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Joined: Sat Jun 09, 2018 9:45 pm

i3: adding a Rex unit to a BEV

Sat Jun 09, 2018 9:51 pm

I have just located a range extender in an i3 wreck and have decided to buy it for a number of possible projects:

My questions are:
- What hacks could be developed or are available to make this unit operate at home to charge a pack up as renewable energy back up unit.
- Is it possible to convert a standard non-Rex i3 with the Rex unit.
- For the purpose of above what parts must I retrieve from the wreck other than the engine system and its fuel tank and control module.
- Challenges
- Barriers
- Any useful links of others who have done this.

Grateful thanks in advance. This is my first post.


Posts: 35
Joined: Thu Sep 15, 2016 10:48 pm

Re: i3: adding a Rex unit to a BEV

Sun Jun 10, 2018 8:16 am

This is my thought . Most probably , the easiest way to do this (and it would not be easy) would be to replace the entire wiring harness and electronics from the wrecked Rex . This would be due to the software issues as well as all the necessary controls , power wiring and gas tank . It would be a huge task , I think .
Last edited by CanisLupus on Mon Jun 11, 2018 8:04 am, edited 1 time in total.

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Location: Nashua, NH USA

Re: i3: adding a Rex unit to a BEV

Sun Jun 10, 2018 9:27 am

The springs and shocks are different on the REx verses the BEV along with the front-right fender and the HVAC system. The computers may not be different, but they have different software in them, so may also need to be swapped. Many BEVs came with the staggered wheels/tires, but the REx works better with them. I'd guess most anything is possible, but I'd expect you will have to essentially tear the car down almost completely to make the changeover.

Now, if you wanted to use the battery pack as a home energy storage, that would seem to potentially be a more doable thing...BMW might not sell you the parts, but they've already done this as a demonstration project. I don't think you'd want to incorporate the REx into that, though. Not sure if the required duty cycle would spell long-term reliability, but you already have ACV to DCV power supplies, but you'd need something to create ACV at the required voltage and frequency to feed your house, but inverters are readily available, just maybe not from 380vdc.
Jim DeBruycker
2011 535i x-drive GT, 2014 i3 BEV

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Joined: Sat Jun 09, 2018 9:45 pm

Re: i3: adding a Rex unit to a BEV

Sun Jun 10, 2018 6:58 pm

There are plenty of inverters with voltage capable up to 500VDC. This is how most large rooftop solar PV works - series connected PV panels. For reasons mentioned, I'm thinking that this may be a bigger project to be worthwhile. My conclusion is that the BEV i3s need to stay that way as the upgrade costs in terms of labour will make a Rex conversion not viable on an economic basis.

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Joined: Sun Mar 11, 2018 11:48 pm

Re: i3: adding a Rex unit to a BEV

Mon Jul 02, 2018 3:35 pm

If I had a BEV and wanted a REX, I think the best thing to do would be to trade it.

I do have a REX and one thing I'd likle to do is figure out how to run things in the house from it in an emergency. Both from the battery and from the REX.

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