[WIP] VW Manx conversion

[Sjanders]

Hi All,

New member from the Netherlands here . For some years I have a project sitting in my garage, it's a VW beetle based Meyers Manx fiberglass dune buggy. Recently I decided to pick up the project again and decided to throw out the old gearbox and ICE and replace it for an electric drive. In my daily job I develop extraction machines to extract molecules from plants, I do not have any experience with EV conversions at all. So this forum feels like a gigantic, and a little overwhelming, playground to me!

My project:


The recent period I've been searching for conversion solutions, most of the solutions keep using the original gearbox of the vehicle, I prefer not to use this. In my search I found the Toyota/Lexus MGR drive via this forum, the form factor and potential power output matches my project quit well. Normally the car weighs approx. 650 kg. My goal is to build a conversion that is capable of doing 110-120 kph with a range of 100 km.

Regarding the MGR drive unit; I prefer to use "off the shelf" parts to do the conversion. So, my idea was to rewind the MGR motor (inspired by the project Ustas is doing) to run on 108-144 Volts @ 400-500 amp (peak) and use a Curtis (or equivalent) motor controller to run it. And that is basically where my plans are. For the next step I need to find some answers, I tried to answer them for myself but I sort of got lost . Hopefully you knowledgeable people are able to point me in the right directions. At this moment I have the following questions:

• Curtis controllers can work with a sin/cos sensor input, see image below. From what I've seen in various photo's, the MGR resolver has 2 sensor revolutions (based on the shape of the resolver) per mechanical revolution while the Curtis controller seems to need only 1 sensor revolution per mechanical revolution. My question on this matter: is it possible to modify the MGR's resolver to be able to use a Curtis controller?

Screenshot from a Curtis controller manual:

• I tried to find information on rewinding the motor to my needs, and found out that I don't really know where to start. If someone could point me in the right direction (or even better: is able to make the calculation for me) I will try to figure it all out.

At this moment I have no parts to start build yet, when I'm confident that I'm able to do a proper conversion for an acceptable amount of money I will start the build.

Thanks for reading and hopefully you can give me some useful tips and tricks!

Cheers

[Sjanders]

Hi All,

I thought I'd sent you all a little update on my thoughts. Yes, still in the process of deciding what to do.

So, as I'm more the builder type of guy, and not a programmer, I prefer to do the conversion using a complete kit of parts. Recently I came across a Zero SR/F motorcycle https://www.zeromotorcycles.com/nl-nl/model/zero-srf that has some damage due to an accident and is now for sale with a decent discount compared to new. The bike is only 1 year old and has a 3500 km drive history.

The bike basically has all components I need for my conversion. The electric motor has a power rating of 82 kW peak and 40 kW continuous. Max torque is 190 NM. Max rpm is ~6700. When applying appropriate reduction that reaches 140 km/h, I should have ~1500 NM of torque at the wheels.

The battery pack has 14.4 kWh (12.8 ish usable), for me that's enough. The bike also has some safety features that will not be applicable anymore in the buggy, I'm not sure how to override these feature to create a derivable car.

My idea now is to swap out the original gearbox for a suitable differential and connect the motor from the bike with a belt to the differential. In that way I'm able to swap out belt pulley's that fit my needs at that moment, smaller ratio for higher top speed and visa versa.

Is there any experience with such a conversion? Do you see any pitfalls to be aware of? Please share your thoughts!
Thanks

[mjc506]

The Zero is a nice package, if it's still running. If you can get all the parts in the vehicles while keeping the electronics convinced that they're still a motorcycle, that's probably the easiest route. Upgrading the battery (more range) might be difficult though.

The MGR has some reputation of being underpowered, but it's also quite difficult to drive. An alternative might be an Outlander rear motor/diff/inverter, which can be driven relatively easily (you 'just' send commands to the OEM converter, which handles all the difficult power electronics/switching/etc).

You will either need to learn some programming as you go, or be willing to throw money at a commercial solution I think. There's lots of little things in the background that can be tricky to integrate (batteries/BMS, charging, interlocks/contactors....)

[Sjanders]

Hi All!

Been a while since my last post...

Recently I decided to choose an Outlander rear drive as the motor for my dune buggy conversion, having made that decision I also bought a drive unit.

Besides figuring out how to control everything, which batteries are best to use, how to transfer the power to the wheels etc etc, I will start with designing a mechanical solution how to mount the drive unit to the VW chassis. Ideally I would like to use the original VW buggy ( = beetle) gearbox mounting points to mount the drive unit.

So I need two drive unit mounting brackets:

• Front bracket: I think I will keep the original drive unit bracket and design an additional bracket to connect the drive unit bracket to the front gearbox mounting point

• Rear bracket: I will remove the original rear brackets from the drive unit and replace them with a bracket that can be mounted to the rear gearbox mounting points

Regarding the bracket (mainly the rear one) design, the easiest way is designing a bracket without vibration dampeners. Of course this will generate some vibration in the car. Has anyone experience driving with this drive unit without using the dampeners? Besides the vibrations, are there other factors why keep the dampeners? If it is a better Idea to use the dampeners, what type of dampeners could i use?

