[DRIVING] Audi A2 /w Prius Gen2 Transaxle & Inverter  [FINISHED]

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Re: Audi A2 /w Prius Gen2 Transaxle & Inverter

Post by johu »

The pump will be always on, it only draws 5W or so. I plan to run through cabin heater and front radiator in parallel. In winter you close the valve for front radiator and all heat goes to cabin.

Charging 80S with Prius inverter from single phase is not so easy, because it would need buck at lower SoC (say 240V) and boost at higher SoC (330V). With Leaf battery you can do boost charging if you never discharge below 320V. Using Leaf BMS is straight forward as well when cells are installed in one block (no front/rear split)
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Re: Audi A2 /w Prius Gen2 Transaxle & Inverter

Post by johu »

Attached cable for A/C today. Thomas made a custom cover for the MG1 outlet.
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Re: Audi A2 /w Prius Gen2 Transaxle & Inverter

Post by johu »

Charging time!
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Re: Audi A2 /w Prius Gen2 Transaxle & Inverter

Post by johu »

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Re: Audi A2 /w Prius Gen2 Transaxle & Inverter

Post by Ev8 »

Always great to see how much progress you’ve made so quickly compared to my own project which seems to just crawl along, did you manage to find a source of new connectors for the HV inverter plug?
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Re: Audi A2 /w Prius Gen2 Transaxle & Inverter

Post by johu »

Thanks, I took the liberty to work full time on this (neglecting some routine tasks like firmware releases).
I got the connectors from a breaker whos also here on the forum, just can't remember the nickname
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Re: Audi A2 /w Prius Gen2 Transaxle & Inverter

Post by johu »

Battery box is coming along nicely. I divided the carpet, the outer parts extend to the front of the box to where they were before. The inner pat folds over contactors, fuse etc. to isolate those from the metal box
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Re: Audi A2 /w Prius Gen2 Transaxle & Inverter

Post by RetroZero »

johu wrote: Mon Mar 14, 2022 11:43 am Trying to run the DC-DC converter now. Unfortunately it's not quite as straight forward as I though.
I am running the buck converter to produce about 230V on the DC-DC input. I hooked up IGCT to "ignition" 12V. When done that way, the DC-DC converter does not start up. It first wants to see some high voltage then IGCT.

Now I could simply add an RC lowpass to delay IGCT. Or produce another signal in the VCU
Time to hook up DC-DC next. I'll use another delay relay to switch IGCT after startup.
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Re: Audi A2 /w Prius Gen2 Transaxle & Inverter

Post by johu »

Finally some progress. I've rivited the rear battery cover and more importantly received the Toyota-to-VW driveshaft adapter today. Now just the passenger side to go and I can finally test drive. Should receive it later in the week
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Re: Audi A2 /w Prius Gen2 Transaxle & Inverter

Post by RetroZero »

Can't wait for you to jump in on testing. 😁.
Looking at your charging setup, I thought the connections were via the pwm outputs for Mg1. Does the AC get rectified being connected directly to the HV Bus?
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Re: Audi A2 /w Prius Gen2 Transaxle & Inverter

Post by johu »

Yes, very eager, too. AC is fed in through the modified A/C inverter (replaced IGBTs by normal rectifier). The battery connection has been moved onto the DC bus. The rectified AC ends up at the input of the boost converter and is then boosted to bus voltage. Had to add a current sensor to be able to control current
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Re: Audi A2 /w Prius Gen2 Transaxle & Inverter

Post by Ev8 »

Awesome we’ve all been waiting for an update on this for ages!
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Re: Audi A2 /w Prius Gen2 Transaxle & Inverter

Post by arber333 »

johu wrote: Tue Jul 26, 2022 6:18 am Yes, very eager, too. AC is fed in through the modified A/C inverter (replaced IGBTs by normal rectifier). The battery connection has been moved onto the DC bus. The rectified AC ends up at the input of the boost converter and is then boosted to bus voltage. Had to add a current sensor to be able to control current
Interesting, what kind of inverter did you use? Couldnt you have used Prius boost converter and add one sensor on its line?
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Re: Audi A2 /w Prius Gen2 Transaxle & Inverter

Post by RetroZero »

Ahh. Now I remember, you are boosting, so normal buck from inverter will not work.
Will be interesting to see what you find with parameters. 😁👍
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Re: Audi A2 /w Prius Gen2 Transaxle & Inverter

