Hpmc 24V20 suddenly dead... SRSLY?!?

hi friends
this is my first post. please excuse my bad english i am from AUSTRIA =)

my problem:

we want to make a kind of “scooter” for a shool project. we want to controll it with an arduino and we also want to make the documentation and the “plans” OpenSource so that everyone can build their own “scooter”

we use 2 pololu high power motor controller 24V 20Amps uncooled 27 Amps Cooled with 2 motors 500Watts
we measured at a dry test that the highest current is 13Amps so this didnt kill the controllers…

we put the whole hardware on a PCB and the first tests went pretty good.

yesterday we connected our sensors from an external supply voltage to an onboard voltage (from the arduino mega)

we wanted to fice up the motors but it didnt work… BOTH OF THEM… AT THE SAME TIME…
i cant believe that all 2 motor controllers suddenly decidet to die at the same time…

now i tell you what i found out:

at first motor controller the pins RESET DIR PWM are connected with GND (i measured that with a mulitmeter at no power on)
at the other controller the pins RESET DIR PWM FF1 and FF2 are connected with GND
is it possible that the controller is internal connected to GND at the pins i told?

the other thing is that you have to set the RESET pin to HIGH at startup.
when i turn the whole thing on and i measure the RESET pin on the controller there is 0.5Vols (there should be 5Volts because it should be HIGH)

when i disconnect the Arduino and i measure the RESET pin AT THE ARDUINO there are the 5Volts…
do i habe something like a SHORTCUT ON TEH MOTOR CONTROLLER?!?
is it normal that the motorcontroller Pins are connected to GND at the switched off state?

i dont know what to do now i hope someone can help us with this problem

when it helps here is a video where you can see how the PCB is made and that it worked…

greetins from snowy and cold austria
hans m steiner


I’m sorry to hear about your motor controller problems. I have separately tried to respond to your email about this problem, but my email keeps returning as undelivered with an “over quota” error. In your email you mention that you aren’t even measuring 5 V on 5 V output, which is a pretty bad sign if you are actually powering them correctly. Are you using their 5V outputs for anything? Can you tell me more about your setup? Specifically, how did you have everything connected? How long are your motor and power leads? What were you doing right before both controllers failed?

- Ben

we drove with the motors the day before then we noticed that a sensor broke we installed a new sensor and changed something by the sensor supply voltage 5V

we tried all (not the motors) and it worked…

then we installed all back and connected the hardware and as we wanted to try everything but the controllers didnt work…

can you tell me if its normal that the pins DÍR ´PWM and RESET are connected to GND on the CONTROLLER can you tell me if that is normal? because i dont think so… =)

it seems that i get here some thing of SHORTCUT!

when i connect 24v to the motorcontroller not even the 5V outputpin delivers 5 Volt!!!

i have this controllers 24V20amps

the leads to the motors are 45cm (1.6 feet)

greetings hoonse

What you are describing is not normal. As I said, it’s a pretty bad sign that you aren’t getting 5 V from the 5 V output, and it seems likely to me that both motor drivers are dead. Have you determined what event killed your sensor? Is it possible that the drivers were also damaged by this event or something you did when you wired in the new sensor?

Also, what is your power supply and how long are your power supply leads? Do you have the 5V outputs from the motor drivers connected to anything? A schematic of your connections would be very helpful if you have one.

- Ben

i couldnt kill the motor controllers because i just soldered a 5 v power supply from the arduino to the sensors and the motor controllers get their voltage from the 24Vbattery

the supply cables are 50cm long

i dont have a drawing from the wiring but i can write it:

controller site---------------arduino site
DIR----------------------------digital output
RESET-------------------------digital output
FF1----------------------------digital input
FF2----------------------------digital input
5V-----------------------------not connected
24V----------------------------not connected

but i dont think that i got a problem there because it already worked =)

what should i do now i cant buy 2 new controllers for 70 euro =)

thanks for your fast awnser

greetings from austria
hans m steinera

I don’t really follow what you are saying here. My main point is that if you killed a sensor, it is likely that something in your circuit wasn’t doing what you thought it was doing or you were connecting things in a sloppy way, and problems like these could affect other parts of your circuit as well, such as the motor drivers. One way to instantly kill the drivers is to accidentally touch your 24 V VIN to the 5V output pin when connecting power. It is also possible to kill the drivers by trying to draw too much current from the 5V output pins or by connecting power backwards. If both controllers initially worked fine and then suddenly stopped working at the same time, it seems almost certain something bad happened in your circuit to kill them.

If you contact us directly, I can probably set you up with a discount on replacement controllers, but I don’t know how practical that is if you have a deadline rapidly approaching. I think the quickest solution would be to get replacements from a local distributor and carefully search your setup for anything that might have killed this first set of drivers.

- Ben


i didnt connect anything to the 5Voutput from the controller because i use the 5 volts from the arduino

where could i contact you when i want a replacement?

that with the deadline is bad because my “holiday” is ending this week and the shool is beginning again but it will work…

thank you very much for the fast awnse

greetings hans m steiner

You can email me at ben at pololu dot com. I know you were having problems receiving emails; have you resolved that issue? If not, maybe you should look into getting an alternate/temporary gmail or hotmail account.

- Ben