# Another Fiero



## jimmo (Jul 8, 2010)

Hi guys, Ive been a stalker for a while and decided to finally ask some advice on a build. 
I would like to build a fiero with this set-up 

http://www.evparts.com/products/str...8-to-96-volt-street-vehicle-motors/mt5615.htm

a.c. motor, controller combo with regen braking. 
I would like to keep the car light with only enough batteries for a short range of under 20 miles, however, I would like to add a small generator to take longer trips. 
Has anyone done this yet?
If the car is kept light enough, it should only require an average of about 6kwh which is possible to maintain with a small generator. I was considering a small diesel generator due to the variety of fuels one can burn in a diesel. 
Is it possible to charge the batteries while driving the car or am I asking too much of the current technology?


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## dougingraham (Jul 26, 2011)

jimmo said:


> a.c. motor, controller combo with regen braking.
> I would like to keep the car light with only enough batteries for a short range of under 20 miles, however, I would like to add a small generator to take longer trips.
> Has anyone done this yet?
> If the car is kept light enough, it should only require an average of about 6kwh which is possible to maintain with a small generator. I was considering a small diesel generator due to the variety of fuels one can burn in a diesel.
> Is it possible to charge the batteries while driving the car or am I asking too much of the current technology?


I've done the calculations and if you want to do longer trips and plan to go highway speeds it will probably take at least 300wh/mile if you are pulling a trailer with a motor generator set and fuel in order to keep your batteries charged. And that is probably optimistic. 300 wh/mile is 21kw if you go 70 mph. Since your charger is going to be about 90% efficient that bumps the power up to 23.3kw which means at least a 31hp generator set just to keep the batteries topped up. And that is more than likely low. It would be safer to go to 40hp (~30kw) genset. And that is a pretty good size setup.

It takes more power to go down the highway than people think. Can it be done? Sure! I would put a trailer hitch on my car and rent such a thing if it was available.

I think you are going to want more like a 40 mile range. My personal daily commute is 8.4 miles. I kept track of my average driving for a month and found that I average a little over 12 miles per day. I bought a battery pack that will take me 60 miles. Why? because I wanted the car to be fun to drive and that weight of batteries will make the car weigh about 15 pounds more than it did with the ICE in it. If I had put a 20 mile range pack in it then I would have had a golf cart instead of a car.


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## jimmo (Jul 8, 2010)

Thanks for the reply.
That seems like a lot more power than I was thinking. That is not too encouraging as my commute to work is 42 miles one way. I dont want to load a car up with enough batteries to drive nearly 100 miles. On the other hand, Im sure I would be able to charge the car at work so that might be an option.
would you mind explaining how you came up with those numbers? I am new to this and Id like to play with the formulas to see if the project can be tweaked to be more efficient. 
Also, do ya think the power plant I am using is a good choice or are there better, more efficient options?


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## MalcolmB (Jun 10, 2008)

dougingraham said:


> I've done the calculations and if you want to do longer trips and plan to go highway speeds it will probably take at least 300wh/mile if you are pulling a trailer with a motor generator set and fuel in order to keep your batteries charged. And that is probably optimistic. 300 wh/mile is 21kw if you go 70 mph.


Your estimate of 300 Wh/mile is an average over a range of speeds. The actual energy consumption at 70 mph will be higher than the average, just as it will be lower at 30 mph.

Edit: my mistake, I missed the bit about highway speeds.


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## tomofreno (Mar 3, 2009)

My about 2300 lb Suzuki Swift ev uses a bit over 8kW at 50 mph, a bit over 12kw at 60 mph, and a bit under 18kW at 70 mph. I would guess a Fiero would use similar or a bit more. If the generator must be pulled on a trailer it will increase drag force and the above power numbers considerably. I think JPR3 said he can go about 50 miles with a pack of 36 100Ah cells in his Fiero (would need to verify), so you would require a bit more than twice that to make it round trip discharging your cells 80% or less. If you can charge at work, you could make it with a pack like his, but 130Ah cells would give you a more comfortable margin. 

