# my first EV project! 300km range...



## cts_casemod (Aug 23, 2012)

Too many wishes Matter45,

The generator itself will use about as much, if not more fuel, as the car giving the losses on weight and efficiency, not just because of the mechanical to electrical to mechanical conversion, but also because these small ICE's are not very efficient (8HP to 3KW Power is normal, so 66% at the output of the generator)

I have been pondering something similar on my conversion, although I am working in background on this (not shown on the topic).

There are other losses like speed related losses, heating and cooling equipment, lights, all that adds up.

To finish you WONT be able to put all this in a small car and remember, at 45KW you have a real time bomb on your hands so you want to make sure the work is neat, tidy and only the best components are used (batteries, charger, wires, protections, etc.

Weight wise... 45KW in LifePo4 is about... 400Kg, with connecting parts (copper!!) and BMS 450Kg... + Generator = 520Kg... + Charger... Not really feasible on a small car

On my particular case I found the best way to be using an efficient ICE (Small Diesel or something) and convert the rear axle of a 4WD to a direct drive one (Like the VW 4 motion). You will have motorway efficiency in the range of 60MPG+ a neat conversion, you wont spend to much in batteries, the weight will be much smaller and even in town you can idle the ICE just to power the accessories and charge the battery a bit.

If you need heavy acceleration you can combine ICE + Electric and you can use regeneration all the time you brake.

Option two is to convert an insight or a prius. You only need to add a bigger battery pack and you're good to go.


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## tomofreno (Mar 3, 2009)

You might check your own back yard. Lots of expertise there:
http://www.aeva.asn.au/


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## Zappo (Sep 1, 2011)

Welcome to the party Matter45. I think what you are proposing is pretty optimistic but you are going in the right direction by reading and asking questions first.

Brushes on a well cared for DC motor should last years. I'm sure they won't last as long on a direct drive application since they will see high amps at low speeds far more often than with a gearbox. Also, keep in mind that performance with direct drive is much worse. It will get up to speed but it will take much longer.

Most EV DC motors like to run in the 2000-4000 RPM range during constant driving. Any less and the motor will run hotter. Too fast and it will tear the motor apart.

Good luck and keep us posted.


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## Matter45 (Jan 2, 2013)

Hi

Thanks for the reply

Yes that didnt come to mind about how efficient it would be. When i crunched the numbers it looked good on paper, but i didnt think of the efficient side of it. The Idea is that I can be in the middle of nowhere and have my car parked having lunch whilst the generator is still kicking over... putting charge back into the battery pack, giving me an extra 25km per 30 minutes...

The other idea with the generator is that it would put less strain on the batteries at higher speeds, and from data I have collected, it seems the less current coming out of the batteries, the more charge you get out of them.

And it sounds like leaving the gear box in is a good idea. I would of thought because you dont need to change gears, you would reach max speed quicker... in the case of white zombie electric car, there custom series motor is direct drive... dont know how they did it....

In regards to batteries, im going to be using 18650 cells. they have an awesome wh / kg ratio, 610wh per kg. My theory is, with the success of Telsa, they will help to drive the price down on those 18650 in the next couple of years. Plus they are in almost every laptop today. They are still out of my price range, 0.5 Aussie cents per watt. It sucks living in Australia with all the import costs...

I was going to build a motor controller but I have decided to bite the dust and pay extra for something that has proven to work.


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## Ziggythewiz (May 16, 2010)

Batteries don't strain at high speeds. They're taxed the most at high amps, which is during acceleration.

Direct drive doesn't mean no gearing, if zombie doesn't chift I'm sure it just has an optimal single gear ratio.

Tesla is small fries for 18650s. They use them because there are already billions on the market for use in every laptop. I haven't heard of anyone using them and wanting to ever repeat it. Keep in mind Tesla uses 6800+ of them for their smallest battery packs.


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## charliehorse55 (Sep 23, 2011)

I'd take a look at this engine, it's lightweight (60kg) and should be able to provide 20kW continuously. 

http://kawpower.com/engines/fd/fd851d-dfi


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## Matter45 (Jan 2, 2013)

Battery cost is stopping me from commencing this project.

ATM 45kwh of battery is about $22550

here is the calculation: to get 45kwh of battery and for the battery to last more then ten years, charge to 80%. SO 55kwh - 20 % = 44kwh.

55kwh bare minimal. Aussie Market is $0.41 per watt. 55000wh x $0.41 = $22550

Someone please tell me I am wrong!


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## charliehorse55 (Sep 23, 2011)

If you have a 20kWh pack and a 20kW genset you should be able to go 300km easily.


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## Caps18 (Jun 8, 2008)

I think you might be better off hypermiling a hybrid or a small compact car. If you can get to 35-45km/L by using a lithium 12V battery, striping the weight down, driving style, different tyres, and other improvements it will work better.

Or get a second job, save every penny for a few years and buy a Tesla Model S. It will be easier.


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## Matter45 (Jan 2, 2013)

Tesla Model S 60kwh battery pack version is about $85 grand to buy here in Australia. meh. I think I will need 3 jobs to pay for it instead of 2...

anyways, Im sure I can get that range under budget. Im pushing my budget at $25 grand as it is.

