Go big or go a little?

[DaveTM]

------^^^^^^^^-------Yeah....what he said....He just beat me to the punch----^^^^

(Like I would know any of that stuff off the top of my head!!)

[Lehman_GT]

JohnnieB

So if I am understanding you correctly, I can go ahead and do the following:
- 48V (6/8v batteries)
- XCT500PDS Controller (tuned down to 400A and set the max speed down for now while still running the stock motor)
- H/D Solenoid

Run that setup for a while until I decide to swap the motor to the 48V FSIP speed motor?
Then tune it all back up to get the full effect?

[Sir Nuke]

Originally Posted by Lehman_GT

JohnnieB

So if I am understanding you correctly, I can go ahead and do the following:
- 48V (6/8v batteries)
- XCT500PDS Controller (tuned down to 400A and set the max speed down for now while still running the stock motor)
- H/D Solenoid

Run that setup for a while until I decide to swap the motor to the 48V FSIP speed motor?
Then tune it all back up to get the full effect?

BINGO.....that's what he said, you understand CORRECTLY.

[JohnnieB]

Originally Posted by Lehman_GT

JohnnieB

So if I am understanding you correctly, I can go ahead and do the following:
- 48V (6/8v batteries)
- XCT500PDS Controller (tuned down to 400A and set the max speed down for now while still running the stock motor)
- H/D Solenoid

Run that setup for a while until I decide to swap the motor to the 48V FSIP speed motor?
Then tune it all back up to get the full effect?

Your understanding is correct, more or less.

Turning the XCT48500-PDS down to 400A for a stock 36V PDS motor is correct, but setting the speed limit (max motor RPM) applies to all motors, stock and aftermarket.

Unless specifically stated otherwise by the motor manufacturer, I believe the armatures of most motors are constructed strongly enough and balanced well enough to tolerate a steady diet of 6500RPM, which is 28.0MPH on 18" tall tires and 29.5MPH on 19" tall tires.

I'm not sure if the 48V FSIP hi-speed motor is your best choice since the 36V FSIP hi-speed motor will safely run at 48V and will reach 6500RPM on 18" tires while the 48V version might not.

The FSIP brochure (Attached) shows the 36V HS motor has 20% less than stock torque, but that is at 36V and by running it at 48V the torque is increased by 33%, so the net increase is 13% over the stock PDS motor.

Of course it depends on how you want the cart to perform on the golf course and either motor will be an improvement over a stock PDS motor.

Be sure to get a field map for the XCT that matches the motor you are running.

[Lehman_GT]

Just trying to ask all the questions and cover all the bases here since I'm new to the group and this will be my first time altering a cart. I just want to make sure I get it right. So i really appreciate all the input.

So it would be fine to run the 36V FSIP hi-speed motor on 48V battery pack? And get better performance vs running the 48V FSIP hi-speed motor?

What settings need to be changed to run the 36V FSIP speed motor on 48v battery pack?

What about (for now) running the Stock PDS motor and switching to 48V battery pack? Or is that a bad idea entirely?

When all is said and done, The performance id like to see from the cart is quick, steady accelleration (but not whiplash). And speeds in the mid to upper 20's while being on the cart path and fairways.

I really don't need an absolute powerhouse since it is only used for playing golf but it would be fun to play golf faster and out run all the other carts in the process :)

[JohnnieB]

Originally Posted by Lehman_GT

Just trying to ask all the questions and cover all the bases here since I'm new to the group and this will be my first time altering a cart. I just want to make sure I get it right. So i really appreciate all the input.

1. So it would be fine to run the 36V FSIP hi-speed motor on 48V battery pack? And get better performance vs running the 48V FSIP hi-speed motor?

2. What settings need to be changed to run the 36V FSIP speed motor on 48v battery pack?

3. What about (for now) running the Stock PDS motor and switching to 48V battery pack? Or is that a bad idea entirely?

4. When all is said and done, The performance id like to see from the cart is quick, steady accelleration (but not whiplash). And speeds in the mid to upper 20's while being on the cart path and fairways.

5. I really don't need an absolute powerhouse since it is only used for playing golf but it would be fun to play golf faster and out run all the other carts in the process :)

It is always better to ask question up front than discover the answers after the fact.

1. DC traction motors, like those used in golf carts, operate over a wide range of voltages and 48V is within the operating range of most motors that are rated at 36V. The key wording is "rated at 36V" and many motors are rated at more than one voltage. If you can find a good picture of a FSIP high-speed motor, the voltage box on the label appears to say "36/48".

2. Other than having the correct field map installed in the XCT, the other settings would be about the same. Maybe some tweaking on the throttle settings to domesticate it for golf course use, but that applies to any motor.

3. Heat is what kills motors and as long as you stick to relatively stock height (18" tall) tires, you may be so satisfied with the performance of the stock PDS motor running at 48V that you'll not replace it. Just set the max battery amps and max motor amps to 400A and enjoy.

4. The XCT has up to three user profiles that can be programmed for different top speeds , acceleration rates and other performance factors. You can set one to spin the tires on dry pavement and another that won't spin the tires on wet grass.

5. PDS carts do make nice "sleepers".

[Lehman_GT]

Ok, last questions I have for now then

Which motor of the 2 (FSIP SPEED 36V & 48V) would you recommend if i do decide to go ahead and switch the motor out from the Stock 36V PDS?

I would much rather tune something down than be maxed out and have no room to tweak up performance if that makes any difference.

I'm sure there is already a post about this but what is a Field Map? And how do i know what field map I need?