If they bulk at charging at work, you might offer to pay them twice their daytime cost per kWh (assuming you charge there during the day). That is what I did when I spoke to the owner of an RV park about charging there. He ended up charging me $2.00 to add 5kWh. Of course they may not know how to handle this payment and not want to deal with it since it is so small. They could dock your paycheck x amount per pay period.


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## dougingraham (Jul 26, 2011)

jimmo said:


> Thanks for the reply.
> That seems like a lot more power than I was thinking. That is not too encouraging as my commute to work is 42 miles one way. I dont want to load a car up with enough batteries to drive nearly 100 miles. On the other hand, Im sure I would be able to charge the car at work so that might be an option.
> would you mind explaining how you came up with those numbers? I am new to this and Id like to play with the formulas to see if the project can be tweaked to be more efficient.
> Also, do ya think the power plant I am using is a good choice or are there better, more efficient options?


To get the good life out of your Lithium batteries you need to keep a safety margin of 20% which means your minimum range needs to be 53 miles. Add another 10% to account for ageing and you will want at least a 60 mile drop dead range. This would give you the ability to make short side trips on the way home from work.

Assume 300wh per mile average (Est wh/mile by vehicle weight in lbs/10 and nudge upwords since most of your miles will be at highway speed).

Battery pack needs to be 300(wh/mi) * 60 (miles) = 18000wh or 18kwh.

The motor/controller you have chosen is known to be a good combo for smaller 2 seat cars. It has a voltage limit of 108 which means a practical limit of 30 cells in a lithum pack (108/30=3.6 volts per cell). The nominal pack voltage of a 30 cell pack of LiFePo4 cells is 30*3.2 = 90 volts. To find the minimum AH pack you need from all this take the 18000wh and divide by the nominal pack voltage 18000/90 = 200AH. That is a nice number because cells in that size are available or you can buy 100AH cells and pair them to get the 200AH.

This will end up being around 400 lbs of batteries of which 1/4 will be countered by the 100 lbs of gasoline and fuel tank you will be removing. Another quarter by the removal of the exhaust, cooling system and battery and the rest by the ICE engine. So the vehicle weight won't change much at all. It could even get lighter. It depends on how heavy the ICE engine is.

The above seem to be reasonable estimates, of course your mileage may vary if you have hills or an average elevation change or if you just plain have too much fun when driving. I could also have made a mistake and I am sure someone will point it out if I did. One good thing I see is that your battery gets paid for in about 3 years from the gasoline savings. 

You may need more batteries to power your heater in the winter or AC in the summer and I didn't take that into account.


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## drgrieve (Apr 14, 2011)

At this link there is a dyno test on the package you're looking at. They run it at 120v (after full charge) and up to 650 amps.

http://jackrickard.blogspot.com/2011/04/this-week-we-return-to-slingblades.html



> Just this past month, Curtis began shipments of a new model 1238-7601 controller which is a bit of an upgrade from the 1238-7501 we had been using. The 7501 was nominally a 96 volt controller with a current limit of 550 amperes. We routinely run this controller at 120v and understand that it can withstand voltages up to 130 before shutting down to protect itself.
> 
> The new 7601 ups the current limitation by a full 100 amps, to 650 amps total. If you could put 120v in at 650 amps, that would render 78 kw. If we are low enough to get it to start, we actually sag to a little over 100 volts at those current levels and ergo, perhaps 65-70kw are truly available. That's potentially 94 eHP input to the motor.


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## JRP3 (Mar 7, 2008)

As Tom said I've done 50 miles in my Fiero in mixed driving with my 36 cell pack of 100ah SE/CALB cells, with an actual capacity of 12.5kWh's and using all of it. I do have a flat belly pan to help with aero. At 55 mph steady speed I can get about 45 miles on mostly flat terrain.


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## algea07 (Oct 1, 2010)

i had thought of this, but i gave up on the idea.

i don't really know much about electronics or electric cars so my solution had to be a simple one. the best/easiest way to do this n my opinion is to buy something like this it has an output of up to 9kw. if you bouht this for $700 and a 9kw charger for much more, you could have a hybrid. it's not a complete hybrid, you cant drive forever but it will give you a substantial range boost. 

