Mark Fickett Art: LiPo Storage Discharger

Discharge a 1-3s (or more) LiPo battery to storage voltage. This uses an ATtiny85 to sense voltage and control a high-power LED to drain a LiPo to 3.85v for storage.

This circuit is for one cell of a LiPo battery. It can be repeated in parallel for an arbitrary number of cells. Thus, the circuit runs on up to 4.2v (for a freshly charged LiPo cell), down to around 3.8v (storage voltage, at which the load is turned off).

Code on GitHub.


circuit diagram

Parts List (one cell)

A right-angle male-male header can connect the circuit to the balance JST connector of a LiPo battery.


I built a 3s discharger, and used a mint tin with holes punched in it as a heat sink for the LEDs (attached with thermal tape). Depending on how far open the tin is, this can provide a desk light, reading lamp, or night-light while discharging.

low light, tin closed more light, tin open

I mounted the discharger on perf board, and left room to add dischargers for more cells if I get batteries that need it later.

circuit top circuit bottom