I love the Idea of having an all electric car. The generator was going to be portable, only for long range. Something you could take off the car if you where not going to use it. I have family 270km away which is the reason for the 300km range. When I first crunched the numbers on 45kwh batteries it came to $18450, which game me about $6 grand to spend on the rest of the system. But 80% DOD? that comes to 36kwh.

What if, I only fully charge the batteries once a month? what life expectancy would I get then? Hmmm... Time to do some research...


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## IamIan (Mar 29, 2009)

If you can improve the 5km/kwh energy usage rate you're listing for the vehicle you won't need as much energy to travel the same 300km ... At a modest speed flat and level ... you should be able to aero-mod a small car to do better than 5km/kwh... even getting to 6km/kwh would reduce your trip energy needs by 20%... I've read some examples of people pushing the long distance cruising energy needs of small aerodynamic cars past 10km/kwh.

If your daily needs are far less than ~225km ... you can shift more than 75% of the 300km distance to the generator and away from the battery.

Instead of trying to use a generator one can lift out of the car by hand ... attach a trailer hitch to the car so a slightly larger support trailer can be towed behind the car on the more rare times when one needs that much longer range.

At your 5km/kwh to do 300km in 3 hours ... a 20kw output trailer generator could do any distance , as it would keep up with the average load , batteries would only be needed for the short times of peak power needs.

A 10kw output trailer generator would do half the load , or 30kwh in the 3 hours time , reducing the battery output size from 45Kwh down to 30kwh.

The support trailer can be a slightly larger generator ... The T-Zero made one like this that worked very well ... see attached image bellow of the 20kw DC output generator trailer they made.

Also a support trailer could be built as a pusher trailer instead of a generator ... this can potentially improve the efficiency a bit ... ICE outputs mechanical power ... just use it as mechanical power to help push the vehicle at the wheels instead of trying to convert it back to electrical for a electric motor to convert back to mechanical.


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## Caps18 (Jun 8, 2008)

Something like that is probably the right answer. If you buy a UTE, you could put the generator in the bed for the long trips. If you are OK with waiting at a halfway point for a few hours on the 300km trip each time, you could reduce the size and cost of the battery.


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## Matter45 (Jan 2, 2013)

IamIan said:


> If you can improve the 5km/kwh energy usage rate you're listing for the vehicle you won't need as much energy to travel the same 300km ... At a modest speed flat and level ... you should be able to aero-mod a small car to do better than 5km/kwh... even getting to 6km/kwh would reduce your trip energy needs by 20%... I've read some examples of people pushing the long distance cruising energy needs of small aerodynamic cars past 10km/kwh.
> 
> If your daily needs are far less than ~225km ... you can shift more than 75% of the 300km distance to the generator and away from the battery.
> 
> ...


Can I just say, this is a fantastic idea. Thank you so much! I dont suppose these powered assist trailers exist for purchase? Im more of an electrical engineer then a mechanical one. So building something like this would be after I finish the electric car. Im very excited about this idea! Cant wait! And I agree that having the engine connected directly to the wheels will save twice the cost and efficiency. 38kwh battery along with a 10kw engine to assist. cant wait!


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## IamIan (Mar 29, 2009)

Matter45 said:


> Can I just say, this is a fantastic idea. Thank you so much! I dont suppose these powered assist trailers exist for purchase? Im more of an electrical engineer then a mechanical one. So building something like this would be after I finish the electric car. Im very excited about this idea! Cant wait! And I agree that having the engine connected directly to the wheels will save twice the cost and efficiency. 38kwh battery along with a 10kw engine to assist. cant wait!


Sadly no it isn't that easy ... they are not producing the trailer for retail ... it like the T-Zero it was make for , were a proof of concept ... built many years ago.

But it does demonstrate the concept of an alternative ... one that can achieve the range / performance goals you were interested in ... probably in the $ budget range as well... sense you will be able to reduce the Battery budget to meet your daily needs instead.

Other Companies do produce and market retail work site trailer generators ... you could try to explore that option if you don't want to go down the path they did with the design and fabrication from the ground up... but the pusher trailer option does potentially save significantly on net efficiency.


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## charliehorse55 (Sep 23, 2011)

I would recommend against using a pusher trailer. It would be inherently unstable, and hard to control.


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## Duncan (Dec 8, 2008)

charliehorse55 said:


> I would recommend against using a pusher trailer. It would be inherently unstable, and hard to control.



Why?

The guys that have built them seem to have had no issues

The basic idea would be to convert the front of a Front Wheel drive car into a power unit

Or the rear of a rear engined rear wheel drive car - Beetle or old fiat

If you use a relatively low powered unit there should be no problems


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## charliehorse55 (Sep 23, 2011)

Duncan said:


> Why?


Think about a normal trailer - it's inherently unstable when reversing or stopping. In both of these scenarios, the trailer is pushing back onto the car. When you are driving forwards, the trailer is pulling on the car, which makes it stable. 

When you have a pusher trailer, the forces are opposite - the trailer will be pushing on the car during forward driving, and pulling while reversing or stopping. This makes the trailer unstable EXCEPT when reversing or stopping, which is not ideal.