If you have the room you might be able to fit this under the hood, but i don't think that is likely. however the generator only weighs 90kg and toe bars can be rated up to 150kg. so you could weld up a frame and bolt it straight to your toe bar like a bike rack. at the back of you car it won't add much to drag and it means that you can take it of when you don't need it.

this is still expensive a 9kw charger wont be cheap. and generators are loud (if you only have it turned on while you're on the freeway that wont be an issue). Not to mention the extra weight on the back of your car.

it's up to you to do the figures, a car with 100mile range is not impossible, so what is cheaper and more practical for you. 

hope this helps


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## jimmo (Jul 8, 2010)

WOW, a lot of good info. I have to familiarize myself with the #s and play with them. At first it seemed out of reach but 8 kw at 50 mph doesnt seem bad but when doing 70 it consumes a lot more juice, I am refering to tomofreno's suzuki swift. I was figuring the wedge shaped fiero would be a good aerodynamic design with a small frontal area.
I was thinking about a belly pan and other mods, possibly lowering the car and using rims and tires much narrower than the stock wide tires. Also gutting the car of anything not needed for driving but I guess that kinda goes without saying.
If I do go with an on-board generator the plan was definitely to incorporate it into the car and not tow it in any way.
What really seems to be the issue is that none of the batteries on the market allow a good discharge. I keep reading about keeping them within 80% of a full charge charge. 
I did figure on the charger costing a lot and weather or not it would be capable of topping off the batteries just as fast as they were being depleted.
Do most of you guys retain the clutch or do ya use a direct coupler and leave the trans in a certian gear throughout the ride?


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## JRP3 (Mar 7, 2008)

I used a direct coupler and just leave it in 2nd for most of my driving. With my AC system that takes me to a little over 65mph, though not much power left up there. I can shift on the fly but it's tricky since regen slows my motor down so much when shifting, you have to do it quickly and get it just right.
Lithium batteries can be discharged much further than 80% SOC with no problems. Personally I don't think your generator idea is practical or worth it. If you can't do it with batteries alone then just go buy a used Prius or Honda Inisght. It will be a better car and cost you less money.


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## tomofreno (Mar 3, 2009)

> What really seems to be the issue is that none of the batteries on the market allow a good discharge. I keep reading about keeping them within 80% of a full charge charge.


 Maybe you are confusing staying above 80% State of Charge (SoC) with 80% Depth of Discharge (DoD)? The general recommendation is discharging them less than 80% of their capacity, 80% DoD, 20% SoC.



> Do most of you guys retain the clutch or do ya use a direct coupler and leave the trans in a certian gear throughout the ride?


 If you use a lower power/torque motor like the AC31 or AC50 you will get faster acceleration by retaining the transmission since they don't have sufficient peak torque to give high acceleration in a gear higher than first. My car accelerates at 6 mph/sec in first, 4 mph/sec in second, and a bit less in third. This is limited both by the peak torque of the motor and the max voltage of the controller. Higher voltage enables the controller to push it's peak current through the motor to higher motor rpm and vehicle speed in a given gear, resulting in peak torque and acceleration to higher rpm and speed. This is the case for both AC and DC motors.

HPEVS is working with Curtis on a new water cooled motor and controller that will be a max 100 HP and have peak torque of 150 ft-lb, and is supposed to be available next year some time. If that fits your time frame it would give you much better acceleration. But of course it depends on how much you want. My car does 0 to 60 mph in 16 seconds, and 0 to 40 mph in 8 seconds, so I can easily pace traffic and keep up with most of the more aggressive drivers off the line, so it works well enough for me. Of course it won't keep up with a more powerful ice powered car if they floor it.


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## dougingraham (Jul 26, 2011)

jimmo said:


> What really seems to be the issue is that none of the batteries on the market allow a good discharge. I keep reading about keeping them within 80% of a full charge charge.
> I did figure on the charger costing a lot and weather or not it would be capable of topping off the batteries just as fast as they were being depleted.
> Do most of you guys retain the clutch or do ya use a direct coupler and leave the trans in a certian gear throughout the ride?


