Shoutout to ScottyB! New Controller and loving this cart!

[TahoeDawgZ71]

Originally Posted by scottyb

I want some popcorn too!

[scottyb]

Originally Posted by TahoeDawgZ71

I want some popcorn too!

I'll hold the tub. You reach in and get some. That way you can keep waving the flag

[TahoeDawgZ71]

Originally Posted by scottyb

I'll hold the tub. You reach in and get some. That way you can keep waving the flag

Sounds like a plan.

[fishbooz]

Originally Posted by greg-g

This is an interesting set of posts, Sergio posted the field map of a stock motor and it clearly shows the stock motor is a 250 amp motor with diminishing results above these limits, So how can it pull more amps unless in a stall condition without negative results.

The motor rides the line on the field map going higher amperage when needed and lower amperage when at full speed. Now unless the programmed field maps are not the same there should be little if any difference in performance.

Maybe Sergio can explain how this motor can use 500 or 600 amps when its designed for 250.

Lets take a series resistor cart where the last speed is straight to the batteries can it pull limited current! or only what it is rated at ??

How exactly does a posi-track rear end work in a Plymouth ? it just does

[jakesnake27]

Where is the like button for this thread...

[SilverWolf]

Sergio

I remember those Student Days… The problem with Right Hand Rules and Left Hand Rules is that there were too many Mondays that we were unable to distinguish our Right from our Left…

Regarding your 400 Amp comment, you are correct. I pulled up some of our data and for a moderate off –road Drive Cycle; even the peaks generally stay below 400 Amps.

The reason our new Controllers are rated at 600 Amps requires a little explanation. Our Controller technology originates in the Materials Handling Industry. In this Industry, the metrics are Efficiency and Reliability. With Tow Motors, you want them to run for a long time and you want them to run every time. We simply don’t encounter people who lift their Tow Motors, install fancy wheels and race them around the plant.

We initially built 500 Amp controllers for Golf Cars because we couldn’t imagine anyone needing more than this. A few years later, some of our OEM customers started asking for more current to get over that hump or out of that ditch. Since then we have verified that they are in fact correct. Sometimes you need that extra 100 Amps to power up a levee or out of a 6-foot drainage ditch. (Of course you could go up on an angle, but that creates a rollover danger.)

In summary… The reason you want to put a more powerful aftermarket controller on your car is to deal with the transients (acceleration and climbing). From a steady state point of view, it is unlikely that your car will draw more than an average of 100 Amps. In fact, it is usually closer to 50 Amps, well within stock controller territory.

As far as motors are concerned, even the most robust aftermarket motors are not designed to accept much more than 120 Amps of continuous current. But they will all accept 100’s of Amps of peak current (even stock motors). As long as things are not saturated, more current means more torque. But remember, as you reduce the field current and/or move outside of the motor’s range of peak efficiency, it becomes more of a space heater than a motor (you get fewer Foot-Pounds per Amp).

At the end of the day, it’s this heat not the torque that is the death of the motor. It melts commutators and toasts armatures.

Ok, so how do we deal with it?... We monitor the energy that we are dumping into the motor. As soon as we believe the motor is getting too hot, we fold back and notify the operator (they have the option to override this). Secondly we do variable field mapping. The algorithm is somewhat controlled by the OTF programmer. The driver gets to decide if he wants to run “hot and fast” or “cool and far”.

To your question regarding “highest sustained current needed”… Most modern Controllers run Cool (efficiently) so battery current gives you a pretty good idea of what’s going on. We recommend the “poor man’s data logger.” Buy or borrow a DC Amp probe (eg. Fluke i410) and a Multimeter capable of calculating peak and time averaged values. Clamp the probe on to any of the battery cables and go find the steepest ditch/hill that you’d like to climb. Once you see how much current is being used, you can decide how much “head room” you’d like to accommodate larger loads or steeper inclines.

It is important to remember that a vehicle demands a certain amount of torque from the motor to perform a function. Then the motor demands as much current as it needs to provide that torque.

The advantage or our Controller/OTF is that the Controller can re-tune the motor in real time so that it needs fewer amps/ft-lb depending on operating conditions. Since we do not have to make the compromises associated with a fixed operating point, our 600A Controller can provide better range than a stock OEM 250A unit as well twice the Torque when required.

Hopefully this is helpful…

[bakerm07]

Like I said earlier, wasn't talking down the Madjax controller. I'm sure many people have enjoyed the Madjax Controller! Just wasn't for me, and thats okay. If there were one controller or one golf cart that worked for everyone, there wouldn't be any need for multiple companies!

[Sergio]

SilverWolf,

Thank You for taking the time to write a very informative post.

In retrospect, I should have qualified my opinion about the controller max amps as being based on my typical driving conditions which are pavement and stock size tires around hills.

Although Sepex motors are my second favorite motor, AC being at the top, I would not think it is the best choice if your driving requires a lot of steep climbing. The old and inefficient Series Motor is better suited to those tough and harsh conditions.

I say this because as the Motor gets hot , the Field coil on a Sepex motor can increase its resistance by a great amount, which prevents it from drawing enough current to create a strong flux needed during prolonged stressful (torque) conditions. It seems that can lead to increase armature current to maintain the torque and even more heat generated by the motor.

I am glad to know that you guys actually have a thermal management and/or warning system to let the driver know they may be operating in that zone, so I would feel better knowing that I can push my cart hard a few times and the controller would let me know when to back off.

Thanks again, the information You posted has been very helpful.

[AWandKW]

The knowledge level this forum has is absolutely incredible.
I
Love
It

[Budule]

Originally Posted by AWandKW

The knowledge level this forum has is absolutely incredible.
I
Love
It

I agree , before I found this site I would just "wing it" and follow the smoke...