So my purchase list is looking like:
- XCT48500 PDS Controller
- H/D Solenoid
- 6/8v T-875 Batteries
- FSIP Speed Motor 36v or 48v

Do I need anything else? or is there anything else I should add?

[JohnnieB]

Personally, I'd go with the 36V motor, run it on 48V, limit the RPMs to whatever FSIP recommended as max or lower if that was too fast and tweak the throttle Rate, Throttle linearity, Throttle Speed and Throttle Torque curves to my driving preferences.

We share the overkill is underrated philosophy. Design and build for about 125% of the desired performance and use at about 80% of max, which ups the longevity factor considerably.

Field maps. Like a series wound motor, the sepex (separately excited) motors like those in a PDS, are wound to be hi-speed/lo-torque or hi-torque/lo-speed by the number of turns of wire in the field (aka stator) and armature windings that are put on at the factory. The field windings and the armature windings of a series motor are connected in series (hence the name), so the same number of amps flow through each and whether the motor was wound for torque or for speed is predetermined at the factory and is cast in stone. Unlike the series motor, the field windings in a sepex motor are powered (excited) by a different power source and by increasing or reducing the amp flow through the field windings, the motor speed/torque characteristics can be altered during operation. In other words, the low end torque of a FSIP Hi-Speed motor can be increased by increasing the number of amps flowing through the field windings. Conversely, the max RPM reached for a given applied voltage can be increased by reducing the amp flow through the field windings. This process is known as field mapping and the field maps that is loaded in the sepex controller has to match the motor being controlled by it or bad things can happen, the least of which is poor performance and the worst is a burnt out motor and possibly the controller also.

An example of field mapping with the motor I'm running is it produces 10ft/lb of torque at about 4,450RPM while the armature is drawing about 190A when the field is at 3A (74% efficient) and when the field amps is upped to 10A, it produces 10ft/lb of torque at about 3,150RPM and the armature draws about 115A (82% efficient).

-------
You will most likely go with six 8V batteries to get 48V and the posts on an 8V batteries are both on the same side, so the interconnecting cables have to be longer.

The standard 36V battery pack uses 225AH 6V batteries and to get the same range (runtime on single charge) you'll need at least 170AH 8V batteries. The t-875 are 170AH, for longer range go to T-890 (190AH) or Ranger 160 (204AH).

[Brob1969]

Originally Posted by JohnnieB

The stock PDS motor has a couple upgrade issues.
1. Heat issue. It can't handle a steady diet of more than 400A for very long, so turn down controllers with greater than 400A throughput.

Tall tires, hi-speed gears, hilly terrain, jackrabbit starts, heavy loads and towing stuff all shorten its life.

Since it is more efficient at higher voltages, it runs cooler at higher battery pack voltages than it does at 36V. In a nutshell, 400A at 36V is 14.4kW while 14.4kW at 48V is 300A and heat is generated by the square of the amps flowing through the resistance (I²R=W), so the 25% fewer amps to do the same amount of work generates far more than 25% less heat.

2. Max RPM is determined by applied voltage. On level pavement with stock height (18") tires a stock PDS motor will spin about 5600RPM when power by a 36V battery pack. Go to 42V and the motor will spin at about 6535RPM and at 48V it'll spin about 7465RPM. The maximum recommended RPM for a stock 36V PDS motor is about 6500RPM, but some suggest 6000RPM max.

The Alltrax DCX controller didn't use a speed sensor, so running a PDS with stock height tires at 48V could get you into trouble, especially going downhill with your foot on the throttle. I was running a stock PDS motor at 42V through a DCX controller and it was spinning about 8000RPM when it exploded. Of course, there were factors other than RPM involved.

Since the XCT uses a speed sensor and max RPM is user programmable, the over-revving issue of running a stock 36V PDS motor at 48V has more or less been eliminated.

---------
As for the TXT48 motor on the slightly higher lithium pack voltage. Not to worry, it is designed to run on 48V at about the same RPM a 36V PDS motor runs on 36V. Remove the RPM limiting of the stock controller (1206HB) and it'll spin at about 5600RPM. At 56V, it increases to about 6500RPM, or about the same as a PDS motor does at 42V.

Not really an issue since you can limit the RPM to a save value with a XCT controller.

Johnnie, this sounds like a story we'd like to hear...

[JohnnieB]

Originally Posted by Brob1969

Johnnie, this sounds like a story we'd like to hear...

It's a $tory I'd like to forget.

I have tiny tires (17" tall) and had a DCX controller (no speed limiting) passing amps to a stock 36V PDS motor from a 42V battery pack. There isn't much level pavement around here, but my best guess estimate with a GPS was that it would do 28.5 on level roads, which is about 7,000RPM at the motor. I had driven about 15 miles over some pretty good hills and got up to top speed on the flats, so the motor case was about 215°F when I stopped to turn around and head back to the house. I climbed a fairly steep hill and at the top I had a brain fart and wondered how fast it would go down the more gentle slope to the bottom. IIRC, the max speed recorded on the GPS was 33.4MPH (about 8,200RPM) and everything was doing fine until I lifted my foot to slow down for the curve at the bottom. At that RPM, the regen braking came on hard, but only for a moment and then the back wheel locked up and it slide to a stop. When I lifted the seat there was smoke and sparks coming out of the Serial port opening on the DCX, so I flipped the run/tow switch to kill power to it.

The ceased motor took out the controller, so got a D&D ES-76-51 and a DCX500. When the XCT came out I replace the DCX. Now I RPM limit the motor.

Attached are what a PDS motor ought to look like and what mine did after the armature exploded.