# Calculate run time of battery to a specified voltage

Started by September 20, 2019
On 31/10/19 17:16, AK wrote:
> On Sunday, September 22, 2019 at 2:49:28 AM UTC-5, Phil Allison wrote: >> whit3rd wrote: >> >> ------------------ >>> >>> >>> No, the mAh rating comes with an explanation of the test conditions, >>> you just need the full manufacturer's data sheets. >>> >>> Sometimes there's a time/voltage graph, and you can chose the cutoff >>> voltage and measure area-under-the-I-V curve. >>> Sometimes there's a specified V when fresh, and V when dead >>> (alkaline, typically 1.5V fresh, 1.0V dead; lithium, typically 3.6V fresh, >>> 3.0V dead). >>> >> ----------------------------- >> >> ** The OP has indicted his load is a clock, dunno what kind but any battery clock will be engineered for absolute minimum DC current draw. >> >> Standard Quartz mechanisms are phenomenal current misers, alkaline AA cells last a year or more. Average currents being in the order of 100uA. >> >> It follows that a D size cell would last much longer, maybe 5 or 10 years. >> >> IOW, its entire shelf life. >> >> Matters more how fresh the cell is when you purchase it. >> >> >> >> .... Phil > > Sorry for the late reply. > > The clock uses about 25 Ma and the AAs lasted about 3 months. > > Andy >
A Duracell AA has 2850 mAh and a D 15000 mAh (*). So, a crude assumption is that your D cell will last about 15 months. (*) Looked it up some time ago Pere
o pere o lunatic wrote:

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>
> > Sorry for the late reply. > > > > The clock uses about 25 Ma and the AAs lasted about 3 months. > > > > Andy > > > > A Duracell AA has 2850 mAh and a D 15000 mAh (*). So, a crude assumption > is that your D cell will last about 15 months. >
** What does 2850 / 25 / 24 = ?? .... Phil