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      09-30-2020, 12:19 AM   #34
X5 45e
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Drives: BMW X5 45e
Join Date: Dec 2019
Location: Belgium

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Quote:
Originally Posted by GrussGott View Post
Quote:
Originally Posted by ketrab View Post
Can someone explain to me how do you calculate 6-7 hr required based on the 3.7kWh max input?
Quote:
Originally Posted by X5 45e View Post
There is some energy loss ... Charging 17 kWh should be 5-6 hours ? Like you calculated
Though I'm purely guessing US vehicles will still have to charge the full 24kWh, it's just that the software limits the usage to 17 - I could be totally wrong ... I'm wondering if the battery is somehow programmed to use 24kWh with 17 kWh of capacity ... not exactly sure what the kernel of thought I have is, but here's a nonsensical attempt:

i.e., the "battery" is actually a bunch of cells bundled into modules that are bundled into the battery. The battery management software spreads the charge / use / decharge cycles across the various cells to extend the life and effectiveness of the overall battery. Thus in EU cars the software spreads those full-usage cycles serially across all cells equally, but in US cars the software limits the full use down to 17kWh which allows the software to spread the cycles longer on each cell thus increasing the life of the battery overall. In other words, in US vehicles the battery is somewhat burning in parallel instead of in series which provides less burden to the overall battery resulting in an easier delivered 17kWh since it has 24kwh to play with ....

That said, it's important at this point that I mention I have no idea what I'm talking about.
Nice thinking. But I am not convinced. What you are basically saying is that the battery is charging to 24 kwh and only has 17 kWh available that when used, require 24 kWh again to be 100% charged. So 7 kWh are lost somewhere. This would give a terrible miles / kWh.

I am not an electric engineer and I al just reasoning like you.

It would be interesting to know what the difference in battery management between the US and Europe is.
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