Very hot components with External Power Supply / Power over Raspberry Pi

woody123 · November 13, 2020, 9:51am

Hello

I bought a GoPiGp3 and am currently using rechargeable batteries.
In order not to discharge the batteries while programming, I wanted to use an external power adapter.

I left the batteries connected and also connected a USB adapter (5.1V, 2.5A) to the Raspberry Pi. Now some of the components seem to get very hot and there is a smell of burnt after a while.

I executed the following code (Running Raspbian for Robots):

import easygopigo3
g3=easygopigo3.EasyGoPiGo3()
g3.volt() # Returns 20.208 with external power supply on raspberry pi and connected batteries
g3.volt() # Returns 9.217 with batteries only

Executing ~/Dexter/GoPiGo3/Troubleshooting/all_tests.sh with batteries only returns:

GoPiGo3 Troubleshooting Script log

Checking for hardware, and checking hardware and firmware version.
==================================================================
Manufacturer    :  Dexter Industries
Board           :  GoPiGo3
Serial Number   :  ....
Hardware version:  3.x.x
Firmware version:  1.0.0
Battery voltage :  11.393
5v voltage      :  4.867

With batteries and power supply on raspberry pi:

===============================
GoPiGo3 Troubleshooting Script
===============================
all_tests.sh: 9: all_tests.sh: cannot create log.txt: Permission denied
tee: log.txt: Permission denied

Checking for hardware, and checking hardware and firmware version.
==================================================================
Manufacturer    :  Dexter Industries
Board           :  GoPiGo3
Serial Number   :  ....
Hardware version:  3.x.x
Firmware version:  1.0.0
Battery voltage :  19.643
5v voltage      :  4.987

Then I replaced the batteries with an external power adapter (12V, 2A). Here, too, some of the components are very hot, there is a smell of burnt and if you listen closer you can hear a high-frequency tone (this tone cannot be heard with the battery only or with connected power supply on raspberry pi and battery).

Everything works and I know that a Raspberry Pi 3B + can get very hot and sometimes smells a bit burnt when the processor has a lot to do.

So here’s my question: Is it safe to use the GoPiGo3 like this and is it normal for the components to get so hot? (What are normal values and what heat can the components withstand?). When do I have to worry that something will melt or even explode?

Thank you so much for your help.

KeithW · November 13, 2020, 1:30pm

Just curious what batteries are you using?
/K

woody123 · November 13, 2020, 1:59pm

I use eight VARTA AA recharge accus (AA, HR6, 1.2V, Ni-MH, 56706, 2100mAh).

cyclicalobsessive · November 13, 2020, 2:48pm

First, fire off an email to support@modrobotics.com for an ‘official’ response.

A while ago, when discussing various battery configurations, the hardware design engineer commented that the battery voltage measurement would max out at 14 volts, so I am surprised to see 19.6 volts period.

Something sounds not right.

You could check the (40-pin) Pi3B+ GPIO pins to GoPiGo3 socket is seated well with no bent pins.
Suggest you don’t use both power methods at the same time to be extra cautious
Check the Pi’s temperature and voltage throttling with:

throttled.sh

#!/bin/bash

# 0x10001  under-voltage 4.63v occurred / occurring
# 0x20002  freq-cap occurred / occurring
# 0x40004  Temp Throttled occurred / occurring
# 0x50000 means throttling occurred, under-voltage occurred
# 0x50005 means throttled now and under-voltage now

while true; do uptime && vcgencmd measure_temp && vcgencmd measure_clock arm && 
vcgencmd get_throttled; sleep 2; echo ' '; done

(Temperature should be under 80 degC to prevent throttling)

jimrh · November 13, 2020, 3:00pm

Interesting! In fact, I’d say VERY interesting!

Question:

Do you have a heat-sink installed on your Raspberry Pi?
Can you send a picture of the top and bottom sides of your GoPiGo (red) controller board? I"d like to know what version of that board you have.
Do you experience this with just a 5v supply plugged in and the external/battery supply NOT plugged in?

Many people, including myself, use their 'bots with both batteries and an external supply at the same time without difficulty, so you have me REALLY interested!