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## Duncan (Dec 8, 2008)

charliehorse55 said:


> Think about a normal trailer - it's inherently unstable when reversing or stopping. In both of these scenarios, the trailer is pushing back onto the car. When you are driving forwards, the trailer is pulling on the car, which makes it stable.
> 
> When you have a pusher trailer, the forces are opposite - the trailer will be pushing on the car during forward driving, and pulling while reversing or stopping. This makes the trailer unstable EXCEPT when reversing or stopping, which is not ideal.


The same as a truck under braking or any rear wheel drive car,
It's not a problem
We use unstable systems all the time
Have you never ridden a bike?


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## Matter45 (Jan 2, 2013)

Heres the plan. 16hp motor with a clutch that engages when the rpm increases passed idle to full throttle, belt connected to a small axle.

clutch example given:
http://www.machines4u.com.au/view/advert/Clutch-Pulley-150-X-25mm-V-belt-twin-type--/48018/

engine example:
http://www.vanguardengines.com/engines/V-Twin%20Horizontal/16-gross-hp-v-twin-hs/

when the car passes 70kmh, I will get the motor to engage at full throttle. when it goes below 70kmh, the motor will idel then shut down after a time delay. The hume highway that we use is none stop for over 1000km and is 110kmh all the way. when the car is travelling at 110kmh, the RPM on the motor will be 3500RPM. no gearing required (as long as the axle ratio is below 4:1). Obviously if i dont have my foot on the accelerator, the motor will idle at any speed.

here is what I have worked out. A motor on its own is 3 times lighter (and 5 times cheaper!!!) then a generator which generators the same amount of power in electrical form. So the trailer itself has to be equal or less of the weight of the motor to REALLY reak the benifits of a trailer assist over a generator on the car (like a ute).

In terms of stability, my father has already created something simular and has worked. in the event that a car breaks down, he created this triangle bar where one side bolts onto the front of his car, and the pointed side of the triangle hooks onto the tow bar of the back of a broken down car. as long as it is low power, the stability is fine. but excessive acceleration does cause the car in front to loose grip on the road when cornering. we wont be doing much cornering at 70kmh or on the highway. so as long as you obey the rules to trailer assisting, its not a problem. practical tests are the best tests!

If any of the above is not logical or doesnt make sense please let me know.


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## TEV (Nov 25, 2011)

Another example here : http://www.mrsharkey.com/pusher.htm


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## charliehorse55 (Sep 23, 2011)

Duncan said:


> The same as a truck under braking or any rear wheel drive car,
> It's not a problem
> We use unstable systems all the time
> Have you never ridden a bike?


I never said it's impossible, just that it's inherently unstable. Wheels allow motion in one direction more easily than others, which helps to stabilize the system. 

If a trailer had ball bearings instead of wheels, such that it could move in any direction with equal resistance, it would jacknife every time you came to a stop.


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## cts_casemod (Aug 23, 2012)

Matter45 said:


> Heres the plan. 16hp motor with a clutch that engages when the rpm increases passed idle to full throttle, belt connected to a small axle.
> 
> clutch example given:
> http://www.machines4u.com.au/view/advert/Clutch-Pulley-150-X-25mm-V-belt-twin-type--/48018/
> ...


Matter45, 

Thats right as long as everything is solid and well bolted it will be the same as a RWD and the same applies to Drive a RWD.

It all makes sense from a mechanical point of view, but you need to find a source for these components and make sure they can handle the peak power required by your conversion. I would use a chain type pulley instead (Industrial chain) they are more efficient than V type belts. I have personally thought about that myself, but couldn't find anything or prices were sky high. There are some industrial clutches you *could* use but they require some homework to be done. They work a bit like a bicycle, so the ICE will engage when the RPM goes higher than the Electric motor. 

You can get something like this. They exist in standard sizes with tapper bushes that could be linked to both your ICE and your electric motor shaft


















Another option would be a CAM BELT. They don't slip, are made to do hard jobs, silent and cheap. You would, however need to modify one of the pulleys with some kind of tapper lock bush and the other with a one way clutch bearing. Bare in mind that they are LOUD at 3500RPM if not engaged (Imagine a bike at 3500RPM!!) and this applies to both types chain or belt.

Also bare in mind when using a motor and a belt that the electric motor and ICE need to be solid in regards to each other, that means a cage with both supported by the engine mounts. With a generator you can weld something into the frame and place mounts on the generator itself, which makes like a bit easier. 



Matter45 said:


> A motor on its own is 3 times lighter (and 5 times cheaper!!!) then a generator which generators the same amount of power in electrical form


You are right, and, if done properly, more efficient as well, because *most* of the mechanical energy goes straight into the wheels, however you can not recharge the batteries on standstill unless you can find a way to put the transmission in neutral and spin both the ICE and the electric motor
Some people, mostly on Australia have successfully used a car engine and an auto gearbox (widely available) to use with their trailers. I would think it is simpler and you have full power available. Just a few links 


http://ecomodder.com/forum/showthread.php/my-hairbrained-hybrid-hidea-4420-2.html

http://www.metrompg.com/posts/phev-pusher-trailer.htm


What do you mean no gearing required? Do you have a direct access to the differential? What about in a situation you'll need to go up the hill with 400kg of batteries and the trailer at 80kmh? The ICE output will drop to less than 10HP at, say, 2000RPM.
I would not say they are lighter, in fact they might be heavier, however if you use a car engine you have full power available like in a stock car and you can recharge your batteries on the go if the electric drive train on the main vehicle supports regenerative braking (part of the ICE output would be used to charge the batteries, not necessarily all!)

