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Re: Grounding for battery in the trunck?
[Re: Monte_Smith]
#1722131
01/12/15 02:44 PM
01/12/15 02:44 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Monte.. I'm still not clear on this... when using a isolated ground... would you run all the sensor grounds to the buss bar or to the chassis.. my way of thinking is that all the sensors(low voltage) would go to the isolated buss  
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Re: Grounding for battery in the trunck?
[Re: Monte_Smith]
#1722133
01/12/15 02:56 PM
01/12/15 02:56 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
I thought I made it pretty clear.........I don't wire ANY grounds to the chassis, other than the lights. Also not exactly sure what "sensors" you are talking about, as they wire through a "sensor ground" output in the ECU anyway
Monte
Ok... yeah I forgot they go through the ECU... ok..
I should be fine
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Re: Grounding for battery in the trunck?
[Re: Monte_Smith]
#1722134
01/12/15 03:10 PM
01/12/15 03:10 PM
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Joined: Feb 2014
Posts: 655
Huntsville, AL
Airwoofer
mopar
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mopar
Joined: Feb 2014
Posts: 655
Huntsville, AL
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Quote:
So in my opinion and this is strictly MY opinion........you are making two serious mistakes. The first is going blowthrough, the second is not rewiring the car.
And it doesn't matter what I had on my mind or what was going on. My thoughts on your project haven't changed. All that factory wiring serves ZERO purpose for what you intend to do and is only asking for trouble to leave it in there..........Not to mention this has been a race car for a long time and all sorts of wiring changes over the years. So STRIP it, do it RIGHT. You didn't want to.
Monte
I went through a complete re-wire on my plane and it was a real pain. I did just about what you described but it isn't laden with a bunch of electronic stuff. Mike rewired the race stuff on the car just before I bought it from him and I intend to replace almost all of that stuff he did to suit my preferences, and gain room for a passenger to sit in the right seat by relocating the MSD 3. Problem is with the left-right bar blocking the dash it all has to be done while laying on your back on the floor looking up into the underdash. Maybe it is my belief that I wouldn't ask anybody to something I wouldn't. Working on my back is just plain painful to me with the plate in my neck. Luckily the car wiring itself is pretty much unmolested (ie the lights work), so all I need to do is change the race car stuff, relocate the MSD box and the switches. The dash isn't coming out anytime soon. Too bad cause I would change it to a rally.
So anyways, why wouldn't having a separate power and ground buss for the race car stuff not work? So far that MSD seems to be happy the way it is.
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Re: Grounding for battery in the trunck?
[Re: Airwoofer]
#1722135
01/12/15 03:26 PM
01/12/15 03:26 PM
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Joined: Nov 2004
Posts: 6,890
North Alabama
Monte_Smith
master
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master
Joined: Nov 2004
Posts: 6,890
North Alabama
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Quote:
Quote:
So in my opinion and this is strictly MY opinion........you are making two serious mistakes. The first is going blowthrough, the second is not rewiring the car.
And it doesn't matter what I had on my mind or what was going on. My thoughts on your project haven't changed. All that factory wiring serves ZERO purpose for what you intend to do and is only asking for trouble to leave it in there..........Not to mention this has been a race car for a long time and all sorts of wiring changes over the years. So STRIP it, do it RIGHT. You didn't want to.
Monte
I went through a complete re-wire on my plane and it was a real pain. I did just about what you described but it isn't laden with a bunch of electronic stuff. Mike rewired the race stuff on the car just before I bought it from him and I intend to replace almost all of that stuff he did to suit my preferences, and gain room for a passenger to sit in the right seat by relocating the MSD 3. Problem is with the left-right bar blocking the dash it all has to be done while laying on your back on the floor looking up into the underdash. Maybe it is my belief that I wouldn't ask anybody to something I wouldn't. Working on my back is just plain painful to me with the plate in my neck. Luckily the car wiring itself is pretty much unmolested (ie the lights work), so all I need to do is change the race car stuff, relocate the MSD box and the switches. The dash isn't coming out anytime soon. Too bad cause I would change it to a rally.
So anyways, why wouldn't having a separate power and ground buss for the race car stuff not work? So far that MSD seems to be happy the way it is.
I never said it would be easy........I just said what SHOULD be done. I have laid on my back in a MANY a car and rewired the whole thing. You just have to do what you have to do. You build the harness OUTSIDE the car anyway and then install it. The "lights work" is also not a very sound way to determine the validity of a wiring harness either.