I will endorse cyclicalobsessive’s suggestion that you look very carefully at the connection between the GoPiGo board and the Pi itself because it’s really easy to get the connector offset by a pin-or-so, or to accidentally bend a pin. Trust me, I know. . .

Let us know what you find out. I have never heard of something like this before, aside from an incorrect connection.

One other thought just came to mind:
Are you ABSOLUTELY SURE that your external 12v supply is REALLY 12v, and not more? (Like 15v or even more?) If you can measure it, it would be really good to know what the actual voltage of your supply is. If it’s more than about 15v or so, you can fry the red GoPiGo controller board.

I mention this because some (so-called) 5v or 12v supplies are poorly regulated, if at all, and their actual voltage can be considerably different from their rated voltage.

P.S.
I don’t work for Modular Robotics/Dexter, I’m just a punter like the rest. Know my way around hardware though.

jimrh · November 13, 2020, 3:14pm

cyclicalobsessive:

throttled.sh

#!/bin/bash

# 0x10001 under-voltage 4.63v occurred / occurring
# 0x20002 freq-cap occurred / occurring
# 0x40004 Temp Throttled occurred / occurring
# 0x50000 means throttling occurred, under-voltage occurred
# 0x50005 means throttled now and under-voltage now

while true; do uptime && vcgencmd measure_temp && vcgencmd measure_clock arm && vcgencmd get_throttled; sleep 2; echo ' '; done

This is going right into my (new) “Big Bag 'O Tricks” folder for Charlie.

Thanks!

woody123 · November 13, 2020, 5:13pm

Thanks for your response and your inputs, I’ve made a lot of pictures…

First, this is the external power supply which I don’t use anymore and I have not tested it again - it sounds very bad - think it’s not the best power supply (I have no experience with such things):

Then there are this batteries and this power adapter I use. The problem occurred when I used them together (I read that this should be possible when programming), and I haven’t used them together for a long time since then (I won’t damage my board).

The output when I have plugged in only the batteries:

The output when I have plugged in both power sources:

And without batteries, only the power from the raspberry pi with the power adapter:

Batteries delivers 10V:

Checked the pins, they are ok:

If I had to guess, I would say that in the picture above the round thing in the middle (the one above the HDMI connection) is causing the high sound when I plug in the cheap power supply as replacement for the batteries (but I’m not sure).

–> When I connected both energy sources (i.e. the battery and the adapter on the Raspberry Pi), the metal around the on / off switch was also hot.

And I have some little heat sinks on the raspberry pi:

And the last pictures with the board itself:

Actually I work only with one power source: when programming I plug in the usb power adapter to the raspberry pi. And when I need the motors, I plug in the batteries and remove the raspberry pi power.

I have not tested anymore plugged in both energy sources because I won’t damage my board. I will send first a mail to support@modrobotics.com to check my first question:

Is it safe to use the GoPiGo3 like this and is it normal for the components to get so hot? (What are normal values and what heat can the components withstand?). When do I have to worry that something will melt or even explode?

The day before yesterday I ordered the same GoPiGo3, it should arrive on Monday. I will then check whether this behaves the same.

woody123 · November 13, 2020, 6:07pm

I’ve found other interesting behavior:

If I start the raspberry pi with the usb-power-adapter, the light near the power switch is red and the script sudo bash /home/pi/Dexter/GoPiGo3/Troubleshooting/all_tests.sh shows this:

===============================
GoPiGo3 Troubleshooting Script
===============================

Checking for hardware, and checking hardware and firmware version.
==================================================================
Manufacturer    :  Dexter Industries
Board           :  GoPiGo3
Serial Number   :  76A49436514E4C47324B2020FF04341E
Hardware version:  3.x.x
Firmware version:  1.0.0
Battery voltage :  4.608
5v voltage      :  5.211

Log has been saved to Desktop. Please copy it and send it by email or upload it on the forums

When I attach now the battery pack, the light near the power switch changes to green and the script sudo bash /home/pi/Dexter/GoPiGo3/Troubleshooting/all_tests.sh shows this:

===============================
GoPiGo3 Troubleshooting Script
===============================

Checking for hardware, and checking hardware and firmware version.
==================================================================
Manufacturer    :  Dexter Industries
Board           :  GoPiGo3
Serial Number   :  76A49436514E4C47324B2020FF04341E
Hardware version:  3.x.x
Firmware version:  1.0.0
Battery voltage :  9.628
5v voltage      :  5.219

Log has been saved to Desktop. Please copy it and send it by email or upload it on the forums

I can then remove the battery pack and it show’s again a Battery voltage of 4.608V.

