# Controller Question



## e_canuck (May 8, 2008)

michieb34 said:


> Hello, ive searched for the answer to my question for a while and am unable to find it, thats why i joined DIY electric car. My question is can you hook up a controller in series or parallel with a twin controller (ie the exact same controller) to increase either the voltage or the amps the controller can handle? It would be very similar in the idea of hooking up several batteries in series or parallel to increase their output. Thanks


Hi michieb34.

Welcome to the forum.

I do not think it is possible to do that.

The way I understand controler they pulse the power from the battery pack. Did you ever had race cars as a kid?

Remember when you would push the button just a little the car would not move. It would buzz. And as you push slowly it would leap sudently. Well if you did that for a long while the motor would burn.

Thats because the voltage was to low for the motor to be strong enough to actually move the car.

The controler we use do not reduce the voltage like that. They reduce the time the voltage is aplyed. At 10% the voltage is full for 10 % of the time. At 50 % the voltage is full 50 % of the time.

That way we can run the motor slowly and have a lot of torque ( power ). And have a cooler motor.

If you had two controler at the same time I don't see how you would match exactly the frequency ( electronic varies slightly between unit ) and match when power is sent to the motor. They just aren't meant to be in pair.

So buying to smaller unit will not replace the one you need.

Sorry. Maybe someone will have a different opinion on the subject.

What would you like to convert? What is you project?

Take care,

DP


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## michieb34 (Nov 14, 2008)

Hey DP,
Well currently a buddy and i are trying to build up a fast acceleration ev which we would like to eventually to turn it into a drag ev, so that said we are going to be running very high amps to be able to power a large motor like we are planning, and that is where the initial question came up is because we need a large and powerful controller so we will not fry it immediately, and since zilla has stopped producing their controllers we are pretty much, out of luck. Are there any controllers out there that even come close to the zillas? Ive seen logisystem has an 800amp one but thats about as close as ive seen


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## e_canuck (May 8, 2008)

Hi again.

Cool project, fun, costly.

I don't think anybody is close to what Zilla did. But that would be for tother to say. Once I chose my controler I pretty much stop researching the subject. I went were others have gone before with the Curtis. I have not even used it yet.

You might have to build your own. Ask around, some of the wizards ( Tech-Heads ) on this very forum are building or designign their own as we speak.

Take care,

DP


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## kek_63 (Apr 20, 2008)

The first successful EV dragracers didn't use any controllers. If you have a big enough motor, or better yet, two (for parallel/series shift), all you need is contactors that can handle the amps and a switch under the "gas" pedal. This of course, is assuming that you don't also want to drive on the street

Good luck with the project,
Keith


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## Qer (May 7, 2008)

michieb34 said:


> My question is can you hook up a controller in series or parallel with a twin controller (ie the exact same controller) to increase either the voltage or the amps the controller can handle?


Short answer: No way in hell.

Long answer: To use multiple drivers (IGBT's or MOSFET's) in parallel they have to be well synchronized. And with well synchronized I mean _WELL_ synchronized. We're talking microseconds. Synchronizing two, or more, modules within the same controller at those powers demands some skill (the Zilla had, for example, hand matched IGBT-modules for perfect synchronization), synchronizing two entirely different controllers that weren't meant for it to begin with is probably stuff for a new episode of Mission Impossible (if it'd be the original series it would take place in the former Soviet Union and the controller would have a label saying Cüntröllär ).

I'd say pick a Curtis or something known to be bomb proof to use for driving to the start point, then disengage the controller with a contactor and have a parallel contactor that SLAMS the full pack power directly into the motor without the losses or limitations of some puny silicon that'll only be in the way for the current. If you need to limit the power to not burn up all the rubber at once, use two contactors that first feeds parts of the pack (just drop off a separate feed from the pack at, say, 70% of top voltage) and then, when the car is moving, slams in the rest of the pack too.

So quite frankly, you don't need a controller (except for transportation). The whole point with a controller is to maximize range by even out the load equally over the batteries, if batteries were virtually an infinite source of power you wouldn't need the controller. Just pick out the voltage you need at the moment with a switch. There's even some guy that posted pictures of his first "controller" that just were a lever made of some wooden board and some bolts that were labeled "12 Volt", "24 Volt", "36 Volt" etc. However, I'd guess that for street racing purposes such a "controller" might arc, melt and maybe even catch fire...


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