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Discussion Starter · #1 ·
Hi guys,

I have an awesome bmw 328i manual transmission that I want to convert to electric soon.

I want to get liquid cool componants, and use thermoelectric devices to turn some of this heat into electricity, which will trickle charge the aux battery. The aux battery will be connected to a security system I plan to buy, and the doors.

The hope is to always keep that fully charged, and run the motor and main system off the main cell.

100 x 12v highest energy density life po

2 x 24 aux cells, trickle charge enabled

liquid cool motor(i've seen a few, not sure which one yet)

I'd like to keep the ac and heat working. BUt I'm not sure if that means I have to keep the radiator.

Also unsure about mating with manual transmission.

I thought about doing a direct drive. If I did that, would I still need a transsmission? I'd love to be able to just remove it, and have the gears be drive, park and reverse.

Please let me know your thoughts. Will upload pictures of the car soon.
 

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Direct drive to Diff is possible, depends on your performance goals. Your BMW qill be a nippy car as it is, so I'd guess you don't want to lose that. You'll need the Diff ratio and wheel size to know what torque advantage you'd get through direct drive and what motor RPMN you'd have to see to achieve/maintain your top speed.

What sort of performance do you want? What's your budget? check basic questions in the sticky about planning a conversion.

Mating to the trans is not a big problem. And your longitudinal layout give alot more space for big motors. Look at the Scottdrive 100 thread in Motors, especially Ruckus' bit 200kW system. That would be serious performance for your BMW, or even the 100kW system with a bigger motor would be plenty. Otherwise liquid cooled AC motors are hard to come by and costly. Pretty much all brushed DC motors are air cooled.

Sounds like a good conversion. Good luck!
 

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Discussion Starter · #3 ·
Well, I knew AC Motors were more expensive. But I didn't realize there up to 7 times more expensive.

The cheapest one at the site I'm looking at is about 7 grand.

http://www.metricmind.com/price-list/

Most expensive about 23k.

Performance is not that much of an issue. I need to stop driving fast anyway. I'm on a budget as well and would like to keep things as cheap as possible. Looking at one of their DC-DC controllers that is 89K. I don't understand that at all.

Top speed at 100 is fine. Range at about 100 is fine.

With one or two DC motors, can I still do regen braking somehow? I'd like to get rid of as many moving parts as possible.

Would also be nice to get rid of all liquids since they don't play well with electricity. But the heat exchanger/thermoelectric device I have in mind works best with hot liquid.

Can someone give me more info about direct drive setups, and the need for a tranny? Looks like I'll be going DC after all.
 

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Sounds like a fun build! I would be a little suspicious of the thermal electric thing as far as the amount of power to weight ratio. I also wonder why you would use "2 x 24" aux batteries. Aux batteries are usually 12 volts and very small. Do you have a 24 volt car? Best of luck with your build... can't wait to see it!
 

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Discussion Starter · #6 ·
I meant 2x12V for the aux battery. But may have to increase that.

I want this aux battery to trickle charge from thermoelectric devices, and perhaps a solar cell.

I'd like to also have it charge from the main battery if necessary. This may complicate things, and I guess I really don't know what to do just yet. I'll have to get the BMS first.

I am probably getting that Scottdrive 100 system. 5k for the motor, and inverter that can handle regen braking will be sweet.

The battery pack I'm getting is liquid cooled, along with the BMS.

The goal is to not have to put anything in the trunk, besides perhaps the aux battery pack.

In the future, I may even want to add hydrogen tank, along with fuel cell to extend range.

I could probably get 300 miles or more range if I had hydrogen, solar, and thermoelectric units that turn heat waste into electricity.
 

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you really don't have much waste heat with electric.... you might want to simplify and leave those parts out. ;) Also forget A/C unless you live in a place you can't live without it.

A liquid cooled controller might dump a hundred watts while under full load, but barely enough to warm a liter of anitfreeze under average use. You don't WANT it to get hot, so you're not going to have a big enough temp diff to work with.

You might be able to wrap a DC motor body with soft copper jacket and pull some heat, but again.... not a lot. considering motor is 85-90% efficient and average output will be less than 20kW even running continuous at highway speed.... you'd only have a couple hundred watts to work with, and the air cooling will be dumping most of that.

