• Cell Authenticity
    Li-ion cells, especially 18650 cells, are ripe for fraud. They are such a commodity these days that sketchy distributors can make a handy profit by wrapping cheap low-quality cells in name brand skins and selling them for a premium. They get creative. Sometimes they’ll take low-end cells from a certain...

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  • Voltage Alarm
    It’s been nearly a month since my last post! Why? Well, there’s been lots to learn. Testing Battery Authenticity In the last post, you saw a picture of 3000 Li-ion batteries that arrived. Although the vendor has a good reputation and seems trust worthy, it seemed like a good idea...

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  • Batteries & Faraday First
    Batteries! They arrived today. 3,000 LG Chem MJ1 cells. These are 18650 Li-ion cells with a nominal voltage of 3.6 V and a capacity of 3.5 Ah. That’s 12.6 Wh in each cell. 37.8 kWh in the whole pile of batteries. Sound like a lot? Well it’s about the same...

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  • Coulomb Keeper
    I need to tell you all about 3D printing flying R/C planes, and I will. It’s really cool! But this blog is about a different type of 3D printed airplane. It’s called the Coulomb Keeper. While at the Sustainable Aviation Symposium, I introduced myself to Phil from How Flies The...

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  • Welding Batteries
    In the previous post on the electric skateboard I alluded to a better way to connect batteries. The steel springs and screw I had originally used led to voltage sag because of the relatively high resistance of steel. A better solution is to use Nickel strips and spot weld them...

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