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Discussion Starter · #1 ·
So I was looking through pictures of both the i4 and iX battery pack, and noticed something interesting which is that the iX looks to have substantially better cooling, now this is all speculation and we'll have to wait and see when people start testing these two vehicles, but let me explain my findings.

The i4 battery module count is a bit weird, on the base layer it has 4 huge modules and 1 small, and the top layer 2 small modules.

The iX base layer consists of 10 modules and 1 module on the top layer, all the same size.

Now for the cooling. The i4 has one huge cooling plate covering the whole base layer of a module, but this cooling plate only has 1 inlet and outlet as the cooling plate only consists of one big cooling cell. While the iX has smaller cooling plates also covering the whole base layer of a module, with 2 cooling cells, and each cell having its own inlet and outlet, this should mean that the water will be in the cooling plate for a much shorter duration meaning the water won't get as hot and effectively cooling the module better. It really seems as the iX has superior battery cooling. What do you think?

*Top picture is the i4 battery pack
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All i can see is that iX cooling seems to be more complex with more connectors. I sure hope there are some benefits because otherwise its just unnecessary complexity. But its different battery size as well.
 

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Welcome to the forum @Sjokosaus and @lnaukkar!

Would the iX's battery layout have anything to do with its size since it's a bigger vehicle than the i4?
The iX and i4 does have different cell dimensions, but the cooling plate design wouldn't have anything to do with that as they can be made to any dimension. I guess we'll have to wait and see in real world tests.
 

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This is a great discussion topic, and thank you for the detailed pictures. So from what I can see, just above the bottom plate are the details of the cooling system, starting with the water intake/outlet manifold in black, then the black piping going into the heat exchangers that look like aluminum plates with striations on top; where as the iX (bottom picture) has 10 heat exchanger plates below the shown main outbound and inbound pipes, and one on top, corresponding to the 11 battery modules, the i4 has 4 large heat exchangers spanning the whole width plus one smaller on the far right, below the main pipes, and two smaller heat exchangers on top. Once the stack is put together, the whole piping seems to fit between the battery modules for the iX and in the "transmission" tunnel for the i4, above the battery modules, with pipes going down to the heat exchangers, between the battery modules, in the trough visible between said modules in the layer above the cooling layer. Above the modules as represented here is the electrical distribution, which connect all the modules to the control module top right, sitting in the front "bump" in the top plate.

The good news is that contrary to AMG's early depiction of their battery pack and possibly Tesla (one may think due to their round form factor, similar to AMG's, compared to the flat BMW battery cells), the water cooling system seems to be completely sealed off instead off "flooding" the whole battery pack around the modules; I think this would promote a better control of the water flow, and the water piping also ensures that the cool water reaches all the battery packs at once and the heated water gets collected again from all the packs at once; the downside is that the water has to be kept very clean, as any debris may clog one of the pipes and allow one of the modules to overheat. I have no doubt that the individual modules are monitored to detect such an issue, and that there are leak detectors in case any of the piping should fail. So while the battery physical build-up is certainly less "symmetrical" in the i4, I don't think that the cooling system would be any less efficient assuming the piping is designed appropriately (and it's a fair assumption, these are German engineers after all, they are known for their OC attention to details). I do like the controlled, positive pressure & flow control, i might say that's typical of German Engineering. I'm sure it is costlier than a "flooding" approach, and time will tell whether the added complexity will pay off reliability-wise, since more complexity unfortunately results in more potential for component failure. BMW's ICE reliability has been less than stellar, I actually swore never to own one again after my 135i (lovely car when I had it but it spent 10% of the time at the dealer's), but I'm taking a chance that they'll redeem themselves with the simpler EV technology, and the Engineering cautiousness they have shown so far.