Below some pics:


Figuring out how to position the drive unit.


The buggy with the body removed.




Keep u posted!

[Sjanders]

Hi Electroheads,

It's been a while since my last update, yeah I'm not the fastest builder, I know...but there still is progress.

At this point I needed to make a choice what the next step in the build process would be, some fiberglass work, installing trailing arms, wheel and brakes, working on seat mounts, or.....get the electrical work done.....

I decided to get the more difficult stuff done; the electrical work. Thing like choosing the inverter (likely Prius or Outlander), charger and other components is pretty self explanatory using this forum (pro tips are always much appreciated of course). Regarding the batteries I'd like some advice tho.

The buggy weighs ~580 kg in its original state. The swap between gasoline engine and the original gearbox for the Outlander rear drive reduces the weight to approx. 500 kg. My goal is to get a range of ~150 km. From various sources I understand that one can travel ~5 km per 1 kWh of energy, that is for your average EV weighing 1500+ kg. Now, is it safe to assume that in a much lighter car your range per kWh will be higher, generally speaking? So if I assume that 8 km/kWh would be achievable, then I need a 20 ish kWh (usable energy) battery.

Please share your idea's!

Then the next point, I want to out some batteries in the front of the car and some in the back. In addition i'd like to use batteries with a high capacity per kg to reduce the volume. Could any one give me some advice on this topic?

Thanks!!

Some pics of the project:

[johu]

I suspect you won't be driving fast in this so 8km/kWh seems achievable.
On the subject of batteries I'm not sure if any car batteries are available at that spec. Either they are plugin hybrid, power dense, not energy dense or proper BEV energy dense and high capacity (unless you drop the voltage to like 150V). Your best bet may be to assemble a custom pack for this one.

Not sure where to source these but they are 60 Ah, 950g, 145x100x28mm

[Bratitude]

being a buggy, I suspect you will be off roading/driving fast?

sand will eat power quick.

Hybrid packs can pack a punch, but generally (as johu stated, they are more power to weight than energy to weight. But newer modules are sticking a good balance. bmw hybrid packs may be of interest.


for the outlander gear box, your In luck, as I have drive shaft adapters available, you’ll be able to use stock vw axles. No custom haft shafts needed.

[Sjanders]

being a buggy, I suspect you will be off roading/driving fast?

sand will eat power quick.

Hybrid packs can pack a punch, but generally (as johu stated, they are more power to weight than energy to weight. But newer modules are sticking a good balance. bmw hybrid packs may be of interest.


for the outlander gear box, your In luck, as I have drive shaft adapters available, you’ll be able to use stock vw axles. No custom haft shafts needed.

IMG_3677.jpeg

Nice, those adapters! I already had the idea of such a solution but never actually checked if it was already available. First things first, getting the electrical system up and running. I gave the BMW packs some more thoughts, based on what I saw in Grekski's build and other information I found a 12 kWh pack will fit my project nicely, maybe a bit less milage than originally planned but for now good enough.

The price for such a pack is substantial in the Netherlands, 3500 - 4000 Euro's, so I'll keep an eye out to see if I can find a bargain. In the mean time I can focus on some other stuff.

Cheers!

[marcexec]

Marty's 24kWh X5 pack could be a good balance regarding usability as well?
viewtopic.php?t=4991
I'd stick with the OEM inverter for the Mitsubishi, 70kW have been confirmed by Arber.

[arber333]

Marty's 24kWh X5 pack could be a good balance regarding usability as well?
viewtopic.php?t=4991
I'd stick with the OEM inverter for the Mitsubishi, 70kW have been confirmed by Arber.

I also tested inverter at 240Vdc and it was still operating.
Likewise for 388Vdc.
I am convinced that inverter contains some MPPT function as it adapted to voltage and kept power at 70kW limit. At 388V i couldnt get more than 200Adc...

[jrbe]

These estimates for mileage seem high, https://www.motortrend.com/news/2024-me ... -buggy-ev/

[Sjanders]

These estimates for mileage seem high, https://www.motortrend.com/news/2024-me ... -buggy-ev/

I've seen that version before, I like the way they managed to stay close to the original design! Apart from the VW beetle front axle the car seems to be totally modified, it has an aluminum monocoque. That saves weight compared to the original steel structure.

The milage also seems high to me, but who knows! The picture below shows the motor and batteries used in the car. Does any one has an idea where the motor comes from (I guess they didn't develop a new engine for this car) and what cells are used?

[jrbe]

I like it too. The multi-link rear suspension with the original front suspension is a funny choice, everything else they shared seems decent.
I tried to search the logo on the side of the motor but couldn't find it. Do you have any more images of that you could reverse image search?
I'd guess there are a lot more cells in the battery and it's just displaying a short stack. No idea what cells they are.

[Sjanders]

I like it too. The multi-link rear suspension with the original front suspension is a funny choice, everything else they shared seems decent.
I tried to search the logo on the side of the motor but couldn't find it. Do you have any more images of that you could reverse image search?
I'd guess there are a lot more cells in the battery and it's just displaying a short stack. No idea what cells they are.

