# Controller Suggestion



## EVfun (Mar 14, 2010)

The most bang for the buck, if you keep the system at 98 volts, is a Zilla Z1k-LV. It can dish out up to 1000 amps -- can your battery pack take that kind of pounding? If you raise the pack voltage you can get more power out of a Soliton Jr. Its limited to 600 amps but can be cranked up to 340 volts, while the -LV Zilla controllers are limited to 156 volts. Both of these controller run about $2000. In many applications these 2 controller will deliver about the same amount of power because of limited pack voltage and the current limits of the pack. 

You can always run another Curtis for less, but it may fail in time too. It is best to keep the motor rpm up-up-up if you run a Curtis. Low rpm operation is one of the quickest ways to kill them.


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## major (Apr 4, 2008)

monkmonkey said:


> I have a 1980 Lectric Leopard with a 98v system. The Curtis controller went out, so I would like some suggestions for another controller. I want the best bang for the buck. Thanks


Does it have the original motor? Which was the Prestolite 7.2" dia. MTA-4001.


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## dladd (Jun 1, 2011)

what kind of battery current can you carry? How about motor current? Those are pretty important parts of the equation here, no point in getting a 1000a controller if you are limited to 300 battery and/or 500 motor amps by your batteries and/or motor.


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## monkmonkey (Mar 23, 2012)

dladd said:


> what kind of battery current can you carry? How about motor current? Those are pretty important parts of the equation here, no point in getting a 1000a controller if you are limited to 300 battery and/or 500 motor amps by your batteries and/or motor.


I'm really not sure. How can I tell. I'm an ev newbie.


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## monkmonkey (Mar 23, 2012)

major said:


> Does it have the original motor? Which was the Prestolite 7.2" dia. MTA-4001.


Yes it is the original


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## monkmonkey (Mar 23, 2012)

Anyone here rebuild mine?


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## PhantomPholly (Aug 20, 2008)

Nice thing about going with a higher voltage controller would be if you hope someday to improve performance with a better motor. Generally speaking, a set of wires can carry nearly the same amp rating if you up the voltage giving you more watts across the same wires.

I'm sure someone will chime in on the limitations of that theory, but I know that it is approximately true because the whole reason airplanes use 24v rather than 6v is to allow more watts with the same wires.


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## dladd (Jun 1, 2011)

I'm a newbie too, but am learning quickly! A good start would be to post up exactly what batteries you have, and whether you have future plans of doing any battery upgrades. And which Curtis controller you currently have. Others may know more specifically how much current the 7" motor could handle.

If you were happy with the performance, you could certainly replace with another Curtis. Maybe find a used one if you are up for taking a bit of a risk?

However, the newer controllers are SOOO much easier to use, being computer programmable. I love that I can enter max and min voltage limits, separate motor and battery current limits, RPM limits, etc.

I'd personally go with the Soliton Jr. or Synkromotive, since they can both be run air cooled at lower power levels (simple is good, right?). The Synkro has a little more motor current avaliable, but I think both will be able to put out more than you have now. The Jr. has more power, but it's only avaliable via higher voltage which you don't have (at least at this point in time). Both will be around $2k and probably require you to buy a new throttle box. If you already have a contactor in place, that will save a few bucks with the Synkro (it's built in on the Jr., but not on the Synkro).


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## major (Apr 4, 2008)

monkmonkey said:


> major said:
> 
> 
> > Does it have the original motor? Which was the Prestolite 7.2" dia. MTA-4001.
> ...


Hi mon,

I think there was only one motor used in those Letric Leopards. It was a Prestolite MTA design similar to the MTC which EVfun uses in his buggy, except the MTA has a 5" core whereas MTC is a 7" long core. Both are good motors and use the same size comm and brushes so are rated for similar current. The shorter core means the MTA will be about 40% faster for a given current at a given voltage with less torque compared to MTC. 

The MTC was originally made as a 96V motor. And MTA was a 48V motor designed specifically for Waterman (Lectric Leopard). From what you say someone has altered your Leopard to 98V and different controller. I think originally they had resistor/battery switching/ transmission shifting speed control instead of PWM. Apparently it was working at 98V....until the Curtis failed.

The MTC motor is series wound and therefore the field doesn't care what voltage is applied to the motor. The MTA is compound wound and has both a series and shunt field. The series field in the MTA is insensitive to applied voltage, but the shunt field is. At higher than design voltage it will draw more current and can overheat depending on time or duty cycle.

You have members here recommending higher voltage controllers. This can be done, but beware applying too high a voltage to the motor. It may be easy to overheat the shunt coils and also watch overspeed. I also see talk of increased current limit. This may present difficulty for the compound motor to commutate with high current and low shunt field voltage.

Regards,

major


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## monkmonkey (Mar 23, 2012)

Thank you for the very thorough explanation.


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## dladd (Jun 1, 2011)

major said:


> You have members here recommending higher voltage controllers. This can be done, but beware applying too high a voltage to the motor. It may be easy to overheat the shunt coils and also watch overspeed. I also see talk of increased current limit. This may present difficulty for the compound motor to commutate with high current and low shunt field voltage.
> 
> Regards,
> 
> major


but just having a higher voltage controller doesn't mean you area applying more voltage to the motor, right? You could theoretically have a 340v battery pack with a Soliton Jr. and limit the motor voltage to 96v if you wanted. That's the beauty of the programmable controllers. Same with current. Just because the controller CAN do it doesn't mean you must let it. At least that's my meager understanding...

or of course you could just buy a replacement Curtis, plug it in and be done.  But I think the cost difference between a new Curtis and the others is pretty close, it's a no brainer to me to go for the upgrade.


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## major (Apr 4, 2008)

dladd said:


> but just having a higher voltage controller doesn't mean you area applying more voltage to the motor, right? You could theoretically have a 340v battery pack with a Soliton Jr. and limit the motor voltage to 96v if you wanted. That's the beauty of the programmable controllers. Same with current. Just because the controller CAN do it doesn't mean you must let it.


Yep, that was my point.

But on the other hand, what sense is there in running a 300V battery if you limit it to 100V for the motor? That is an awful lot more cells to manage and more expensive contactors, fuses and charger. 

But this is DIY, so decide for your own self how you want your system  I'm just relating some facts which I know about that motor 

major


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## dladd (Jun 1, 2011)

i'm certainly not suggesting running a 300v pack at 96 volts, just saying that with a modern day controller you COULD do that.

Obviously I think the Synkromotive is a good controller, that's why I have one in my car! But I know the Jr. is a good controller too. Just because it is rated up to 340v doesn't mean it would not function well at 96v (which is what it sounded to me like Major was warning about).


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## Qer (May 7, 2008)

dladd said:


> But I know the Jr. is a good controller too. Just because it is rated up to 340v doesn't mean it would not function well at 96v (which is what it sounded to me like Major was warning about).


I think the limit is 9 or 10 Volt (don't remember directly what we decided at in the end) and the reason for that is that we wanted people to be able to test the controller with a single 12 Volt lead-acid battery.

It's not really practical to run it on only one battery since sag will limit the current almost instantly, but you could definitely run it on somewhere around 20 Volts or so in the pack, for example by using two 12 Volt lead-acid batteries to be able to get the car up on a trailer or something...

96 Volt is definitely fine.


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