Like the speed wifi offers but hate the battery drain? Try WifiOpti for Android and make sure it's only on when it counts!

Especially useful for tablets and other 'wifi-only' devices

This app is *not* intended as a battery-saver (except maybe tablets or other wifi-only devices) but rather to keep wifi's battery drain to a minimum.

Current version: 0.07.46
For Android 2.1 and up 

Rules: (this is how it works)

1. Is wifi on? Yes: goto 2, no: goto 4
     
2. Is wifi connected? Yes: goto 3, no: goto 5
     
3. Don't change anything, keep wifi enabled, goto 9
     
4. Is screen on and unlocked? Yes: goto 5, no: wait until screen is unlocked *then* goto 5
     
5. Turn on wifi, scan for available networks, goto 6
     
6. Are known networks available? Yes: goto 7, no: goto 8
     
7. Connect to network, keep wifi on and goto 9
     
8. Turn wifi off. Goto 9
     
9. Check wifi again in 'x' minutes

Options:

• Sleep Policy [changed, 0.07.21]
  Turn off wifi when device is idle for a certain amount of time and data traffic < 64kbs. This option is now *enabled by default* and will no longer change Android native sleep policy (you may do this manually, see Home > Settings > Wifi > Advanced > Sleep policy)
    
• Keep wifi on when charging
  Sleep policy is ignored when USB or charger is connected. Scheduled checks will run also.
    
• SSID Blacklist
  You may ignore networks by their SSID (name) (for example: unsecured networks that you only want to access manually)
    
• Handle connection loss
  When connection is lost, goto 5.
  
  
• Handle wifi tethering
  WifiOpti will never scan when Wifi-tethering is enabled (since tethering is generally used when no wifi is available). However, when this option is enabled it will also check if clients are actually connected; if not tethering is disabled and a scan is run.
    
• Handle low battery
  Wifi and WifiOpti Service are disabled when battery < 10%

Good to know:

• WifiOpti no longer connects to unsecured networks automatically. If you want to do so, disable 'Skip unsecured networks' in Settings [changed, 0.07.26]. You may still blacklist specific networks by SSID.
  
  
• WifiOpti's 'Sleep Policy' may cause issues when a user or other application makes changes to the wifi-state. You can temporarily disable WifiOpti Service (Menu > Temp Off); the service will be automatically re-enabled after 5 minutes. 
  
  
• Tether-features only available for Android 2.2 and higher 

As of 0.07.29 tablets (10") are detected automatically and the app is configured accordingly.

...on a phone

Just enable WifiOpti Service, all other settings should be fine.
You may configure scheduled checks and sleep policy if necessary. 

...on a tablet (wifi only)

Enable WifiOpti Service. Configure scheduled checks and sleep policy if necessary.
If you have an Asus Transformer with dock leave 'Keep wifi on when charging' disabled. If not you may enable it.
Scroll down to Advanced Options and disable: 'Handle wifi tether' and 'Handle low battery'. Enable 'Scan on unlock'. 

• WifiOpti00746.apk