The Smell of Molten Projects in the Morning

Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.

The New Hotness

  • HW Bucked Lithium AA Cells

    The trail camera uses two parallel banks of four series AA cells to get enough oomph for its IR floodlight. I’m not convinced using bucked lithium AA cells in that configuration is a Good Idea, but it’s worth investigating.

    These are labeled HW, rather than Fuvaly, because it seems one cannot swim twice in the same river:

    HW bucked Li AA cells
    HW bucked Li AA cells

    In any event, they come close to their claimed 2.8 W·hr capacity:

    HW bucked Li AA - 2023-05
    HW bucked Li AA – 2023-05

    The lower pair of traces (red & black) are single cells at 2.7-ish W·hr, the blue trace is a pair at 5.4 W·hr, and the green trace is a quartet at 9.8 W·hr. Surprisingly close, given some previous results in this field.

    Recharging the cells after those tests shows they all take 3 hours ± a few minutes to soak up 730 mA·hr ± a few mA·hr, so they’re decently matched.

    Measuring the terminal voltage with a 10 mA load after that charge lets me match a pair of quartets to 1 mV, which is obviously absurd:

    HW bucked Li cells - initial charge 2023-05-05
    HW bucked Li cells – initial charge 2023-05-05

    The numbers in the upper left corner show the initial charge of four cells at a time required the same time within a minute and the same energy within 4%.

    Sticking them in the trail camera must await using up the current set of alkaline AA cells.

    Bonus: a lithium fire in a trail camera won’t burn down the house.

    After all, pictures like this are definitely worth the hassle:

    Young Buck in velvet - 2023-05-03
    Young Buck in velvet – 2023-05-03

    Looks like a pair of WiFi antennas …