.....as for the 'normal' questions... spend about 10 hours reading thru the sticky threads to cover the basics regarding motor choice, tranny adaptors, controller choice, dc-dc, vacuum brake pumps, battery balance/BMS, then ask questions on things you're not clear about.

I think you'll gravitate to a 'standard' build with
warp9 motor, clutched adaptor from CanEV or similar
soliton/zilla/synkromotive controller
144v or 156v of CALB or Winston cells
ACME/Belktronix/Chennic always on dc-dc
tiny aux battery (4ah ATV gel is fine) in parallel w dc-dc
Elcon/Manzinita charger
Thomas/Gast or VBS vacuum system
in-line liquid, or ceramic element heat


....start with a basic build, and see how much room you DON'T have left over. ;) You might wanna go with an AC-50 motor to get regen braking if you can afford it, but I think it is more cost effective to buy more batteries unless you are looking for that last mile of range, drive constant stop/go, or live in a place as hilly as san francisco.
 

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I could probably get 300 miles or more range if I had hydrogen, solar, and thermoelectric units that turn heat waste into electricity.
What is that assumption based on? AFAIK no one has done a DIY hydrogen build due to all the complexities, inefficiencies, and safety issues involved. Solar can get you a few miles/day.
 

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Discussion Starter · #9 ·
I read about a car done in asia, that had a hydrogen range extender. The guy claimed to get almost 300 mile range. It was a light truck, the bed was filled with battery's, fuel cell and a tank.

If I do something like that, it will be years down the road.

My main goal is to get it working on electric.


In the first list of items I had in mind, 4 of the componants were liquid cooled. So I thought perhaps the liquid would get hot enough to where I can channel it into a system where thermoelectric strips would convert 15% of the heat into energy.

But the main goal is to get the car working. I'd like to leave room to experiment with a solar cell, and the thermoelectric strips. They don't really add any significant weight, but also won't create a ton of electricity either. If the liquid won't get that hot, then I can remove the radiator and save lots of weight.

But I'd like to just experiment and see how many miles they do add. Same with solar. Point is, those extras can be added later.

As far as getting ac working, what would be needed? I can do without it. But a heater would probably have to be a necessity.
 

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Sounds good. I want to add more solar to mine someday, but it can't do 100% anyway unless I can get 40% panels.

To do AC you have to have an electric compressor or run a stock belt off of an ACC shaft. I think most systems run around $500-1000. I'm too cheap so I just suck it up.
 

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While I have my doubts about thermal electric and solar power being on board, I have deep respect for those who experiment. In my younger days, I mated an alternator to a motor an battery to verify that you can't get more than one unit of work out of something that only has one unit of work going in, in spite of knowledge of thermal dynamics. If you experiment with stuff like this, you learn alot. To the best of my knowledge, solar panels don't add up unless you leave them behind when you deploy, ie solar charging grid that is bolted to the earth, and not your car. When a car manufacturer adds solar or hybrid technology, the consumer usually buys it because it sounds good, even though it doesn't really work. It sounds even better if it was implemented by a reputable car manufacturer. Ok, I will stop rambling, so good luck with your build!
 

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Discussion Starter · #12 ·
I saw your VW set up. How come you used lead acid? just to save money?

The lead acid in this bmw is on it's way out. I was researching on how to replace it with LI POLY, but I was told it wouldn't recharge the same way.

The AC is not absolutely necessary. But I am willing to do a little extra work to get it working. If not, I'd like to remove all unnecessary components.
 

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Yes, I used lead for the upfront cost. My first pack was ~ $800. I'm working my way toward all lithium (LiFePO4 ~$4k). It does charge different (faster and way more efficient) but can be done using a lead charger with proper monitoring.
 

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Welcome to the 328i Conversion Club :D

Is the CANbus going to cause you issues? i.e. will you have to fake some of the ICE signals to the ECU get everything (e.g. ABS/ASC) to work?

On my E36 everything(?) is a lot more traditional (simple electrical signals) so didn't cause any problems (that I know of :)). Not that I'm on the road yet...

I found this thread from Thaniel about his hacking of the E46 cluster CANbus.
 
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