Another conclusion is that if you own the car (I put a deposit for an i4 M50), and an warning message appears regarding a leakage in the battery cooling system, or if suspicious liquids drip down below the car (other than A/C condensation, of course), I would not wait to bring the car to the dealer during the battery warranty period (the i3 has 8 years/100,000 miles, with a guaranteed 70% capacity by the end of the period, so I would not expect anything less for the i4 or iX), and to a qualified mechanic afterwards.

An i3 owner did a great job verifying his degradation over the 3 years/70,000 miles he owned an i3 at BMW i3 Long Term Battery Capacity Report: Better Than Expected, and he reported a 0.8kWh degradation over the rated 18.8kWh or 4%. A Google search on i3 battery failures shows several hits on the 12V accessory battery (not even sure there is such a thing in the i4/iX), but no complaints on the high-voltage battery degradation or fire (Chevy Bolt, the EV owner's nightmare). For reference, Tesla's numbers (Check Out This Official Tesla Model S/X Battery Capacity Degradation Chart) show an average of 5% after 25,000 miles, 10% after 100-150,000 miles and 15% after 150-200,000 miles, so the i3 owner above could be lucky or BMW's technology might be a bit better for long term reliability, though I would not draw a conclusion based on one sample. I'm eagerly awaiting the release of BMW''s user manual, to see whether they recommend the same "charge only to 82% daily, reserve the 100% to the road trip days to maximize the longevity of your battery pack" recommendation that Tesla provides.

Please share your thoughts! What's your confidence level that BMW will do at least as good as Tesla or even better in the long run?


So I was looking through pictures of both the i4 and iX battery pack, and noticed something interesting which is that the iX looks to have substantially better cooling, now this is all speculation and we'll have to wait and see when people start testing these two vehicles, but let me explain my findings.

The i4 battery module count is a bit weird, on the base layer it has 4 huge modules and 1 small, and the top layer 2 small modules.

The iX base layer consists of 10 modules and 1 module on the top layer, all the same size.

Now for the cooling. The i4 has one huge cooling plate covering the whole base layer of a module, but this cooling plate only has 1 inlet and outlet as the cooling plate only consists of one big cooling cell. While the iX has smaller cooling plates also covering the whole base layer of a module, with 2 cooling cells, and each cell having its own inlet and outlet, this should mean that the water will be in the cooling plate for a much shorter duration meaning the water won't get as hot and effectively cooling the module better. It really seems as the iX has superior battery cooling. What do you think?

*Top picture is the i4 battery pack
View attachment 1019 View attachment 1020
 

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This is a great discussion topic, and thank you for the detailed pictures. So from what I can see, just above the bottom plate are the details of the cooling system, starting with the water intake/outlet manifold in black, then the black piping going into the heat exchangers that look like aluminum plates with striations on top; where as the iX (bottom picture) has 10 heat exchanger plates below the shown main outbound and inbound pipes, and one on top, corresponding to the 11 battery modules, the i4 has 4 large heat exchangers spanning the whole width plus one smaller on the far right, below the main pipes, and two smaller heat exchangers on top. Once the stack is put together, the whole piping seems to fit between the battery modules for the iX and in the "transmission" tunnel for the i4, above the battery modules, with pipes going down to the heat exchangers, between the battery modules, in the trough visible between said modules in the layer above the cooling layer. Above the modules as represented here is the electrical distribution, which connect all the modules to the control module top right, sitting in the front "bump" in the top plate.

The good news is that contrary to AMG's early depiction of their battery pack and possibly Tesla (one may think due to their round form factor, similar to AMG's, compared to the flat BMW battery cells), the water cooling system seems to be completely sealed off instead off "flooding" the whole battery pack around the modules; I think this would promote a better control of the water flow, and the water piping also ensures that the cool water reaches all the battery packs at once and the heated water gets collected again from all the packs at once; the downside is that the water has to be kept very clean, as any debris may clog one of the pipes and allow one of the modules to overheat. I have no doubt that the individual modules are monitored to detect such an issue, and that there are leak detectors in case any of the piping should fail. So while the battery physical build-up is certainly less "symmetrical" in the i4, I don't think that the cooling system would be any less efficient assuming the piping is designed appropriately (and it's a fair assumption, these are German engineers after all, they are known for their OC attention to details). I do like the controlled, positive pressure & flow control, i might say that's typical of German Engineering. I'm sure it is costlier than a "flooding" approach, and time will tell whether the added complexity will pay off reliability-wise, since more complexity unfortunately results in more potential for component failure. BMW's ICE reliability has been less than stellar, I actually swore never to own one again after my 135i (lovely car when I had it but it spent 10% of the time at the dealer's), but I'm taking a chance that they'll redeem themselves with the simpler EV technology, and the Engineering cautiousness they have shown so far.