Agree, seems a decent build. Totally newly developed car with an old school VW front axle as a tribute to the beetle.

I have done some additional searching, unfortunately I haven't found reliable information on the motor and batteries. ChatGPT suggests Nidec or AEM as the supplier of the motor, but I can't reproduce that information. I cant find the logo either.

Regarding the batteries, from some video's I understand that there are indeed more than 1 stack of cells, all nicely positioned under the back seat. Further searches on the batteries did not give any information on the possible brand/source/producer.

The picture below might be helpful in logo searching. Looking at the plug on the inverter, it very much looks like the plug they use on Curtis and Sevcon motor controllers. I guess there are 2 inverters, one for each motor. All in all, it is a nice compact package!

[tom91]

just reverse image search.

https://www.caranddriver.com/news/a4084 ... -revealed/

[Sjanders]

Hi all,

So, I'm taking little baby steps here! Got the Zombie soldered and it's working. I have setup communication with the Outlander rear inverter and the Outlander charger/converter. Communication with the Outlander rear motor (already in the car) was also succesful when connected to the inverter.

With succesful communication in mean i was able to read temperatures and applied voltages (where applicable).

As a next step, I would to test the motor and see if it spins when pushing the pedal. At this point I have no pre charger and contactors in my setup, so I was wondering if it is possible to safely test the motor using a lower voltage (for example 50-60 volts DC) without the need of contactors and a pre charger.

My idea now is to buy a BMW battery pack including the s-box, but I'm still looking for a decent deal. So if testing with a low voltage can be done with destroying the inverter, that would be nice. Of course I could always build a pre charge setup myself using a large resistor.

Suggestions are most welcome, thanks!

[tom91]

Outlander inverter does not work below 220v. No real need to test it if things show up well, you can spin the motor by hand to see if the speed updates on the spot values, best to graph it.

[Sjanders]

Outlander inverter does not work below 220v. No real need to test it if things show up well, you can spin the motor by hand to see if the speed updates on the spot values, best to graph it.

Thanks for your fast response! All clear. The hand spinning test was already on my to-do list, good to hear that it's a good validation test

Then I'll keep an eye out for a decently priced battery pack to get to the next steps in the testing process.

BR Sander

[Sjanders]

Hey all,

I've searching for a BMW 530e battery pack. I have found various suppliers with a rather large price range. The found range was from 495 to 4200 euro for a 12 kW pack. Comparing the build year an car milage there was not a huge variation between them (45000-58000 km), except for one supplier that offered a pack from a 2024 BMW with barely 1000 km on the clock, this pack was in the middle of the price range.

I think I will buy one of the cheaper packs, the supplier gives a 3 month warranty on it. Before ripping apart the whole pack, is there a way to test the capacity of the pack? Of should I test on module of even cell level? I expect that the SOH will be somewhat degraded, but I'd like to know if there are modules/cells that worse than others.

Could anyone point me in the right direction how to test a pack, preferably on a budget ofcourse.

Edit: I think I might have found something to test the battery on module level: https://nl.aliexpress.com/item/4001153199791.html? has anyone got experience with these testers?

Thanks a lot!

BR Sander

[Sjanders]

Look what arrived on my doorstep today!

Time for some next steps in my journey, I'm super excited!

[manny]

Nice,

Good luck with the disassembly.

PS: Jouw adres staat op de foto

[Sjanders]

Nice,

Good luck with the disassembly.

PS: Jouw adres staat op de foto

Hey Manny, thanks! Aangepast.

[Sjanders]

Hi all,

Yesterday I safely opened up the BMW SP41 pack, seeing the inside of the pack in real life is such a joy! I've never opened up a HV pack before, but i can really enjoy how well such a pack is designed!

After disconnecting the HV cables I measured the voltage of all modules, they were all reading between 55.3 and 55.4V, I did not measure the total pack voltage however. This morning I removed the S-BOX for testing with the Zombieverter. Initially I tested it without a battery module, when all seemed fine I tested with a single module.

I made the following observations without a battery module connected:

Pin 14 powers the contactors, in precharge mode the precharge contactor is pulling ~0.5A, when the contactors are closed it is pulling 0.86A.
Pin 13 powers the PCB (maybe something else?), when active it pulls 0.23A.

Measuring resistance over the S-BOX connections I found the following:
Open contacts -> 4.21 M ohm over the positive contacts, the negative contactors had no conductance
Precharge mode -> positive contacts resistance went up to 15.2 ohm followed by precharge fail (UDCSW set to 330 V in the Zombie)
Closed contacts -> 0 ohm for both contacts (UDCSW set to 0 V in the Zombie)

Allthough I couldn't find the resistance specification of the precharge resistor, my observations seems to show me all functions as it should be. Next step was testing this a module attached:

I started with UDCSW at 330 V, this gave a precharge fail as expected. After changing UDCSW to 50 V precharge was succesful and the Zombie entered RUN mode.

So, this was a really successful next step, I'm really happy with the progress. But....to be honest I could have done it without the expertise available here! Especially the super boring( ), no cat containing, YouTube vids from Damien and Gregski were of a lot of help to me

Cheers!