# i3 style range extender DC conversion?



## brian_ (Feb 7, 2017)

AdHocManiac said:


> I know the i3 suffers severe power loss once the generator is active, often unable to maintain highway speeds, but wouldn't the available use of the 5 speed tranny alleviate much of that since the i3 is only working with a direct drive AC?


The i3's problem is not the transmission, it is programming to meet rules for "zero emission" vehicles. The i3's performance is deliberately limited when the engine is used, just so that it is considered an "electric" car under the regulations rather than what it is... a hybrid.

There is also the option using the good old solution: a generator trailer. You would only need to take it with you on those long trips.


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## PStechPaul (May 1, 2012)

For the generator-trailer, you could use a 6000 watt propane generator, which costs about $900 and weighs 171 pounds. It has a 16 HP engine, and will provide a full 10 kWh charge of your battery pack in about 90 minutes, which will give you perhaps 40 miles of range. If you go with a larger unit it will increase the energy consumption. You might be able to run the generator while moving, but it will only supply 8 HP to the electric motor. 

https://www.homedepot.com/p/Sportsm...-Start-Portable-Generator-GEN7000LP/202222975










According to my EV Calculator, a vehicle this size might use about 13 HP to maintain 50 MPH on a 1% slope and 9.6 HP on 0% slope. So running continuously would not be quite enough to make a 100-150 mile trip without stopping for a charge.


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## AdHocManiac (Jan 30, 2018)

Thanks for the input brian and paul, I unfortunately can't utilize the old trailer idea, I park my car on the street, and it has to be moved weekly to avoid tickets. So unless I want to cough up $600 a month for a garage I would have to deal with attempting to park a car with a trailer- and if i learned anything from driving my parents old SUV around a few years back- parking something of that length is no easy task in manhattan. The only sustainable way for this setup to work is if I moved the car+trailer only during alt side parking hours and literally never drove it anywhere to ensure that I was able to camp out the next days spot (look up nyc street parking, its hell). From what you guys are saying i gather the concept of driving-while-generating is possible. I'm more than willing to sacrifice my trunk to a generator, what would the drawbacks be to throwing a 2-stroke motorcycle engine in the trunk? From what I remember those are pretty energy dense, and I'm pretty sure I could get one to fit given I make custom mounts and re-tune the suspension to hold that weight. Also, if i was able to get a 2-stroke into the trunk, what kind of motor would be suitable as a generator? I've been drooling of EV specific motors for years but never thought to research a compact ~30kw(the exact math will come later) generator motor. I think that's the kind of engine the i3 uses, unfortunately I haven't found somewhere to purchase a Rex module, perhaps wrecked i3s but i wouldnt even know where to start trying to find one of those.--thanks for the feedback so far!


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## brian_ (Feb 7, 2017)

AdHocManiac said:


> I'm more than willing to sacrifice my trunk to a generator, what would the drawbacks be to throwing a 2-stroke motorcycle engine in the trunk?


Noise, pollution, and poor fuel economy. Isn't that all of the stuff one is typically trying to avoid with an electric or hybrid vehicle?



AdHocManiac said:


> Also, if i was able to get a 2-stroke into the trunk, what kind of motor would be suitable as a generator? I've been drooling of EV specific motors for years but never thought to research a compact ~30kw(the exact math will come later) generator motor. I think that's the kind of engine the i3 uses, unfortunately I haven't found somewhere to purchase a Rex module, perhaps wrecked i3s but i wouldnt even know where to start trying to find one of those.


BMW uses a 650 cc parallel twin-cylinder engine (from Kymco, also used in BMW's C650 maxi-scooter) in the i3, but it is a modern 4-stroke unit. Any mid-displacement (under about 700 cc) motorcycle, ATV, or snowmobile engine is a possibility; there are salvage yards (like auto wreckers) which specialize in motorcycles, and motorcycles crash a lot, so engines are apparently not hard to find. The advantage of an engine which is normally used with a belt-type CVT (as is common in scooters, snowmobiles, and some ATVs and UTVs) is that they don't have a gear-type transmission with them; motorcycle transmissions are built into the engine case, so they are extra work to eliminate and they make the setup bulkier. For an example, Polaris likes to use CVTs on their ATVs, so those ATVs have reasonably suitable 4-stroke engines without an unwanted transmission. I suggest a liquid-cooled (not air-cooled) engine, since it will be enclosed in a trunk... and adjacent to the car's occupants; all but the smallest engines are liquid-cooled now.


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## sjd.aliyan (Jan 17, 2018)

First of All tell us what is your purpose?

do you want to build a car with a good mileage to save some money?
or making a zero pollution car?
or just making something new for your hobby?


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## AdHocManiac (Jan 30, 2018)

Yes I guess the motorcycle engine does go against the idea of an efficient vehicle. Thanks guys for the info about the ATV motors and how the i3 functions, you've given me a lot to think about which is exactly what I was hoping for. As to what my purpose here is, I want to have a vehicle capable of short bursts of ~200kw while still being an economy vehicle the majority of the time. I never have to maintain that sort of power, I get my thrills from the 3-10 second bursts of heavy acceleration during day to day driving, being the first out of the gate on a red light and being able to pass easily on the highway. I would say however that the overwhelming majority of my driving is bumper to bumper sub 15mph, perfect for pure EV, or maintaining 30, 50, or 70 respectively. So really I want to have my cake and eat it too, and I'm hoping giving up living space in the vehicle will let me do that. Whether or not this project is going to come to reality will be decided during the summer when I'll have a bit more time and savings to play with.


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## sjd.aliyan (Jan 17, 2018)

In another word you want your own white zombie with an economical twist.
If you have couple of hundred grands ok we are all in.
I know john wayland.he has 100,000$ worth of military grade batteries in his trunk.and only 100 miles of range.


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