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Wiring directly to the battery, how do you do it? #1773969
03/07/15 03:45 AM
03/07/15 03:45 AM
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Posts: 290
Dayton, WA
wesgtx440 Offline OP
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Dayton, WA
So I am going to be installing an MSD ignition and FAST EZ EFI. Both of the instructions call for wiring directly the battery + and -. I don't like the look of extra wires hooked up to the battery posts as I think they look tacky. I was thinking about getting a negative cable with the extra pigtail built in and connect both - wires to it. As for the positive wires, cutting the aux wire that goes to the starter relay and tying in close to the battery. Anyone else have better ideas on this? Car is 68 charger with 440.

Re: Wiring directly to the battery, how do you do it? [Re: wesgtx440] #1773970
03/07/15 03:53 AM
03/07/15 03:53 AM
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Aurora, Colorado
451Mopar Offline
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The closer to the battery, the better because the battery helps filter electrical noise.

Re: Wiring directly to the battery, how do you do it? [Re: wesgtx440] #1773971
03/07/15 04:47 AM
03/07/15 04:47 AM
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Lincoln Nebraska
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RapidRobert Offline
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If these (msd/efi) need to be hot all the time & you wanted to keep the ammeter honest, for the aesthetics you could connect the neg leads to the end of the batt large neg cable that's bolted to the block and connect the pos leads to the alt "batt" stud. That'd keep em off of the battery


live every 24 hour block of time like it's your last day on earth
Re: Wiring directly to the battery, how do you do it? [Re: wesgtx440] #1773972
03/07/15 10:20 AM
03/07/15 10:20 AM
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Georgia
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Steve Bryant Offline
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On my E-Body, the starter relay is a little below the battery and there is a large positive lug you can connect to.

Not sure what car you have there, but with a little cloth tape, you can dull down the wires too so it doesn't look like a Christmas Tree.

8452258-DSC04114.JPG (167 downloads)
Re: Wiring directly to the battery, how do you do it? [Re: 451Mopar] #1773973
03/07/15 01:12 PM
03/07/15 01:12 PM
Joined: Oct 2011
Posts: 290
Dayton, WA
wesgtx440 Offline OP
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Quote:

The closer to the battery, the better because the battery helps filter electrical noise.




Thanks for the replies everyone. The main reason they list directly to the battery in the instructions is for the electrical noise. This might be one of those "cant have your cake and eat it to" issues, I will just do it the way they say to avoid problems.

Re: Wiring directly to the battery, how do you do it? [Re: wesgtx440] #1773974
03/07/15 07:24 PM
03/07/15 07:24 PM
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Colorado
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denfireguy Offline
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Wiring to the starter relay is as close as you want to go. Wiring to the battery cable gets you lots of very nice green terminals on your wiring as it ages.
As mentioned before, wiring to the battery makes for a very clean source as the battery acts like a gigundous electrolytic capacitor filtering noise on the electrical system. That is why if you start hearing alternator wine in your stereo, it is time to get a new battery or at least make sure the connections to the battery are good.


2014 Ram 1500 Laramie, 73 Cuda
Previous mopars: 62 Valiant, 65 Fury III, 68 Fury III, 72 Satellite, 74 Satellite, 89 Acclaim, 98 Caravan, 2003 Durango
Only previous Non-Mopar: Schwinn Tornado
Re: Wiring directly to the battery, how do you do it? [Re: 451Mopar] #1773975
03/07/15 07:56 PM
03/07/15 07:56 PM
Joined: Jul 2007
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North Carolina
cjskotni Offline
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Quote:

The closer to the battery, the better because the battery helps filter electrical noise.




Horrible misinformation. The electrical noise would be no different anywhere on the charging circuit. The only thing that would differ would be the voltage itself as there will be small drops across various connections (i.e. bulkhead). The "shakiness" of the voltage will be no different as it's all the same circuit.

The only thing you gain from wiring on the battery (or starter relay) is pulling additional current through the dash harness (unless you have done a bypass), making the car that much more unsafe not mention making the ammeter totally unreliable.

The "noise" from radio is not necessarily from the alternator but from the ignition circuit, not the alternator. This is EMF and if present on one side of the charging circuit, will also be present at the other. If you have noise now, wiring from the battery probably won't help.

I pull my two electric fan relay loads from the alternator stud. No noise on my radio and my ammeter is dead accurate.

Re: Wiring directly to the battery, how do you do it? [Re: cjskotni] #1773976
03/07/15 11:44 PM
03/07/15 11:44 PM
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NEW JERSEY
AARCONV Offline
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so you tap power right from the alt stud for the fans?..I wonder if that would be a good thing to wire up my fuel pump to instead of to the battery terminal..I guess it would lesson the draw thru the bulkhead connections...

Re: Wiring directly to the battery, how do you do it? [Re: AARCONV] #1773977
03/07/15 11:51 PM
03/07/15 11:51 PM
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North Carolina
cjskotni Offline
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Quote:

so you tap power right from the alt stud for the fans?..I wonder if that would be a good thing to wire up my fuel pump to instead of to the battery terminal..I guess it would lesson the draw thru the bulkhead connections...




Yes. Tap the power here and no extra current through the dash harness while the car is running (alternator charging).

Re: Wiring directly to the battery, how do you do it? [Re: cjskotni] #1773978
03/07/15 11:54 PM
03/07/15 11:54 PM
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Posts: 5,399
Aurora, Colorado
451Mopar Offline
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Not misinformation. All wires have some resistance and inductance. Just because they are the same "circuit" does not mean the same location. That same common circuit could be broken down showing small resistances due to wire length (and even connections) between each part of the circuit.
Having the connections closer to the battery, and on a different connection than the starter or other high current loads will also help prevent dips in the voltage when a high current load turns on. E=I*R

Re: Wiring directly to the battery, how do you do it? [Re: 451Mopar] #1773979
03/08/15 12:09 AM
03/08/15 12:09 AM
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Michigan
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Kiddart Offline
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Not to Hi Jack but I feel this questions is relevant, if the instructions say to go directly to battery what do you do if you run a cut off/ electrical kill switch?? would you go to the out side of the switch??

