# Max current at 120V??



## rsisson (Feb 5, 2009)

I am still in the planning stages, but something does not quite make sense,,,

There are some controllers out there with some crazy current ratings...

How can you get that much current into an mid-sized EV?
(trucks, sports cars, etc I can understand the need for POWER!)

600A (1 min) at 144volts is 86KW or ~115 Hp
650A (boost) at 144v 93 125hp

yes, yes this doesn't account for voltage sag...

OK...an ICE motor may have more, but that means keeping the pedal to the floor for 1-min... WOW... Floored for a min even a Suzuki swift will be doing 90+.

Ok..The Question...

Assuming a 2400# vehicle and a Warp-9 motor and a 120V Pack(10-12v bats)... what size controller do I need so the CONTROLLER won't be the limiting factor MOST of the time? 

OR... what are people seen in real life for currents both at startup and cruising (40mph and 60mph)

Yes, yes, starting up on a hill, with 3 people and groceries in the car will need LOTS more... I know that from my low-voltage Quad-cycle build... so I start up a bit slower... but it has never taken me a MINUTE to get up to my cruising speed...


Bob


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## Technologic (Jul 20, 2008)

rsisson said:


> I am still in the planning stages, but something does not quite make sense,,,
> 
> There are some controllers out there with some crazy current ratings...
> 
> ...


I'd say a 500amp max controller would be a bit overkill for your appplication, but probably a safety net's worth of capacity.

I've heard that the max a 105v Corvette (old corvette) pulled was 300amps from someone who built one, but don't trust me on that one.

Since torque curves for most DC motors are fairly linear, it's sort of a whole new way to look at "hauling" stuff.

You're going to need a lot less amperage to go from 40mph to 60mph up a steep hill than going 0mph-10mph up the same hill. A LOT less (few orders of magnitude less)

a 115HP continuous EV would be either 6000-8000lbs or a race car.


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## Bowser330 (Jun 15, 2008)

Technologic said:


> I'd say a 500amp max controller would be a bit overkill for your appplication, but probably a safety net's worth of capacity.
> 
> I've heard that the max a 105v Corvette (old corvette) pulled was 300amps from someone who built one, but don't trust me on that one.
> 
> ...


 

About 115hp continuous making a racecar...

Are you saying that If you were to get a controller that could supply 600A continuously at 144V (with V sag accounted for) that you would have enough power to be racecar fast?? with only 115hp???

...Can you explain how this is happens?


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## Qer (May 7, 2008)

Bowser330 said:


> with only 115hp???
> 
> ...Can you explain how this is happens?


You can't compare electric horse powers with ICE-horse powers, it's like you can't really compare a gasoline powered ICE with a diesel powered ICE since they have different behaviour. The reason electric motors can "get away" with less horse powers is because the torque is instant already at 0 RPM and then forms a flat line until the back-EMF starts to limit the current.

That torque curve is simply completely superior to the torque curve than any ICE, thus an EV with some serious oomph will blast away unbelievably fast from a red light.


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## Bowser330 (Jun 15, 2008)

Can you use the formula with electric motors?

HP = (TQ * RPM)/ 5252

115HP = (TQ * 1000RPM)/ 5252

= 604ftlbs Torque @ 1000rpm (motor rpm)


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