Battery Bug works
I just tried the battery bug for the first time this weekend. It appears to work as advertised.
You attach it to the battery terminals and it gives you a count down while it boots up. It then gives you the battery's voltage output (volts). Then you start up the vehicle and it gives you a per centage rating of your battery. the bug flashes between percent and the batteries output voltage. When the vehicle is turned off, the bug continues to flash between the startup percentage and the battery's output voltage. I tried it on a month old truck and the percentage was 100%, as expected. I tried it on a Jeep which is only run in the summer but the Optima battery is kept charged and it gave an 88% rating. The batter was about 3 and a half years old under Phoenix (hot desert) use.
I won't know if it can predict a battery failure until I have a failure, but it appears to work as advertised on preliminary observations.
I appears to be an excellent inexpensive way to keep tabs on your vehicle's batteries.

batery bug
batery bug
GET ONE

save yourself trouble and embarrasement from the dead batery.
simple and quick to install. this gadget actualy measures
the voltage drop during cranking and displays it each time
the engine is cranked. better than an idiot lite. better than
just a meter....(a meter does not actualy measure voltage drop
while cranking)....nice features, (low bat. warning) (replace soon
warning) etc. GREAT IDEA, GREAT GADGET, GREAT PRICE.

5 STARS

Should be standard equipment
Took me 2 minutes to install. Anyone can read and understand what it displays. Know I know my 5 year old battery is still reliable and don't have to worry about when it would fail. Even with having road service the BatteryBug is worth the peace of mind knowing that I won't need to call them. Need to put one on my wife's car for my peace of mind.