Next I removed the power supply from the raspberry pi, plugged in the battery pack and powered on the GoPiGo3 with the power switch, the light near the power button is green and the script shows now:

===============================
GoPiGo3 Troubleshooting Script
===============================

Checking for hardware, and checking hardware and firmware version.
==================================================================
Manufacturer    :  Dexter Industries
Board           :  GoPiGo3
Serial Number   :  76A49436514E4C47324B2020FF04341E
Hardware version:  3.x.x
Firmware version:  1.0.0
Battery voltage :  9.114
5v voltage      :  4.871

Log has been saved to Desktop. Please copy it and send it by email or upload it on the forums

Now I plug in the usb power adapter and I have a Battery voltage of 19.771:

===============================
GoPiGo3 Troubleshooting Script
===============================

Checking for hardware, and checking hardware and firmware version.
==================================================================
Manufacturer    :  Dexter Industries
Board           :  GoPiGo3
Serial Number   :  76A49436514E4C47324B2020FF04341E
Hardware version:  3.x.x
Firmware version:  1.0.0
Battery voltage :  19.771
5v voltage      :  4.999

Log has been saved to Desktop. Please copy it and send it by email or upload it on the forums

If I remove the battery pack, the light is still green… and the Battery voltage still shows 19.771.

I thought it didn’t matter in which order I start and plug in the adapter or the battery, but it seems that I have to start the rasperry pi with the usb power adapter plugged in and then remove and attach the battery if I need the motors.

I tested another use case:

Plug in the usb-power-adapter, the raspberry pi starts and I can connect to it
Executing the script shows Battery voltage : 4.608
Plug in the Battery pack, Battery voltage shows 9.08
Remove the Battery pack, Battery voltage: 4.608
Plug in the Battery pack: 9.08
Turn off the usb-power-adapter plugged in the raspberry pi: 9.08
Turn on the usb-power-adapter plugged in the raspberry pi: 19.591!!!
Remove the battery pack: 19.591!!!

…and it starts to heating up and smells a little burned.

Sorry for all the text…

Hope someone can tell me what I can and what I should not do - because I see that a voltage of 19.5 is not good.

Maybe I have overlooked something in the documentation.

jimrh · November 13, 2020, 7:04pm

Woody,

You have a “new” version GoPiGo3 controller board. The large electrolytic capacitor at the edge of the board near the camera cable slot used to be located between the large inductor coil labeled “3R3” and the smaller silver electrolytic capacitor to the right in that picture.

It was moved to make room for a heat-sink for the Pi-4. Note that if you try to use a heat-sink with a fan, the inductor will interfere with it. I solved that problem by trimming about 3mm from the tops of the fan blades.

the 10.23v that you get from the batteries is normal. Since NiMH batteries are rated at 1.2vDC each, these must be fully charged. (I have some Varta brand batteries too.)

The artifact you noticed with the light and the presence and/or absence of the battery is normal. The “19.2” volts you see with both power supplies combined is an artifact of the fact that the GoPiGo board’s power sensing logic was not designed with the idea that power would be supplied both ways. On older boards it’s 14.something volts. I don’t have a new version GoPiGo3 board so I cannot compare.

Regarding heating:
I cannot see any heat damage on the GoPiGo board, so I suspect that the heat is coming from the Raspberry Pi itself.

With the boards separated that way, and the Pi running from 5v power, what gets hot?

woody123 · November 14, 2020, 3:49pm

I worked the whole day with the GoPiGo3. It worked well and I had no problems anymore.

My solution is to ALWAYS plug in FIRST the USB-Power-Supply to the raspberry. Then I can attach and remove the battery as often I need the motors.

But when detaching the USB-Power-Supply from the rasbperry pi, I shutdown first, remove the batteries and attach the USB-Power-Supply and start.

NEVER attach the USB-Power-Supply after the battery-pack and it works very well and no burned smell.