I can see that you drive mostly on Motorway, to be fair the large savings of an electric car come from city driving where you have a lot of stop and go and idling. An electric will actually have worse mileage on motorway. The Polo I am converting to Electric was converted to LPG before and while I would easily use 10-11L in city I would easily do 5-6l on motorway at 110-120Km/h. Now 6l @ £0,72/l is MUCH cheaper that the average diesel/petrol car (Of course this will vary in different parts of the word but you get the idea).
Given my short trips I decided on Electric, but keeping the other Diesel I have for the long journeys. I've addressed this issue myself and I just don't believe using a smaller carburetor engine will be more efficient (and its noisier, louder than a car motor), but having a light and spacious electric car is clearly an advantage, especially when you start talking about conversion cost.

Of course everything changes if you do 300km like once a week or less, you could just pop the generator on the engine bay for such occasions. You would have worse mileage than an equivalent petrol/diesel car for sure, but the savings from the remaining days would mostly neglect this. 

Then comes all the boring stuff. Before you even start make sure your insurance company will insure the car like this and that you are not stopped by the police using an "undeclared" fuel type on the car. I know some countries are prone to have problems with this.

If using the trailer make sure your car can legally be used to tow (same as above depends on your country regulations and you can get fined) and of course you might want to install some parking aid sensors, just in case


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## Matter45 (Jan 2, 2013)

cts_casemod said:


> but you need to find a source for these components before you even start thinking about using them


Yes, a good point. The idea is sound, but the parts are not. Thankfully I do have the resources to sort these parts out. I already have the axle believe it or not that could potentially do the job. I dont know how much it weighs though.




cts_casemod said:


> There are some industrial clutches you *could* use but they require some homework to be done


Whats wrong with using a clutch that engages when it spins faster than idle speed? there are plenty of them around. the one mentioned in the link is for a max of 16hp. Whats wrong with this one?




cts_casemod said:


> What about in a situation you'll need to go up the hill with 400kg of batteries and the trailer at 80kmh?


there is a 50km range window, so if i need to use more electric power then so be it. plus it would be extremely rare doing 80kmh up a hill. I will be using the trail less than once a month.

Most of my driving in the car will be in the city (good old Sydney!).




cts_casemod said:


> I've addressed this issue myself and I just don't believe using a smaller carburetor engine will be more efficient


I calculated at most 5 litres per 100km. I think thats something to consider, whether a generator thats 3 times the size is actually more economical then direct drive. The main purpose is to extend the range on the rare occasion without purchasing a second vehicle.




cts_casemod said:


> Then comes all the boring stuff. Before you even start make sure your insurance company will insure the car like this and that you are not stopped by the police using an "undeclared" fuel type on the car. I know some countries are prone to have problems with this.





cts_casemod said:


> If using the trailer make sure your car can legally be used to tow (same as above depends on your country regulations and you can get fined) and of course you might want to install some parking aid sensors, just in case


LOL I didn’t even think of the legal requirements.


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## mileojule (Jan 7, 2013)

There are other losses like speed related losses, heating and cooling equipment, lights, all that adds up.


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## cts_casemod (Aug 23, 2012)

Matter45 said:


> Yes, a good point. The idea is sound, but the parts are not. Thankfully I do have the resources to sort these parts out. I already have the axle believe it or not that could potentially do the job. I dont know how much it weighs though.
> 
> 
> Whats wrong with using a clutch that engages when it spins faster than idle speed? there are plenty of them around. the one mentioned in the link is for a max of 16hp. Whats wrong with this one?
> ...




WOW, You've beat me just before I change the topic lol!

There is something you said now that makes all the difference


Matter45 said:


> Most of my driving in the car will be in the city (good old Sydney!).
> 
> 
> I calculated at most 5 litres per 100km. I think thats something to consider, whether a generator thats 3 times the size is actually more economical then direct drive. The main purpose is to extend the range on the rare occasion without purchasing a second vehicle.


I was going with the idea that you wanted an electric EV for long range trips only, in wich case you would be better using an ICE instead, since you have losses on the conversion.

Back to topic,

There is nothing wrong with the puley in question or with the system that lets the engine idle, in fact thats what I was taking about, just a different one for efficiency reasons. The industrail clutches I am talking about are exactly that but they are heavy duty and come with tapper lock bushes so you can choose your shaft size. I would oversize them, so for 15HP I would use a 25 or so, just in case.

What I was telling you is that V Belts are not very efficient, so from those 15 HP you may get 13 out. Other problem with this aproach is that you have to carry it all the time with the car (Its not exactly removable) so for short trips only you may be better off with the trailer/generator set as you can remove if not needed. I would use a 1800RPM 10HP Generator or larger and would charge the batteries straight from the Induction generator to avoid further losses. You can use a modified VFD to controll the DC BUS Voltage Current.

Of course the trailler would do it as well, if it was removable.

