I have a solar/24 V battery bank for a remote application, continuous running of a Pi4. Would you recommend the Witty Pi 3 hat for the Pi4, and do you have any recommendations about heat sink/fans for that input voltage? I also need an RTC with that chipset so this seems like a good fit. Thank you!
Hello @taylor2112 and welcome to the RobotShop community,
The Witty Pi 3 adds an onboard LDO voltage regulator (LM29150) and hence it can accept up to 26V. But that doesn’t mean you can simply use 24V, the LM29150 is a linear regulator 9not the best option for you application), which means the dropped voltage will be dissipated as heat and the heating power can be calculated by:
Pheat = Vdrop * Iout
For example, when using only Raspberry Pi 4 and no other devices attached, the Iout is about 0.5A. If we input 24V and let the regulator to regulate it to 5V and power Raspberry Pi, the thermal dissipation power will be:
(24 – 5) * 0.5 = 9.5W
This needs to be dissipated soon enough, so you would need to install an external heat sink. You can find more information about this in the product’s manual.
A better option would be a switching regulator, you can find some options here, for example:
Choose one according to the current requirements of your project!
Let us know if you have further questions