Order Date: March 18th 2025
Order #: 349xx
Shipped: Not yet
Destination: United Kingdom
Arrived: Not yet
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Order Date: April 20th 2025
Order #: 368xx
Shipped: Not yet
Destination: Germany
Arrived: Not yet
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Wow. Iām wondering if theyāre improving the battery fire/explosion hazard too (caused by plugging power into pico while picocalc is powered on, under certain conditions)
Unlikely. Have there been any issues with that? Iāve never heard of any devices catching fire or exploding, and Iām guessing such things would be mentioned here on the forums or on the discord.
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I myself have found a issue on two different picocalc boards where plugging USB into the pico will apply that power directly to the batteries and overcharge them. I have also seen it happen to someone on discord, but he had no clue it was overcharged (his orange charge light had the fast ādangerā flash when he plugged USB into his picocalc).
I had been in communication with Alex, but his reply was a bit vague on whether or not they confirmed the problem existed. I had asked them to put out an official warning, but it seems they havenāt done so ĀÆ\_(ć)_/ĀÆ
Therefore, consider this an unofficial warning from some random internet stranger: Do not plug power into pi pico (or your module of choice) while picocalc is powered on and batteries are installed. Doing so can overcharge them to dangerous levels.
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Iām assuming youāre referring to the micro-USB port on the core module (e.g., the Raspberry Pi Pico included in the PicoCalc kit). Is there a specific reason one would connect power to this micro-USB port? My understanding is that the PicoCalc should be charged using the USB-C port on the main board.
Or do you mean to say that simply connecting the core module to our computer is applying the power to the batteries when the PicoCalc is turned on?
People use this port to flash the pico as well as to upload/debug programs (especially with the current micropython ports that do not redirect the default input/output to the picocalcās USB-C port)
No, that I understand. Iām wondering if simply using it for upload/debug purpose will cause the batteries to over charge. That doesnāt seem right indeed.
Perhaps this will give an indication of the severity of the issue. When certain conditions are met (picocalc is on, power is plugged into pi pico, batteries have high internal resistance or are at/near full charge), ~1.6A of current at near-USB voltage will leak through to the batteriesā¦
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Apologies, Iām still a bit confused. Where is the other end of the mint/green wire from the usb connected to? A power brick/wall socket or your computer/laptop?
And thanks for taking the time to get into details here. Really appreciate it.
Thanks for this info, and warning! Iāve had the orange light flash quickly too once or twice, and didnāt know what it meant. Iāve been doing a lot of firmware flashes while testing new builds of PicoMite/Webmite, and I noticed that the battery seems to charge on both the USB-C and on the micro USB. (I only ever have one connected at once, and Iāve rarely used the USB-C at all, since Iām mostly just flashing firmware these days) I figured that was expected behavior though, and that it wouldnāt be an issue, but I guess I was wrong. I think it only happened when I left the micro USB connected for a while, presumablly topping up the battery too much. Only reason I noticed was that I havenāt really had to charge the batteries normally with USB-C, and yet while the battery level dropped as expected from use, it would actually go up sometimes from being plugged into the micro port for firmware upgrades.
I only recently started displaying battery percentage in my startup routine under WebMite, and thatās when I noticed the number changing unexpectedly.
Okay so that clears it up. Thanks for the explanation.
@pkr - thanks for pointing this out.
It depends on the batteries. Some batteries have internal protection circuitry against overcharging. If yours donāt, you need to buy better batteries.
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Thats rough id be pulling my hair out by now
ciao! Ti eā poi arrivato? In caso affermativo, quante settimane ci ha impiegato?
thanks
Franz
Ciao Franz,
ho ordinato PicoCal il 16 marzo ed ĆØ arrivato il 29 aprile.
Paolo
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Still no news for shipments? 
I havenāt received an email about shipping yet. 
As soon as I get an email about this, Iāll let your all know. 
Order Date: March 19th 2025
Order #: 349xx
Weeks since ordered: 8
Business days to date: 39 & counting
Shipped: Not yet
Destination: BC, Canada
Arrived: Not yet
Alex said it would be shipped before the end of April
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Indeed, using unprotected batteries on picocalc is a real hazard, especially if the 2 slots are used (there is no balancing circuit).
I only had unprotected cells in reserve, so I had to check to avoid any nasty surprises.
From what Iāve seen, the only way to charge batteries āproperlyā via the AXP2101 is via the Type-C portā¦ But if you plug in the pi pico board, the voltage goes backwards switch U102, powering the AXP2101.
And if, in this configuration, you āswitch onā the picocalc using the usual button, hop USB voltage directly to the batteries and happy fireworks
Unfortunately, the picocalc lacks circuitry to switch/protect the VSYS coming from the picoā¦
So if youāre doing dev/debug work, I also recommend removing the batteries and only using them in āstandaloneā mode.