If you have the ICE as a complement you need to have it solid with the electric motor, as part of the drivetrain. Not easy to remove (Possible but not 2 minutes task). On the MOT they would class it as an hybrid so you would have to do C02 checks and similar. I would ask on your local vehicle authority and a few MOT stations just to be on the safe side. Here in GB and a few other european countries they may ask you to open the bonnet from time to time. Never happened with me, but I have some fellow tunners that got fined by having changes not declared to the insurance company or the insurance company didnt acept the claim after an acident.


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## Matter45 (Jan 2, 2013)

Yes bit of confusion there, the car will be pure electric with 150km of range, give or take a few.

based on information provided in this forum (thanks guys!) the trailer (not the car) will be powered by a 16hp motor, and push the electric car when traveling at higher speeds. thanks for the efficency issue on v belts, as i said im not much of a mechanic.

Sad news is I wont be commencing this project for another 3 months, but i will be sure to post updates!

Now to find out the legal stuff about a push trailer in Australia.


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## cts_casemod (Aug 23, 2012)

Matter45 said:


> Yes bit of confusion there, the car will be pure electric with 150km of range, give or take a few.
> 
> based on information provided in this forum (thanks guys!) the trailer (not the car) will be powered by a 16hp motor, and push the electric car when traveling at higher speeds. thanks for the efficency issue on v belts, as i said im not much of a mechanic.
> 
> ...


I wish you luck by then, once you start there is always something to keep you busy! 

Thats more feasible  I would say depending on the size of your car you could get away with 20KWH of batteries 
A drive by wire system to your small engine would be nice, so you could share power between the electric and the ICE, keeping the car stock

So lets say you find a suitable differential, I would go direct drive without the belts for optimun efficiency!

Instead of a clutch pulley, if you could get a centrifugal clutch. This would allow the ICE to be kept idling if required, even with the car stopped.

I would have a look at the smart car (Mercedes) engine, maybe it has all you need, its small (600cc) and there is a version which I believe has some kind of centifugal or hydraulic clutch that engages once the engine revs are above a certain level only.


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## cts_casemod (Aug 23, 2012)

Speaking about the smart car, I've found this that you could use as part of your trailler with a suitable cover/enclosure.










That would save you all the hard work fixing the engine, wheels, etc.


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## PStechPaul (May 1, 2012)

An interesting project, indeed. I just wanted to to toss a few more suggestions or ideas onto the pile to consider.

1. The push trailer might be a good idea to get sufficient range for occasional long trips, and the problem of instability can be addressed by adding a force sensor so that the trailer's powered wheels only take care of propelling its own weight. So the trailer could have additional batteries, generator, and fuel to supplement the EV which could be made small and efficient for city driving.

2. A manual transmission can allow the use of a much smaller electric motor. You need only about 15-20 HP to cruise at 60 MPH on a flat road, but without a transmission you would need a motor that could provide enough torque at low speed to negotiate as much as a 25% grade. Probably about 60 HP.

3. One possibility for low speed torque is a V-belt drive with a large pulley on the driveshaft and a small pulley on the motor. It could be tightened when you need the torque, and then loosened at higher speeds. Belt drives are used on tractors, and they are very inexpensive. Efficiency won't be a major factor if it's only used for steep grades at low speed.

4. For maximum efficiency, a three phase induction motor and VFD may be better. The technical details should be no problem for an EE, and there are many ACIMs used in Australia. I think you can just use a 230V motor on 460 VAC to get 2x overclocking without a total rewind.

5. I found a source for 18650 LiPo batteries for $0.22/Wh, with free shipping. They are 41 grams each for 3.7V 3600 mAh, so 3 kG/kWh. For 20 kWh (reasonable for the city vehicle), it would be 60 kG and $4400. You would probably connect them in banks of 160 cells each for nominal 600 VDC bus. If you can get 250 Wh/mile you might get 200 mile range with 80 kWh or about $18,000 worth of batteries.
http://www.ebay.com/itm/20-Pcs-1865...geable-battery-silver-Tab-W-Tab-/150971877317


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## Matter45 (Jan 2, 2013)

if your going to spend 18 grand on batteries, one of the last things that you want to do is stuff it up.

Can I just say as a caution to the public, there is a huge fraudulent market out there in regards to 18650 batteries.

Be sure to do your homework on where the source of the batteries come from. make sure you buy a small amount and test them extensively before making the big purchase.

18650 batteries and CONSTANTLY being overrated there original capacity. Its such a nasty world out there... BE CAREFUL!

Personally, I would only buy my batteries from a source that has a very good reputation.

On another note, anything over 3000mah only comes from manufactures with the latest technology, such as Samsung, Panasonic etc...


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## PStechPaul (May 1, 2012)

Yes, I was warned that these may be the same as those once labeled "Ultra Fire", and lived up to the name. They have 1800 Ah LiFePO4 batteries as well, but for $0.61/Wh. I might buy like four of the LiPo batteries for $10 or so and then test the hell out of them with a BMS/cell tester I am planning on designing and building. I will probably need to build a safety enclosure as well. I have some "battery safe" fireproof bags that I bought with some other LiPo cells I got from Hobby King last summer.

