EZGO TXT PDS Motor Upgrade DIY

[JohnnieB]

The picture that you posted of your new motor shows it has two bolts holding each field winding shoe in place, so nothing will move if you R&R one of them to install the ring terminal the thermocouple is mounted in.

I don't have a ring terminal type thermocouple, so I put a dollop of thermal compound close to one of the field winding shoe mounting bolts and place the thermocouple bead in the goo. I hold it in place with a piece of foam rubber type weather stripping and cinch it tight with a big Ty-wrap. Here is a picture of the kluge on my dearly departed PDS motor.

OMG, I just spotted the reason that motor failed.

[yurtle]

I installed my ExRay sensor on a field winding bolt. I didn't say anything, since mine is a since mine was a series, and I wasn't 100% positive that a SEPEX was the same.

[beach cart]

Make sure you recheck your motor nuts in a few days after a few runs and they have been warm a few times. ABSOLUTELY HOLD THE BOTTOM NUT WITH A WRENCH WHEN YOU CHECK FOR TIGHT.

Sent from my Torque using Tapatalk

[UroGator]

Thanks for advice. Will check on it


Sent from my iPhone using Tapatalk

[JohnnieB]

Originally Posted by yurtle

I installed my ExRay sensor on a field winding bolt. I didn't say anything, since mine is a since mine was a series, and I wasn't 100% positive that a SEPEX was the same.

Except for the length and gauge of the wire in the field (aka stator) windings, Series wound and Shunt wound (Sepex) motors are pretty much the same physically.

If each winding shoe is held in place with two bolts, nothing should move if one was removed to install the temperature sensor, but I'm not 100% sure about it if the shoe is held in place by one bolt only, like my stock PDS motor. Chances are that it wouldn't be a problem or ExRay would have a caution or warning about it in their installation instructions.

I still use the same kluge setup on my D&D motor that does have two bolts in each shoe, but only because I don't have a thermocouple embedded in a ring terminal and I'm too cheap to buy one even if I could find one.

However, I might try soldering one into a non-insulated ring terminal, since a K type measures up to about 2300°F and the insulation on the wires ought to handle 361°F melting point of the 63/37 solder I use.

[yurtle]

It'd be nice to embed it in the windings, like the big motors have. We generally use RTDs.

[UroGator]

Originally Posted by JohnnieB

If each winding shoe is held in place with two bolts, nothing should move if one was removed to install the temperature sensor, but I'm not 100% sure about it if the shoe is held in place by one bolt only, like my stock PDS motor. Chances are that it wouldn't be a problem or ExRay would have a caution or warning about it in their installation instructions.

ExRay actually does state in the instructions that the connection of the temperature sensor to the bolt holding the shoe should only be done by a qualified technician. They include some aluminum tape for those "not qualified" to do this. I'll just consider myself not qualified and not risk screwing up the motor. The tape may actually provide a more accurate motor temperature as it may limit heat radiation from the motor (no evidence to back this up though)

[JohnnieB]

Originally Posted by UroGator

ExRay actually does state in the instructions that the connection of the temperature sensor to the bolt holding the shoe should only be done by a qualified technician. They include some aluminum tape for those "not qualified" to do this. I'll just consider myself not qualified and not risk screwing up the motor. The tape may actually provide a more accurate motor temperature as it may limit heat radiation from the motor (no evidence to back this up though)

I stand corrected about the ExRay installation instructions.

But, like I said, I don't see an issue with the aftermarket motors with two bolts holding each field winding shoe in place.

One thing to remember, measuring the motor temp on the case is an indirect measurement. It continues to climb after the motor stops turning.

Since I cannot easily watch the DMM in real time because it is behind me in the sweater basket, I put it in min/max mode and read the max temp reached after the trip. A thermocouple with longer leads and a dedicated temperature meter are on my list of things to get.

[UroGator]

Just installed my ExRay monitor and took some measurements. Very nice system and makes monitoring all vital aspects simple. Max speed with my 19.75" tires (as measured by rolling tire method) is 29.1 MPH. JohnnieB, can you calculate my max RPM at this speed based on my new ( more precise) tire diameter and max speed?

As JohnnieB mentioned, motor temp does continue to rise even after you are stopped (due to it taking time for the heat to dissipate) as the temp probe is an indirect measurement of motor temp. I noticed that the motor temp after 7 miles of driving was 135 F. But after stopping and letting the motor sit for 5-10 minutes, the temp rose to a max of 145 F. But it seems like this ventilated and fan cooled motor is cooling like it was designed to do!


Sent from my iPhone using Tapatalk

[JohnnieB]

Originally Posted by UroGator

Max speed with my 19.75" tires (as measured by rolling tire method) is 29.1 MPH. JohnnieB, can you calculate my max RPM at this speed based on my new ( more precise) tire diameter and max speed?

Yes, but it'll be Tuesday before I can get to it.

I'm out of town and the laptop I have with me doesn't have the tire size vs motor RPM on it.