Jess and I collaborated on the idea of investigating the in-and-outs of potato batteries. We know they are used to make potato clocks, but even that was a surprise to me when learning in class. The journey to understand what we can power with potatoes has been an interesting one. We started with reading a lot of articles online and seeing what people have already done with using potatoes as battery.

Week 11 - Potato Battery links

Jess and I have a running document of links we’ve looked at, videos and our process.

https://docs.google.com/document/d/1eW5biq6_hhp5XPb4r8Hy4OUrH9qjwRWSdOgfuRid9dQ/edit?usp=sharing

The project has once again, evolved into yet another measurement project.

We took A LOT OF measurements.

Starting from one single potato, to gradually growing to 20 potatoes, we put five of them in series then four rows in parallel trying to reach the max amount of current we can get. One single potato can provide 0.8-1.0 V, the current is around 0.051 mA. But in later experiments, we noticed that by boiling them in water for 8 mins, the current increased by 10 times, as proven by the articles we read.

We know that five potatoes put in series can light up an LED.

Some photo documentation of all of that:

We felt pretty ambitious at first seeing the measurements and attempted to power a low power consuming microcontroller with it. We wanted to test with ATTiny and a simple blink. It took us a couple tries to realize that even if in theory we are providing enough voltage, it drops hugely when we connect the potatoes to the ATTiny. Jess found out that it is because of the internal resistance of the potatoes is quite high. To provide the 3.3V needed for the ATTiny, we need a lot more potatoes. We also decided to see how much we can achieve with boiling all the potatoes and maximizing the voltage and current we could get.

Unfortunately our findings shows that

We need ~4mA for the ATtiny using the lithium battery, and the max current we could read from the potatoes connected to ATtiny is ~0.2mA, we can estimate that we need 20x the amount of potatoes that we tested (4/0.2 = 20), or 20x30 = 600 potatoes.

We had big plans initially to power an ATTiny and send potato recipes when the potatoes are plugged in. Clearly we will need a lot more potatoes to do that.