It's funny how this project has evolved over time. It started with the #LiFePO4wered/USB, which I once connected to a Raspberry Pi as a demo for a Mini Maker Faire. It seemed to work well, and out of that the LiFePO4wered/Pi was born.

Then people wanted to use the LiFePO4wered/Pi as a UPS for the Pi 3, which drew more power than the #LiFePO4wered/USB charger could support, so I created the #LiFePO4wered/18650 as a more powerful charger and the LiFePO4were/Pi3 was born.

Now people are trying to power complete systems including hard drives and LCD screens from the LiFePO4wered/Pi3 and turns out it still isn't powerful enough. It seems the power craved by makers is insatiable. :)

I have received reports of customers powering Pi 3s with LCD screens successfully, and others reported that this failed. The worst thing was that according to the reports the LiFePO4wered/Pi3 did not do a clean shutdown first but power just went away, indicating the boost converter went into thermal overload and switched off. I decided that instead of calibrating this with "it can power a Pi3 at 100% CPU", I needed to come up with some real numbers. So I got a nice electronic load from AliExpress and did some testing:

Testing indicates that the maximum continuous load that doesn't cause the boost converter to go into thermal shutdown, at room temperature and with no extra cooling, is around 0.9A. The system had been designed with components rated for 2A, but on the tiny PCB it seems the boost converter just can't dump enough heat. Keep in mind that this is a thermal effect, so it takes time for the temperature to build up, meaning peak currents of 2A may be fine but are not sustainable over time.

The LiFePO4wered/Pi was originally designed for a Pi Zero or Model A+ or B+ load, for which it works fine. Then the "ping" of making the charger more powerful made the LiFePO4wered/Pi3 possible, still using the same boost converter. But now people want to power all kinds of peripherals as well, and a "pong" to bump up the current capability of the boost converter may be in order.

Luckily new and improved components arrive on the market all the time, allowing more powerful circuits in even smaller dimensions. One such component is the TI TPC61235P, which is a significant step-up to the MIC2876 I currently use. So I made a new layout based on this component and have prototype boards on order from OSH Park:

Tight, but it all fit. Can't wait to test performance of these prototypes!