[WattsUpDoc]

Hi all,

I'm new to the forum, and just getting started on a conversion project for a 2007 VW Golf. My goals for the project are to build a useful EV daily driver, with ~100km range and performance comparable to the original ICE engine, and to learn a whole lot along the way. I'm still at the planning stages, so all design options are on the table.

I have a decent background on the electronics, software, and motor control design, but relatively limited experience in the mechanics and fabrication piece, so will be leaning on some helpful friends for some advice and assistance there.

My initial plan based on conveniently web-searchable components looks like:

• Netgain Hyper9 AC motor and controller
• 4 or 5 x 5.3kWh Tesla battery modules (total ~91V or 114V, 232Ah)
• BMS - Orion?
• Elcon PFC2500 charger
• Adapter plate to existing 5-speed manual transmission

I can fit this into a budget that works, but don't want to spend more than I need to. I'm always open to saving money and learning more with some extra DIY, as long as it doesn't derail the project too much .

I'd love some feedback on the big components. Will the Hyper9 motor and 4 (or 5) battery packs give the performance/range I'm aiming for, or is it under/over-designed?

My next question is around battery placement. Any suggestions on mounting the Tesla modules in a Golf Mk4 while maintaining a reasonable weight balance, and not eating into the trunk space? I'm considering 2 or 3 modules in place of the gas tank and muffler (and perhaps cutting out the spare wheel space). Before pulling the gas tank out, it's been tricky to measure how much space I'll have under there. Another 2 modules I'd plan in the engine bay.

Any suggestions are appreciated!

 

[hexbolt]

Super interested in how this turns out. i have a new beetle(pretty similar platform to the golf) ive been planning for years to convert. I would like to make my own packs like jehugarcia has done. It feels like it would give alot of flexibility to fit them in otherwise hollow spaces.

the center tunnel and gas tank for battery packs seem like a great idea. Engine bay would pack alot of batteries and the spare tire as well. have you looked behind the trunk interior panels? you might find even more space for components, wiring, more battery packs.

If you do use the tunnel and tank areas, do you think you'll have to lift the body a bit?

 

[brian_]

My goals for the project are to build a useful EV daily driver, with ~100km range and performance comparable to the original ICE engine...

My initial plan based on conveniently web-searchable components looks like:

• Netgain Hyper9 AC motor and controller
• ...

...

I'd love some feedback on the big components. Will the Hyper9 motor and 4 (or 5) battery packs give the performance/range I'm aiming for, or is it under/over-designed?

I think that depends on how you assess performance. You may be satisfied with the performance and not notice that it is inferior to the original; however, with more vehicle mass and much less power, it will be slower.

 

[WattsUpDoc]

Hexbolt, I agree, there's all kinds of opportunities for squeezing custom crafted packs in there. But the price/performance of the Tesla modules makes me think that it's better to make them fit rather than spending a lot of time chaining together a string of small packs through the exhaust channel. Cutting out the spare tire tub under the trunk space will help a lot.

Brian, thanks for the expectation setting 🙂. The car is a City Golf with a 2.0L 115 HP engine, so it's not a ton of power as it is. I could tolerate a bit slower pickup, but want to make sure it's still going to be a practical car for short highway trips.

 

[brian_]

The car is a City Golf with a 2.0L 115 HP engine, so it's not a ton of power as it is. I could tolerate a bit slower pickup, but want to make sure it's still going to be a practical car for short highway trips.

That sounds reasonable. Most people don't use the full performance capability of their cars, and a moderate decrease might not even be noticed.

 

[WattsUpDoc]

The Chevy Volt battery arrived today, and looks in decent shape. Modules are all sitting at about 3.75 volts/cell. The final configuration is still TBD, but I'm brave enough to break apart the big modules, running 3 chains of 30s cells would be just about ideal.

 

[Greenbeast]

This must be a MKV golf as they stopped the MKIV in about 2003/2004?
At least in the UK.

 

[brian_]

The Chevy Volt battery arrived today, and looks in decent shape. Modules are all sitting at about 3.75 volts/cell. The final configuration is still TBD, but I'm brave enough to break apart the big modules, running 3 chains of 30s cells would be just about ideal.

I assume that you mean 30S 3P chains, for 3P(30S 3P) overall, assuming that this is a first-generation Volt battery. With 12S and 6S modules (both 3P), you would need two 12S and one 6S in each chain to get 30S, but there are only two 6S modules in the pack (and seven 12S). Breaking down below the module level is much more work than just mechanically separating the three larger blocks into the nine individual modules.

The first-generation Volt battery pack is mechanically arranged (bolted-together stacks) into three pieces which I'm going to call "blocks", because they're larger than modules and smaller than a whole pack:

• 3 x 12S3P + 1 x 6S3P bolted together across the back (4 modules totalling 42s3p = 126 cells, 33" or 84 cm long)
• 2 x 12S3P + 1 x 6S3P bolted together at the front of the tunnel (3 modules totalling 30s3p = 90 cells, 25.5" or 65 cm long)
• 2 x 12S3P bolted together at the back of the tunnel (2 modules totalling 24s3p = 72 cells, 20.5" or 52 cm long)

Some builders have been keeping these blocks intact, which is the easiest way to handle the battery if these block lengths fit in the car. An example would be the 911 RSR with Tesla Motor.

One of the stock blocks is already your desired configuration, but there's no way to make two equal groups out of the remaining modules without at least breaking up one 12S module (shortening it to 6S). Since that modification is only trimming off a module, with no new cell interconnections required, maybe it's practical.

 

[WattsUpDoc]

I assume that you mean 30S 3P chains, for 3P(30S 3P) overall, assuming that this is a first-generation Volt battery. ....

One of the stock blocks is already your desired configuration, but there's no way to make two equal groups out of the remaining modules without at least breaking up one 12S module (shortening it to 6S). Since that modification is only trimming off a module, with no new cell interconnections required, maybe it's practical.

Yes, that's exactly the configuration I was considering. Thanks for the pointer to the RSR / Tesla / Volt build - that's a beautiful reference.

One thought on shortening a 12S module to 6S was spot welding a terminal onto the cell tab of the 6th cell. That would leave the top 6 cells along for the ride, but unused. I feel like a spot weld would be safer than trying to cut the cell tab. Do you know if anybody has tried that?

 

[WattsUpDoc]

Answering my own question for future reference, I see that Yabert has proven out a lot of parallel cell wiring on the Volt batteries.

https://www.diyelectriccar.com/forums/showthread.php?t=178681
https://www.diyelectriccar.com/forums/showthread.php?t=190906

 

[zepol_wube]

Are you making progress? We are doing an MK4 and it is running, you may get useful information from our blog : lopified.blogspot.com

 

[Nuffz]

Are you making progress? We are doing an MK4 and it is running, you may get useful information from our blog : lopified.blogspot.com

im thinking of doing a golf for my 1st conversion, probably will be DC but i read your blog with much interest . thank you

 

[WattsUpDoc]

Are you making progress? We are doing an MK4 and it is running, you may get useful information from our blog : lopified.blogspot.com

Thanks for the link to your blog - some great material there!
I've made a change of plans on the VW conversion, and found another platform for the build. Just starting to make some progress on that, and it deserves it's own build thread.