eXodus
Posts: 50
Joined: Tue Dec 22, 2020 6:06 am

Re: Solid State Battery Progress

Wed Jan 13, 2021 5:09 pm

The Rex implementation of BMW is mainly bad in the US due to compliance laws and has nothing to do with the technology. The euro version is much better. You can drive 90+ mph with the Rex on empty battery in Germany

https://www.youtube.com/watch?v=CmCOdHZF91Q

And the batteries sold today - should last longer then people usually keep their vehicles.

jadnashuanh
Posts: 5149
Joined: Thu May 22, 2014 2:07 pm
Location: Nashua, NH USA

Re: Solid State Battery Progress

Wed Jan 13, 2021 9:27 pm

Depending on the MY, you may have up to 38Hp available when your battery is essentially 'empty' (but BMW won't let that happen). The EV motor is 170Hp...you will not have full capabilities when running only on the REx. Will the vehicle go? Yes. On the level, as long as it can overcome drag, yes...try to climb a long grade or have good acceleration, not going to happen at that speed. The conversion of mechanical Hp to electrical Hp is still Hp, but there's some lost in the conversion, so you don't really have 38Hp to drive the wheels. A 38Hp engine is sort of a slug. Reminds me of a 2CV, except the i3 weighs more.

The i8's motor is significantly larger, and can maintain pretty much any legal speed, regardless of the battery SOC. Not enough is known how they are implementing the new Mazda.
Jim DeBruycker
2011 535i x-drive GT, 2014 i3 BEV
Soon (hopefully!) A 2021 X5 45e will replace the above

eXodus
Posts: 50
Joined: Tue Dec 22, 2020 6:06 am

Re: Solid State Battery Progress

Thu Jan 14, 2021 3:34 am

jadnashuanh wrote:
Wed Jan 13, 2021 9:27 pm
Depending on the MY, you may have up to 38Hp available when your battery is essentially 'empty' (but BMW won't let that happen). The EV motor is 170Hp...you will not have full capabilities when running only on the REx. Will the vehicle go? Yes. On the level, as long as it can overcome drag, yes...try to climb a long grade or have good acceleration, not going to happen at that speed. The conversion of mechanical Hp to electrical Hp is still Hp, but there's some lost in the conversion, so you don't really have 38Hp to drive the wheels. A 38Hp engine is sort of a slug. Reminds me of a 2CV, except the i3 weighs more.
The i8's motor is significantly larger, and can maintain pretty much any legal speed, regardless of the battery SOC. Not enough is known how they are implementing the new Mazda.
Ok I understand what you meant now. Still part of this issue could be solved with programming the Rex to actually recharge the battery, not only hold the charge. It is surprising how little energy you need to drive straight.

Here a little calculator: http://www.wallaceracing.com/Calculate% ... 0Speed.php
the i3 has a coefficient of .29 about 21 sqft frontal area - weight 3000

Only needs like 22hp to drive 70mph.

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