The iON BatteryTimer application is extremely simple to use. I started by downloading the app from Mobihand via the free trial offering, although it can also be had for a very respectable $9.95.
On the Nokia N95 I was then able to easily navigate to the app using the following path: Main menu > Applications > iON BatteryTimer. From the main screen it becomes very intuitive to setup the application. I started by setting the homescreen plugin by going to "options" and then "standby plug-in." At this point my remaining battery life in terms of a percentage and actual hour and minute times showed on my homescreen.
This was a great option for quickly realizing how much battery time I had remaining with just a simple glance. I also noticed that the plugin was placed where there was already "empty space" on the OS without reformatting my homescreen which I've come to love and which I am already very familiar with. You don't find many applicaitions these days that add functionality without changing other functions, this app does that flawlessly. The plugin even starts automatically everytime you turn your device off and then back on, as long as it has been enabled.
Of course just watching your battery drain is a passive monitoring method. When I wanted to try a few power saving methods I simply navigated to Tools > Settings > General > Personalization > Themes > Power saver > iON Power saver. That path may slightly change based on the Symbian device you're using, but it should be similar. I also went to Personalization > Display menu.
After setting my preferences, I then took a look at the battery estimate times to check what the new consumption was set to. This screen is very useful and shows remaining battery times and percentages, discharge time rates and even the overall time your battery can handle based on your power settings.
The program also offers the ability to check on the charging levels for your battery. The screenshot shown below shows a battery at 91% with a nice green display, if that same battery was at 5% it would change to red, flagging the user to the low standby times remaining.
The "PowerSaver" part of the iON BatteryTimer application is fairly standard fair, as is the battery time remaining section of the application, i've seen those options on many other applications. However where iON excels is the excellent placement of the homescreen plugin which offers quick battery updates at a glance, while utilizing an otherwise blank part of the Symbian screens output.
Overall it's a simplistic application that works as advertised. It's worth the $9.95 cost if you absolutely need to make sure your phone is up and running for the time you need it to be, otherwise you may find it pointless if you're a light user who tends to charge there phone on a regular basis.