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Re: Grounding for battery in the trunck? [Re: CHAPPER] #1722031
01/05/15 11:41 PM
01/05/15 11:41 PM
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Bend,OR USA
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Cab_Burge Offline
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Directly to the frame is ALWAYS your best bet - for grounding everything. Least # of attaching points for the starter / alternator. Next best is something that is welded to the frame. Worst is something that is bolted to the frame. Doing voltage drop tests are always in order when doing / checking grounds.


Not close to correct...........in fact that is the WORST way to wire a ground system. Just because people do it all the time and it is passable, does not make it right. Work with a lot of EFI cars as I do and you will quickly find the flaws in this type system. Your frame or sheetmetal is a TERRIBLE conductor.

What I do on all the EFI and actually everything I wire now, is a "floating" ground system. I attach a copper bus bar on rubber isolators under the dash. I run the cable from battery to bus bar and run all high draw grounds to this bar, such as ignition, pumps, fans, etc. I also tie both heads together and run a ground wire to bus bar as well. The ONLY thing I ground to the actual chassis or sheetmetal is the lights

Monte



Lets look at a new Charger or Challenger. Battery in the trunk, tons of components that are Can Bus based. Cars are even sent to the lab to check for radio and magnetic interference. Guess where the ground connects? Frame rail next to the battery. What do you think?
Doug





Frame has high copper content.




Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: Grounding for battery in the trunck? [Re: Cab_Burge] #1722032
01/06/15 12:21 AM
01/06/15 12:21 AM
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Canton, Ohio
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Sport440 Offline
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Directly to the frame is ALWAYS your best bet - for grounding everything. Least # of attaching points for the starter / alternator. Next best is something that is welded to the frame. Worst is something that is bolted to the frame. Doing voltage drop tests are always in order when doing / checking grounds.


Not close to correct...........in fact that is the WORST way to wire a ground system. Just because people do it all the time and it is passable, does not make it right. Work with a lot of EFI cars as I do and you will quickly find the flaws in this type system. Your frame or sheetmetal is a TERRIBLE conductor.

What I do on all the EFI and actually everything I wire now, is a "floating" ground system. I attach a copper bus bar on rubber isolators under the dash. I run the cable from battery to bus bar and run all high draw grounds to this bar, such as ignition, pumps, fans, etc. I also tie both heads together and run a ground wire to bus bar as well. The ONLY thing I ground to the actual chassis or sheetmetal is the lights

Monte



Lets look at a new Charger or Challenger. Battery in the trunk, tons of components that are Can Bus based. Cars are even sent to the lab to check for radio and magnetic interference. Guess where the ground connects? Frame rail next to the battery. What do you think?
Doug





Frame has high copper content.








Along with some silver and gold I heard.

Last edited by Sport440; 01/06/15 02:42 AM.
Re: Grounding for battery in the trunck? [Re: gregsdart] #1722033
01/06/15 01:52 AM
01/06/15 01:52 AM
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Canton, Ohio
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I have had great success running a rear battery and using the cage for a ground for the most part. I ground the heads AND block to the frame, use two 3/8 bolts welded to the frame, one for the electronics and one for the starter circuit.
My question is, for my street dart there is no cage, and I am moving the battery to the back. I am looking for a good way to ground the battery and thought that the same system would work, provided the ground connections are big enough (bolt welded all around the head?)to not create resistance at those points. I would drill a hole in the floor at the subframe area and weld it to the sub. The car has frame connectors. Input?





IMO, the way you suggested is Fine and maybe overkill.

IMO, where people go wrong is when they bolt a battery end against a painted surface#1 Number#2, they don't make sure they have good grounds from the engine to the body.

IMO, the unibody works fine as a ground circuit as long as every ground connection is clean and solid.

That's where the problem lies with some that have had problems. Bolt the neg to a painted surface and don't bother to check the quality of the engine ground to the body. Problems!!


I run two separate neg grounds to the engine from the body. I run the bat neg to a quality ground to the factory multi welded trunk brace. Never a problem. Greg, your methods will work fine.

Re: Grounding for battery in the trunck? [Re: Sport440] #1722034
01/06/15 08:23 PM
01/06/15 08:23 PM
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Ontario, Canada
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A lot of electronics like a dedicated ground cable to the battery. The ground ensures they don't get nuisance calls on the tech line because of bad grounds. Who can blame them. On the flip side, the starter draws more current than ANY other component - and its grounded through the casing/block/chassis.


