[Nexus One General] 5to1:
I thought it may help if someone provided some clarification about some of the points discussed in this topic. As reading through the thread, I think some people may have got the impression the calibration procedure improves the performance of the battery itself. When actually it just makes your phones reading of the battery capacity more accurate.

Firstly why is the calibration procedure needed?

Calibration can be done in the factory, however with devices which have removable batteries there will be some form of in device field calibration. It will be done automatically, however since the readings at extremes of charge are harder to accurately judge out of the box, sometimes the device won't accurately judge the capacity of your battery.

This will result in the calibration procedure picking up two incorrect readings. Firstly when the capacity is at 0 and secondly when the capacity is at 100%.

If you believe your device has incorrectly calibrated your battery capacity you should do the following:

1) Fully discharge your battery. This will set the capacity counter to 0 when it should be 0 (i.e battery is fully discharged).

2) Remove and replace the battery. So the phone knows a new battery has been placed into it and it needs to recalibrate (may not be needed for devices that automatically recalibrate after the battery dies).

3) Leave your phone to charge overnight. This will set the capacity counter to 100 when it should be 100 (i.e, battery is fully charged).

You can tell if your calibration is incorrect by running the following tests:

1) Charge the battery and watch the reading as it approaches 100%. If it suddenly jumps to 100% from a lower reading, the phone has over estimated the capacity of the battery. If it stays at 100% for some time but continues to charge the phone has underestimated the capacity of your battery.

2) Allow the phone to completely discharge. If you can power up the phone and continue to use it for some time, the phone has set the counter to 0 to early. If it suddenly powers off from a higher battery reading (i.e. phone says 10% then the battery dies), the phone has over estimated the capacity of your battery. The second event usually happens some time into the life of your battery, when it no longer has the same level of capacity as when it was new and the calibration was first done.

A complete discharge and recharge as detailed above should re-calibrate. As with a removeable battery the device would always need to recalibrate should you change batteries at some point.

In terms of the battery itself, it is important to note the capacity of the battery is not affected by the calibration procedure. Only the the phones understanding of the batteries capacity is made more accurate by calibration. Obviously you will see increased uptime, as the more accurate the calibration, the more of the batteries capacity the phone will actually use.

Lithium-Ion batteries do not have the "memory effect issue". So there is no need to charge cycle the battery to ensure optimal performance. This is only needed for calibration as set out above.

Infact, charge cycling a Lithium-Ion battery will reduce its life, rather then improve its performance. Therefore, it is something you should avoid doing regularly. However, the occaisional charge cycle won't make a huge difference and the benefits you'll see from accurate calibration will far outweigh the minute hit you take on the batteries performance two years down the line.

You have to remember that two years down the line when your battery does die, or has greatly reduced capacity, the device will probably be obsolete. Or the cost of a replacement battery will be negligible. Therefore there is no need to drastically change your usage habbits as there was with older battery technologies. You are not going to suddenly kill your battery because you ran it down a few times