MobileRead Forums - View Single Post - PRS-500 PRS-500 power consumption measurements

rothe957 · 01-26-2007, 06:53 AM

I charged my PRS-500 today using a lab power supply.
The battery was empty (reader came up, said "LOW BATTERY", then "NO BATTERY", then shut off immediately).
After I found out that USB charging won't work without driver,
I used plan B: a power plug from a universal adapter set and a lab power supply. I set it to 5.20V, turned output on and the reader started charging right away at about 560mA. Now, about 2 hours later, current is down to 140mA.
I then switched the reader on, it showed the "starting up..." screen.
During startup it consumed about 140mA more than when it was off (and only charging).
As long as the unit is just sitting there and no buttons get pressed, there is little or no additional current consumption (less than 5mA, maybe zero; the accuracy of the ampmeter in the lab power supply does not allow for more precise measurements, sorry).
A page turn causes a short (<2s) increase in current consumption, with a peak of about 220mA.

So much for the raw data.

Now a few ballpark figure calculations just for fun:
Lets assume a page turn consumes 180mA for 2 seconds. This means 360mAs or 0.1mAh per page turn. Judging from the physical battery cell size, it has a capacity somewhere in the 800mAh range. At 0.1mAh per page turn, you would get 8000 page turns out of a full charge in a perfect world. Well, pretty close to the 7500 claimed by Sony, considering that these are just ballpark figures..

^_^

01-26-2007, 06:53 AM	#1
rothe957 Ingenieur Posts: 8 Karma: 65 Join Date: Nov 2006 Location: Berlin - Germany Device: Sony PRS-500 / Hiebook / SonyEricsson P910i	PRS-500 power consumption measurements I charged my PRS-500 today using a lab power supply. The battery was empty (reader came up, said "LOW BATTERY", then "NO BATTERY", then shut off immediately). After I found out that USB charging won't work without driver, I used plan B: a power plug from a universal adapter set and a lab power supply. I set it to 5.20V, turned output on and the reader started charging right away at about 560mA. Now, about 2 hours later, current is down to 140mA. I then switched the reader on, it showed the "starting up..." screen. During startup it consumed about 140mA more than when it was off (and only charging). As long as the unit is just sitting there and no buttons get pressed, there is little or no additional current consumption (less than 5mA, maybe zero; the accuracy of the ampmeter in the lab power supply does not allow for more precise measurements, sorry). A page turn causes a short (<2s) increase in current consumption, with a peak of about 220mA. So much for the raw data. Now a few ballpark figure calculations just for fun: Lets assume a page turn consumes 180mA for 2 seconds. This means 360mAs or 0.1mAh per page turn. Judging from the physical battery cell size, it has a capacity somewhere in the 800mAh range. At 0.1mAh per page turn, you would get 8000 page turns out of a full charge in a perfect world. Well, pretty close to the 7500 claimed by Sony, considering that these are just ballpark figures.. ^_^