Obviously you are going to do it the way YOU want to do it and are just trying to get somebody to tell you that it will be fine. Maybe it will, maybe it won't........who knows. My point was that MYSELF, I wouldn't risk it. And from my side........if I wired the car the way YOU wanted it and then there were issues, those "issues" fall on ME to find and fix. Sorry, but given those options, I will pass on the job instead of just taking the money to do something I feel is wrong and may potentially cause me and you both real grief.
Monte
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Re: Grounding for battery in the trunck?
[Re: Monte_Smith]
#1722136
01/12/15 07:45 PM
01/12/15 07:45 PM
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Joined: Feb 2014
Posts: 655
Huntsville, AL
Airwoofer
mopar
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mopar
Joined: Feb 2014
Posts: 655
Huntsville, AL
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Quote:
So anyways, why wouldn't having a separate power and ground buss for the race car stuff not work? So far that MSD seems to be happy the way it is.
Like this in the picture, except not grounded to the chassis... The rest of the stuff like fans, water pump, fuel pumps, lumped in with the car stuff like lights. BTW, this is kinda how the car is wired now and the box sticking into the space a passenger's legs would normally go is a hassle.
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Re: Grounding for battery in the trunck?
[Re: Airwoofer]
#1722137
01/12/15 08:15 PM
01/12/15 08:15 PM
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Joined: Jan 2003
Posts: 10,001
Frostbitefalls MN (Rocky&Bullw...
gregsdart
OP
I Live Here
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OP
I Live Here
Joined: Jan 2003
Posts: 10,001
Frostbitefalls MN (Rocky&Bullw...
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To all that are following this thread, as the OP I would like to invite any other electrical knowledge anyone is willing to post here, in the hopes this thread will become a great resource(it already has WAY surpassed my expectations!!!) for all of us, especially now in the age where we are getting into more and more sensitive electrical issues and systems.
One thing that comes to mind would be charts like used to figure wire gauge for load and length, etc. Math used in electrical work is another.
At this time I would also like to thank all that posted here with info. I appreciate it, and have learned a lot so far. Thanks, Greg
8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
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Re: Grounding for battery in the trunck?
[Re: gregsdart]
#1722138
01/12/15 09:00 PM
01/12/15 09:00 PM
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Joined: Nov 2006
Posts: 733
jacksonville,FLORIDA
slammedR/T
super stock
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super stock
Joined: Nov 2006
Posts: 733
jacksonville,FLORIDA
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Monte; I for one appreciate all the info you have given, I have printed it out and will be re-wiring my truck as I'm guilty of using the rollcage/chassis as my main ground point. I also switched to firecore50 plug wires from my moroso ultra40's (they were old anyway). I also appreciate you answering my questions I asked you and hope to see you at a track soon 
2000 Dakota R/T, 408 magnum, 727, Indy heads 1000cfm 4150 carb, 93 octane fuel. motor; 10.258 @ 132.78 200 shot; 9.262 @ 144.69 racemagnum
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Re: Grounding for battery in the trunck?
[Re: Airwoofer]
#1722139
01/12/15 09:29 PM
01/12/15 09:29 PM
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Joined: Mar 2006
Posts: 9,839
MI, usa
dvw
master
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master
Joined: Mar 2006
Posts: 9,839
MI, usa
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Quote:
Quote:
So anyways, why wouldn't having a separate power and ground buss for the race car stuff not work? So far that MSD seems to be happy the way it is.
Like this in the picture, except not grounded to the chassis... The rest of the stuff like fans, water pump, fuel pumps, lumped in with the car stuff like lights. BTW, this is kinda how the car is wired now and the box sticking into the space a passenger's legs would normally go is a hassle.
It looks like someone tried to do a tidy job here. But I see something I don't like. Why have 6 relays that are nowhere near the device they are controlling? Also why control the relay with the same size wire that feeds the device? I would suggest placeing the relay near the device, water pump, fuel pump, fan, etc. Feed the relay with sufficient gauge to run the device ( 12ga, might even need larger) direct from the nearest power source. I like to use the battery cutoff positive feed terminal for the fuel pump. The alternator output or firewall pass through for the fans, etc. The control circuit can be light duty. My relay power feeds run a fusible link. They could be fused but my feeling is if the water pump, fuel pump shorts bad enough to kill the fusible link that item is toast anyway. In the pic the relays are on the motor plate for the water pump and 2 fans. The alternator on one side, coil and crank trigger on the other. Coil and crank trigger wire run down the right side. The alternator on the left
Doug
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Re: Grounding for battery in the trunck?
