2005 TXT slow up hill

[JohnnieB]

The faster the armature of a DC traction motor spins, the fewer amps it is capable of drawing. The max motor RPM (which is also max cart speed) is the RPM at which the torque produced by the amps flowing through the armature, at the voltage being applied, equals the mechanical drag opposing it.

When the mechanical load increases, (IE: going up a hill) the armature slows until the motor is capable of drawing a the amount of amps that will produce an amount of torque equal to the new load.

Series wound motors are most effected by this fact because the same amps flow through both armature and field windings and their torque/speed curve is cast in stone when their armature and field windings are wound at the factory. On the other hand, the field windings of SepEx motors excited separately from the armature and their torque/speed curve can be adjusted on the fly to produce more torque when the mechanical load increases in a process known as Field Mapping.

In other words, SepEx motors don't slow as much as series motors under the same voltage and loading parameters.

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Factors common to both series and SepEx motors:

Tire height. The taller the tires are, the more the cart slows on an incline.

Battery capacity. The voltage of all lead-acid batteries drop when amps are drawn from it and the greater the amp draw relative to the battery's AH capacity, the greater the voltage drop and the lower the voltage applied to the armature, the few amps it can draw, thereby producing less torque at a given RPM, so it has to slow more to draw enough amps to produce enough torque to equal mechanical load.

Total cart weight. The more the cart weighs, the more it slows on inclines.

Excessive resistance in the high current loop. All the cables, connections and contacts have resistance and when amps pass through resistance volts are dropped. Volts that could be pushing amps through the armature and producing torque.

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Technically, Watts (Amps X Volts) are what a motor converts to torque.

[bighanded]

translation: big hill+ my big ol butt = cart gonna slow down



but hoping to see good performance out of my sepex at the big hill campground..

around my home and on my property...the upgrades have really impressed me.

thanks johnny...

Ed

[Mooncarter]

Originally Posted by JohnnieB

The faster the armature of a DC traction motor spins, the fewer amps it is capable of drawing. The max motor RPM (which is also max cart speed) is the RPM at which the torque produced by the amps flowing through the armature, at the voltage being applied, equals the mechanical drag opposing it.

When the mechanical load increases, (IE: going up a hill) the armature slows until the motor is capable of drawing a the amount of amps that will produce an amount of torque equal to the new load.

Series wound motors are most effected by this fact because the same amps flow through both armature and field windings and their torque/speed curve is cast in stone when their armature and field windings are wound at the factory. On the other hand, the field windings of SepEx motors excited separately from the armature and their torque/speed curve can be adjusted on the fly to produce more torque when the mechanical load increases in a process known as Field Mapping.

In other words, SepEx motors don't slow as much as series motors under the same voltage and loading parameters.

-------------
Factors common to both series and SepEx motors:

Tire height. The taller the tires are, the more the cart slows on an incline.

Battery capacity. The voltage of all lead-acid batteries drop when amps are drawn from it and the greater the amp draw relative to the battery's AH capacity, the greater the voltage drop and the lower the voltage applied to the armature, the few amps it can draw, thereby producing less torque at a given RPM, so it has to slow more to draw enough amps to produce enough torque to equal mechanical load.

Total cart weight. The more the cart weighs, the more it slows on inclines.

Excessive resistance in the high current loop. All the cables, connections and contacts have resistance and when amps pass through resistance volts are dropped. Volts that could be pushing amps through the armature and producing torque.

----------
Technically, Watts (Amps X Volts) are what a motor converts to torque.

This should be made into a STICKY and put in every electric section in here.

Thanks JohnnieB!

[cgtech]

Originally Posted by JohnnieB

The faster the armature of a DC traction motor spins, the fewer amps it is capable of drawing. The max motor RPM (which is also max cart speed) is the RPM at which the torque produced by the amps flowing through the armature, at the voltage being applied, equals the mechanical drag opposing it.

When the mechanical load increases, (IE: going up a hill) the armature slows until the motor is capable of drawing a the amount of amps that will produce an amount of torque equal to the new load.

Series wound motors are most effected by this fact because the same amps flow through both armature and field windings and their torque/speed curve is cast in stone when their armature and field windings are wound at the factory. On the other hand, the field windings of SepEx motors excited separately from the armature and their torque/speed curve can be adjusted on the fly to produce more torque when the mechanical load increases in a process known as Field Mapping.

In other words, SepEx motors don't slow as much as series motors under the same voltage and loading parameters.

-------------
Factors common to both series and SepEx motors:

Tire height. The taller the tires are, the more the cart slows on an incline.

Battery capacity. The voltage of all lead-acid batteries drop when amps are drawn from it and the greater the amp draw relative to the battery's AH capacity, the greater the voltage drop and the lower the voltage applied to the armature, the few amps it can draw, thereby producing less torque at a given RPM, so it has to slow more to draw enough amps to produce enough torque to equal mechanical load.

Total cart weight. The more the cart weighs, the more it slows on inclines.

Excessive resistance in the high current loop. All the cables, connections and contacts have resistance and when amps pass through resistance volts are dropped. Volts that could be pushing amps through the armature and producing torque.

----------
Technically, Watts (Amps X Volts) are what a motor converts to torque.

A masterpiece!

[Mooncarter]

Originally Posted by cgtech

A masterpiece!

