36 volt versus 42 volt set up?

[JohnnieB]

Originally Posted by 93yellowclubcar

Is there any reason not to go 48 volt with sepex? Never owned one, just curious.

Exceeding the Max RPM recommended for the motor is the reason.

With my set-up up I'd be spinning my motor at about 7,500RPM at 48V and according to one engineer at D&D 6,000RPM is max while another engineer at D&D says 6,500RPM is max for my motor.

At 42V on 18.3" tires with 12.44:1 gears, it's turning almost 6,500RPM.

Taller tires and/or longer gears require more torque to turn, so the motor will not reach as high of an RPM at 42V, therefore 48V may be safe to use.

You might run into the Max RPM issue with a series motor at 48V if the cart had stock height tires and a motor that was wound for high speed.

Originally Posted by scottyb

Johnnie could probably expound on this but the Sepex motor is more efficient and actually requires less voltage/amperage than a series motor for a given task. My 42v PDS out performs my 48v series Ezgo.

A series motor can be wound for high torque at the low end, or high speed, or something in between the two. A stock series cart motor is in between the two. Each winding type has a sweet spot for maximum efficiency.

A sepex motor can also be wound for low end torque, or high speed or middle ground, however the Armature and Stator (Field) can be excited separately, so the torque curve (Torque vs RPM) can be altered on the fly (Field Mapping) for better efficiency under the load conditions that exist at the time.

Originally Posted by bxlt

But that is for a PDS correct? If it is DCS a 42v conversion won't be as impressive as it would be on a PDS cart from what I've seen on this forum.

A stock DCS motor leans towards being a low end torque motor while a stock PDS motor is wound in the middle ground or may leaning a bit towards the speed end. That is why a DCS with a DCX400 is a torque monster while a PDS with a DCX400 is a speed demon. They use different field maps also.

Both a DCS and a PDS are quick and powerful at 42V. A DCS has more low end torque than a PDS, but not as high of a top speed.

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Ironically, Vic at D&D thinks there is something weird with my set-up because an ES-76-51 shouldn't spin as fast as mine does at 42V.

I'll be adding some instrumentation to get empirical data instead of inferred data for him. (IE: Connecting a tachometer to motor sensor, current shunts in Field and Armature cables, voltmeter on controller's B+ and B- terminals, Etc.)

One of the things I've already discovered is that my tire height may be shorter than what I thought. I've been using the MTD height published by Carlisle (18.3"), which would have a circumference of ~57.5" and I wrapped a tape measure around one of the rear tires when I had the back end jacked up to inspect the differential gears last weekend. I only got 56.675", which is just a whisper over 18" (18.04), so my motor may be spinning about 1.4% fast than I thought.

To get a highly accurate tire circumference, I'm going the mark the side of the tire and the ground, drive the cart for ten tire revolutions and mark the ground when the mark on the tire is at bottom, then measure between the two marks on the ground and divide by 10. Then do the other side and use the average of the two if there is a difference. That ought to be close enough.

[derkdaigler]

Ive started looking at my cart and pulling some stuff apart. Im thinking according to the link above this is a series cart. I plan on just runnin around my neighborhood poundin pavement cruising no offroading zippin around lol

[derkdaigler]

I believe i have a series cart i may have replied this in a wrong thread a moment ago lol i plan on just poundin pavement zippin around no offroading to speak of

[derkdaigler]

And johnie b i appreciate your reply! No i just gotta take some asprin lol thats one deep rabbit hole brother!

[bxlt]

That is a series cart but I am confused by the Club Car motor as the picture in the start of this thread was an EZ-GO and I thought that the two axles are different and you couldn't run a CC motor on and EZ-GO

[93yellowclubcar]

Looks like someone put a CC rear end and motor in that EZGO.

[scottyb]

Originally Posted by 93yellowclubcar

Looks like someone put a CC rear end and motor in that EZGO.

Yup!

[derkdaigler]

Oh hell.... i was thinking that there shouldnt be a club car rear end and motor... ****

[93yellowclubcar]

It isn't necessarily a bad thing, as long as you don't mind it running better than an EZGO.

Kidding aside, that swap shouldn't be an issue as long as whoever did it fabbed it up fairly solidly. Good functioning Club Car brakes are better than good functioning EZGO brakes anyhow. I personally run that same motor on 48 volts in a cart that belongs to my cousin and on stock tires, cables, and controller it pulls 18ish MPH with real good torque.

[scottyb]

Half Ezgo half Club Car ....... all the other golf carts are gonna make fun of it