There is a thread on "cheap lithium" and someone suggested Balqon who have LiFePO4 for $0.34/Wh. They are 40 Ah for $44 and a good deal, but for my tractor projects I only need about 2-5 kWh at 300-600V. My best bet may be the 12V 12Ah SLAs I got for $20 each. It will add about 300 lb to my tractor but weight is a good thing there. For a 20 kWh battery pack with SLAs it would be 1667 pounds and $2800. And unless you are just barely using them the Peukert will get you.

Hopefully some of my other ideas may be more useful. Good luck!


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## CrazyAl (May 9, 2011)

Matter45 said:


> LOL I didn’t even think of the legal requirements.


When doing your EV conversion and the trailer, you will want to speak to a RTA approved engineer signatory prior to starting your project.
For NSW, I prefer talking to VMC engineering as he knows what an electric car looks and drives like and he knows heaps about cars.
His mobile is 0403 328 574.

Also, when selecting a car, you may want to pick a pre 1996 car so that you don't have to worry about one of the ADRs (Australian Design rules) for front crash testing.

You also want to check out Infrastructure Govo's site
and this
VSB for EVs

Also, do you have your donor car already?
In my opinion, I reckon it would be best if the donor car was already registered under your name or business name prior to conversion (as it makes it easier to establish ownership after the conversion).
Also, check that the car has never been written off prior to starting your conversion.

Also, start talking to the insurance companies prior to conversion. I've been told that NRMA and Shannons are EV friendly (as long as you talk to the right person in the company who can make a decision).

In NSW and the rest of Australia, there is more paper work to consider prior to even starting the technical side of an EV conversion, unlike in other jurisdictions around the world. 

Another option you may want to consider is a getting a Gen 2 Prius (NHW20) and look into the nilco2 kit for it.


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## Matter45 (Jan 2, 2013)

CrazyAl said:


> When doing your EV conversion and the trailer, you will want to speak to a RTA approved engineer signatory prior to starting your project.
> For NSW, I prefer talking to VMC engineering as he knows what an electric car looks and drives like and he knows heaps about cars.
> His mobile is 0403 328 574.
> 
> ...


Wow! Thanks for the info. Would of taken me ages to figure all this out. thank you!


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## cts_casemod (Aug 23, 2012)

PStechPaul said:


> I found a source for 18650 LiPo batteries for $0.22/Wh, with free shipping. They are 41 grams each for 3.7V 3600 mAh, so 3 kG/kWh. For 20 kWh (reasonable for the city vehicle), it would be 60 kG and $4400. You would probably connect them in banks of 160 cells each for nominal 600 VDC bus. If you can get 250 Wh/mile you might get 200 mile range with 80 kWh or about $18,000 worth of batteries.
> http://www.ebay.com/itm/20-Pcs-1865...geable-battery-silver-Tab-W-Tab-/150971877317


I'll pay you a beer if they are what they advertise 
By the way those are Li-ion, not lipos.

Lipos are more suitable for an EV, but more danerous as well.
This batteries can be discharged at mostly 2C (of their true capacity) so for a 144V 500Amp you will need 250AH of batteries a board (~36Kw) with a shelf life of 2years.

I've been using 18650 since 2005 due to low quality market on the NiMH and the phase out of the Nicd. 

I still have panasonic cells from that time operating, folowed by the sonys. All the other brands have failed. Unfortunatly they are either too expensive or hard to find so I havent tested any new.

I did a few tests on 18650 batteries before ordering my two LiFePO4 batches from china

Results as new:

*Sony US18650GR* cells at 2400mAh (~$4ea @100pcs)
2C Discharge down to about 2-2.2Ah
1C Charge Rate
250 cycles before capacity degradation started to occur
150 cycles before you could only discharge them to 1C
Weight: 50g

*Cheap laptop cells*

No Brand cells advertised at 10.8V 9000mAh and 6000mAh (3s3p and 3s2p)
Found 2000mAh cells inside
1C Discharge Rate
0.5C Charge Rate
100cycles before they could no longer be used due to degradation (internal resistance) 
Weight 40g
Most China cells fall in this cathegory, or are labeled at 2x the actual capacity.

*UltraFire* Protected cells

Advertised at 3000mAh
Protection IC Inside was found to cut prematurely on currents as low as 500mAh when battery capacity was low.
Charge and discharge rates had to be limited to account for this, so I would say 500mA is a safe limit, althought at most of their capacity I could discharge at 1A. The Voltage sag was big thought and the IC would cut at about 3.3V
Cycle life - Not tested
Real capacity - Varies from 600 to 1000mah at 500mA discharge current
Weight 25-30g

I found these to be completly unsuitable even for my lowest wattage CREE Flashlights. On normall cells as the voltage droped the torch would reduce the current to a safe level untill the cell was at 3V. 

I also did some discharge down to 0 on some cells.

If charged quickly I have noticed no difference in performance other than a slightly increased internal resistance (DO NOT TRY THIS AT HOME)
If left for a few months the internal resistance would go up a lot and the cell got warm both at charge and discharge. Capacity was reduced.

Some cells would open during discharge cycles at 1C which could create a hazard if it happened on an EV.

The brand cells did recover best, but not to 100%
The UltraFires were obviously not tested as they have built in protection IC

*Shelf life:*
As tested on applications other than EVs at average charge of 4V, charge and discharge at 0.5C

*Panasonic*
4 years / 300 cycles - Capacity loss 250mAh/Year
End of life = ?? - They go on forever!

