Help with possible PDS purchase

[LBB]

Originally Posted by coosa

The camo cart was already upgraded when I bought it, though I found they cut a few corners and had to add a few upgrades myself. It has the Altrax 500 controller with larger cables, solenoid, and tires. I liked it so much I bought another one and built it to keep at my farm. I bought all the components from ScottyB and it has been a trouble free cart. I've had one minor issue due to it sitting up too long, but a good cleaning of all connections fixed it. This cart has low pressure tires because I already had them and the cart is only used on dirt. They knock about 2 mph off the top speed, but this cart seldom sees top speed.

Beware of the carts similar to mine that you see for sale at feed stores and such places. Most of them have been lifted and bigger tires installed and maybe a rear seat added. They look good, but open them up and they are just stock underneath. Such carts are doomed to failure. They will run over 20 mph because of the tires, but won't last long.

The controller JohnnieB recommended is an update from the ones I have. Also, the original controller on the camo cart failed after 2 years. It was used, so I don't know how it had been treated. But a 500 amp controller is too much for my factory motor anyway. I have turned them both down to 80% and essentially made them 400 amps. They lost a little torque, but I can't tell if it changed top speed. If it did, it isn't much.

Good luck finding what you want. The PDS is a great system.

Thanks man - great advice, especially from someone who essentially has the same cart.

I've gone from hesitant and naive to excited (but probably still pretty naive). This is a great site.

[scottyb]

DCS & PDS were great drive systems. Look a little further and you will find that in 2010 Ezgo introduced a 48v PDS cart called the TXT48. This cart is an improvement over the old PDS system. I did an install thread below with pics for the XCT400 control & HD solenoid in the TXT48. The cart has plenty of power, lots of zip, impressive torque, and 23-24 mph on the stock tires. Customers with bigger tires getting 27 mph.
While my 2008 PDS has been my favorite cart for years (running it on 42v), the 2010 TXT48 has taken it's place. The F&R mod I did moved the rocker switch from the dash to a position where you can reach it without leaning forward out of the seat. Now it's just fun to jockey it around.

http://www.buggiesgonewild.com/elect...-upgrades.html

http://www.buggiesgonewild.com/elect...ery-meter.html

[JohnnieB]

Originally Posted by LBB

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1. + I've seen 500a controllers as well.

2. My guess is that you need a better motor than the PDS has, that can handle more RPM to support a 500a?

3. + Does 34v vs 48v relate to any of these factors?

4. + If so, do any of the stock Ezgo carts handle a 500+a?

5. + So I now think I understand how it affects acceleration rate. How does the new controller also allow more speed? (if it does)

Sorry, but this is so helpful to know. :-)

1. The Alltrax XCT comes in 300A, 400A and 500A versions. Their DCX controllers had versions that went from 300A up to 650A. I'm not sure, but other manufactures may have sepex controllers that will pass 1000A or more. Of course, at some point how many amps the battery pack can produce and the high current cables, contacts and connections can deliver become the limiting factors.

2. A stock PDS motor will handle about the same max RPM as most of the aftermarket motors. The recommended max RPM for most of the DC motors found in golf carts is in the 6000 RPM to 6500 RPM range. (I asked D&D the max RPM for my motor was and got both figures from two different people, one a co-owner of the company and the other one a chief engineer). Those values are max continuous RPM and are likely to be conservative. How fast an armature can spin without being pulled apart by centrifugal forces combined with vibration depends on how strongly it is constructed and how well it is balanced. The max RPM rating of the bearings is also a factor.

A motor's impedance increases as the RPM increases, which in turn decreases the maximum amps it can draw for a given voltage as the RPM increase. Therefore, after a certain RPM, it does not matter how many amps the controller is capable of passing, the motor in and of itself is incapable of drawing them.

For example, with 42V applied and 25A of field current, my motor is only capable of drawing a maximum of 300A at 2150RPM or below due to the Laws of Physics, so in my setup the difference in acceleration between a 300A controller and a 1000A (or larger) would only be from Zero up to 8.8 MPH. From that speed on up to the max RPM achievable for the applied voltage, the acceleration is the same.

Motors are not 100% efficient and the amps not converted to torque are converted to heat, so a motors amp handling capacity is determined by it efficiency (which varies with RPM) and its heat dissipation ability. Stock PDS motors tend to fail fairly rapidly on a steady diet of 500A or more, but live a long time when 500A controllers are turned down to 400A or so. The XCT has a peak output of 460A and stock PDS seem to tolerate it okay.

3. 36V vs 48V. In general terms a stock PDS motor (or any other DC motor) Has 33% more torque throughout the RPM spectrum at 48V than it does at 36V. The RPM it will reach is 33% higher also and it runs cooler since the heat generated is the square of the current flow and the same amount of work is done with 33% fewer amps at 48V.

4. Stock series wound motors handle 500A controllers okay, but other heat producing factors are involved in sepex motors, so they cannot handle quite as much even though they have the same sized motor case. I don't know about stock RXV (AC type) motors.

5. The stock PDS motor will spin at about 5600 RPM with 36V applied, but the stock controller limits the motor 4400 RPM. The speed sensor on a PDS motor was not attached the the DCX controller, so there was no speed limiting. The XCT uses the speed sensor, but is user programmable and the RPM limit can be set up to 8000 RPM. Theoretically, a stock PDS motor that will reach 5600RPM at 36V, will reach 6533RPM at 42V or 7466RPM at 48V.

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It takes a wile, but the fog does eventually lift.

The trick is to figure out what you want for the end product and then build towards that goal. Just about everything about carts is a compromise of some sort.

