Another data point: (but no motors and no multi-core video pattern recognition)
My philosophy for Carl is to manage load to find limits and stay out of trouble. Perhaps, if you want to try really pounding a Pi4 get another one and put it on your desk. The GoPiGo3 board will not supply enough 5v to drive the Pi4 to the max, but will serve up enough for exploring lots of topics.
You can also just add a usb-c powerbank to the Pi4 power connector and use the existing batteries to power the GoPiGo3, no?
I really want to post a picture of Charlie connected to a 12v car battery with huge-honkin’ jumper-cables as a goof. Not really connected, but to make it
like I’m powering Charlie off a gigantic DieHard! look
question! What happens if I connect something to my power connectors? both
More better goodness for longer. (Saw that in some forum post long, long ago …)
How do I go about creating the load-map. Perhaps yours is a sufficient guide that (at the very least) gives me relative magnitudes?
Put Charlie up on a pedestal, strap a multimeter between the battery and bot, and start plugging and unplugging, driving and not, sensing and not, speaking and not, etc.
But only when Carl gets off. Don’t you have him “up on a pedestal” already?
I have Charlie sitting on my desk with a fresh set of batteries installed. With that, the battery voltage returns 9.6.
If I attach a True and Authorized Raspberry Pi-4 Power Supply to the USB type-C connector, the “measured” battery voltage jumps to 18.something!
Obviously, the battery voltage hasn’t jumped by that amount. I suspect I’m going to have to take a look at the GPG driver board schematic and propose a hardware change.
nice way of giving me a heart attack!!!
r u sure? usb-c allows it.
actually, I think Also remember matt saying something about that happening and to ignore it.
USB-C allows a lot of things, including video.
The Raspberry Pi supply itself spec’s at “5.1V (DC) 3.0A”
Even with the GoPiGo battery connector removed, it still reads 18+ volts.
Translation: The “battery voltage” is only trustworthy if nothing else supplying power is connected.
Looks like I have a problem with the battery pack. I connect each one of the batteries to it, then turn the ON switch in the board and nothing happens (e.g no R.Pi3 lights at all)
I have a multimeter and made voltage test to the 9V connector (of the pack) and there is no output voltage at all ! 0V !
Then I made the same test to each one of the batteries, they are brand new and they are supplying the expected voltage.
Is possible the connector is defective, I’ve seen other posts of people…
. . . has a link to the voltage regulator data-sheet, and according to that, the absolute drop-dead max voltage is 45 volts for the garden-variety version.
Ergo, an 18v battery should work.
Ah, yes, but… but no biggie at 18v…
The DMP3017SFG power switch has a 30v breakdown voltage and who knows what the caps are rated at, but Matt didn’t seem to be too worried about being slightly over the 14v limit.
Here is one of Matt’s post on powering the GoPiGo3:
If the output is between 7.2v and 13v, and it’s rated to supply a constant 1.5A or greater, then yes, it should be suitable to power the GoPiGo3.
and a more specific “The absolute maximum voltage should never exceed 14.5v.”:
The board is labeled (on the bottom, under the power jack) center-positive “9-12V DC”. That is the target voltage that you should supply. If using 8xAA fresh batteries, the voltage could be as high as about 13.5v, which is acceptable. The absolute maximum voltage should never exceed 14.5v.
and this one also - he expressed concern about someone exceeding the 14.5v limit:
Please disconnect the batteries immediately. Unfortunately something might be blown. 3.96v times four cells in series is 15.84v, which is significantly above the recommended 9-12v, and is even notably above the
absolute maximum 14.5v. (emphasis added by Alan)
So it would appear the answer is:
The absolute, drop-dead, maximum input voltage is 14.5v
I can accept that, but I wonder why?
I guess that GoPiGo schematic is coming out of the drawer again.
Not sure if this big cap is on the input side?
Perhaps this is it?
Definitely possible. I have to look at it myself - when I get back from visiting friends.
I’m seriously considering unsoldering that cap and moving it to a different place on the PCB attached with a twsted pair so I can attach my Pi-4 without having to completely re-engineer the 'bot.
Or you could consider getting the newest board
Yea, all the way to Russia, right?