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Topic: Pro Mini VIN Problems / can I use LI-ON 4s pack ? (Read 210 times) previous topic - next topic

sfdgvh234523io3452

Im trying to power my pro mini with a pack of 4 18650's that are in series to the raw pin but it frys the board instantly, I know its only meant to handle 12v but I seem to have the same issue with my bench supply as soon as i went over 6v the PCB started to smoke... So my question is could i run the pro mini off 1 cell to the VCC pin ? i have a cell balance board but wouldnt that cause problems having a small drain on 1 cell and not the other 3 ? (the pro mini is only driving 6 neopixels and a PWM signal for a ESC)

jremington

#1
Jun 14, 2018, 04:01 am Last Edit: Jun 14, 2018, 04:03 am by jremington
In addition to obeying the Vin voltage restrictions, you may not exceed the maximum recommended power dissipation of the on board regulator.

For the tiny regulator on the Pro Mini, that means you can't power more than a couple of LEDs, and the problem gets worse, the higher the voltage on Vin.

How are you powering the Neopixels? Post a wiring diagram (not Fritzing).

sfdgvh234523io3452

#2
Jun 14, 2018, 04:12 am Last Edit: Jun 14, 2018, 04:13 am by sfdgvh234523io3452
sorry i should also note at the time the mini died i had nothing but vin hooked up and I had this happen before so i slowly turned up my bench supply and as soon as i reached 6V the capacitor started to smoke below the regulator.

jremington

#3
Jun 14, 2018, 04:22 am Last Edit: Jun 14, 2018, 04:24 am by jremington
Sounds like you connected the power backwards, or to the wrong pin. We have all done that at one time or another.

sfdgvh234523io3452

but it runs at 5v just fine? its as if the regulator isnt working and the chip just gets the input voltage :/ there inland brand pro minis, i put the positive to the corner pin and ground to the left of it

Wawa

i put the positive to the corner pin and ground to the left of it
the capacitor started to smoke below the regulator.
Statements are sort off useless without a proper picture, with the pins/part marked.
Is this the tantalum cap between the 5-pin regulator and the RST pin.
What are the markings on it (should be 106/16), and is the stripe closest to the corner of the board.

One neopixel, powered from the 5volt pin, could already generate >0.4watt in the ProMini's onboard regulator when powered with 12volt. Enough to send it to SiliconHeaven in seconds.
Might be wise to power the ProMini and the Neopixels with a 5volt micro-power buck converter.
Leo..

sfdgvh234523io3452

#6
Jun 14, 2018, 05:49 am Last Edit: Jun 14, 2018, 05:56 am by sfdgvh234523io3452
OK yeah looking at heat output and things i guess its jsut not going to be worth running the regulator. That brings me to the other half of the question can i run the pro mini at 2.8V - 4.3V ? by using 1 cell in a 4 cell pack in series with a cell balance board? or would one cell drain too fast ? (the device only gets turned on every few minutes for about 5-10 minutes with usually at least a few minutes break)

Wawa

Not wise to draw power from a single cell in a battery stack, if that's what you mean.

As said...
"Might be wise to power the ProMini and the Neopixels with a 5volt micro-power buck converter."
Leo..

P.S. could use a car USB charger for that.

sfdgvh234523io3452

Not wise to draw power from a single cell in a battery stack, if that's what you mean.

As said...
"Might be wise to power the ProMini and the Neopixels with a 5volt micro-power buck converter."
Leo..

P.S. could use a car USB charger for that.
even with a cell balance board and a draw of like 100-300ma ? Im going to go with the buck converter tho as it seems the most reliable way :( back do re designing the entire project to fit it (I have 0 room for any more stuff in the housing) sigh this is why math is important and knowing what you are doing...

Wawa


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