[scottyb]

Quote "The trick is to figure out what you want for the end produce and then build towards that goal. Just about everything about carts is a compromise of some sort."

Hmm, lets see what do I want, big badass golf cart or wife ?

[JohnnieB]

Originally Posted by scottyb

Quote "The trick is to figure out what you want for the end produce and then build towards that goal. Just about everything about carts is a compromise of some sort."

Hmm, lets see what do I want, big badass golf cart or wife ?

I changed "produce" to "product", but you can have both, Of course you still have to compromise with a badass wife to build a badass golf cart.

I met SWMBO (She Who Must Be Obeyed) at work. She was doing periodic safety and performance inspections on medical equipment, so I don't get blank stares when I lapse into techno-speak.

[LBB]

Originally Posted by JohnnieB

1. The Alltrax XCT comes in 300A, 400A and 500A versions. Their DCX controllers had versions...

That is all super helpful and educational. Thanks for taking the time on that.

Originally Posted by JohnnieB

3. 36V vs 48V. In general terms a stock PDS motor (or any other DC motor) Has 33% more torque throughout the RPM spectrum at 48V than it does at 36V. The RPM it will reach is 33% higher also and it runs cooler since the heat generated is the square of the current flow and the same amount of work is done with 33% fewer amps at 48V.

... Theoretically, a stock PDS motor that will reach 5600RPM at 36V, will reach 6533RPM at 42V or 7466RPM at 48V.

It's so funny. When I started thinking about getting a cart (before I found this site), I looked around for info and asked what the difference was between 36v and 48v. I was told that the only difference was that it would run longer before needing charged! Not even sure if the part about running longer is true.

So it sounds like then, if I have the extra money, that getting a 48v could end up in a faster cart that wouldn't run as hard (meaning it would be easier on the components).

Originally Posted by JohnnieB

It takes a wile, but the fog does eventually lift.

The trick is to figure out what you want for the end product and then build towards that goal. Just about everything about carts is a compromise of some sort.

Thanks man. I'm trying.

[LBB]

Originally Posted by scottyb

DCS & PDS were great drive systems. Look a little further and you will find that in 2010 Ezgo introduced a 48v PDS cart called the TXT48. This cart is an improvement over the old PDS system. I did an install thread below with pics for the XCT400 control & HD solenoid in the TXT48. The cart has plenty of power, lots of zip, impressive torque, and 23-24 mph on the stock tires. Customers with bigger tires getting 27 mph.
While my 2008 PDS has been my favorite cart for years (running it on 42v), the 2010 TXT48 has taken it's place. The F&R mod I did moved the rocker switch from the dash to a position where you can reach it without leaning forward out of the seat. Now it's just fun to jockey it around.

http://www.buggiesgonewild.com/elect...-upgrades.html

http://www.buggiesgonewild.com/elect...ery-meter.html

Thank you!!!! You answered the question I've been meaning to ask. Gave me the exact year that Ezgo made a 48v TXT so I can look for it.

So would the upgrades cost any more for a 2010 TXT over a 2008 PDS, or would it be all the same equipment?

And would the upgrades be any harder to do?

I'm looking for all these factors on my budget.

[JohnnieB]

Originally Posted by LBB

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1. It's so funny. When I started thinking about getting a cart (before I found this site), I looked around for info and asked what the difference was between 36v and 48v. I was told that the only difference was that it would run longer before needing charged! Not even sure if the part about running longer is true.

2. So it sounds like then, if I have the extra money, that getting a 48v could end up in a faster cart that wouldn't run as hard (meaning it would be easier on the components).

1. Run-time or distance cart will go between battery charges (range) depends on how much energy is stored in the battery pack and how much energy the cart uses per mile. In automotive terms, it equates to how many gallons the fuel tank holds and the MPG the vehicle gets.

When comparing battery packs of the same voltage, AH (amp-hours) can be used and the higher the AH, the more energy stored, but if the battery packs have different voltages, watt-hours (wH) need to be used. The standard 36V battery pack is made up of six 225AH 6V batteries and stores 8100 wH (36 X 225 = 8100). A common 48V battery pack used in upgrades is six 170AH 8V batteries, which has 8160 wH and will have roughly the same run-time as the standard 36V battery pack, while the cart has about 33% more speed and torque.

Greater run-time can be obtained by using higher AH 8V batteries and the highest AH 8V batteries commonly available are either Trojan's 204AH Ranger 160 (9792wH) or US Battery's 205AH US 8VHATB XC2 (9840wH).

48V battery pack can also be made up of eight 6V batteries and the highest AH 6V batteries available have 260AH for 12,480wH. Of course, eight 6V batteries weigh more than six 8V batteries, so the is some performance loss due to the additional weight.

2. Yes and no. It will be faster and more powerful, but has the potential of being driven harder than it could have been at 36V, so it only easier on the components when not driving it any harder than you would have at 36V.

For example, at 1900RPM and 25A of filed current, my motor is only capable of drawing 398A through the armature while it is capable of drawing 531A at 48V. That is a electrical input of 14,328W at 36V and 25,473W at 48V, which equates to 19HP and 34HP respectively. Of course my motor is only about 70% efficient at that RPM with 25A of field current, so the HP being applied to the spline couplings, differential gears and the rest of the drive train isn't quite that much, but the mechanical stress ratios between 36V and 48V are the roughly same.

[scottyb]

Honestly you can put a XCT400 control and 200 solenoid into the TXT48 and away you go! It's that easy to get 35% more torque and 22-24 mph.

PDS drive was good, the best in it's day, but it needed more voltage which requires a new charger. TXT has a 48v system but, Both PDS and TXT are factory equipped with a weak charger.