Speed disappointment, what to do?

[noahau]

I currently have a 2000 TXT series cart that has been converted to 48 volt. It has an Alltrax SPM 48500, 400 Solenoid, HD F&R, and 2 GA wires throughout. Tires are 23x10.5x12 at 30psi. I have a Plum Quick Black Widow II 17.9 HP motor that is built for torque. The batteries were replaced last week with new Trojan T875s.

I am only getting 18mph on flat ground. Despite it being built for torque, it seems slow for all of these upgrades.

Should I have faster speeds and if so, what do I need to check?

[scottyb]

You might want to get a speed motor. PQ has one. The high torque motors produce lower rpms.

[orangeman6]

Originally Posted by noahau

I currently have a 2000 TXT series cart that has been converted to 48 volt. It has an Alltrax SPM 48500, 400 Solenoid, HD F&R, and 2 GA wires throughout. Tires are 23x10.5x12 at 30psi. I have a Plum Quick Black Widow II 17.9 HP motor that is built for torque. The batteries were replaced last week with new Trojan T875s.

I am only getting 18mph on flat ground. Despite it being built for torque, it seems slow for all of these upgrades.

Should I have faster speeds and if so, what do I need to check?

Johnnieb has posted charts a few times that will tell you theoretical mph based on actual tire size at a given rpm. You can plug your laptop up to your controller and see what rpm’s your getting at full throttle. From there, you’d need to know the specs on your motor from pq.

[JohnnieB]

Without knowing the PQ motor's relative speed increase or decrease compared to a stock 2000 TXT series drive motor, there is no way of knowing if your setup is running fast, slow or normal.

In general terms, a series motor specifically wound for torque spins slower than a stock motor with the same voltage applied, so 18MPH may be normal.

Contact PQ, give them your battery pack voltage, rear end gear ratio (probably 12.44:1) and tire height, and they might be able to answer your top speed question.

[orangeman6]

Originally Posted by JohnnieB

Without knowing the PQ motor's relative speed increase or decrease compared to a stock 2000 TXT series drive motor, there is no way of knowing if your setup is running fast, slow or normal.

In general terms, a series motor specifically wound for torque spins slower than a stock motor with the same voltage applied, so 18MPH may be normal.

Contact PQ, give them your battery pack voltage, rear end gear ratio (probably 12.44:1) and tire height, and they might be able to answer your top speed question.

Johnnieb, my mistake, I was thinking he could see his rpm’s by monitoring the controller then use your chart to see what speed he should be getting based on his tire size and gear ratio. All it would really do is confirm he wasn’t being slowed down by brake drag, etc. He could then confirm with pq that he was getting what he is supposed to from the motor.

[cgtech]

Originally Posted by orangeman6

Johnnieb, my mistake, I was thinking he could see his rpm’s by monitoring the controller then use your chart to see what speed he should be getting based on his tire size and gear ratio. All it would really do is confirm he wasn’t being slowed down by brake drag, etc. He could then confirm with pq that he was getting what he is supposed to from the motor.

Series motors don't have tach sensors

[orangeman6]

Originally Posted by cgtech

Series motors don't have tach sensors

Gotcha. Thanks cgtech, always appreciative of the knowledge I pick up from you guys.

[Sir Nuke]

Originally Posted by noahau

I currently have a 2000 TXT series cart that has been converted to 48 volt. It has an Alltrax SPM 48500, 400 Solenoid, HD F&R, and 2 GA wires throughout. Tires are 23x10.5x12 at 30psi. I have a Plum Quick Black Widow II 17.9 HP motor that is built for torque. The batteries were replaced last week with new Trojan T875s.

I am only getting 18mph on flat ground. Despite it being built for torque, it seems slow for all of these upgrades.

Should I have faster speeds and if so, what do I need to check?

noahau….as suggested, you need to change your motor to a speed motor. as you can see in my sig, my set-up is the same as yours, except for my motor, I have a AMD 7126 "RAPTOR" Motor and I can run all day long on flat ground 28 - 30 mph (depends in the wind, my top can slow me down).

[noahau]

I appreciate all of the responses! When I spoke with PQ, he stated I should be getting around 25mph. His suggestion was to increase tire pressure.

I would much rather have the torque considering it is primarily for hunting. Although I have nothing to base it on, I just thought I should be getting faster speeds.

[scottyb]

Torque and speed are in constant trade off as the electric motor rpms increase.
Typically the motor produces the most torque at the lowest rpms and the highest speed at the greatest rpms.
This all works well for cart operation because it doesn't take nearly as much power (torque) to keep a cart going 20 mph as it takes to get it rolling from 0 mph.
Speed motors designed for high rpms produce less torque at all rpms than torque motors. You have chosen correctly. While a torque motor can be a little disappointing on the flat road. A speed motor will fail in most all off road situations.