Club Car DS problem, will stop on it own after short ride

[bligbrad]

Hey guys, first post here so any help is appreciated. I have a 2002 Club Car DS 48V. Just installed new batteries and 2g cables. Now it will run great for a short time then just stop after maybe 10-15 minutes or so of riding. Now that is riding just around my house going rather slow and some small hills. When it stops I have to let it sit around 5 minutes or so and it will start going again. Almost like something is overheating. I have checked all the connections and tested all the batteries. I am thinking it could be the controller but not sure. Any suggestions?

[camaroluvz28]

Sounds like your controller may be shutting the cart down from overheating, but lets start with a little more info to help the guys out...was the cart doing this Before battery and wire install or was this the reason for install? Is cart lifted with bigger rims/tires? does it have back-seat kit or standard road cart? Have you checked to see if the solenoid is hot to the touch when it shuts down? I know a lot of questions but will help to narrow down problem..

[CustomCurt]

double check the pack chain to make sure one battery is not installed wrong

[bligbrad]

Cart was not doing this before battery change. Batteries would not hold charge anymore reason I bought new ones. Yes cart is lifted with 14inc wheels and 23inc tires and has a backseat kit installed on it. Have not checked the solenoid. I have checked the motor to see if it was hot to the touch, it was warm but not to hot I would say. I will check the solenoid next to see how hot it is. Will also check the pack chain just to make sure. Thanks guys.

[Fairtax4me]

What batteries did you get? Brand and model?
Does the charger work?
Brand new batteries don't come at their full capacity. Voltage is usually pretty close to what's considered a full charge, but they need to break in condition the plates to get the full capacity from them.
This usually takes 10-20 charge cycles. Most battery manufactures will say 50 cycles.
Usually by the time you get 10 cycles on the pack you won't notice the difference anymore, but a brand new pack that either hasn't been charged or only charged once or twice can fall flat on its face after driving only a short time.

Driving slow might seem like a good idea, but it actually draws more amps to drive slower.

Make sure the pack is getting fully charged, let the charger run until it shuts off on it's own.

[simicrintz]

Originally Posted by Fairtax4me

Driving slow might seem like a good idea, but it actually draws more amps to drive slower.

Probably a dumb question, but why is that?

[simicrintz]

OK-so it IS a dumb question!! And I will admit to not being the brightest tool in the chandelier, but I still want to know why!

[Tom47]

Originally Posted by simicrintz

OK-so it IS a dumb question!! And I will admit to not being the brightest tool in the chandelier, but I still want to know why!

Golly, I want to know also.

I get less pack voltage drop when I cruise at 10 to 12 than when I run the same distances at 18 to 20, usually 3 to 4 miles.

And I'll admit my bulb went out years ago!

Edit: Wait a minute, maybe my light just flickered on. Less voltage sent to the motor by the controller at low speed actually will increase the amp draw! However, the power used [P=IxE] will be less. The solenoid will see more amp draw and heat generated.

Or not......

[Fairtax4me]

Originally Posted by simicrintz

OK-so it IS a dumb question!! And I will admit to not being the brightest tool in the chandelier, but I still want to know why!

Originally Posted by Tom47

Golly, I want to know also.

I get less pack voltage drop when I cruise at 10 to 12 than when I run the same distances at 18 to 20, usually 3 to 4 miles.

And I'll admit my bulb went out years ago!

Edit: Wait a minute, maybe my light just flickered on. Less voltage sent to the motor by the controller at low speed actually will increase the amp draw! However, the power used [P=IxE] will be less. The solenoid will see more amp draw and heat generated.

Or not......

Not a dum question. It's not an intuitive thing. Driving something with a gasoline engine, the lower the engine speed, the lower the fuel usage... Sort of.

All DC electric motors create their highest current draw at 0 RPM. If the motor is stalled the armature will melt itself in a matter of seconds because of the amount of current running through it. A motor at 0 rpm can pull several hundred amps just trying to get moving, depending on what it's trying to push.
As a motor spins it creates current in itself. That current is called Counter Electro-Motive Force. Electro-motive Force is most commonly referred to as Voltage. It's the ability to perform electrical work. The ability to move electricity. EMF is the same thing that creates electricity in a generator.
The faster a motor spins the more EMF is created. The windings of the motor are moving through a magnetic field and are pushing back against the current that is driving the motor. The voltage induces current flow in the windings of the motor, which reduces the current consumption of the motor as it spins faster.
At full speed, the incoming current and the CEMF are theoretically equal.
But in actual real life usage, the motor never really reaches full speed. It reaches a point where the load on the motor is balanced against the amount of torque the motor can produce to spin against the load.

In a golf cart that has a motor controller it gets a bit more complicated than that because the controller is acting as a current limiting device, but the basic principle is still there.
Basically the controller is providing resistance to control the motor speed.
The slower the motor spins, the more current it will pull. This against the resistance in the controller means lots of heat buildup. Not just in the motor, but also in the cables, and the controller especially, since that is generally the point of greatest resistance when going slow because the FETs in the controller are providing resistance to control the motor speed.

In a sepex cart the effect is not as pronounced, because of the way that current is controlled in the field coils of the motor. In a sepex setup the controller changes the field current separately of the armature current. Separate Excitation eg SepEx.
Usually in a sepex cart the field current is less than 20% of the armature current. (which is the reason they can use much smaller wires for the field windings)

But in a series cart the field current is exactly the same as the armature current. Whatever current is going through the armature is then also going through the field windings. That means the series cart is pulling far more amps at low speed than a sepex cart, simply due to the motor design. It's not good for either one to run at slow speeds for an extended period because of the higher current draw.

There is a point at which the load on the motor and current draw is so unbalanced against the resistance of the controller that heat generation will be at its peak. Slower than that and the controller will overheat first. Faster than that and the motor will overheat first. Usually this is around walking speed of only a few mph. The effect is made worse when trying to climb a steep hill, or trying to pull something heavy (like a trailer).

At some point the CEMF in the motor is balanced against the amount of load on the motor even if it is not running at full speed. Wind resistance, cart weight, tire inflation, all play a factor, so its impossible to say that a motor will always pull the most current at "X" speed, but generally a cart that is running at full speed is pulling slightly more amps than it would if its running just a few mph slower. There is a butter zone where throttle vs motor speed vs load is at an optimum balance and the amp draw will be at its least.

I tried to make that make some sense. It's sort of a broad topic, and the rules vary quite a bit for motors in a golf cart. But you can google Counter electromotive force and read all you want about it.
In general, the highest amp draw that a motor will pull is at it's lowest speed (zero) and the current decreases from there as the motor speed goes up.

[Tom47]

Thanks, Fairtax, for the in-depth answer.

I trailer my cart to a neighboring town that is very golf cart friendly. We typically ride 18 to 20 miles twice a week. Average speed is in the 10 to 12 mph range for the 2 hour cruise.

My March 2013 batteries [Yes, 8 years + on Crown CR-165's] perform very well. The voltmeter usually shows 49.2 to 49.8 when I get back after the rest on the trailer. Today I went 17.3 miles and returned home to 50.1 volts.

Is this operation bad for my Sepex cart? I've been doing just this since I upgraded to IQ in 2017.