing at that moment in time and therefore how many kWhs are available. It is not a true reflection of capacity.



Consider the following scenario, it has been cold overnight you haven't preconditioned so the battery is at 4c well below its preferred operating temperature of 24-28c, Max Kappa will show a corresponding low number as due to the cold the pack is less chemically active, as you drive the load starts to warm the pack up, so you then lose range but Max Kappa goes up due to battery reaching operating temperature.



The only way to test true capacity and health of a battery is to charge and discharge the pack to known points and record the input and output rates. It is perfectly possible for Max Kappa to read 19.1kWh (on a 60aH) on a full charge but the battery actual be degraded, or vice versa for it to read well under 15kWh but be perfectly fine.

 

[Gonville]

This graph can help. Speed determines range. Mostly except for temperature. The dotted line is for REX with one tank of fuel consumed.

 

[nickp]

2018 i3s 33kw battery with 60k I get about 90-100 miles until battery fully drained. My driving style is between lead foot and moderate.

Finally someone reporting with real battery range instead of 150 miles on a 33kw. On my 16 Rex I get around 70 miles mixed driving. But if i drive like a granny at a constant under 55, I can get as high as 95 miles. But that's not real range.

 

[mojo]

But that's not real range.

Why not? If most of your driving is within a city, or on non-motorway routes, it could easily be at an average of a lot less than 50MPH!

I did a real journey earlier in the week which was mostly on the M25 (London orbital route) and my range at a low temp of 6 degrees C was 165 miles (42kWh model). That's "real range" - it's just that the circumstances on that trip where different from (for example) your typical journey.

 

[Lothi]

I'll be that bothersome guy and point out that "kW" is power while "kWh" is energy (capacity). The 33 kWh and 42 kWh battery packs both have the same maximum power output, 125 kW for the i3 and 135 kW for the i3S.

I haven't read that the BMS reduces the sizes of the low and high charge level buffers as the battery cells lose capacity. I have seen the BMS data displayed by the mi3 app on a battery pack that was about to be replaced under the excessive capacity loss warranty. It low charge level buffer remained the same ~10% as when it was new. The high charge level buffer was displayed as much larger than when new which I think is how the BMS displays capacity loss. The capacity to % charge level ratio remains constant, so when the capacity decreases, the highest attainable charge level, which must be relative to when the battery pack was new, decreases. However, the battery pack voltage at a full charge was similar to when it was new indicating that the high charge level buffer hasn't changed much.

If you calculated the 72% capacity compared with new by using the Batt. Kapa. max value, this is only a calculated estimate that can vary considerably over time. 120 miles on a full charge might be excellent for a 94 Ah battery pack, even in Eco Pro mode, depending on the driving conditions and assuming that you're not including the REx range. This exceeds the E.P.A. rated range when new and probably wouldn't be likely were the capacity of your battery pack only 72% of the new capacity.

Good try Alohart but it's still a long way before the difference beween kW and kWh is understood and accepted!
Thanks anyway for your many contributions on this forum and keep being this precious "bothersome guy"

 

[alohart]

Good try Alohart but it's still a long way before the difference beween kW and kWh is understood and accepted!

I know. But I'll keep trying because using the wrong units can be confusing. Maybe I should equate kWh with ICE vehicle fuel tank capacity in gallons or liters and kW with horsepower.

 

[EvanstonI3]

still waiting for OP to say exactly how they found "72%" Battery Health on their dash.

 

[mojo]

My guess would have to be that they tapped the BC button on the left hand stalk and got to the display that shows battery % (State of Charge, but not marked as such) and confused that with Battery Health?

 

[EvanstonI3]

My guess would have to be that they tapped the BC button on the left hand stalk and got to the display that shows battery % (State of Charge, but not marked as such) and confused that with Battery Health?

still waiting for OP to say exactly how they found "72%" Battery Health on their dash.

 

[anticat900]

Max Kappa (short for “Kapazität”) is the BMS estimated snapshot capacity at that point in time, its based on external factors (temperature, current load), coulomb count, these factors are then fed into a statistical model to provide an educated guess of what the current capacity of the pack. This is what is shown in the service menu. It is not like a fuel tank you can't just measure it as there is chemistry involved.



Max Kappa as such is not a measure of anything, it is a guess of what the BMS thinks the pack is doing at that moment in time and therefore how many kWhs are available. It is not a true reflection of capacity.



Consider the following scenario, it has been cold overnight you haven't preconditioned so the battery is at 4c well below its preferred operating temperature of 24-28c, Max Kappa will show a corresponding low number as due to the cold the pack is less chemically active, as you drive the load starts to warm the pack up, so you then lose range but Max Kappa goes up due to battery reaching operating temperature.



The only way to test true capacity and health of a battery is to charge and discharge the pack to known points and record the input and output rates. It is perfectly possible for Max Kappa to read 19.1kWh (on a 60aH) on a full charge but the battery actual be degraded, or vice versa for it to read well under 15kWh but be perfectly fine.

Thanks for the info, my check was on a cold wet day. If i do another say in warm Spring it could go up?

 

[mojo]

still waiting for OP to say exactly how they found "72%" Battery Health on their dash.

Seems you'll never know....