DCX500 with stock motor

[720Deere]

Alright resident experts, I need advice. I just installed a DCX500 and am planning to run the stock PDS motor until late Spring. Scottyb recommended setting the controller at 85%. It came set to 100% and I experimented with some settings today. At 85% with Turbo on, it does pretty much everything I need it to do. Which is worse for the motor, turbo or higher amps?

I ran it a little over 4 miles this afternoon and the motor was barely 130°. Primary use is on the street and in campgrounds. It does see some off road use for sporting clays and around the yard. I know it will generate a lot more heat off road and will be careful not to abuse it in those situations.

My next question is how much regeneration is acceptable with the stock motor? I have it set to 75% now and that feels about like mild hill on the stock controller. I guess a piece of that puzzle would be if I keep my foot in it down hill, I see about 6200 rpm max. I try not to lift 100% all at once at top speed. On flat ground it is turning around 5400 rpm.

My goal obviously is to not explode the motor and lose a $600 controller in the process! The good news is other than Disney in November, it won't see much use between now and April.

[JohnnieB]

Unless you are climbing hills steep enough to slow the cart down to less than walking speed (3-4 MPH), the only time the controller will be pass max amps is during a max effort acceleration from a standstill, and then only for the first few yards. This is because the faster a motor spins, the fewer Amps it can draw.

Basically, the windings of a stock PDS motor can dissipate the heat generated repeated short term Amp draws in the 400A range, but not much more than that, or for longer periods of time. With 23" tires, your motor will both be turning slower for a given cart speed and will take longer to accelerate from Zero RPM, so limiting the max Amps the DCX500 controller will pass to about 400A (80%) is a good idea.

Turbo mode operates on the other end of the RPM scale. What happens is that the field current is reduced, which allows the armature to draw more Amps and more torque is generated at a higher RPM, so the cart goes faster. It is inefficient and generates a lot of heat, but with 23" tire, you might get another 4 or 5 MPH at the top end.

You motor temperature looks good. Keep it under 239°F (115°C)

As for how much regen braking, it depends on the battery pack voltage and motor RPM. At 36V on 23" tires, I probably stay below 90%. I ran it at 85% when I was running a stock PDS motor at 36V on 17" tires. When I upped the pack voltage to 42V, I went to 100%.

If your motor only spins up to 6200 RPM going downhill with the pedal on the metal, and your motor only gets to about 130°F, you might not be treading on all that thin of ice. My stock PDS motor was spinning over 8000 RPM and the motor temperature was well over 200°F when 100% regen kicked in and everything got exciting.

The replacement motor and controller are more robust, but I try to keep below 6500 RPM. Fortunately, that is where the motor maxes out on level ground at 42V. Unfortunately, there is very little level ground in this area.

[720Deere]

Thanks, JohnnieB! You pretty much confirmed what I was thinking. The biggest thing I have going for me is limited run time. The cart rarely goes more than 1 to 2 miles at a time. The hardest duty it sees is when my daughter drives it around the yard. If I let her play around for more than 10 minutes or so, temps start to rise.

My concerns were/are more related to regen due to your past experience and the turbo function. Turbo definitely makes several mph difference. Much more of an effect than cranking the power up to 100% without turbo. I'm happy at 25-27 mph on "level" ground. I just have a couple of long hills that slow me down to the 12-15 mph range. I'm sure a motor upgrade and 48v will eventually take care of that problem. Until then, I can live with 16-20 mph on average hills. Disney Ft Wilderness is relatively flat so we should have no issue maintaining their 20 mph speed limit.

[JohnnieB]

I think you hit the "hardest duty" nail on the head. Driving it slow around the yard probably generates more heat in the motor than climbing the long hills at 15 MPH. On the other hand, you might be a bit overly cautious about how long you let your daughter drive the cart around the yard. At 130°F, the motor is barely getting warm.

The Max Amps and Regen levels, and whether Turbo is on or off, are essentially three separate subjects. Max Amps mostly affects low end performance while Turbo mostly affects top end speed, but all three generate more motor heat and heat kills motors. However, your motor isn't getting hot, so you can up the ante some if so desired.

Oddly enough, 42V and 48V systems run cooler than 36V systems. It is often stated here that Amps = Torque, which is true if the voltage remains the same. In actuality Watts = Torque and Watts = Amps Times Volts and that means you can get the same torque with fewer amps if the applied voltage is higher. Since the amount of heat generated is exponentially related to Amp flow, halving the Amp flow will quarter the heat generated.

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You can connect a laptop to the controller and log the amount of current flow and applied voltage while cart is being driven. The file saved can be reviewed after the fact in a spreadsheet and see how many Amps are drawn while driving around the yard vs the amps drawn climbing the long hills.

