# New/First EV project



## mistareno (Jul 15, 2014)

G'day,

I'm about to embark on an EV build. I'm a mechanic by trade so feel pretty confident with the Mechanical side of things, less so with the electric side of things.

We have a fairly new family car so I was going to convert a tray style truck that can be used both for commuter and practical purposes.

I do have a fairly long commute of 50k each way.

The vehicle I have been looking at is a Mazda E2000 tray.

They are actrually pretty light when they don't have a steel tray or box on the back. I believe they have a kerb weight around 1000kg and that's with a cast iron engine and rather heavy gearbox.

They have a ladder chassis from front to back of the car so I was going to mount the batteries between the rails so they are low down.

I was going to make a thin long tray that is the width and shape of the cab body.

I know this outline has been floating around for a while and I was going to try and duplicate the rear section.










Something like this (but with some fairings around the front wheels and with the dumbo ear mirrors removed) -










I was going to use semi flexible solar panels for the top panel of the teardrop rear cover, because they are not much heavier than plain aluminium sheet and because it needs to be covered anyway, so it's not adding weight. I should be able to fit 500W of panels on the top which should trickle a little into the battery while parked for 10 hours in the sun.

The side would probably be clad in alumlite over a light frame to keep weight down. I was going to have the teardrop roof bit on hinges at the front, so I can lift it up and prop it in an 'up' position to fit larger objects on the tray if needed.

I'm happy with top speed of 100 - 120km/h or so so I was going to go direct drive with a NetGain Warp 11 DC motor to keep the weight down.

The other option is a HPEVS AC-51 but I'm not sure how that would go with Direct Drive. 

I was thinking of making it a lead sled to start off with while I get it running and then swap to LifePo4's down the track.

I could easily fit 12 220AH 12V batteries between the rails (starting a foot or so from the front bumper) for a cheap 144V system to get it going.

Is there a technical reason why people stick with 8 or 6 Volt cells?

Would 144V/220AH of Lead get me a range of 120K without to much DOD?

Could I use an AC-51 for direct drive if I got a short enough final drive ratio?


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## Jan (Oct 5, 2009)

mistareno said:


> Would 144V/220AH of Lead get me a range of 120K without to much DOD?



Unlikely. With SAG, Peukert and a DOD that will not kill them instantly, there is not that much usable energy. The wheigt, frontal area and its frontal shape, will need a lot at 100-120km/h. My guess is 80-90 km range at the most. More likely 60. I would only use lead, to proof the concept. And upgrade to lithium to make it usable. If the concept fails, your losses are less worse.


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## Yabert (Feb 7, 2010)

Hi
Don't worry too much about electrical side of things... if you learn easily, you are at the good place to do a good conversion.

With the AC-51 you'll cried to your mom with the tiny 110-140 lbs-ft of torque available.
I suggest to you to use a Warp 9 (or modified forklift motor) with a 1000 A controller to go direct drive.
The 230-270 lbs-ft of torque from this system will give you good acceleration and after, considering your efficient vehicle, the Warp 9 will easily push this "lightweight" truck at cruising speed.
I suggest you W9 over W11 because the first one can spin faster (useful for direct drive), cost less, weight less and will give you plenty of torque and continuous power for your application*.

*Except if you have a lot of long hill to climb in your area!


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## rwaudio (May 22, 2008)

Yabert said:


> Hi
> Don't worry too much about electrical side of things... if you learn easily, you are at the good place to do a good conversion.
> 
> With the AC-51 you'll cried to your mom with the tiny 110-140 lbs-ft of torque available.
> ...


I agree with Yabert on the choice of a Warp9 for such a light vehicle (assuming no crazy hills as he mentioned) but just point out you will need some very good forced air cooling on the motor. With direct drive you may spend a lot of time at low RPM where the motor won't cool itself enough with the built in fan. Also very important is the gearing, choose wisely, or better yet have something that you can swap ratio's as that would make or break this project.


