PDS cart, stock motor, how fast can I go?

[sportcoupe]

Good point on actual tire size vs. advertised number. I just measured my 23" tires and they are actually 22.5" exactly. The max pressure on sidewall is 20 psi and I'm running 25 psi. I may drop that down some and see if I loose any speed.

I have not been able to measure amps under load because I don't have a RS-232 to USB cable that is compatible wit the DCX500. I may pick one up from Radio Shack as I heard theirs works well.

ScottyB programmed the DCX500 with turbo on with no amp restrictions also. He had asked if I wanted 80% power due to having stock motor, I said heck no, give me all you got Scotty! LOL

I do need to reprogram reverse for 60-70% because it's full 100% and barks the tires way too easy going backwards. I also need to drop the throttle ramp-up slightly as it's a bit sensitive too.

[JohnnieB]

22.5" means the motor is spinning at 5,390RPM at 29MPH.

Lowering the air pressure will shrink the tire height a bit since the center of the tread bulges when overinflated, effectively growing the tire height.

I don't know one way or the othert about the Radio Shack offerings, I use a Cablestogo #26886 USB to Serial and a #52031 Serial extender cable that I ordered on-line from Newegg.

[TerryH]

The stock motor worked well in mine but you'll need to be careful to monitor how hot it is getting. I highly recommend the 8:1 gears and the D&D motor combination if you are eat up with it like I am. The 8:1's will lower the rpm of the motor and gain speed. Both good things but the higher gears alone will likely force the stock motor into submission. I wouldn't do the gears without upgrading the motor.

[sportcoupe]

Full charge got me 30 mph. Very nice.

[sportcoupe]

I was told to watch motor temps running a pds on 48v and 500 amp alltrax. Today I rode for an hour on-road at moderate speed with one passenger. I got home and measured motor temp with inferred temp gun. I showed 192°F case temperature. It was 85°F outside too.

Info to all who overvolt stock pds motor. I don't know how long it will last but it's fun!

[Turbo_Pumpkin]

30 is pretty impressive!

[sportcoupe]

Originally Posted by Turbo_Pumpkin

30 is pretty impressive!

So is the 192°F motor case temp

I don't know how much longer it'll take this. I'm sure someones running a 48v pds here with stock motor. Waiting to hear from them and the history on it.

[yurtle]

My Alltrax ExRay measures motor temp. Both with stock and the HS motor in my sig below, I've exceeded 200°. I try not to do this, but it's not just about the over-voltage, it's all about the amps. I guess technically it's power, which is both volts and amps, but...

I've thought about a water-cooled solution. I was gonna build a hood, with a cloth towel covering the motor. I could fill it up with ice before taking off and it would eat however much cooling power it needed. Since every house has an ice-maker, I could top it off however much it needed. Prolly never gonna build it.

[JohnnieB]

It is about power (V*A=W) but it is also about the ratio between the volts and amps used to obtain that power.

Heat is generated by Amps (I^2 * R = W), so a higher voltage system will run cooler at the same power level.

A prime example of this is the voltages used on AC power grid to move megawatts of energy from the power plants to the end user. By kicking the transmission line voltage up to 500kV, a megawatt can be moved from Point-A to Point-B with only 2A of current flow, keeping the energy loss due to heat to an acceptable level.

200°F case temperature is still within the normal operating range for a Class-H motor.
But, I wouldn't let it go much higher than that.

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I doubt if I'll have any motor temperature issues since my set-up will be fairly mild and I'm staying with stock height tires, but I'm kicking around the idea of circulating fluid system, should more than forced air cooling be needed.

Basically several feet of small diameter copper tubing wrapped around motor case, fed by a small centrifugal pump, from a vented reservoir.
The fluid would be either Propylene Glycol or cooking oil, since it is less corrosive and moves more BTU's per volume than water.

[sportcoupe]

Found another cart I want to start modding so this 48v PDS is for sale now. Price is negotiable.

http://www.buggiesgonewild.com/golf-...tom-paint.html