Expert: Cleggsan - 11/26/2009

Question
Hi
I want to install a Car CD/Radio (Mutant MT2200BT Car CD MP3 WMA SD USB Bluetooth Player+) in my caravan along with two speakers (Mutant Euphony 6" 6.5" Car Door Component Speakers)When i am on the 240v ac hook up i would like to be able to power the radio from a mains power supply, what Amp rating PSU would i require assuming 13.5vdc was the voltage i would use.

Answer
The specifications for the Mutant MT2200BT says it has 4 amplifiers in which each is rated at 40w output.  Therefore, the total power capability is 120w.  If it were running full power that would be about 10 amps.  (P = v times a or 12v nominally times 10a = 120w).   But, there are other power consuming parts of the unit such as the front end and cd player mechanisms.  They don't draw alot, but some. Let's say another 2 amps would cover it  (the manufacturer does not give specifications for these items).  So, we are up to 12 amps.  Then, since it is not a pure resistive type load and the power factor may require some extra amperage we should add a 10% coverage factor.

Therefore, I would guesstimate you will need a supply that can furnish 15 amps. This would give you some headroom and keep the converter from crashing under heavy audio volume settings.

Hope this will help you.   

PS:  Be sure you have some switching capability to completely disconnect the system from the vehicle electrics when you are connecting to the mains system.