I’m interested in setting up a Raspberry Pi that can be powered by a battery while said battery is able to be charged by a solar panel simultaneously. (It’s OK if the battery runs out of charge and the Pi shuts down, I’m just curious to see how much the solar panel could extend the battery life.)
Is this… physically possible? I don’t know much about electronics. I read something about needing a charging circuit and a “passthrough” battery.
I found the SunnyBuddy <https://www.sparkfun.com/products/12885> – do I just need this plus a LiPo battery plus some wiring? And once I’ve got all that, the Pi needs a power source with a micro USB connector, not a bare battery – what’s the trick to that?
Sadly we don’t have an all in one solution for a solar powered Pi, but we have something close and by combining a few parts we do carry, you should be able to make something work.
The Pi requires at least 5 volts to run and the Sunny Buddy can’t supply that much so I’d skip that unless you want an engineering challenge. I’ve never tried to solar power a Pi before but out of the parts we carry, I’d recommend is the following parts:
- Solar panel that outputs 4.2 to 10 volts max. (Our [[9 Watt panel](https://www.sparkfun.com/products/13784) would probably work OK.)
- 4.2 - 10 volt DC to DC converter to limit voltage if your solar panel outputs more than 10 volts max.
](https://www.sparkfun.com/products/13784)
The PiJuice HAT takes care of battery charging and boosting battery voltage to 5 volts for the Pi. It also includes a RTC for keeping time when the Pi is off and includes a battery. (You can substitute your own external battery if you wish.) Plus, there’s software that allows you to monitor the battery and input voltage and shut the Pi down if needed.
I already own a RAVPower 16W panel that says it outputs a maximum of 5V / 2.4A. Seems like it would work with the PiJuice directly… I’ll give it a shot!
Sadly we don’t have an all in one solution for a solar-powered Pi, but we have something close and by combining a few parts we do carry, you should be able to make something work.
The Pi requires at least 5 volts to run and the Sunny Buddy can’t supply that much so I’d skip that unless you want an engineering challenge. I’ve never tried to solar power a Pi before but out of the parts we carry, I’d recommend is the following
Just out of curiosity, why can’t the sunny buddy supply that?
From what I understand, The sunny buddy takes an input voltage of 6V minimum but no specifics about the output voltage. Is it because this is an MPPT board and the voltage might drop below 6 in which case the Sunny Buddy wouldn’t work?
Just out of curiosity, why can’t the sunny buddy supply that?
The Sunny Buddy is only a battery charger and at most will output 4.2 volts when the battery is fully charged. Since the Pi needs at least 5 volts to run, the Pi wouldn’t work with the output the Sunny Buddy has.
You could add a DC to DC boost converter to the output of the Sunny Buddy to boost the output voltage up to 5 volts to make the Pi happy, but that comes at the cost of consuming more current from the battery/Sunny Buddy combination. There’s a 450mA limit on how much the Sunny Buddy can supply and the typical modern Pi idles at 400 to 575mA.
All your solar energy would end up powering the Pi and none would be left over to charge the battery. Or worse, your Pi might need more than 450mA and you’d be draining the battery and using all 450mA from the Sunny Buddy. In that case, the battery would slowly discharge and would never be able to charge again since the Pi was using everything you have available. Shortly after the sun went away, the battery would die, everything would shut down and you wouldn’t make enough power the next day to recharge.
What you need is something that can output enough current to charge the battery and run the Pi at the same time. The only product we currently carry that can do that is the PiJuice. What I’m trying to get at is for the most part, the Sunny Buddy’s output isn’t large enough to run a Pi. It’s made for a much less power hungry circuit.
I don’t know much about electronics. I read something about needing a charging circuit and a “passthrough” battery.