[Re: gregsdart]
#1722141
01/12/15 10:44 PM
01/12/15 10:44 PM
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Joined: May 2003
Posts: 2,414
St. Croix, US Virgin Islands
David_in_St_Croi
top fuel
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top fuel
Joined: May 2003
Posts: 2,414
St. Croix, US Virgin Islands
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Quote:
To all that are following this thread, as the OP I would like to invite any other electrical knowledge anyone is willing to post here, in the hopes this thread will become a great resource(it already has WAY surpassed my expectations!!!) for all of us, especially now in the age where we are getting into more and more sensitive electrical issues and systems.
One thing that comes to mind would be charts like used to figure wire gauge for load and length, etc. Math used in electrical work is another.
At this time I would also like to thank all that posted here with info. I appreciate it, and have learned a lot so far. Thanks, Greg
Here is the basic formula for wire sizing. I use it when designing boat electrical systems. With a composite boat, you are grounding back to the battery, similar to how Monte describes. The formula is as follows: CM = K*L*I/E
This will give you the wire required in what is called circular mils. There are conversions from circular mils to AWG on the internet
Now, here is the definition of the variables mentioned.
K is a constant representing the resistance of copper, it is 10.75 ohms /mil-foot
I = load current in amperes
L = length of conductor from centre of distribution, in feet
E = voltage drop at load, in volts
If it is a system where you have the ground going back to the battery, multiply by two.
Now, the rest is relatively straight forward. Load is given by the manufacturer of the device.
Length of conductor, get a tape measure and read it correctly.
Voltage drop: sort of like how fast do you want to go, how much do you have to spend? For a boat inspected by the USCG, you can have a voltage drop as high as 10%. The other standard in the marine world is 3% voltage drop. You want less voltage drop, there are three things you can do. One is to shorten the length of the run. This has the advantage of using less wire, which is less cost and weight. Second is to up voltage. Third is to go to a larger wire size.
I have a spreadsheet written to do this, it was not hard to create.
I use tinned marine grade wire wherever possible, and the end connectors from Pacer or Ancor that have the adhesive heat shrink insulation.
Hope I have not muddied the waters too much.
Regards, Dave
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Re: Grounding for battery in the trunck?
[Re: 72Swinger]
#1722142
01/12/15 11:07 PM
01/12/15 11:07 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
Quote:
Quote:
I thought I made it pretty clear.........I don't wire ANY grounds to the chassis, other than the lights. Also not exactly sure what "sensors" you are talking about, as they wire through a "sensor ground" output in the ECU anyway
Monte
Ok... yeah I forgot they go through the ECU... ok..
I should be fine
That is why the ECU + and - go direct to the battery, so they are as isolated as possible from EVERYTHING, including the isolated ground. Im guessing that grounding the chassis solely amplifys EMI for everything. I think I get it.
I thought it was to maintain the memory... but I did
run direct to the battery
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Re: Grounding for battery in the trunck?
[Re: David_in_St_Croi]
#1722143
01/12/15 11:42 PM
01/12/15 11:42 PM
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Joined: Feb 2011
Posts: 4,302
Nebraska
72Swinger
master
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master
Joined: Feb 2011
Posts: 4,302
Nebraska
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Quote:
Quote:
To all that are following this thread, as the OP I would like to invite any other electrical knowledge anyone is willing to post here, in the hopes this thread will become a great resource(it already has WAY surpassed my expectations!!!) for all of us, especially now in the age where we are getting into more and more sensitive electrical issues and systems.
One thing that comes to mind would be charts like used to figure wire gauge for load and length, etc. Math used in electrical work is another.
At this time I would also like to thank all that posted here with info. I appreciate it, and have learned a lot so far. Thanks, Greg
Here is the basic formula for wire sizing. I use it when designing boat electrical systems. With a composite boat, you are grounding back to the battery, similar to how Monte describes. The formula is as follows: CM = K*L*I/E
This will give you the wire required in what is called circular mils. There are conversions from circular mils to AWG on the internet
Now, here is the definition of the variables mentioned.
K is a constant representing the resistance of copper, it is 10.75 ohms /mil-foot
I = load current in amperes
L = length of conductor from centre of distribution, in feet
E = voltage drop at load, in volts
If it is a system where you have the ground going back to the battery, multiply by two.
Now, the rest is relatively straight forward. Load is given by the manufacturer of the device.
Length of conductor, get a tape measure and read it correctly.