Re: Grounding for battery in the trunck? [Re: Stanton] #1722035
01/06/15 10:51 PM
01/06/15 10:51 PM
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Frostbitefalls MN (Rocky&Bullw...
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One thing we can agree on, there needs to be good grounds from the heads and block to where ever the main ground is. I also like to use a ground right to a starter mounting bolt. The heads and block ground can be much smaller if you are using a big ground independently for the starter.


8.77 153 mph best, 3055 lbs 528 indy 440-1 alky
Re: Grounding for battery in the trunck? [Re: gregsdart] #1722036
01/06/15 11:23 PM
01/06/15 11:23 PM
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Balt. Md
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I ground my trunk mounted battery to the body in the trunk. But I have a few extra grounds from the frame to the unibody and an extra one from the eng to the body. Working for a Dodge dealer for 24 years I would see some strange ground problems over the years like the one that causes the trans bearing to have problems or seeing sparks from a throttle cable because the body to eng ground is bad. So in my opinion if your not sure put another ground on it as you can not have to many grounds. Ron

Last edited by 383man; 01/06/15 11:24 PM.
Re: Grounding for battery in the trunck? [Re: 383man] #1722037
01/07/15 12:08 AM
01/07/15 12:08 AM
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Soooo, what's everyone's opinion on running static straps for them highly sensitive electronics?


Fastest 300
Re: Grounding for battery in the trunck? [Re: 383man] #1722038
01/07/15 01:16 PM
01/07/15 01:16 PM
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I am not sure I agree, I would rather have one reliable, properly sized, tested/measured ground, then, unless in an in an emergency, a random selection of undersized, maybe good grounds, and let the electrical devices figure which one is best. IE, if a ground is thought to be not correct, then any additional backup grounds have to all be the same proper size, thinking you can "share" or combine grounds is unwise and asking for future problems.

"static straps", are primarily for grounding static charges, not grounds.

Last edited by jcc; 01/07/15 01:18 PM.

If you can't dazzle them with diamonds, don't waste your time, because nothing will
Re: Grounding for battery in the trunck? [Re: jcc] #1722039
01/07/15 01:48 PM
01/07/15 01:48 PM
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Quote:

I am not sure I agree, I would rather have one reliable, properly sized, tested/measured ground, then, unless in an in an emergency, a random selection of undersized, maybe good grounds, and let the electrical devices figure which one is best. IE, if a ground is thought to be not correct, then any additional backup grounds have to all be the same proper size, thinking you can "share" or combine grounds is unwise and asking for future problems.

"static straps", are primarily for grounding static charges, not grounds.


"properly sized" - would a frame be big enough?


Fastest 300
Re: Grounding for battery in the trunck? [Re: Crizila] #1722040
01/07/15 01:58 PM
01/07/15 01:58 PM
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North Alabama
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A ground is NOT a ground so to speak. Lot to be said for "clean" grounds and "noisy" grounds. Something like a starter, doesn't NEED a clean ground.......ANYTHING electronic DOES. You want to use the chassis as one big ground conductor, that's fine, many do, but it is NOT the best way to do it. I prefer to do it right and prevent any future issues. Seen too many problems too many times that drove guys crazy, that was fixed with a proper ground system.

I used to ground stuff like everybody else, to the chassis, until I learned better. Just because it is the way you have ALWAYS done something doesn't mean its the BEST way. You would like to think you do something long enough, that you find BETTER ways to do it........not the same old same oh.

Monte

Re: Grounding for battery in the trunck? [Re: Monte_Smith] #1722041
01/07/15 02:33 PM
01/07/15 02:33 PM
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Romeo MI
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Quote:

A ground is NOT a ground so to speak. Lot to be said for "clean" grounds and "noisy" grounds. Something like a starter, doesn't NEED a clean ground.......ANYTHING electronic DOES. You want to use the chassis as one big ground conductor, that's fine, many do, but it is NOT the best way to do it. I prefer to do it right and prevent any future issues. Seen too many problems too many times that drove guys crazy, that was fixed with a proper ground system.

I used to ground stuff like everybody else, to the chassis, until I learned better. Just because it is the way you have ALWAYS done something doesn't mean its the BEST way. You would like to think you do something long enough, that you find BETTER ways to do it........not the same old same oh.

Monte




While this is true, I've seen that more wires CAN
create more issues... like is it REALLY grounded after
its been on there a while

Re: Grounding for battery in the trunck? [Re: Monte_Smith] #1722042
01/07/15 04:43 PM
01/07/15 04:43 PM
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Crizila  Offline
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Quote:

A ground is NOT a ground so to speak. Lot to be said for "clean" grounds and "noisy" grounds. Something like a starter, doesn't NEED a clean ground.......ANYTHING electronic DOES. You want to use the chassis as one big ground conductor, that's fine, many do, but it is NOT the best way to do it. I prefer to do it right and prevent any future issues. Seen too many problems too many times that drove guys crazy, that was fixed with a proper ground system.

