Max input current on PiJuiceZero - using with larger 12v Solar Panels #1107
Description
I didn't get any replies on the discussion thread, so I'm hoping someone might have some advice for me posted on an issue instead.
Discussed in #1098
Originally posted by robcoward September 16, 2024
I have a PiJuice Zero attached to a Raspberry Pi Zero 2 W driving a USB webcam, with a 10,000mAh battery attached. My aim is to power this by Solar / battery alone, so that it can run off-grid making either a Wifi connection (or maybe later a 4G USB modem) back to my network.
Initially I tried powering it with a 6W panel with a 5v USB output, but due to the non-ideal location of the solar panel not getting direct full sunlight on it, I never had the pijuice_cli status show the USB Micro input as anything other than NOT PRESENT or BAD.
Next I tried upgrading the panel to a 30w 12v panel, theoretically capable of generating 2.5A in optimum conditions, connected to a 12v to 5v buck converter before attaching it to the PiJuiceZero. This now occasionally now gives me a WEAK input and every now and then changes to PRESENT - however when switching off the mains input on the PIZero power connector, this immediated drops back to WEAK and the battery level starts to drop as the current from the panel is clearly still not enough to power the pi and keep the battery charged.
Now I want to try a larger panel but not being an electrical engineer, I need some advice from the community please. I read in the PiJuice hardware docs that the USB Micro Input has configurable current limiting, with settings at either 1.5A or 2.5A. If I use a 120W 12v solar panel, that is theoretically in optimum conditions (not where this panel is going to be used) capable of generating a 10A current. As long as the buck convertor I use to step down to 5v can support 10A, can I connect this then into the PiJuice and have it limit the current to the required 2.5A (if the panel ever generates something higher)?
The buck convertor I am currently using has a micro usb connector output which I use to connect to the PiJuice board - would I be better off soldering the buck convertor output to the J4 pads instead of using the micro usb ? It's a shame the input only supports 4.2 - 10V - it would be a lot handier if it could take the 12v feed direct without needing to step down.