I just installed an Aeroforce gauge.... great product. The directions indicate the extra 12v switched source is not needed which is true. One issue that is not made clear however is that the gauge draws about 50ma and will drain the battery if left hooked up for an extended period without the car being used. Their directions suggest unplugging from the OBD port if the car is not used for 5 days. Anyway if the external 12v wire is hooked up to a switched 12v supply and the jumper removed from the back of the gauge there is no drain then on the system. The extra step takes about 15 min to do and in my opinion is the better way to hook up the gauge. This only became clear to me after I had it installed without the external 12v supply.