My tires are only 17" tall, so they very easy to turn and about the only way I can get my aftermarket motor to draw the max Amps my DCX500 controller will pass is to accelerate from a standstill on a 15° incline. Your 23" tires take about 25% more torque to turn, so you can probably max out your DCX500 on level ground and keep it maxed out for a longer period of time.

Basically, your setup has the potential of burning out a stock PDS motor, but it doesn't appear to be getting hot, so the way you and your daughter are driving it doesn't appear to be endangering it.

[720Deere]

130*F is on the street. With the stock controller on a hot day she could get the motor up over 200*F in short order with her slow cruising the yard and back field. So it sounds like if I keep the heat and rpm in check life should be good.

[JohnnieB]

Originally Posted by 720Deere

130*F is on the street. With the stock controller on a hot day she could get the motor up over 200*F in short order with her slow cruising the yard and back field. So it sounds like if I keep the heat and rpm in check life should be good.

Guess I'll have to backpedal on my statement about being overly cautious.

You can back off on the Max Amps and keep the motor heat down, or tell her to drive faster.

Also, just because the motor temperature climbs to 200° rapidly, doesn't mean it will get any hotter. Start/stop driving at low speed probably generates more motor heat than anything else and when I pull my little red wagon with my cart while picking up fallen branches and other lawn debris, the motor temp climbs to about 210° quickly, but never gets any hotter.

You're right about keeping the heat and RPM in check to prolong motor life and it sounds like your are doing it.

For a stock PDS motor with a few years on it, I'd limit it to about 6000 RPM, which is 33 MPH on 23" tires, keep the motor case temperature under about 230°F and set the regen brake current to no more than 85% at 36V.

[Turbo_Pumpkin]

Is there a way to monitor motor temps without logging them with the controller and then pulling the logs? I am planning on upgrading to an alltrax at some point soon but was wondering how I can monitor that easily on the fly. I have aircooled VW's and we always use VDO Cylinder head temp gauges but was wondering if something like that exists for these golf cart motors.

(Sorry to hijack the thread but I'm trying to learn about all this controller business)

[JohnnieB]

Originally Posted by Turbo_Pumpkin

Is there a way to monitor motor temps without logging them with the controller and then pulling the logs? I am planning on upgrading to an alltrax at some point soon but was wondering how I can monitor that easily on the fly. I have aircooled VW's and we always use VDO Cylinder head temp gauges but was wondering if something like that exists for these golf cart motors.

(Sorry to hijack the thread but I'm trying to learn about all this controller business)

Motor temperature is one of the topics being discussed in this thread.

First of all, the controller does not measure motor temperature. Just the parameters with check boxes shown on the attached menu screen.
The selected parameters can be monitored in real time, but a laptop display screen is difficult to see and is dangerous to look at while driving.

I simply attach a thermocouple to the motor and use a Digital Multimeter that has a temperature function to read it.
There are devices such as the Ex-Ray Volt that have a motor temperature feature: http://www.edt-exray.com/
IR thermometers can also used, but not for real time monitoring.

In fact, real time monitoring is not actually used by cart owners.
The critical temperature point is in the motor windings and you would have to have temperature sensors embedded in the windings to monitor their temperature, so case temperature is measured and there is a time lag between winding temperature and case temperature, so it isn't real time even if the meter is being observed constantly.

The motor case temperature can continue to rise after the motor stops. I run the DMM in Min/Max mode to capture the highest temperature reached during a trip.

The maximum allowable temperature for Class-H insulation is 356°F (180°C), but is degraded to 239°F (115°C) when measured at the motor case.

Heat damage is cumulative, but in normal driving conditions, if the case temperature is kept below 239°F, the insulation on the windings will outlast several sets of brushes and couple sets of bearings.

If you have other controller questions, or cart questions in general, just start a thread and ask away, you'll get answers.

[720Deere]

Originally Posted by Turbo_Pumpkin

(Sorry to hijack the thread but I'm trying to learn about all this controller business)

No worries about hijacking. It doesn't hurt to ask questions. I currently just check the motor case temp with an infrared gun. The Ex-Ray is on my wish list, but probably won't happen this year. It would be nice to have a nearly heads up display for speed, volts and motor temp. From what I have seen so far, controller temp is probably not going to be an issue. I have barely had the controller over 100* let alone the heat sink. With the stock controller, the heat sink would be well over 110* just from a ride around the block.

[beach cart]

I have had the EX-RAY volt for over 2 years, some of the best money I have spent, you can monitor motor Temp, voltage and voltage drop when accelerating, plus miles driven. Great product and support.