The batteries will get 1000 cycles if you run them flat every time. They get 3000 or more cycles if you only discharge to 80%. It is economics that dictate the 80% not really the quality of the batteries. One brand claims more than 5000 cycles if you limit to 70%. That would be almost 14 years of a cycle per day.

I am keeping my clutch. Others direct couple to the transmission and then use one gear (usually second) until they get on the highway and then shift up. You can shift without a clutch if you pay attention and are not in a hurry. With purpose built cars like the Tesla there is a reduction that was chosen to match the motor characteristics so it didnt need a transmission. But the motor they are using has a 14000 rpm limit so it gets a good top end and good torque. The final drive ratio is 8.28:1 which gives them a top speed of 129mph.

I earlier said you pay for your batteries in 3 years. I thought I was mistaken so I ran the numbers and here is what I get. If you drive the commute and nothing else 5 days a week and 50 weeks a year that is 21000 miles per year. Fuel cost at 30mpg and $4 per gallon is $2800. Add in the 7 oil changes at $30 each and you are up to $3010. The cost of electricity for that 21000 miles would be 21000(miles)*300(wh)=6,300,000 watt hours or 6,300 kwh. With 90% efficiency in the charger that goes up to 7000 kwh. At a cost of $0.11 per kwh is $770. Difference per year is $2240. The batteries will cost around $8000 to meet your goals so 3.6 years to break even. I expect gasoline to average $4 per gallon over the next few years. My electricity is $0.102 per kwh and I figured a little extra for a rate increase. If you can get your work to pay for the charging at the office the savings go up to $2625 per year or payback in 3 years and 17 days. Your motor/controller is paid for in just 2 more years of savings. If you drive on the weekends it also shortens the payback time.

Best wishes!


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## sbagdon (Nov 11, 2011)

_(first post, gotta start somewhere...)_

If using a dc motor and dc batteries, why not generate dc current with your ICE generator? That way, you aren't using an ac generator, which has to go through the ac/dc conversion to charge the batteries, and can charge directly with a dc charger. It has the added expense/trouble of a second charging circuit (_ac/dc for the house, dc for the car_), yet I'd presume you can size your dc generator smaller, as you aren't going through the ac/dc conversion loss. Seems logical, even with the added cost/effort.

Thoughts?


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## JRP3 (Mar 7, 2008)

dougingraham said:


> You can shift without a clutch if you pay attention and are not in a hurry.


True if you have a motor with no regen. Regen changes that behavior, you have to time it just right and shift it quickly before regen slows the motor too much. If you take your time you'll be trying to mesh with a motor that isn't turning.


> Add in the 7 oil changes at $30 each and you are up to $3010.


I hope no one is still wasting time and money doing oil changes every 3K miles, there is simply no need, especially when your owners manual usually shows 7K or so.


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## dougingraham (Jul 26, 2011)

sbagdon said:


> If using a dc motor and dc batteries, why not generate dc current with your ICE generator? That way, you aren't using an ac generator, which has to go through the ac/dc conversion to charge the batteries, and can charge directly with a dc charger. It has the added expense/trouble of a second charging circuit (_ac/dc for the house, dc for the car_), yet I'd presume you can size your dc generator smaller, as you aren't going through the ac/dc conversion loss. Seems logical, even with the added cost/effort.
> 
> Thoughts?


Strictly speaking there aren't any DC generators. They all rotate a coil through a magnetic field which alternates voltage as it turns. DC generators have a mechanical method for converting AC to DC which is the brushes and commutator. There are losses in this mechanical system.

With a PFC charger you can just feed the output of the generator directly into the charger and within reasonable limits it doesn't care about the quality of the power. Most of them you can feed DC into and they dont care. There are losses in the AC -> DC conversion but they are less than the losses in the brushes and commutator of a dc generator. This is the reason we have alternators instead of generators under the hoods of our ICE cars. What seems like a very long time ago now we did have DC generators in our ICE vehicles to charge the battery.


