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Topic: 2 boards destroyed by using the Vin pin (Read 370 times) previous topic - next topic

amadeok

Hello,
I've destroyed 2 boards, a Leonardo and a Uno, by trying to power them using the Vin pin (not the 5V pin). The first time i was using a mosfet to control a 12v motor with PWM, everything was working fine even with the arduino powered by the Vin pin, but at some point i disconnected it and when i tried to reconnect it, boom, smoke. also the wire burnt a little. I was using a 12V 5A power supply.
Today i was testing a e-bike project with a 24V DC motor controlled by an arduino using the method shown in this video:  https://www.youtube.com/watch?v=ipFxYQkB5uw&t=281s
I was outside so i was powering everything from batteries, i had three 12V batteries in series supplying 38V to the controller and the motor was attached to the controller. I had an Uno powered by two 18650 lithium ion cells in series (about 6.4v). The ground between the motor  controller and the Uno was common in order for the PWM to work. Same thing, everything was working fine with the Uno powered through the Vin pin, when i was done testing i disconnected the ground pin from the arduino, then tried to reconnect it and boom smoke again.
Both boards are not recognized by the pc, have some leds on all the time and get really really hot as soon as they are powered.
I'm not sure why this happened?
Is it possible that is it because i had the ground terminal of the 18650 cells wired directly to both the Uno and to the Power In ground terminal of the controller?
thanks

hammy

I think we need some circuit diagrams  .

Depending on your circuit , disconnecting the ground may have put a reverse voltage or a higher voltage onto the Arduino than it can tolerate - disconnecting via the ground pin is never a good idea , and maybe the root cause .

You need to be careful with your wiring and have an understanding of what you are doing  with Connecting voltages from other devices operating above 5v. Higher than 5v voltages onto pins other than Vin can destroy it .... as you may have found .

WattsThat

If you're connecting and disconnecting power and or grounds when voltage is present, that would be why things are failing.
Vacuum tube guy in a solid state world

DVDdoug

"Motor" and "smoke" sound like a missing (or misused) flyback diode.

Another possibility is electrostatic discharge (from not grounding yourself when you touch the circuitry).

TomGeorge

Hi,
Have you got fuses on your power supply lines, especially if you are using batteries that are capable of 5A or more.

Any short and the current will, will as you have found, make the smoke appear.

How are you connecting your project components?

Can you post a picture of your latest smoking controller?

Thanks.. Tom.. :)
Everything runs on smoke, let the smoke out, it stops running....

amadeok

I think we need some circuit diagrams  .

Depending on your circuit , disconnecting the ground may have put a reverse voltage or a higher voltage onto the Arduino than it can tolerate - disconnecting via the ground pin is never a good idea , and maybe the root cause .

You need to be careful with your wiring and have an understanding of what you are doing  with Connecting voltages from other devices operating above 5v. Higher than 5v voltages onto pins other than Vin can destroy it .... as you may have found .

If you're connecting and disconnecting power and or grounds when voltage is present, that would be why things are failing.

That means i should have had a ON/OFF switch for the batteries?
If i had used a AMS1117 for the arduino it would have saved it?
"Motor" and "smoke" sound like a missing (or misused) flyback diode.

Another possibility is electrostatic discharge (from not grounding yourself when you touch the circuitry).
The motor controller does have a big diode that looks like a mosfet at the motor+ and motor-
Hi,
Have you got fuses on your power supply lines, especially if you are using batteries that are capable of 5A or more.

Any short and the current will, will as you have found, make the smoke appear.

How are you connecting your project components?

Can you post a picture of your latest smoking controller?

Thanks.. Tom.. :)
The motor controller has a 20A fuse but that one did not blow. by the way, either 1 or both of the mosfets on the motor controller are damaged, i can no longer control them with pwm, source and drain are always shorted.

aarg

Please provide circuit diagrams as requested in the first reply.
  ... with a transistor and a large sum of money to spend ...
Please don't PM me with technical questions. Post them in the forum.

TomGeorge

Hi,

Quote
That means i should have had a ON/OFF switch for the batteries?
Or just unplug the batteries.

Tom... :)
Everything runs on smoke, let the smoke out, it stops running....

amadeok

Please provide circuit diagrams as requested in the first reply.
This is the schematic:

Note that there are 2 mosfets, not only one, there is review of the motor controller here: https://www.youtube.com/watch?v=kgs_FILyppk

PerryBebbington

#9
Aug 09, 2020, 04:47 pm Last Edit: Aug 09, 2020, 04:50 pm by PerryBebbington
You have 36V* for a 24V motor...
Do you have a link to the motor controller? Is it designed for 40V?

*It will be closer to 40V if the batteries are fully charged.

MarkT

You may need lots of decoupling capacitance on the DC rail for a motor controller, 470µF or more is good, to
prevent overvoltage spikes and ringing from the motor inductance.

With a PWM motor controller you have the issue of back-feeding overvoltage when the motor is
suddenly throttled back when spinning fast - if the supply is a decent battery with high current
handling it should keep this under control though, as any current pushed back from the motor
as it decelerates just recharges the battery.

Your lead acid batteries are likely 2Ah, not 2A.

You always need a fuse with high current batteries like lead-acid or lipo, else you risk burning the wiring
up if there's a short circuit...
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

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