*Sony,*
4 years / 300 cycles - Capacity loss 400mAh/Year
End of life = 5 years

*Sanyo*
3 years / 250 cycles - Capacity loss 500mAh/Year
End of life = 4 years

*No Brand Chinese cells* 
2 years / 100-150 cycles - Capacity loss 500mAh/Year
End of life = mostly unusable after 2 years
Cels behave differently on a pack, possible lack of batch and quality control (unbalanced)

Another batch of Sonys used on my torches, disharged mostly at 100% and left charged at 4.2V until used.
Cycle life - 2Year - 150 cycles to half capacity (1200Mah)
Most capacit was lost in winter if cells are charged at low temperatures below 5C


So, the *conclusions*:
For higest ell life charge at 3.9 or 4.0V
For highest Capacity charge at 4.1V
Charging at 4.2V will not damage the cells but will reduce their cycle life. This may seem obvious, but when the cells are in series the BMS will cut when the first cell reaches 4.25V. After a few cycles this cell will how even reduced capacity and the pack is compomised.
With LiFePO4 it will cut at 3.9V, But most manufacturers recomend 3.65V, same care applies.

The point is they are in fact light weight, however the voltage SAG, a bit like on the Lead batteries will reduce efficiency. They are also unsuitabe to use on an EV after 2 years unless you have a really big pack that can be discharged at 0.5C
High temperatures are a problem if the packs are stored inside the car

I have seen most performance degradation on my cells when i left them charging overnight with temperatures arround -5 to 3C on winter. I am unsure about this on LiFeP04 but would take some precautions.

After al this is taken into account LifePO4 is the wise choice if you want to trade a litle bit more weight (in realistic terms 30% on the first year) by a long life.
After 2 years your Li-ions are mstly dead and the LiFePo4's will still be running strong, so the weight issue questionable.
Price wise if you're going to buy decent cells they will cost same or more and they will give you a life of trouble finding a failed one in a pack with 2000cells


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## PStechPaul (May 1, 2012)

Thanks for the information and correction about LiPo vs Li-Ion. I'll see if I can run similar tests on the cells I get. I can automate the test to do a sequence of charge/discharge as well as a measurment of internal resistance or droop at 1C (based on rated capacity). I would assume that this can be done by taking the difference between open circuit voltage and the voltage at a constant 1C charge or discharge. I would make this measurement at perhaps 60 second intervals to see if it changes based on SOC and charging vs discharging. A lifetime test would take 2 hours per cycle at 1C, so to see any degradation over 100 cycles would take 200 hours or about 8 days. I could also do an accelerated test at 2C or 3C. I don't see any current multiple spec on these cells, but the ones I got from Hobby King were as much as 10C and 30C for the pouch cell. I'm not sure how high would be safe for these unknown cells, but I would suppose there would be a limit based on voltage droop and resultant internal power dissipation and heating. For this size cell I suppose about 1-2 watts would be OK, which would be a sag of about 0.5 volts at 3.6 amps, to 3.2 volts.

As for the cell opening during discharge, that is a problem I had not considered. One way to deal with that would be a 5 volt zener which could handle nominal charge or discharge (in this case) of 3.6 amps or 1C, which would be 18 watts. For 3C it would be 54 watts. A better option would be a relay that would disconnect the cell and short out its position in the pack. I will need to think about that to see how it could be implemented. An SPDT relay rated at 15A and 240V(AC) is about $2 and would work for a low current pack. 

Actually, an open cell should be a rare event that would justify shutting down either charging or discharging by tripping the main interlock contactor. In that case, a 5V zener (or the equivalent) would only need to carry the full charging current long enough for the charger to be shut off. And if the cell opened during discharge, it would actually cause voltage reversal which could be handled by the reverse diode in the shunt MOSFET of the BMS, long enough for the fault to be detected and the pack shut down.

I realize this has gone a bit off topic, but since the OP is an EE I think it may be valuable information. However, I think I will start a separate thread for my ideas of a DIY BMS and modular high voltage battery packs using small cells.


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## cts_casemod (Aug 23, 2012)

PStechPaul said:


> Thanks for the information and correction about LiPo vs Li-Ion. I'll see if I can run similar tests on the cells I get. I can automate the test to do a sequence of charge/discharge as well as a measurment of internal resistance or droop at 1C (based on rated capacity). I would assume that this can be done by taking the difference between open circuit voltage and the voltage at a constant 1C charge or discharge. I would make this measurement at perhaps 60 second intervals to see if it changes based on SOC and charging vs discharging. A lifetime test would take 2 hours per cycle at 1C, so to see any degradation over 100 cycles would take 200 hours or about 8 days. I could also do an accelerated test at 2C or 3C. I don't see any current multiple spec on these cells, but the ones I got from Hobby King were as much as 10C and 30C for the pouch cell. I'm not sure how high would be safe for these unknown cells, but I would suppose there would be a limit based on voltage droop and resultant internal power dissipation and heating. For this size cell I suppose about 1-2 watts would be OK, which would be a sag of about 0.5 volts at 3.6 amps, to 3.2 volts.
> 
> As for the cell opening during discharge, that is a problem I had not considered. One way to deal with that would be a 5 volt zener which could handle nominal charge or discharge (in this case) of 3.6 amps or 1C, which would be 18 watts. For 3C it would be 54 watts. A better option would be a relay that would disconnect the cell and short out its position in the pack. I will need to think about that to see how it could be implemented. An SPDT relay rated at 15A and 240V(AC) is about $2 and would work for a low current pack.
> 
> ...


