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Battery Performance

A project log for Street Sense

Portable electronic device to measure air and noise pollution

mike-teachmanMike Teachman 12/31/2019 at 19:110 Comments

I did some testing to see how long the unit can operate on a fully charged 3000mAh LiPo battery.

Before this testing the MicroPython code was tuned to optimize the runtime on battery power:

Starting with a fully charged battery, voltage is logged every 15 minutes to a SD Card file. Here is the profile of the battery voltage versus time.    Blue is the average voltage, Red is the minimum voltage over the 15 minutes log period.  I chose 3.3V as the battery voltage level that marks the end of the test.

Runtime:  41 hours

The standalone runtime of 41 hours exceeds the initial requirements of 8 hours standalone runtime. 

Next, I measured the recharge performance.  When the battery voltage was 3.1V I powered the unit with a 5V wall adapter.   Similar to the discharge test, average and minimum battery voltages are recorded to SD Card every 15 minutes.

The LiPo battery is recharged using the TP4054 Li-Ion battery charger component that is built into the Lolin D32 Pro module.   The plot below shows that the battery charger quickly ramps up the charge to 3.63 V and then a slower ramp-up to 4.21V over a period of 4.25 hours.  A constant voltage of 4.21V is applied for 3.0 hours.  The drop in voltage to 4.18V is a clue indicating that the charging is complete.

Recharge time = 7.5 hours

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