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Low battery shut-off voltage?

Discussion in 'Android Lounge' started by jseyfert3, Dec 20, 2011.

  1. jseyfert3

    jseyfert3 Newbie
    Thread Starter

    Having switched from an LG Ally to a Samsung Galaxy Nexus, I noticed a related drop in battery life with heavy usage. :D

    I installed Current Widget, charged my battery until the voltage topped out at 4.206V, rebooted into Clockwork Recovery, wiped the battery stats, rebooted and then unplugged my phone. Let it sit overnight, dropped 5% in 6 hours on standby, then I used it during the day today until it auto-powered off during my game. Upon checking the log, I found the lowest voltage to be 3.573V.

    I did some research, and I found the safe cutoff voltage for Lithium Ion cells is about 3V, not 3.6V. So, now I have two questions:

    1) Why is it set so high if the safe low voltage is almost 0.6V lower?
    2) Can I change this low-voltage auto shutdown level somehow, and if so, how?

    Before someone says it won't add much, I know:
    But if the graph is accurate it looks like you lose about 6% of your available power with the high cutoff. Which again isn't much, but every little bit helps with these power hogs.

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  2. Paul_T

    Paul_T Lurker

    You are right that modern phones are power hogs, I imagine that is why the limit is set so high. As the voltage of the battery decreases so does the max current that can be drawn. If you can run the voltage down to 3V you might find the phone shutting down suddenly as soon as you do anything that needs mode current than the battery can provide.

  3. chanchan05

    chanchan05 The Doctor

    You run the danger of getting too close to below critical charge. As the phone shuts down, it still uses a little bit of power to properly shut down running apps, kind of like your PC, why it takes some time to shut down. If you take it to extreme min level, if the amount of power the shutting down process takes the battery below critical charge, your battery will be useless. A li-ion battery that was drained below critical charge cannot be recharged anymore.

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