# EV Hybrid Race car idea.



## UncleRico (Nov 21, 2015)

Hello, I'm new to the forum. I have some questions, and I'd love to hear what you guys think. 

I have an idea to build a Hybrid EV for performance. The aim would be to use the electric system to augment the power of the Internal combustion engine, but also be used to drive in EV mode only for short distances to the shops so around 10-20miles... 

The base vehicle would be a light front wheel drive (actually a car derived van so plenty of space in the back), with a live driven axle added to the rear to provide essentially 4x4 drive (EV rear ICE front). The plan would be to aid traction off the line, and act a bit like a nitrous system without damaging the engine and smoking the front tyres by making the rears do 100hp work using electricity! 

The vehicle would have a conventional Internal combustion engine producing around 300bhp, and w/o the electric drive weighs around 1300kg / 2860 lbs

I'd want to have at least 100 bhp to make the weight penalty worth while, and I'd like to avoid having lots of batteries (no need right if it only needs to go 10 miles)? 

Questions: 

1) What motor could deliver that power in short bursts - up to 10 sec? 

2) This is my biggest question really.... How could I get the voltage high enough, say 144v @ 550amps without using loads of batteries. (I need high *KW* but not high KWh if you catch my drift ) 

3) Should I go for AC or DC motor? 

4) Could the motor 'freewheel' when not in use? 

5) Can I avoid a gearbox and have direct drive? 

6) Could I use the ICE engine to 'tow' the motor and recharge the batteries. I.e on the way to the drag strip. 

7) Because I'd only want high power for short bursts, could I 'overpower' a small motor to save weight and size?

Road EV mode would need 50hp max. 

The idea is that it would be kind of Jeckyl and Hyde. Smooth, cheap to fuel, fairly low power EV for plodding around in, then fire up the IC engine and hit the drag strip. It's only a weekend toy, not an everyday car/van. 

I'm a mechanical engineer, so I have some background knowledge.


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## arklan (Dec 10, 2012)

headway batteries
one of those 6.7inch adc motors would be the lightest weight option but u could go a warp9
zilla z1k

go direct drive and make it detachable

u only need torque for accelleration not hp so the rpms dont need to be too high..
id want to use a more aerodynamic shape than a van to be honest, the electric addon wont take up a lot of space


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## galderdi (Nov 17, 2015)

Those are all great questions but I think you are aiming for Nirvana. However I wonder with a few tweaks of your requirements maybe there are some opertunities.

Idea 1: You could pick a light weight car with a long hood (like an 240z, 280z). Take out the original ICE and replace with a smaller turbo 4 Cyl. Mount the new motor as far forward as possible then run the output of new ICE into one end of an electric motor and the other end of the electric motor into the gearbox.

Idea 2: You could pick a car where the engine and gearbox are already separated. I think Alpha or Fiat might have examples. Then you could possibly add the electric motor in between the ICE an gearbox. But I don't think you'll see 300HP from one of those motors.

Idea 3: take a small mid or rear engined car (like a toyota MR2). Leave the original motor and gearbox untouched. Mount the electric motor in between the ICE and gearbox without needing to move the ICE or gearbox. Only hassle here would be fitting the electric motor into the transmission tunnel.

With any of these options you would need to significantly upgrade your alternator and the cables etc. You would need to do some calculations to determine ICE run time required to charge the batteries based on alternator size, battery capacity, and capacity used for each race.

My race car (yet untested) is full electric and I wanted to keep the cost low so I have gone with High cranking AGM batteries. 12 x 14Ah which is not much capacity but you don't tend to go far when racing. I estimate I will get about 8 miles range from a charge.


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## ferd (Dec 1, 2015)

Don’t have answers to all of your questions, but I’ll share some related experiences.
2) To obtain the voltage level you’re considering, the number of batteries will depend on each battery’s individual voltage rating – which is true no matter how many amps you intend to draw. Where you save space and weight is in the kWh rating of those batteries. A pack of low kWh batteries can supply the voltage and amps you want, but not for very long. Since you’re intending to drive on public roads for around ten miles you’ll need to calculate the kWh size of your batteries to do that at whatever weight your car (with driver) comes to, then possibly add an engineering “fudge factor”.

4) By “freewheel” I assume your design allows the drivetrain to spin the electric motor’s armature while that motor is not powering the vehicle? If so, you can – but be careful not to allow the drivetrain to spin that armature faster than it is rated. We’ve seen electric motors blown apart just by towing because the vehicle’s rear axle speed, multiplied by the transmission gear, spun the armature too fast. Also realize that if your motor is able to act as a generator (such as, has permanent magnets or has coils with power always applied to them) then the motor will produce some drag. You might use the energy produced to help recharge your batteries, but in a racing situation you might want to uncouple the electric motor so it doesn’t fight against your ICE. Uncoupling it also removes the danger of over-revving the armature when the electric motor is just along for the ride.

5) A gearbox on the electric motor probably won’t help during racing, but can be an asset on public roads – especially if you are purposely minimizing the size of your battery pack.

6) Yes, the ICE can help charge the batteries. But I’m not sure if the added complexity and weight is worth it in a race car – particularly when its road usage is only about ten miles. I’m not sure you’d get enough charging to be worth it.

7) Yes, you can “overpower” a smaller motor. Add a way to cool it and you can get away with doing this (up to a point). Realize that you will shorten the life of this motor, but race vehicles expect to wear and replace drivetrain parts anyway. By the way, if you size your battery pack so that you pretty much deplete it during each race you will also shorten battery life. As with any racing, it’s “how fast can you afford to go?”.


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## dougingraham (Jul 26, 2011)

UncleRico said:


> 2) This is my biggest question really.... How could I get the voltage high enough, say 144v @ 550amps without using loads of batteries. (I need high *KW* but not high KWh if you catch my drift )


The way to do this is to use the Amphaulic packs. They are nominal 22.2 volts 4.5 AH and can do 450 amps for the duration of a drag race. For your purpose I would parallel 3 or maybe 4 and then to get your 144 volts you need 6 in series. This would give you a 1.798 or 2.398 kwh pack. The packs weight about 2 lbs each so 18 would weigh 36 lbs and 24 weighs 48 lbs. With a 3500 lb vehicle expect this to give 5 or 7 miles. You can always parallel more packs and go to a higher voltage by going to 7 or more packs in series to increase the range.


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