Thanks for all your inputs and help!

I sent an email to support@modrobotics.com, I’m curious what they will report back.

jimrh · November 14, 2020, 4:17pm

Interesting!

I never noticed that, and I’ve added and removed power supplies in random order many times.

Of course:

I have the older style board. (though that should not make a difference)
I am using a Pi-4 with a heat-sink and fan. Otherwise I get a “hot” smell too that comes from the Raspberry Pi.

If you decide to add a heat-sink and fan assembly to your Pi, let me know and I’ll send pictures describing how I did it.

woody123 · November 15, 2020, 8:31am

@jimrh I need the GoPiGo for a Machine Learning project and I would like to use a Pi4 in the future for more computing power (maybe I need another power source with more capacity too?).
I would be very interested in which heat-sink and fan you are using and how it is installed.

jimrh · November 15, 2020, 7:37pm

Things are a bit busy, I’ll try to get you some pictures in a day or two.

jimrh · November 17, 2020, 1:54pm

Here are the pictures I promised:

This is the picture of my Pi-4 with the heat-sink and fan installed.
(Note that I did the same thing for my Pi-3)

Two things to note:

The two wires are attached directly to the 5v reverse-voltage protection diode. (red wire/+ at the top)
Advantages:
a. It has direct access to un-buffered 5v DC.
b. It doesn’t use up any GPIO pins.
Disadvantages:
a. It’s always running whenever the power is on, even if the board itself is not running.
b. There’s no dynamic speed control.
c. There’s no tachometer feedback to detect fan stall/failure.
Note that these disadvantages - at least to me - are of trivial importance compared to the advantages in enhanced cooling, particularly the part about not using up any GPIO pins or i²c addresses.
There is a (relatively) large IC directly above the power connector in the lower left.
This is the power control/monitoring IC and it also gets quite hot according to the Pi-3/Pi-4 heat maps. Eventually I plan to cut a small piece out of another Pi heat-sink and attach it to the top of this chip.

Here are additional pictures of the heat-sink’s fan. Note that I have cut the tips of the fan blades a millimeter or so below the top edge of the fan’s shell. This is important because many fans actually “lift” slightly, floating on a magnetic field like a MAGLEV train. This causes the tips of the fan blades to rise above the outer shell.

This is another view, showing how the fan-blade tips are cut slightly below the edge of the fan’s outer shell.

The amount to remove should be determined by experiment. Trim them, place the board back on the Pi, fasten two screws on diagonally opposite corners, and power it up. (you don’t need to have a SD card installed, in fact it’s better to NOT have any kind of boot-device connected.)

Later on, if there’s sufficient interest, I will post pictures of how I installed an Adafruit Real Time Clock module to the bottom of the board with some ribbon cable.

Let me know if you need anything else.

mitch.kremm · November 17, 2020, 9:48pm

Hey woody123,

It looks like we’ve made some progress on here! I had sent you an email on Friday the 13th from our helpdesk. Please let me know if you didn’t receive it! Don’t forget to check any spam filters you might have active.

Talk with you soon,

jimrh · November 18, 2020, 2:42pm

Any chance you can, at the very least, summarize this for the benefit of the rest of us?

Thanks!

mitch.kremm · November 18, 2020, 3:01pm

This shouldn’t be the issue, as the GPG board is designed to handle both power sources at the same time. We suspect @woody123’s power supply to the Raspberry Pi is outside our recommended norms, but haven’t had a chance to test it.

jimrh · November 18, 2020, 3:09pm

Would not surprise me.

He’s using an Asiatic supply of a kind that I have too. It’s well worth testing both the output voltage and the ripple. (assuming you have a 'scope), as either or both can be, (shall we say), “interesting”.

Some of them say “12v”, but it appears that the “12v” is the nominal voltage under a relatively significant load. Open-circuit, or under light load, they can both have a higher-than-rated voltage and non-trivial ripple.

Another possibility is that he’s using a Pi-3. If he has inadequate heat-sinking, and/or inadequate air-flow, the board will get hot and smell hot. @cyclicalobsessive’s little test script is a valuable tool here as it allows you to monitor the temp of the board. In my case, (using a Pi-4), the presence of a fan drops the CPU temp by at least 20° Celsius, which can be the difference between a hot, burning smell or not and throttling or not.

