Alltrax XCT48500 limiting RPMS

[esports15]

Hi all,

I recently upgraded my PDS cart from 36V to 48V. I installed the heavy duty solenoid, 2ga wires, Admiral B2 Motor, and Alltrax 500 amp controller. I have 22x10x14 tires. I installed the bluetooth device as well. In all three modes (N, 1, 2) using amps ranging from 400 to 500 and rpms speed from 4000 to 6000, my motor gets limited at 3600 RPMS. My batteries are brand new Crown 190s. The motor feels like it has lots of room to go left but it is speed limiting. When I turn speed limiting off (using the app), the cart goes about 21mph. With the speed limiter on (and 4 - pole selected), I go 18-19 mph. Something seems like it is set wrong but can't figure out what. The field map is the MOTB2 V3 map preloaded by ScottyB so I am sure it is correct! Please help! Screenshots attached

Thanks, Eric

[Volt_Ampere]

You can set max motor RPM in the Windows App. It's probably set too low. I don't have the Bluetooth so I have no idea what you can set with that. I use my laptop and I can set everything from max current to throttle curve to max RPM. I have to use Turbo mode to get enough field weakening to get the max speed I want with my Yamaha cart.

[esports15]

Originally Posted by Volt_Ampere

You can set max motor RPM in the Windows App. It's probably set too low. I don't have the Bluetooth so I have no idea what you can set with that. I use my laptop and I can set everything from max current to throttle curve to max RPM. I have to use Turbo mode to get enough field weakening to get the max speed I want with my Yamaha cart.

I connected my laptop and confirmed. Speed limit RPM is set to 6000, but when I full throttle, my max RPM limits at 3600ish.

[JohnnieB]

I suspect you have low pressure (Less than 10PSI max pressure) type tires with an aggressive tread design.

They take a lot of torque to turn and your motor is running out of torque at about 3600RPM with about 6A of field current.

Check the field amps when the speed limiting is turned off. It'll probably be a few amps higher giving the motor a bit more torque and allowing it to reach about 4000RPM (21mph on 22" tall tires)

In the speed limiting mode, the field weakening leans more towards speed (fewer field amps) and doesn't always play well with low pressure tires.

[DaveTM]

Originally Posted by JohnnieB

I suspect you have low pressure (Less than 10PSI max pressure) type tires with an aggressive tread design.

They take a lot of torque to turn and your motor is running out of torque at about 3600RPM with about 6A of field current.

Check the field amps when the speed limiting is turned off. It'll probably be a few amps higher giving the motor a bit more torque and allowing it to reach about 400RPM (21mph on 22" tall tires)

In the speed limiting mode, the field weakening leans more towards speed (fewer field amps) and doesn't always play well with low pressure tires.

Who knows this stuff???

[esports15]

Originally Posted by JohnnieB

I suspect you have low pressure (Less than 10PSI max pressure) type tires with an aggressive tread design.

They take a lot of torque to turn and your motor is running out of torque at about 3600RPM with about 6A of field current.

Check the field amps when the speed limiting is turned off. It'll probably be a few amps higher giving the motor a bit more torque and allowing it to reach about 400RPM (21mph on 22" tall tires)

In the speed limiting mode, the field weakening leans more towards speed (fewer field amps) and doesn't always play well with low pressure tires.

JohnnieB, you are right on with my tires. They are the 22inch OVERKILL aggressive tires and i'm running at 9 PSI (12 psi is their max load rating). I did however talk to Alltrax this morning and I reconnected my spliced speed sensor wires and I am getting much better RPMs (4500ish) at full throttle now. Seems like something was going funky with the wires and it seems to be operating at higher speeds now (closer to 24 mph). Wasn't quite sure what my setup should achieve but I was thinking I was going to have to dial down the RPMs as I don't need to be going 30mph on a golf cart haha

[scottyb]

Turns out there were some bad speed sensor wire connections. Connections repaired and now reporting 24mph.

[esports15]

Originally Posted by scottyb

Turns out there were some bad speed sensor wire connections. Connections repaired and now reporting 24mph.

Scottyb, you are great... i don't know how you have the time to respond to everyones emails so quickly. Now I just hope Alltrax can get the bluetooth module app updated so profiles can be switched.

Is 24 mph about the best I should expect?

[JohnnieB]

Lucky to get 24MPH with those tires.

Theoretically, 12.44:1 gears, 22" tall tire and 6000RPM will be 31.6MPH, but the cart won't go that fast due to the wind load, rolling resistance load and how far the battery pack voltage drops under load.

You mentioned the batteries are new, so you might get a whisper higher speed when they are broken in. New batteries only have about 75% of their rated storage capacity (AH) until they are broken in and the higher the storage capacity, the less the voltage drops under the same load.


Upping the tire pressure will also up the top speed some.

[Volt_Ampere]

I would say that 24mph is a good max speed. I once forgot to hook up my speed sensor after working on the cart and it was slow and throttle response was messed up. I think Alltrax has some sort of "limp mode" if it doesn't see a good speed sensor signal.