I have read that ant efi system doesn't like noise


Thank you
Kiddart
Re: Wiring directly to the battery, how do you do it? [Re: 451Mopar] #1773980
03/08/15 12:17 AM
03/08/15 12:17 AM
Joined: Jul 2007
Posts: 1,526
North Carolina
cjskotni Offline
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Quote:

Not misinformation. All wires have some resistance and inductance. Just because they are the same "circuit" does not mean the same location. That same common circuit could be broken down showing small resistances due to wire length (and even connections) between each part of the circuit.
Having the connections closer to the battery, and on a different connection than the starter or other high current loads will also help prevent dips in the voltage when a high current load turns on. E=I*R




The inductance or capacitance of wire in a DC circuit is nill. When you get into the Ghz, that's a different story.

I agree that being on one side of the circuit vs another can result in higher or lower voltage which is due to resistance of the wire + connections in the bulkhead.

Also when a car is running, the alternator will be the source of the current, not the battery so your reasoning is backwards.

Re: Wiring directly to the battery, how do you do it? [Re: cjskotni] #1773981
03/08/15 12:46 AM
03/08/15 12:46 AM
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UPPER MICHIGAN, MARQUETTE COUN...
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NITROUSN Offline
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Quote:

I pull my two electric fan relay loads from the alternator stud.




That is not a good idea. If it works for you fine. It is not right.

Re: Wiring directly to the battery, how do you do it? [Re: NITROUSN] #1773982
03/08/15 12:55 AM
03/08/15 12:55 AM
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North Carolina
cjskotni Offline
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Quote:

Quote:

I pull my two electric fan relay loads from the alternator stud.




That is not a good idea. If it works for you fine. It is not right.




Oh really? Please explain...

Re: Wiring directly to the battery, how do you do it? [Re: cjskotni] #1773983
03/08/15 01:04 AM
03/08/15 01:04 AM
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IN
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ahy Offline
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I run EFI and MSD with battery in trunk. + on the MSD is connected to the fender relay. 6 gauge goes to the starter terminal, then 1 gauge to battery in trunk. 6 gauge also from fender relay to alternator. - on the MSD goes to the heavy frame to block ground. Not quite the same as "hook to the battery" but close due to heavy gauge wires. Works fine.

Re: Wiring directly to the battery, how do you do it? [Re: cjskotni] #1773984
03/08/15 01:06 AM
03/08/15 01:06 AM
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CA
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crackedback Offline
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Quote:

Quote:

Quote:

I pull my two electric fan relay loads from the alternator stud.




That is not a good idea. If it works for you fine. It is not right.




Oh really? Please explain...




Same as pulling headlight power from the alternator charge stud. It works absolutely fine and keeps the amp load off the bulkhead. The charge stud is a better solution unless you've done the wire around using a significantly better sized wire.

Re: Wiring directly to the battery, how do you do it? [Re: wesgtx440] #1773985
03/08/15 01:27 AM
03/08/15 01:27 AM
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Illinois
StrkrDart69 Offline
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http://www.summitracing.com/parts/rfw-gw16/overview/
Put one of these on your car. They sell them with plastic covers too. You can run a wire from the battery or I would take the power from the starter relay. Much cleaner and safer and you can multi tap. You can usually hide it under the battery.

8453005-RFW-GW16_ml.jpg (80 downloads)
Re: Wiring directly to the battery, how do you do it? [Re: cjskotni] #1773986
03/08/15 01:41 AM
03/08/15 01:41 AM
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Quote:

Quote:

Quote:

I pull my two electric fan relay loads from the alternator stud.




That is not a good idea. If it works for you fine. It is not right.




Oh really? Please explain...




Like I said if you are happy than fine. Not to make a debate on your logic but to put it in simple logic when have you seen a production auto have accessories tapped of the alternator stud.

The original poster of this thread was concerned as to proper wiring of his MSD. The correct way is to have the power and ground close or directly from the battery. RFI interference is not always something related to radio noise. RFI can play into today's digital and multiplexing world without radio issues.

I would wire my loads directly to the battery and let my charging alternator and wiring maintain the battery.

Re: Wiring directly to the battery, how do you do it? [Re: Kiddart] #1773987
03/08/15 03:08 AM
03/08/15 03:08 AM
Joined: May 2008
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Aurora, Colorado
451Mopar Offline
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The EFI compensates the injector timing on the voltage it gets, so I think that is one (of many) reasons the EFI wants a connection close to the battery. With a kill switch, I would run a separate circuit through a relay that is activated by the kill switch (and maybe the ignition key too.)

With all the warnings FAST has for their EFI to connect directly the the battery, I'm suprised they don't supply a large capacitor to be installed?

Re: Wiring directly to the battery, how do you do it? [Re: 451Mopar] #1773988
03/08/15 04:21 AM
03/08/15 04:21 AM
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Bend,OR USA
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Cab_Burge Offline
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Does anyone who has put comments on this post understand current flow in D.C.(Direct Current) circuits? If I understand(edited) the operation of the electrcial operated injectors on EFI systems they pulse the negative(battery) side of the injector with -5.5 volts, correct , ? If so then doesn't all the elecrtons need to return to thier source to complete the circuit?(make the injectors pulse) That being said you might want to follow the instructions from the manufacture to the T

Last edited by Cab_Burge; 03/08/15 03:03 PM.

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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