Overview

The only information the PlayBook provides a user in its current form is a battery "percent remaining" level. This is merely an estimate based on a calculation involving several different factors. It doesn't always reflect the actual state of your battery.

Battery Guru digs below the surface to pull out more data. It shows you the actual battery voltage, as well as power consumption when charging or discharging. Note that the readings you see in Battery Guru come directly from the Tablet OS itself; the app is not in control of when they are updated or what values they have. In normal use, running off the battery, the readings are updated once every two minutes. When charging the time may be shorter, generally about 30 seconds. Sometimes a value may spike or show a bizarre reading for one sample: this is not a bug in the app, though it may reflect a bug in the operating system.

Help Us Improve Battery Guru!

We could really use more data. To help us improve Battery Guru, please use the app frequently or continuously over the course of a few days or weeks, then hit the Export button and send us a copy of the file in an email. We'll use that to identify unusual situations that may arise, determine "typical" values across all PlayBooks, and improve the app's capabilities for future updates. You can use the support address below, and please accept our thanks in advance for your time and assistance.

What is "battery health"?

In short, it's how much charge your battery holds compared to the manufacturer's specifications.

The PlayBook's two batteries, combined, are designed to hold 5400mAh of energy. In actual fact, no lithium battery ever makes it out of the factory with the full capacity as printed on the label (i.e. with 100% health) and, over time, this capacity slowly drops further.

Most batteries even a month old will likely have dropped to around 90%, and over the next couple of years this will drop gradually to around 50%. At that point your battery will provide only half the designed capacity.

What does the battery voltage mean?

The voltage should range between 3.4V and 4.2V. Lithium batteries are protected against over-charging and over-discharging. The PlayBook will never allow your battery to go much outside this range. The importance of being able to see the voltage level is that it lets you check whether the "percent remaining" estimate is accurate.

Some tablets may appear to go down only to 20% before shutting off. If the voltage is actually getting down near 3.4V, then everything is probably okay.

Likewise, some tablets charge up to only 92% and then appear to "jump" to 100%. If the voltage is actually about 4.2V at that point, everything is probably okay.

How does "recharge count" work?

This value, as with all the others, is provided by the Tablet OS itself. This value represents roughly the number of times you've charged up the battery but, since you may not always drain or charge it fully, it will sometimes change at unexpected times, or not change when you expected it to. Consider it an approximation, since that's all that really matters here anyway.

What is "charger type"?

This simply reflects whether there is a charger attached and detected. If it reads "NONE" then your charger is not connected properly or not working properly. Because the PlayBook will continue to use power even when charging, it's possible for a charger to be connected but for the battery to continue draining. We'll go into this in more detail some time later...

What's In the Export File?

When you export, which can take up to a minute if you have many months of readings, a CSV file is generated and stored in the "documents/BatteryGuru" folder. This is the folder accessible via Wi-Fi as a network share under your PlayBook's IP address. In Windows, you would get there using an address something like \\192.168.0.55\media\documents\BatteryGuru, with the number replaced by your PlayBook's own address. You can discover this address in your Settings under About by selecting Network in the drop-down, and looking at the IPv4 entry.

The actual export file will be named with a timestamp based on the first and last reading in the file. An example would be export-20110708T142140-20110717T141743.csv which contains data from July 8, 2011 at 14:21:40 until July 17 at 14:17:43 (24-hour time).

These values are currently exported in this file:

  • Session: a number that goes up each time you run the app
  • Timestamp: date and time of a given entry or reading
  • Level (%): the battery percent-remaining estimate
  • Voltage (V): the battery voltage
  • Current (A): current charge or discharge current; this will read 0 when the battery is fully charged but the tablet is still connected to the charger
  • Power (W): power, which is Voltage ×Current, as supplied by the OS
  • Energy (Wh): an estimate of remaining energy in the battery
  • Temperature (°C): an estimate of tablet internal temperature
  • Notes: optional, notes about various events or infrequently changed values such as the battery health

Note again that each of these values, with the exception of Session, Timestamp, and Notes, is just reported as supplied by the OS.

What Else?

You tell us! To be the PlayBook's "Battery Guru", we need to hear what you want to learn. Email us at with your requests or suggestions. And thanks for the feedback!

Finally, please leave us a nice App World review and rating for Battery Guru if you liked it. Thank you!