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by jjtheblunt 817 days ago
You skipped the complex heat pump system needed to regulate battery pack temperatures (and used for cabin temps as well).

BMW i4,i5,i7,iX built in mid to late 2023 use an outsourced system that widely failed in cold temps. Tesla has a famously ingenious simpler but efficient custom in house design.
1 comments
stephen_g 817 days ago
This kind of comment is perplexing to me. I'm always really confused why people try to claim heat pumps are complicated because they're not really (especially compared to many of the systems in ICE cars). Most cars have even already contained a heat pump for many decades (an air conditioner is exactly the same, just moving heat the opposite direction. It literally takes one extra valve to make it bi-directional).

There are videos of hobbyists making heat pumps from compressors salvaged out of fridges or ice makers, and other scrounged parts, maybe an Arduino controlling it! They're amazingly simple when you see what they're made up of.

Sure, it sounds like there were problems with this system used in BMWs, but that's likely just a design issue. Pumping a coolant around a battery and then through a heat exchanger (that is part of the heat pump) is not that difficult compared to the cooling of an extremely complex internal combustion engine!

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bryanlarsen 817 days ago
The complexity and ingenuity in the Tesla heat pump system is the octovalve, not the heat pump. 8 different places to source/sink heat, with different set points. Keep the battery, motor, interior each at different optimal temperatures with a single heat pump.
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jjtheblunt 817 days ago
Yep. the non octovalve complex of separate valves and tubes between is where the BMW outsourced design failed.
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jjtheblunt 817 days ago
Right: it’s not conceptually complex and Tesla, as i mentioned, shows such.

The parent comment to which i replied was listing significant systems in an EV, and hadn’t mentioned thermal regulation.

BMW’s outsourced Vitesco (part of Continental Power Trains originally) design differs in engineering (materials, components integration), with more disjoint components and more components therefore needing interconnections, and had cars (service bulletins applied to thousands) across Finland, Germany, Canada, US, UK, failing and leaking in a juncture not present on the Tesla design. (“Ask me how I know…twice.”)

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