Electric 02 on Vintage Voltage

[2002FjordBaur]

Coincidently, I'm looking at a few design options of a model badge for another owner who has converted a 1602 to electric. Obviously, he could just add an 'EV' badge of some sort elsewhere if desired, but the request is to potentially redesign the 1602 badge.

 

I think it has possibilities? If it goes ahead, I'll 3D print the badge.

 

Edited May 10, 2020 by 2002FjordBaur

[WisDesign]

Brian here.  Working on a 400Vdc conversion of a 1968 1600 as Geoff mentioned.  Yes - I'm retaining the 4-speed.  At present, I've got a 3.91 ratio open diff, but have been keeping an eye out for a LSD.  Check out my blog.  I am building this up as a "kit" so that others could do the same in the future.  I'm also keeping track of my costs along the way.  It's not cheap by any stretch, but I doubt anyone here got into vintage cars as a way to save money.  Let me know if you've got any questions...

[TobyB]

Quote

I doubt anyone here got into vintage cars as a way to save money.

 

I did.  But they weren't 'vintage' at the time.   Now they're just 'old.'

 

I have to say, I can't for the life of me see why anyone'd keep the longitudinal drivetrain of a BMW
to electrify it.  The rear suspension is very amenable to dropping the power unit right there, and then the

batteries have enough room to actually provide some range.  And maybe trade the back seat for a usable trunk.

 

But then, I also don't see any value in NOT modifying the shell- they stamped them out in the hundreds of thousands,

and you wouldn't start with anything nicer than a 'scruffy but solid' driver for a conversion, anyway.

 

t

tried once.  Might try a conversion again.  If the price of used Tesla S's doesn't crash.

[rceldib]

My first three cars were each under $500. A Truimph TR-4, a Saab 96, and a Saab 99. Definitely all I could afford. 
I got my Tesla Model S small rear motor as a trade for my 2002 tii engine Happy that the engine was going to a good home. With the motor just under my rear battery pack I am able to fit 55 kWHrs of Tesla batteries into my 2002.

[WisDesign]

12 hours ago, TobyB said:

I have to say, I can't for the life of me see why anyone'd keep the longitudinal drivetrain of a BMW

to electrify it.  The rear suspension is very amenable to dropping the power unit right there, and then the

batteries have enough room to actually provide some range.  And maybe trade the back seat for a usable trunk.

 

tried once.  Might try a conversion again.  If the price of used Tesla S's doesn't crash.

 

I think there is more than one "right" answer depending on what you're trying to achieve.  If you've got a plan to do it better... I say go for it.  I'd love to follow your build as it sounds like you've got a ton of experience with these cars and I'd learn a thing or two!  

 

My hesitance to go all in on the Tesla route is based on the fact that the performance of that drivetrain is based on having a very large capacity (70-100kWh), 400Vdc battery to provide it with power.  It seems that many in the conversion world like to quote the specs of the Tesla motor in terms of what it is capable of in a Tesla and avoid the fact that they have far less battery voltage and capacity supplying it, which will certainly limit its performance.  I can understand the sex appeal of the Tesla system and I imagine most customers don't really care what the peak power is.  I just wanted to try something different by engineering a custom solution for the car.  I reserve the right to be completely wrong on all of my opinions...  

[rceldib]

Brian, yes, we are all experimenting now and I am not sure how this will turn out as we are plowing new ground. I decided to go the Tesla route without a transmission for several reasons and am not sure what the outcome will be. You are correct as I am only using twelve modules and each one has a nominal voltage of 22.8V, pack voltage will be 274V. Data is scarce and conflicting but I am expecting that to be about 200 HP which for a 2002 that will be more than adequate for me. The twelve  modules I am using are from a Tesla Model S 60 so each has 4.5 kWHr or a total of 54 kWHr. The car weight should be a little over 2400 lbs. I eliminated engine, radiator, trans, drive line, exhaust, large bumpers, fuel tank, and AC unit. Elimination of trans and driveline eliminates losses by almost 20%.  I am thinking this will give me a range of about 140 miles. Another plus going this route is the instant torque of an electric is very hard on the clutch and transmissions so I get rid of that issue. A negative is with half the battery pack in the trunk, I lose a good bit of the storage back there and I think I will have about five inches of ground clearance to the motor, which worries me a bit. The other issue is what motor controller to use. 
Your route of going with the transmission will be simpler but I just had to try this as I am a big Tesla fan. 

[gary32]

Love what you guys are doing.

I looked seriously at an electric 2002 using Tesla batteries and motor. (single)

Toby's rear mounted motor and under hood batteries controls etc. is where I was going.

Tesla does not make easy using their components and the cost of used parts or wrecked cars is high.

I already own an over the top 2002 but I love seeing the efforts of others silly power levels are preferred.

 

[gary32]

History gives thoughtful direction.

BMW in 1972 had a rear motor front battery electric 1600. 

Smart for weight distribution service access and driving dynamics.