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## sbagdon (Nov 11, 2011)

dougingraham said:


> Strictly speaking there aren't any DC generators. They all rotate a coil through a magnetic field which alternates voltage as it turns. DC generators have a mechanical method for converting AC to DC which is the brushes and commutator. There are losses in this mechanical system.
> 
> With a PFC charger you can just feed the output of the generator directly into the charger and within reasonable limits it doesn't care about the quality of the power. Most of them you can feed DC into and they dont care. There are losses in the AC -> DC conversion but they are less than the losses in the brushes and commutator of a dc generator. This is the reason we have alternators instead of generators under the hoods of our ICE cars. What seems like a very long time ago now we did have DC generators in our ICE vehicles to charge the battery.


Thanks for the response! So what I'm hearing is, if you really want to have unlimited extended-range, you might as well go with a normal/traditional ac gen-set, sized accordingly, and feed it into the primary ac charger. As most gensets above 5-6kw are almost always 220v (_or dual 110v_), is it easiest to engineer a solution using a 220vac charger?


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## dougingraham (Jul 26, 2011)

sbagdon said:


> Thanks for the response! So what I'm hearing is, if you really want to have unlimited extended-range, you might as well go with a normal/traditional ac gen-set, sized accordingly, and feed it into the primary ac charger. As most gensets above 5-6kw are almost always 220v (_or dual 110v_), is it easiest to engineer a solution using a 220vac charger?


If you work the numbers it comes out to requiring a least a 30kw genset (about 40hp) to power a small car at 70mph. You can verify by looking at the hybrids and see how big an ICE they have. (Prius is 98hp, Volt is 83 hp.) They need to oversize a little because people do crazy things like drive up long steep grades in the mountains and they expect their car to be able to do it.

A charger with a PFC front end will usually accept 47 to 400hz and 110-240VAC and usually DC at 110 to around 300V even though they don't always say this. It just happens to be a side effect of the power factor correction circuitry. There is an internal DC voltage at the output of the PFC stage of 350-400 volts that then gets bucked down to pack voltage to charge the batteries. This makes them extremely tolerant of crummy power which would be a kind thing to say about some gensets outputs.

A big problem with gensets is they are not very friendly. They don't have pollution controls or good mufflers and usually they have not been tuned all that carefully to get the best efficiency. They are almost certainly going to be worse than the car's original ICE engine in all these areas.


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## jimmo (Jul 8, 2010)

tomofreno said:


> Maybe you are confusing staying above 80% State of Charge (SoC) with 80% Depth of Discharge (DoD)? The general recommendation is discharging them less than 80% of their capacity, 80% DoD, 20% SoC.
> 
> 
> 
> AH, got it now. thanks for clearing it up.


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## jimmo (Jul 8, 2010)

HPEVS is working with Curtis on a new water cooled motor and controller that will be a max 100 HP and have peak torque of 150 ft-lb, and is supposed to be available next year some time. If that fits your time frame it would give you much better acceleration. But of course it depends on how much you want. My car does 0 to 60 mph in 16 seconds, and 0 to 40 mph in 8 seconds, so I can easily pace traffic and keep up with most of the more aggressive drivers off the line, so it works well enough for me. Of course it won't keep up with a more powerful ice powered car if they floor it.[/QUOTE]


Yea, Im not in any hurry. At this point Im am starting my very early homework to absorb as much knowledge about it before deciding which path I want to take. In the meantime Im hoping to see some advances inthe technology. I just dont have the 8000 to throw down on batteries. I am hoping to see cheaper batteries or more efficient motors in the near future.
Now I am in search of a lighter car. I am having 2nd thoughts about the fiero even though I think its the perfect platform for a conversion. Not sure of too many production cars that are much lighter though.


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## JRP3 (Mar 7, 2008)

I would not count on any significant price reductions on batteries in the next two years or so. Hopefully I'm wrong.


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## jimmo (Jul 8, 2010)

nother question.... Is anyone using the heat created by the motor and/or controller to heat the car? is it enough to do that? a 2 seater car does have less cubic feet to heat.


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## JRP3 (Mar 7, 2008)

I've toyed with the idea in mine, might work with milder temps, but I doubt enough heat is available when it actually gets cold.


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