Amp ground location question?
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Cruiser
Joined: Nov 2013
Posts: 120
Likes: 4
From: Pa
Amp ground location question?
Getting ready to install a b2 amp in my 08 Sg. I did search this but didn't find my answer.
I know majority run both positive and ground to battery terminals. I'm curious why run ground to battery? I've read a couple of amp install directions and most state not to extend ground any further than what's supplied. Also noticed that most ground wires are considerably shorter in the amp wiring kits you buy. Witch also state not to extend ground wire. Just looking for some insight on this from the knowledgeable ones. Appreciate the help.
I know majority run both positive and ground to battery terminals. I'm curious why run ground to battery? I've read a couple of amp install directions and most state not to extend ground any further than what's supplied. Also noticed that most ground wires are considerably shorter in the amp wiring kits you buy. Witch also state not to extend ground wire. Just looking for some insight on this from the knowledgeable ones. Appreciate the help.
Road Warrior
Joined: Sep 2014
Posts: 1,871
Likes: 1,325
From: DeLand, Florida
Where else would you put the ground wire? The frame? Bad choice as it is steel and not a good conductor for a high current amp. I don't understand the instruction saying not to extend other than they are concerned on the splice and wire size of extension.
Road Master
Joined: Jan 2012
Posts: 1,090
Likes: 243
From: Maine
Huh? Isn't everything else including the battery grounded to the steel frame?
Elite HDF Member
Joined: Aug 2008
Posts: 4,150
Likes: 459
From: S. FL
From another post. Read Fosgates amp install guide it specifically recommends the battery on motorcycle installs.
"It's a resistance issue... resistance = total area of the circuit or wire... with a wire, you can calculate resistance as length X diameter. So, a shorter wire will have less resistance. The basis of the short ground wire is from the early days of car audio where a high powered amp was pushing 200W. The typical power wire was 8ga. Compard to 15ft of 8ga wire the chassis of the car (whaich was quite substantial in the 80s) is of low resistance. Look at where we are today. A modest system has over 1000W and the primary power wire is at least 4ga if not 0ga. At the same time the metal of the car itself has gotten thinner and as such a worse conductor. Length doesn't matter. Resistance does. As long as the ground is of low resistance, there won't be an issue. The same goes for the power wire. If you are looking at using 0ga for the power wire, you will proably get a better ground by going straight back to the battery with the same size cable."
"It's a resistance issue... resistance = total area of the circuit or wire... with a wire, you can calculate resistance as length X diameter. So, a shorter wire will have less resistance. The basis of the short ground wire is from the early days of car audio where a high powered amp was pushing 200W. The typical power wire was 8ga. Compard to 15ft of 8ga wire the chassis of the car (whaich was quite substantial in the 80s) is of low resistance. Look at where we are today. A modest system has over 1000W and the primary power wire is at least 4ga if not 0ga. At the same time the metal of the car itself has gotten thinner and as such a worse conductor. Length doesn't matter. Resistance does. As long as the ground is of low resistance, there won't be an issue. The same goes for the power wire. If you are looking at using 0ga for the power wire, you will proably get a better ground by going straight back to the battery with the same size cable."
Road Master
Joined: Jun 2007
Posts: 1,092
Likes: 35
From: Fl
My amp install kit had a short ground wire, but way too much power wire. I simply cut the power wire to length for both power and ground, ran both back to the battery, and marked each end of the ground with a sharpie. No law says you can't use the power wire for ground also!
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Cruiser
Joined: Nov 2013
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From: Pa
Thanks, haze324..
Knew there had to be a reason, majority of installs were running both to battery terminals. I just couldn't find the answer. Also after reading your post most of the pdf's I read are geared towards the auto market and not bikes like stated.
Knew there had to be a reason, majority of installs were running both to battery terminals. I just couldn't find the answer. Also after reading your post most of the pdf's I read are geared towards the auto market and not bikes like stated.
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Cruiser
Joined: Nov 2013
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From: Pa
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Road Warrior
Joined: Aug 2013
Posts: 1,505
Likes: 31
From: Las Vegas
just use left over Plus cable for ground (I heat shrink wrapped the ends with black of it so you cannot make a mistake 
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Go to the auto parts store and get black wire. I ran it to the grounding post between the seat and tank instead of to the battery. It's been like that for over a year and have had no problems. Positive right to the battery with a fuse.
Maybe not the right way but it has worked.
Maybe not the right way but it has worked.
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