Voltage drop: sort of like how fast do you want to go, how much do you have to spend? For a boat inspected by the USCG, you can have a voltage drop as high as 10%. The other standard in the marine world is 3% voltage drop. You want less voltage drop, there are three things you can do. One is to shorten the length of the run. This has the advantage of using less wire, which is less cost and weight. Second is to up voltage. Third is to go to a larger wire size.
I have a spreadsheet written to do this, it was not hard to create.
I use tinned marine grade wire wherever possible, and the end connectors from Pacer or Ancor that have the adhesive heat shrink insulation.
Hope I have not muddied the waters too much.
Regards, Dave
Would you consider the tinned marine grade cable a better conductor than say the solid copper SGX? I understand the tinning is for corrosion prevention?
Mopar to the bone!!!
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Re: Grounding for battery in the trunck?
[Re: David_in_St_Croi]
#1722145
01/13/15 01:59 AM
01/13/15 01:59 AM
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Joined: May 2006
Posts: 1,260
New Mexico
Adobedude
pro stock
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pro stock
Joined: May 2006
Posts: 1,260
New Mexico
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I agree with Monte, keep the relays close to the what it's triggering, with that said, I use the Relays on my ARC switch panel to trigger another a relay close to what it's running FP in the back pulling power off the battery, fan, water pump in the front. I really like using Leash Electronics small relay boards, they are fused and easy to wire in. All my signal wires are either twisted pair or Shielded Tefzel wire All my grounds go to a couple isolated lugs that are grounded back to the battery. When sizing what ga wire to use, include the length of the ground. Panel before it was finished. 
2001 Dodge Dakota
408 All Motor
11.27 @ 117.83 mph
2017 NM Mopar Challenge Series Champion.
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Re: Grounding for battery in the trunck?
[Re: bonefish]
#1722147
01/13/15 01:36 PM
01/13/15 01:36 PM
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Joined: Feb 2014
Posts: 655
Huntsville, AL
Airwoofer
mopar
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mopar
Joined: Feb 2014
Posts: 655
Huntsville, AL
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This is a great thread. There is a plastic plate in my Demon similar to the one I posted a pic of which looks to be aluminum (and bolted to the cage). My MSD7-3 sticks out in the passenger area just like that example which is kind of a pain for passengers. Also has an electrical do-dad to time the Naws second system, and some other stuff on it. The fuse block is under the dash, switches for all the race stuff on the shifter. None is as pretty as the pic I posted which is from a guy here's website. This is now a street car that I play at the track with, driving there if I feel like it. I will be replacing all the race wiring Mike put in cause I want my switches located up front and the line loc / TB behind the shifter on their own stand. So, as I plan to rewire the car and all this talk of isolating grounds comes up, I chimed in. Here is why: I also am taking the naws off the 496 and am gonna first run it NA on (10-1) pump swill. I wanted to boost the motor instead of spray to get the same 1200 HP, and to keep things under the cowl a 90* setup off the tall single plane (that matches the heads), with a EFI throttle body would have been way better than a blow through. Blowing through a Dom on a tall manifold will make me have to cut a hole in the hood for the hat. After I got the news about wiring from Monte and having to completely rip out the 44 yr old stuff, my plans changed immediately. Especially after an hour later where I was offered a killer deal on a E-85 blow through V7-YSi setup that I could watch run that night on the car. Way, way cheaper and not sensitive to stray electrons any more than the NA setup. So I jumped on the deal. But the car still needs the race stuff redone and I would like to do that right. I would still like to know why running the car stuff as is (I include the water pump, fuel pumps, fans, line loc, TB in that category also) and the race stuff (electronic ign) on a separate circuit won't work. Hell, the thing went mid 9000's like this so the sparks were sparking. Another thing is the new wires will be user friendly and easy to get to. It is a real pain to try to crawl backwards over X door bars to get to a fuse or change a wire. I don't know how Mike did it. 
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Re: Grounding for battery in the trunck?
[Re: Airwoofer]
#1722150
01/14/15 12:52 AM
01/14/15 12:52 AM
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Joined: Nov 2004
Posts: 6,890
North Alabama
Monte_Smith
master
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master
Joined: Nov 2004
Posts: 6,890
North Alabama
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Quote:
Quote:
So anyways, why wouldn't having a separate power and ground buss for the race car stuff not work? So far that MSD seems to be happy the way it is.
Like this in the picture, except not grounded to the chassis... The rest of the stuff like fans, water pump, fuel pumps, lumped in with the car stuff like lights. BTW, this is kinda how the car is wired now and the box sticking into the space a passenger's legs would normally go is a hassle.
This is NOT grounded to chassis. Plate is mounted on rubber isolators
Monte
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