I used to ground stuff like everybody else, to the chassis, until I learned better. Just because it is the way you have ALWAYS done something doesn't mean its the BEST way. You would like to think you do something long enough, that you find BETTER ways to do it........not the same old same oh.

Monte


I agreed with your post - in principal, but you gotta look at the bigger picture some times. For instance, is the added weight of having to run a ground cable from a rear mounted battery to the front of the car off set by the better conductivity of the cable over the frame? Doubt if you could measure the difference. The reason that it is still done the way it was done 30 years ago is because nothing "practically" better has come along. Change for the sake of change is not better. Who ever coined the phrase "change is good" must be in sales. Who ever invented "scotch-locks" should be shot. Minimum wiring, minimum ( and clean ) connections, still the best bet IMO.


Fastest 300
Re: Grounding for battery in the trunck? [Re: Crizila] #1722043
01/07/15 04:55 PM
01/07/15 04:55 PM
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jcc Offline
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Quote:

Quote:

I am not sure I agree, I would rather have one reliable, properly sized, tested/measured ground, then, unless in an in an emergency, a random selection of undersized, maybe good grounds, and let the electrical devices figure which one is best. IE, if a ground is thought to be not correct, then any additional backup grounds have to all be the same proper size, thinking you can "share" or combine grounds is unwise and asking for future problems.

"static straps", are primarily for grounding static charges, not grounds.


"properly sized" - would a frame be big enough?




Yes, most definitely but may not be properly electrically connected, circumventing the benefits of being properly sized. In my previous reply example I intended the "properly sized" to more refer to any of the wiring size that is being used to connect to the battery Negative. The chassis is just a multi sheet metal steel welded sometimes questionable conductor in that goal.


If you can't dazzle them with diamonds, don't waste your time, because nothing will
Re: Grounding for battery in the trunck? [Re: jcc] #1722044
01/07/15 06:32 PM
01/07/15 06:32 PM
Joined: Aug 2003
Posts: 39,970
Bend,OR USA
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Years ago, 1976 to 1990, the telephone industry went from old analog mechanical equiptment to digiatl computer to do the calling, billing and offer a lot of features we now know as standards. The conversion process and the debugging took a lot of work and energy as well as dicovering some new ways to get the job done without problems, grounding being a big factor in noise and problem prevention. All the phone companys I know of use banks of batterys to power the equiptment offices, we used commercial power ran through inverters to charge the batterys but all the equiptment drew its power from the battery banks. The reason I'm clarifying this is all power, voltage and amperage, comes out of ALL batterys from the negatve battery post and travels through the circuit and returns back to the positive post My main point is we had to convert our grounding(positive side) in the offices from conventional to perephial grounding, we had copper buss bars aroud two to three inches tall by 1/4 inch thick, depending on the office size and the power used, running all the way around the equiptment in the offices with multiple 000 or larger ground wires hook to them We lived in the Mojave Desert in SO CA and the summer thunderstorms could wreak havoc with the digital offices through the air and telephone lines Noise can be induced from many sources into digital devices is my message. You can never have to good of a ground on any thing using electrical power to run digital devices IHTHs someone


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: Grounding for battery in the trunck? [Re: Monte_Smith] #1722045
01/07/15 07:22 PM
01/07/15 07:22 PM
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Blue Ridge, VA
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Quote:

Quote:

Directly to the frame is ALWAYS your best bet - for grounding everything. Least # of attaching points for the starter / alternator. Next best is something that is welded to the frame. Worst is something that is bolted to the frame. Doing voltage drop tests are always in order when doing / checking grounds.


Not close to correct...........in fact that is the WORST way to wire a ground system. Just because people do it all the time and it is passable, does not make it right. Work with a lot of EFI cars as I do and you will quickly find the flaws in this type system. Your frame or sheetmetal is a TERRIBLE conductor.

What I do on all the EFI and actually everything I wire now, is a "floating" ground system. I attach a copper bus bar on rubber isolators under the dash. I run the cable from battery to bus bar and run all high draw grounds to this bar, such as ignition, pumps, fans, etc. I also tie both heads together and run a ground wire to bus bar as well. The ONLY thing I ground to the actual chassis or sheetmetal is the lights

Monte




I agree 100%, this is the ONLY way I will wire a car!

