STM CircleOS forum / Shutdown Voltage of Primer2

todotani · 2009-10-21 15:28:00

Hi,

I have a question on battery supervision threshold of Primer2 (CircleOS).
Voltage thresholds of CircleOS 3.80 are as follows;

BAT_FULL_VOLTAGE 4200mV
BAT_LOW_VOLTAGE 3750mV
BAT_EMPTY_VOLTAGE 3500mV --> Shutdown Voltage

As discharge termination voltage of Li-Ion battery for Primer2 is 2.75V, I think I can use battery until around 3V.
If I can discharge battery less than current shutdown voltage, I can extend operating duration mach more.

Why shutdown voltage is set to 3.5V currently? Taking into account of voltage drop in DC-DC converter,
I think it is possible to discharge battery less than 3.5V.

todotani · 2009-10-24 14:59:20

Hi,

I measured shutdown voltage of my cell phone. It also use single-cell Li-Ion battery.
When low battery alarm generated - no operation other than battery charge was accepted -
battery voltage was 3.5V, same as shutdown voltage of Primer2.

Now I understood that substantial minimum voltage of Li-Ion battery is 3.5V. Because of
discharge characteristics of Li-Ion battery, voltage drops rapidly after discharge to 3.5V.

Regards

Francis · 2009-10-26 07:56:50

Yes, 3.5 is somehow a break. If you try to continue, you will get power for a short time, but you will increase the chances of damaging the battery.

# 1 2009-10-21 15:28:00 Shutdown Voltage of Primer2

Shutdown Voltage of Primer2

# 2 2009-10-24 14:59:20 Shutdown Voltage of Primer2

Re: Shutdown Voltage of Primer2

# 3 2009-10-26 07:56:50 Shutdown Voltage of Primer2

Re: Shutdown Voltage of Primer2

Board footer