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## dougingraham (Jul 26, 2011)

Converting a vehicle is a big enough project that you want to simplify it as much as possible to ensure success. To this end I would suggest you save the aero modifications to the body as one of the last things you do. If you do most of your driving in town they won't do anything significant for you. Aero starts to matter at speeds of around 60 kph. Below that and rolling resistance is far more important. Besides this way you can discover if your aero mods were worth doing because you can do a before and after comparison.

Keep us updated and best wishes!


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## mistareno (Jul 15, 2014)

Yabert said:


> Hi
> I suggest to you to use a Warp 9 (or modified forklift motor) with a 1000 A controller to go direct drive.
> The 230-270 lbs-ft of torque from this system will give you good acceleration and after, considering your efficient vehicle, the Warp 9 will easily push this "lightweight" truck at cruising speed.


What system voltage would you go with. NetGain only have 72V data on their site but the retailer says it's rated to 192V.

I was going for 144V as that's what is Netgain Sales Sheet says re continuous power.


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## Duncan (Dec 8, 2008)

Hi
Your motor does not "see" system voltage,
The controller adjusts the motor voltage to achieve the desired current (throttle position)

It does this by a magic power in = power out

So 1000amps (motor) x 15v (motor) = 15000watts = 150v (battery) x 100amps (battery)

So don't worrry about system voltage go as high as your controller can go


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## dougingraham (Jul 26, 2011)

mistareno said:


> What system voltage would you go with. NetGain only have 72V data on their site but the retailer says it's rated to 192V.
> 
> I was going for 144V as that's what is Netgain Sales Sheet says re continuous power.


As high as your controller will let you go. For example a Soliton can do up to 340 volts on the battery. Set the motor voltage to 172 if you want to be conservative. The higher voltage on the motor will increase the RPM where the motor holds full torque. You can use smaller batteries and set the battery limits to match the batteries and still get full motor current if you do this. A reasonable pack would be 94 cells of 60 AH. This would be an 18 kwh pack with a nominal voltage of 300 and a battery current limit of 600 amps (10C). At 172 motor volts and 1000 motor amps you are consuming 172kw from the battery. This would be 573 battery amps at 300 battery volts (230 HP into the motor). If you set the motor limit to 192 volts it will taper off the current so the battery never goes over 600 amps. At 300 volts and 600 amps the controller would only deliver 937 amps to the motor (241 HP into the motor).

These are peak currents battery and the time spent there will usually be a couple of seconds right before you shift. You could only hold this in your highest gear at felony speeds. If you are going for speed records you would want a different battery arrangement.


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## Yabert (Feb 7, 2010)

The above advices are good and I'm interested to add than if you select a controller with a voltage input < 200V, still go with the maximum voltage this one can take instead of sticking at 144v (45 lifepo4 cells in series)

As exemple: With 175v of maximum input battery voltage (like Zilla LV or Zeva MC1000C), go with 48 to 50 cells in series instead of 45 to have higher peak power.


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## mistareno (Jul 15, 2014)

I had a look at other vehicles of a similar size and there is a Kia k2700 cab chassis that might be alot better from an aero point of view.

It's far more rounded at the front, both from the side and when viewed in plan with far better transition into the roof.

It's probably as close as I can get to the 'ideal' outline.

It's also newer and probably safer.

A little more expensive than the older Mazda, but not a great deal more. 

I'm having trouble finding how much they weigh as they all have a rather solid steel tray with side gates fitted from factory. I'd imagine that would add to the weight quite a bit. I don't think they'd weigh much more than the Mazda.



















It also has a lift up nose section that could house the charger cords and charge point etc which keeps it neat and tidy I suppose.


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## piotrsko (Dec 9, 2007)

Don't focus on the weight so much. it's only when you're accelerating, climbing hills or descending hills the weight actually makes any problem. Steady state is mostly aerodynamics, especially above 35 mph


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