Ive seen a topic on another forum in which a car got fire and one of the possibilities was an open cell. The higher voltage fried the PIC that would end data to the BMS and seems like the balancing resistor took a few volts over its rated capacity.

I always advise people to use a zenner like you say and an aditional fuse on each wire going to the BMS as under large current the zenner will likelly short.

As with cell testing dont forget that you need to account the aging effect and the temperatures you'll find on a car, mostly overnight freezing and high tempratures on summer. Most tests I've done were recorded by smart IC's under real life operation. 

At the moment I have an headway running some wireless equipment on the car broadcasting 24/7. I charge it every two days (36V 10Ah). he tempratures will drop now so I would like to see the BMS readings on capacity.

As with internal resistance I am not sure if that is a good method. On my particular tester the voltage drop in the wires is quite significant if charging one cell, so good part of the charge is done on CV. Charging battery packs of higher voltage is not an issue, but at 5Amps a good 4.1V may well be 3.8 on the battery terminals.

You will notice that the cells will get warm when charging/ discharging if they are not good. Also you will notice that a cell discharged to 2.5V will go to 3.7 under no load after a few minutes, which represents 30% capacity, but you can only use it at a very small C rating, like C/50.

As with capacity is pretty straightfoward, but remember that on a LifePo4 the capacity test is done down to 2V. On ur vehicles we are certainly not going so low and the battery will not be happy either, so anything under 2.5V (or 3.3 on Li-ions/Li-pos) is rubish.


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## Matter45 (Jan 2, 2013)

Project wont commence until late March, but updates will follow here: http://www.diyelectriccar.com/garage/cars/417


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## cts_casemod (Aug 23, 2012)

Matter45 said:


> Project wont commence until late March, but updates will follow here: http://www.diyelectriccar.com/garage/cars/417


Will keep an eye. But expect a bit over 2300lbs with 35KW batteries.
I would also build some carton boxes with the dimensions of the batteries so you can start placing them on the vehicle and calculate the weight distribuition. With 400Kg of batteries you'll want to upgrade your suspension.

You might also find it easier to go with 48 cells. Plenty of chargers/BMS available (175V).


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## Matter45 (Jan 2, 2013)

Plan so far:

i plan to hook a warp11 motor directly to the drive shaft. the warp11 has 2 shafts on either end. IF there is enough room in the engine bay after taking away the gear box and engine, ill stick a 16hp ICE engine in series with the warp11.

the best weight ratio for cost is WB-LYP100AHA @ 411kg. 2 strings 100ah each.

Manufactures website states 0.5c normal discharge, which gives 50a per string for a total of 100ah @192v. now here is a question, i want that 150kw power to the wheels. so ive decided to use the zilla Z1K-LV. Question: even if i have a battery pack of 192v, does it presents problems if the zilla is limited to 156v? does it really matter that there is a voltage difference between the battery and the output of the charge controller?

EDIT: on Zilla's specsheet it says:
* Controllers buck but do not boost so output voltage will be less than or equal to input voltage.
**Maximum battery current at: 200V = 950A and at 300V = 885A.

it doesnt specify whether this implies to either the high voltage or low voltage model.


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## cts_casemod (Aug 23, 2012)

Matter45 said:


> Plan so far:
> 
> i plan to hook a warp11 motor directly to the drive shaft. the warp11 has 2 shafts on either end. IF there is enough room in the engine bay after taking away the gear box and engine, ill stick a 16hp ICE engine in series with the warp11.
> 
> ...


 
Bare in mind that the definition of Direct Drive is motor to Diferential output without gearbox.

If you hook the motor to the driveshaft as you say you will have 1000RPM at 100Kmh / 60MPH

3000RPM Direct Drive is actually going to a 3/1 Diff or similar.

There are other issues driving without dif, if one wheel looses traction the car will pull to the oposite side.


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## Matter45 (Jan 2, 2013)

cts_casemod said:


> Bare in mind that the definition of Direct Drive is motor to Diferential output without gearbox.
> 
> If you hook the motor to the driveshaft as you say you will have 1000RPM at 100Kmh / 60MPH
> 
> ...


its 3000rpm 100kmh with the ratio. i thought thedefinition of diy direct drive was without the gearbox and connected to the drive shaft which is connected to the axle which has a turn ratio of 3:1 to the wheels.

Im guessing you dont know the answer to the question? if its fine running 156v+ battery voltage (192v) on a Zilla 1k LV? is there anyone out there with experience with Zilla 1k LV?

EDIT:

got an email from zilla support, here is the response:

Unfortunately this setup will not work. The controller will be in
high voltage shut down from 175V and up so nothing will be hurt but
nothing will work. We can upgrade your Z1K to an HV for $700 plus
shipping and handling.


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