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RotaryCell / build guide

Prepare the battery

This build uses one Samsung 58E 21700 cell. It is a flat-top, unprotected 5330 mAh cell. The LilyGO provides the charging and battery protection used here.

The finished battery harness uses 10 cm lengths of 24 AWG wire: yellow for battery positive and black for battery negative. I soldered each wire to a nickel tab before attaching the tabs to the cell.

Yellow and black battery leads soldered to nickel tabs

Attach and insulate the tabs

Spot-weld the black lead to the negative end and the yellow lead to the positive end. The photographs show the sequence I used, but this guide does not attempt to teach battery spot welding.

The first nickel tab attached to the cell

Fold the tabs along the side of the cell so the leads leave in the same direction. Insulate both ends of the cell and every exposed part of the tabs.

Both nickel tabs fitted and folded along the cell

Fit the red two-pin connector in the same orientation used by the LilyGO battery harness. The completed battery should look like this:

Completed and insulated 21700 battery assembly

Check the connector polarity once before plugging it into the LilyGO. The black lead goes to LilyGO BATN; it is not the same connection as the system ground used by the carrier board.