How much amperage is required to run a 400 watt amp? There is a 16 amp fused outlet in the back for the R/W defroster which I never use. Is this sufficent? Any help would be appreciated since I know nothing about stereos etc...

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Happy Benzing
Darryl, Hill
2005 SL55 AMG Kleemanized
1984 500 SEC
1967 W113 California Coupe
[SIGPIC]
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Amps = watts divided by volts. (plus a safety factor).

Amps = 500watts divided by 11.5 = 43 amps. (25% load safety factor on the watts, 11.5 V minimum voltage draw.) Even assuming you don't use a safety factor and always get 12.4 volts at the wire you want to use, you would need 400/12.4 = 32 amps. Your 16 amp line will safely handle about 200 watts maximum. Do you have an MB with the battery in the trunk? That would simplify things - just remember to use a ground wire at least as large as the positive supply wire to the amplifier, and the longer the run, the larger the wire diameter.

http://www.thezeb.com/caraudio/rockfordfosgateaccs.html shows an install kit for a 500 watt amp. It requires a 40 amp fuse, 8 guage supply wire, and short (1.5 foot) ground wire of 8 quage. If your ground is over 1.5 feet away, I would use a 4 guage ground wire.

__________________
John

2003 Firemist Red/grey leather SL 500
2015 Palladium Silver/black mbtex GLK 350
1987 Smoke Silver/burgundy mbtex 300E Sportline (SOLD)

Click to see 87 300E

Thank you very much for the info. I checked my junkpile and there is a Rockford amp that says 200 watts so thats the way I'll go.

__________________
Happy Benzing
Darryl, Hill
2005 SL55 AMG Kleemanized
1984 500 SEC
1967 W113 California Coupe
[SIGPIC]
https://picasaweb.google.com/lh/myphotos

I would still be cautious on using the rear window heater wires, as they were designed for about 20 minutes use at a time! You will be using the radio a lot more than that, and heat build up will accumulate possiblu damaging the insulation, so I would run a 10 guage cable anyway with an 8 guage ground if it were mine. Either that, or restrict yourself to a 100watt class D amp or keep the volume down on the sub. It is a lot harder to replace existing window heater wiring that is fused and burned than it is to add new radio wiring. There are a couple of threads talking about how to easily come throught the firewall and where to run the cables for a pretty easy job, depending on your model. if you have to run the amp off the window wiring, i would switch the fuse from a 16 amp to a 10-12 amp just to add a little safety margin. Easier to replace the fuse than the wiring. Good luck!

__________________
John

2003 Firemist Red/grey leather SL 500
2015 Palladium Silver/black mbtex GLK 350
1987 Smoke Silver/burgundy mbtex 300E Sportline (SOLD)

Click to see 87 300E