Battery in trunk and master disconnect switch question
10-14-2018, 12:19 PM
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Battery in trunk and master disconnect switch question I have a bit of an interesting setup and I need help from those much smarter than me. I have my battery relocated in the trunk and I am trying to install a master disconnect switch on the negative terminal. The current wiring is as follows:
Power connections at battery
1 gauge wire ran back to front of car feeding starter, etc. off of that one wire.
4 gauge wire ran to stereo amp in front of car for mids and highs
4 gauge wire ran to amp in back of car for sub
Ground connections at battery
1 gauge wire grounded to frame under back of car
Sub amp ground is ran back to the battery
Mids and high amp is grounded to car under passenger seat (this becomes my concern)
My plan is to install the master disconnect switch on the 1 gauge ground wire at the back of the car, but then I got to thinking. This would obviously disconnect the circuit for my main wire and also my sub amp as that ground for the amp is ran back to the battery, but would the ground from the other amp in the front of the car (grounded to the car) effectively ground my whole vehicle? Thus the vehicle would not be protected from a slow drain or worse, if I positive cable were to short it could still complete the circuit through the amp and spark, melt, etc.? Does this logic seem right? If so, do I need to run the ground back from the amp in the front of the car to the battery as well? Or would the fuse in that amp blow before any damage from a split positive happen? Any other thoughts / recommendations?
Power connections at battery
1 gauge wire ran back to front of car feeding starter, etc. off of that one wire.
4 gauge wire ran to stereo amp in front of car for mids and highs
4 gauge wire ran to amp in back of car for sub
Ground connections at battery
1 gauge wire grounded to frame under back of car
Sub amp ground is ran back to the battery
Mids and high amp is grounded to car under passenger seat (this becomes my concern)
My plan is to install the master disconnect switch on the 1 gauge ground wire at the back of the car, but then I got to thinking. This would obviously disconnect the circuit for my main wire and also my sub amp as that ground for the amp is ran back to the battery, but would the ground from the other amp in the front of the car (grounded to the car) effectively ground my whole vehicle? Thus the vehicle would not be protected from a slow drain or worse, if I positive cable were to short it could still complete the circuit through the amp and spark, melt, etc.? Does this logic seem right? If so, do I need to run the ground back from the amp in the front of the car to the battery as well? Or would the fuse in that amp blow before any damage from a split positive happen? Any other thoughts / recommendations?
10-15-2018, 08:16 AM
#2
No, the amp in front will not complete the circuit regardless of where it's grounded. The object of a master disconnect is to disconnect one side of the battery (either positive or negative). The front amp grounds to the chassis which allows current to flow to and through the amp to the chassis and back into the battery through its chassis ground. If the chassis ground at the battery is disconnected then there is no place for the ground current at the amp to go... no current flows.
I would be more concerned with the rear amp which you say has its own separate connection to the battery negative terminal. Your master switch must cut off all connections to the battery's negative terminal (both the one to the chassis and the one to the amp) to ensure no current flows.
I would be more concerned with the rear amp which you say has its own separate connection to the battery negative terminal. Your master switch must cut off all connections to the battery's negative terminal (both the one to the chassis and the one to the amp) to ensure no current flows.