No doubt. Although I mostly understand these things there is something to be said about being able to explain complex concepts in a concise way.

Very well said.

[bighanded]

so for my sepex 36v system...is there a translation of your comment into the throttle/torque curve programming in our beloved Alltrax toolkits?

or is the cart simply gonna do what/all it can do on a hill climb?

i know there are a ton of older threads out there around programming in the Toolkit...just wanted to make sure I wasn't missing something here while this thread is active.

if the throttle/torque "patterns" I've set in toolkit are giving me a smooth pedal, good offroad torque, and the stock motor is getting all the juice it can via 2ga cables through the 48400 with turbo on and rpms set high enough...

is there anything in the "curve" that helps it hold speed up hills...

again..currently only able to test against a mild/long incline and I'm not unhappy with 12-15mph speeds

thanks again Johnny

[Jsoyars]

[QUOTE=cgtech;1594126]If you decide 48v might be an option, your controller is already capable of 48v, your motor will be fine on 48v too. Expect 33% more speed and torque if using the stock motor. So, that leaves batteries, charger, solenoid, F&R. Cables should be in the plan too, the stock cables are undersized, and won't reach the terminals of 8v batteries. Every single one of the bigger cables needs to be top notch, including the ones to the motor. The whole entire system is limited by the worst cable.

I currently have six 6v batteries. If I decide to go to 48v I’m not sure I’ll have room for 2 additional 6v batteries under the seat. Is it possible to keep the six 6v batteries I have and add 1 12v?

[mgray70]

[quote=Jsoyars;1595015]

Originally Posted by cgtech

If you decide 48v might be an option, your controller is already capable of 48v, your motor will be fine on 48v too. Expect 33% more speed and torque if using the stock motor. So, that leaves batteries, charger, solenoid, F&R. Cables should be in the plan too, the stock cables are undersized, and won't reach the terminals of 8v batteries. Every single one of the bigger cables needs to be top notch, including the ones to the motor. The whole entire system is limited by the worst cable.



I currently have six 6v batteries. If I decide to go to 48v I’m not sure I’ll have room for 2 additional 6v batteries under the seat. Is it possible to keep the six 6v batteries I have and add 1 12v?

Not a good idea! I have added two extra batteries before. One on the drivers side, and one in the bag well. Worked great! The 48 volt upgrade is well worth the money and effort. It is about the only way to get more performance from a series cart.

Sent from my SM-G930R4 using Tapatalk

[JohnnieB]

Originally Posted by Jsoyars

I currently have six 6v batteries. If I decide to go to 48v I’m not sure I’ll have room for 2 additional 6v batteries under the seat. Is it possible to keep the six 6v batteries I have and add 1 12v?

Regardless of the battery pack voltage, all the batteries are charged and discharged in series, so all of the batteries have to have the same storage capacity or unequal charging and discharging will occur, shortening the cradle to grave lifespan of all the batteries as well as causing premature failures of the lower AH capacity batteries amongst them.

All the batteries in a battery pack ought to be the same brand, the same AH ratting and the same age. The closer all of the batteries are to each other, the better.

Adding a 12V battery to a 6x6V 36V pack is one of the worst possible mismatches.

[JohnnieB]

Originally Posted by bighanded

so for my sepex 36v system...is there a translation of your comment into the throttle/torque curve programming in our beloved Alltrax toolkits?

or is the cart simply gonna do what/all it can do on a hill climb?

i know there are a ton of older threads out there around programming in the Toolkit...just wanted to make sure I wasn't missing something here while this thread is active.

if the throttle/torque "patterns" I've set in toolkit are giving me a smooth pedal, good offroad torque, and the stock motor is getting all the juice it can via 2ga cables through the 48400 with turbo on and rpms set high enough...

is there anything in the "curve" that helps it hold speed up hills...

again..currently only able to test against a mild/long incline and I'm not unhappy with 12-15mph speeds

thanks again Johnny

With one exception, maybe two, there is nothing user programmable via Toolkit that can be done to reduce the cart's speed loss on inclines.

For the most part, Throttle Rate, Throttle Linearity, Throttle Speed and Throttle Torque adjustment control how the cart accelerates from a standstill. Once the PWM (Pulse Width Modulation) output of the controller is at 100% duty cycle, the laws of physics are the controlling factors.

The first exception is when the (SepEx) controller is limiting the max motor RPM to something less than the motor will spin at when max battery pack voltage is applied. For example, my cart has tiny tires (17" tall) and with with my 42V battery pack, I can spin the motor at 7000RPM, but I limit it to thee manufacturer's recommended max of 6500RPM, so when I have my foot on the floor on level pavement, the PWM output from the XCT controller is less than 100% to keep from exceeding the max RPM setting. When I encounter an incline the controller increases the PWM duty cycle to maintain the RPM until it reaches 100%, then the laws of physics take over and the cart slows, but the net effect is my cart does slow as much on inclines relative to its top speed on level ground. However it is an illusion since the top speed is lower rather than the speed on the incline being higher.

The second, or the maybe, different field maps can be loaded via Toolkit and there may be a specific field map for the specific motor that does better on hills. Of course, doing better at one task may be reducing performance in other areas.

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For less speed loss on hills, increase battery pack voltage, reduce cart weight and install shorter tires.