Another conclusion is that if you own the car (I put a deposit for an i4 M50), and an warning message appears regarding a leakage in the battery cooling system, or if suspicious liquids drip down below the car (other than A/C condensation, of course), I would not wait to bring the car to the dealer during the battery warranty period (the i3 has 8 years/100,000 miles, with a guaranteed 70% capacity by the end of the period, so I would not expect anything less for the i4 or iX), and to a qualified mechanic afterwards.

An i3 owner did a great job verifying his degradation over the 3 years/70,000 miles he owned an i3 at BMW i3 Long Term Battery Capacity Report: Better Than Expected, and he reported a 0.8kWh degradation over the rated 18.8kWh or 4%. A Google search on i3 battery failures shows several hits on the 12V accessory battery (not even sure there is such a thing in the i4/iX), but no complaints on the high-voltage battery degradation or fire (Chevy Bolt, the EV owner's nightmare). For reference, Tesla's numbers (Check Out This Official Tesla Model S/X Battery Capacity Degradation Chart) show an average of 5% after 25,000 miles, 10% after 100-150,000 miles and 15% after 150-200,000 miles, so the i3 owner above could be lucky or BMW's technology might be a bit better for long term reliability, though I would not draw a conclusion based on one sample. I'm eagerly awaiting the release of BMW''s user manual, to see whether they recommend the same "charge only to 82% daily, reserve the 100% to the road trip days to maximize the longevity of your battery pack" recommendation that Tesla provides.

Please share your thoughts! What's your confidence level that BMW will do at least as good as Tesla or even better in the long run?
Welcome to the forum @MinhSATx! My guess is that BMW will recommend the same charging to 80% as other companies do. Seems to be the standard these days for all car companies. As for any warnings about leaks, if that happens for anyone (god forbid) I'd hope they take their i4 to their dealer immediately. That's something you shouldn't ignore.
 

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Thanks for the detailed specs! This is great info that is really not readily available in the US.

I would add that these power outputs are maximum values; so the 250kW of the i4 eDrive 40 would typically be sustained for a maximum of 13.7 seconds when racing to 0 to 190km/h (roughly the quarter mile time); when running at max speed, since said speed is not power-limited, it may or many not draw the maximum power for sustained periods of time. EG, for the eDrive 40, at 94km/h average 131km/h max, the range is 395 km, thus averaging 18.8 kW (higher uphill/with headwind, lower downhill/with tailwind). Using the worst case where 100% of said power is spent fighting aerodynamic forces, which are proportional to the square of speed, this extrapolate to an average of 82kW at maximum speed (190km/h). For the i4 M50, the 400kW (Boost mode) is only allowed for 10 seconds in a row, the 350kW is typically sustained for a bit more than the 11.7 quarter mile time, the average consumption at 91km/h average 131km/h max is around 21kW, and 128kW at max speed (225km/h) on average. Do note that the previous calculations is purely based on the face value of the published specs, and intended to give orders of magnitude more than specific values, and it reinforces that the cooling requirements are significantly higher for the i4 M50 compared to the i4.

from what I read in the spec: iX as higher power output (385kW vs 250kW @e40 and [email protected]) so it needs a better cooling, it also allows a longer charge @max charging power (0-40% @iX vs 0-20% @i4)
 
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