In my case, (using a Pi-4), running his script with the fan running vs the fan stalled with a small screwdriver, made a significant difference in the temp of the board.

Suggestion:
If the GoPiGo O/S and/or firmware can keep track of the CPU temp, and cause the power lamp to either change color, or flash in a particular way, when the temp rises/CPU throttles, (or even both), that would be a Good Thing.

Nicole could add a block/construct to the Blockly programming environment that allows the measure of the CPU temp. (If it does not exist already, I haven’t checked yet.)

woody123 · November 18, 2020, 4:02pm

@mitch.kremm I sent a response to you - it contains mostly the same like what I wrote in this thread.

@jimrh I don’t use the asiatic supply https://forum.dexterindustries.com/uploads/default/optimized/2X/c/c63bd9ff78e591f6079a6485ba56d31ec3a5a4b9_2_367x499.jpeg anymore, I tested that only once and because it generated a high frequency tone, I never used it. The power supply I use is only the one for the raspberry pi like the one in the picture https://forum.dexterindustries.com/uploads/default/optimized/2X/5/58fda7c0170f7eb32834c155e22e528d3cc33699_2_690x397.jpeg.

I’m a little bit surprised only I can see a voltage of 19V with the following steps:

Plug in the usb-power-adapter, the raspberry pi starts and I can connect to it (power light is red)
Executing the script shows Battery voltage : 4.608
Plug in the Battery pack, Battery voltage shows 9.08 (power light changed to green)
Remove the Battery pack, Battery voltage: 4.608 (power light changed to red)
Plug in the Battery pack: 9.08 (power light changed to green)
Turn off the usb-power-adapter plugged in the raspberry pi: 9.08
Turn on the usb-power-adapter plugged in the raspberry pi: 19.591!!!
Remove the battery pack: 19.591!!! (The power light is still green!)

I can reproduce this behavior all the time and then it seems (imho) that it heats up more than normal.

I apologize very much for the big wave my entry is making . I have received a second GoPiGo3 with Raspberry Pi and will see if I can reproduce the same effect with the steps above.

But now apart from the heat that is produced (which unfortunately I cannot measure exactly at the moment and is just my feeling!!!), should the script “all_test.sh” never show such a high battery voltage of 19V?

jimrh · November 18, 2020, 4:41pm

I have learned to trust my gut “feelings” a lot more than a lot of (supposedly) expert texts. Science is only as good as its data - and it’s not uncommon for the data to be “interesting”.

The “19” volt reading is an artifact of using both supplies at the same time. I do not know exactly why this happens, but I would suspect that the presence of the Raspberry Pi adapter causes the “reference” voltage used to measure the battery to change. That would cause the readings to change dramatically.

Informational side-bar:
A measurement, ANY measurement, is nothing more than a comparison of what you’re measuring against some kind of so-called standard, and represents nothing more than a measurement of that ratio.

A mechanical kitchen or bathroom scale measures your apparent mass against the resistance of a spring - with the tension of the spring being the “standard”. An electronic scale, (if it is truly electronic), measures the deformation of a strain-gauge against a calibrated resistance.

A voltmeter, and it doesn’t matter if it’s a “mechanical” d’Arsonval mechanical meter movement, or an electronic multi-meter, works the same way. The mechanical meter measures against the tension of the springs in the meter movement - with calibrated resistances to take up the extra voltage. An electronic meter has a calibrated voltage provided by a special electronic circuit - or external components - that generates the “standard” that the unknown voltage is measured against.

Obviously, if that “standard”, (the tension of the spring in the bathroom scale, the value of the calibrated resistance in an electronic scale, or the calibrated voltage in an electronic voltmeter), changes, the “reading” will change too - often dramatically in proportion to the change in the “standard”.

In any event, the change in measured battery voltage is a result of the two power supplies being present at the same time, and not an actual measurement of the true battery voltage. (at least as far as I know as I have never done any significant research on this.)

Does your meter have a thermocouple input?
Have you tried running cyclicalobsessive’s script?

It would be very interesting to see what the temperature of the CPU does when either one, or both, supplies are attached.