13mph @ 47V

[Clubcarken]

Hi all,
I just built a 2015 48v ezgo txt, and it has 22” tall tires. Im new to the ezgo product. It’s topping out at 13mph with 47v at full pedal.
I connected my voltmeter to the motor and while driving I'm only getting 31vdc to the motor, but I continue to have 45-47vdc at the battery pack.
Maybe a bad controller or solenoid? or a faulty throttle sensor? Anything you can recommend to help me figure this out is appreciated

Thanks

[bronsonj]

A 48v lead acid pack is dead when it gets down to 48v. Charge it up and see how it drives when you've got 50.7v or so.

[Clubcarken]

ok, are there any upgrades available for the stock Curtis 1206hb-5201 controller? I'm thinking something is wrong with the controller itself. I have 48V at the solenoid all the time, but if I measure the voltage coming out of the controller, with the cart up in the air and the pedal 100%, I only get around 28Vdc at M and B+. 28Vdc to the motor? Doesn't that sound wrong?
Maybe I'm missing something

[BobBoyce]

Originally Posted by Clubcarken

ok, are there any upgrades available for the stock Curtis 1206hb-5201 controller? I'm thinking something is wrong with the controller itself. I have 48V at the solenoid all the time, but if I measure the voltage coming out of the controller, with the cart up in the air and the pedal 100%, I only get around 28Vdc at M and B+. 28Vdc to the motor? Doesn't that sound wrong?
Maybe I'm missing something

Spinning the tires unloaded is not a true measure... The motor hits the max set RPM in the controller, and the controller cuts back on the motor output to prevent severe over-rev, which usually destroys the motor and takes out the controller with it! Rev limits can be changed, but it needs to be maintained within reason for the installed motor.

That controller can be reprogrammed to allow for some improved torque and a few more MPH with STOCK tires. BUT...

Larger tires will quickly swamp the capability of that stock controller! 22" tires will really need a 500A controller to wake it up, and 23" tires will need 600A to perform at a decent level. I've done a few custom tunes on TXT48's with larger tires, but the motor remapping required is a royal pain, and you will still hit a brick wall on performance when the controller maxes out. The stock controller is detuned by 50Amps, not a lot considering what is required to turn much larger tires!

[Clubcarken]

ok thanks Bob. I'm having an issue where the Stock controller is only outputting 27-28V at full throttle , with a full 50V pack. I was looking at the 4-pin throttle connector and realize between the black and white I am getting 14Vdc. At full throttle I get 11Vdc. I'm thinking this is the culprit. The throttle is not responding and the controller output is limited. What do you think about this?

[BobBoyce]

Originally Posted by Clubcarken

ok thanks Bob. I'm having an issue where the Stock controller is only outputting 27-28V at full throttle , with a full 50V pack. I was looking at the 4-pin throttle connector and realize between the black and white I am getting 14Vdc. At full throttle I get 11Vdc. I'm thinking this is the culprit. The throttle is not responding and the controller output is limited. What do you think about this?

I had edited the above post to include the answer to this. Reread...

Voltage is not the only criteria to judge performance. It is an important part, but is not the only factor at play. You are dealing with a SepEx motor and controller. I suggest you do some reading to understand what the requirements are for SepEx motors...

SepEx = Seperately Excited

[BobBoyce]

BTW, I am an engineer with multiple degrees. But I do not make a very good instructor. I lack a lot of the people skills required to teach. I'm great at designing and fabricating things. Not so great at trying to explain it in ways that untrained people can understand. This is why I referred you to study what you are working with BEFORE you make some very costly mistakes.

[Clubcarken]

OK will do! Thank you!

[bronsonj]

Club, what speed do you get when you have a 50v pack? You had 13mph on a 47v pack, what's your actual speed when fully charged?

Also, is that 50.0v or 50.9v? 50.9 is 100% charged but 50.0v is 80% charged. You never want to take the batteries below 50% SOC which is 48.4V.

[JohnnieB]

Also the 100% SoC voltage depends on the battery manufacturer. Trojan and clones is 50.9V while US battery is 51.3V, Crown, Exide and others falling mostly in between those two.