Post by johu »

arber333 wrote: Tue Jul 26, 2022 7:26 am Interesting, what kind of inverter did you use? Couldnt you have used Prius boost converter and add one sensor on its line?
Yes, that's exactly what I do.
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Re: Audi A2 /w Prius Gen2 Transaxle & Inverter

Post by arber333 »

johu wrote: Tue Jul 26, 2022 1:24 pm
arber333 wrote: Tue Jul 26, 2022 7:26 am Interesting, what kind of inverter did you use? Couldnt you have used Prius boost converter and add one sensor on its line?
Yes, that's exactly what I do.
Ah... ok. 😁
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Re: Audi A2 /w Prius Gen2 Transaxle & Inverter

Post by johu »

Finally the drive shafts are connected :D

I think driver side is pretty safe. Passenger side is an experiment: it is glued with Loctite 648 metal glue. Let's test how well that goes. I have to wait 3 days now for the glue to reach its final stiffness

If it doesn't work it will still be a good template for a drive shaft company.

The transmission sits forward quite a bit, not sure how much the shafts will like that being permanently "bent"?
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Re: Audi A2 /w Prius Gen2 Transaxle & Inverter

Post by Ev8 »

My mg2-mg1 coupling has multiple parts press fitted with loctite 648, and one part also has a pair of parallel pins on mg2 end, so not a weld in sight and is holding up just fine! It’s awesome stuff
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Re: Audi A2 /w Prius Gen2 Transaxle & Inverter

Post by lsh3rd »

Ev8 wrote: Fri Aug 05, 2022 3:17 pm My mg2-mg1 coupling has multiple parts press fitted with loctite 648, and one part also has a pair of parallel pins on mg2 end, so not a weld in sight and is holding up just fine! It’s awesome stuff
Sorry if this is straying off topic, but if anyone was as compelled by this idea as me... here's EV8's post where this was discussed:
https://openinverter.org/forum/viewtopi ... 237#p36237

I haven't disassembled my nearly free ($50 USD) gen 3 Prius transaxle yet, so I'm interested to see how this could potentially be applied there instead of Damien's welded planet gears. If I understand these transaxles are all pretty similar. I'm quite interested in Johannes's conversion since VAG group cars are on my list of potential swap candidates to get the coupled Prius transaxle.

Bringing it back around to the original thread, the details of the press fit passenger side axle is quite interesting to me as well since it could make the swap more economical and easier. I'm curious if there is a possible path toward doing this on the driver's side as well. If I recall the VAG shafts are hollow on one side and solid on the other, so I suppose it would be a matter of coupling solid-to-solid shaft with a coupler in the middle.
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Re: Audi A2 /w Prius Gen2 Transaxle & Inverter

Post by johu »

Yes the driver side shaft is solid and could be joined with a similar technique. So a sleeve that has the one diameter on one side and the other on the other. And then glue it. Of course it's always debatable how well this competes against custom made driveshafts e.g. from motomax.pl which cost less than 200€ each.
Material reuse is maximized "my" way for sure :)
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Re: Audi A2 /w Prius Gen2 Transaxle & Inverter

Post by Ev8 »

Lol I wouldn’t recommend anyone else do what I’ve done with a Lexus transaxle I personally think I belong in the crazy house for doing it!

Definitely interested to see how well that bonded shaft hold up to the strong unwanted regen you may experience!
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Re: Audi A2 /w Prius Gen2 Transaxle & Inverter

Post by SciroccoEV »

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Re: Audi A2 /w Prius Gen2 Transaxle & Inverter

Post by johu »

That didn't work too well... The handbrake is all crusty and won't release and was stronger than the glue. Car was still on ramps. I knew what would happen - at some point the ramps just shot forward. Just didn't expect them to puncture my Loctite cleaner bottle :(

No gotta get the whole thing out, clean it properly and glue again. If it don't hold up get a driveshaft made
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Re: Audi A2 /w Prius Gen2 Transaxle & Inverter

Post by Ev8 »

Ahh nuts
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Re: Audi A2 /w Prius Gen2 Transaxle & Inverter

Post by MattsAwesomeStuff »

I'll second Scirocco... shrink fit is stronger than welding. Doesn't take much temp difference could do it on a stove and deep freeze if you had to. Course... now that you're already smaller than press fit that's not going to work.

Why not just weld them and then grind them balanced-ish?
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