Place the Tesla motor/ power transfer unit as low as possible in the trunk/rear seat area.

As much Tesla battery pack placed low and wide as would fit under hood requiring new subframes and parts of an IT type cage. I know this is simplifying the million little details but a pure simple plan always ends best.

Make sure you have stupid power goals so you love it when you are done.

 

Edited May 17, 2020 by gary32

[WisDesign]

First of all, let me say that I am thankful for a forum in which we can have a friendly exchange of ideas.  Anybody just thinking about, interested in, or actually building a conversion is more than alright in my book!  Not because I doubted anyone, but out of my own curiosity, I ran my own spreadsheet on the Tesla small motor solution and it looks like a very good solution.  At 274Vdc nominal, you're around 78% of nominal voltage for a full pack, so base speed on the motor should fall around the same percentage.  Agree that you will land around the 200hp mark at the wheels and the bonus is that the gear reduction and differential should be overbuilt for that power level.  The 54kWh battery seems adequate to hit that peak power level/current at less than 4C discharge, although I noted that they require some form of cooling if you intend to run them at over 1C continuous (54kW), which would only be the case if you were taking the car to the track. I think the only downside is that it's a bigger tear-up to the chassis to fit the motor/gearbox unit in the rear and you may end up with a unique solution on spring rates based on how the front/rear weight distribution turns out (same can be said with my solution though).  

 

IMO - What really matters in end when it comes to performance is rear wheel torque and power-to-weight.  The motor torque is pretty inconsequential if you don't understand the intermediate and final drive gearing.  In the case of the Tesla small motor, the single, fixed ratio is 9.34:1 with a peak motor torque of 330Nm.  This provides 3082 Nm / 2273 lb-ft of rear wheel torque up to the 5100 rpm base speed (my assumption - could be wrong), which will come at about 40mph and then begin to taper off.  

 

Compared to my solution of integrating the 4-speed gearbox, the Tesla solution looks like a pretty darn good way to go.  However, I'll have a 257Nm motor coupled to a 4-speed and differential that will provide a 14.72:1 ratio in 1st gear = 3782 Nm / 2789 lb-ft of torque, but only up to about 20mph before it begins to taper off.  It remains to be seen if the drivetrain turns to shrapnel at that input torque though.  Second gear will provide a more manageable 1500 lb-ft of torque, and carry me up to ~90mph, so I'm guessing this is the gear that will see the heaviest duty cycle.  Third is for the highway and Fourth is for the Salt Flats...

 

For me, I've had experience in many direct drive and gearbox coupled electrics and I still enjoy the feeling of rowing through the gears and having a bit more control over the vehicle. For example - gear selection also influences the amount of regen you'll receive as you let off the throttle, similar to downshifting a gas engine as it's the mechanical ratio slowing the wheels.  It is novel to me that you can apply the latest electric drivetrain technology and still retain the romance of driving a vintage car.  My Dad's electric MGBGT has the stock four-speed and a racing clutch and it's pretty fun to drive.  I wouldn't race a Tesla with it, but that's not really the point of the car for him or myself.  To each their own, but I thought I'd provide a bit of my own justification.  

 

I'm anxious to see these builds completed as they represent different approaches, but are both seemingly being pursued with a lot of passion and consideration into making a high quality conversion.  On that note... better get back to it!  

[gary32]

Brian I applaud your efforts.

 

[rceldib]

Brian,

I agree, it will be good to see both solutions and all can learn from them. I have active liquid cooling of my two packs courtesy of ElectricGT's very nicely engineered pack design. It uses the Tesla module cooling system in a tightly integrated system. I want to use the Tesla Super Bottle and if Vintage Air will help me make their HVAC system fit in our small 2002 space.

[rceldib]

Gary, I was at the Munich BMW museum last July and was happy to see a poster of the BMW 1602 Electro which they took to the Olympics. Wish they had the car there too. 

[WisDesign]

9 hours ago, rceldib said:

Brian,

I agree, it will be good to see both solutions and all can learn from them. I have active liquid cooling of my two packs courtesy of ElectricGT's very nicely engineered pack design. It uses the Tesla module cooling system in a tightly integrated system. I want to use the Tesla Super Bottle and if Vintage Air will help me make their HVAC system fit in our small 2002 space.

 

Ooooh... keep me posted on the Vintage Air solution.  I've got no plan at the moment for such driver comforts... 

[fastricky]

I'm a fan of VV and did see that episode - however it was odd that the last 10 minutes of every other episode usually features driving footage of the modified car and the 1602 episode didn't. Not sure what to make of that?

[saaron]

I'm really glad you guys are doing these conversions.  I like my 02, and like the variety of 02s the folks on this board own, and in some cases, have built.  

 

I hope you are successful in these conversions, and I hope over time they get simpler and cheaper.  Because I want to spend my golden years driving an electric 02.  I think that would be super cool.  

 

And yes, we need to figure out the AC thing, lol.  

 

Onward!

 

Scott