Mike Gray
Plumb Wired


RIP Monte Smith

aka: OutlawFish
'98 Bickel Dodge Dakota PST
Re: Grounding for battery in the trunck? [Re: Monte_Smith] #1722046
01/07/15 08:05 PM
01/07/15 08:05 PM
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Posts: 579
Deep DEEP SOUTH
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What I do on all the EFI and actually everything I wire now, is a "floating" ground system. I attach a copper bus bar on rubber isolators under the dash. I run the cable from battery to bus bar and run all high draw grounds to this bar, such as ignition, pumps, fans, etc. I also tie both heads together and run a ground wire to bus bar as well. The ONLY thing I ground to the actual chassis or sheetmetal is the lights

Monte




Monte, I assume you run the MAIN -ve batt cable to the bus bar under the dash so that the bus bar gets is grounding from the batt cable itself, and NOT the body ? Or in other words, the bus bar is NOT grounded to the body/mounted on isolators/non conductive mounts....right?

That would be a decent gauge cable if thats the case - do you run it inside the car ?

Re: Grounding for battery in the trunck? [Re: LAD 524] #1722047
01/07/15 08:13 PM
01/07/15 08:13 PM
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jcc Offline
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If anything is grounded to the chassis, and he said the lights are, this floating ground buss bar, must also have a connection to the chassis someplace, or no lights. This is the best in our situations, and most complex(?) solution, and a bad ground is a lot easier to trouble shoot, and all grounds are very close to the same resistance.


If you can't dazzle them with diamonds, don't waste your time, because nothing will
Re: Grounding for battery in the trunck? [Re: jcc] #1722048
01/07/15 08:46 PM
01/07/15 08:46 PM
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Holly/MI
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The "bussbar" would be for electronic devices that NEED a "clean" ground free from noise. And that same bussbar would have its own dedicated cable to the battery. The whole idea is to separate/isolate the high tech digital devices away from the old school analog devices like alternators, wiper motors, headlights and such. Motors and alternators create electromagnetic fields that cause noise.

When it comes to the starter motor......it is the highest current drawing device in the vehicle. Of course it needs just as high current carrying a path as the positive cable that feeds the starter (A basic law of DC voltage). One little ground strap is not going to do it. If the motor is solid mounted, it should be fine.

High current devices like, headlights, starter motors, wiper motors, when poorly connected will seek the path of least resistance creating a "groundshift" or a voltage drop that causes more problems for sophisticated devices like electronic modules.

Bottomline.......run a separate ground for your ignition modules/boxes and otherwise the use of the rollcage is perfectly acceptable for the rest of the old school automotive circuits.

And the electron flow is within the metal of the wire (copper being best) but the electromagnetic field travels along its outer layer.


R.I.P.- Gary "Coop" Davis 02/09/68-05/13/04
Re: Grounding for battery in the trunck? [Re: Dean_Kuzluzski] #1722049
01/07/15 09:29 PM
01/07/15 09:29 PM
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MI, usa
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No one has answered how production cars with numerous electronic devices rely on the "terrible" floor pan/unibody to attach ALL the grounds in the entire vehicle. This remains the same regardless of where the battery is located. There is a heck a lot of surface area in a unibody. I do agree if the car is a rust bucket the unibody spot welds could possibly be an issue. If its so bad that the majority of the spot welds are suspect there is a way bigger issue than the ground path. When my car was completed I voltage drop tested my ground side under load. There was .2 volts drop at 28 amp draw from the center ground post of the battery to the ground wire of the dual cooling fans. The battery is grounded to a 3/8" stud welded to the cage with 1awg cable. The block/trans is also grounded with 1awg cable.
Doug

Re: Grounding for battery in the trunck? [Re: Crizila] #1722050
01/07/15 10:59 PM
01/07/15 10:59 PM
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Monte_Smith Offline
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Quote:

Quote:

A ground is NOT a ground so to speak. Lot to be said for "clean" grounds and "noisy" grounds. Something like a starter, doesn't NEED a clean ground.......ANYTHING electronic DOES. You want to use the chassis as one big ground conductor, that's fine, many do, but it is NOT the best way to do it. I prefer to do it right and prevent any future issues. Seen too many problems too many times that drove guys crazy, that was fixed with a proper ground system.

I used to ground stuff like everybody else, to the chassis, until I learned better. Just because it is the way you have ALWAYS done something doesn't mean its the BEST way. You would like to think you do something long enough, that you find BETTER ways to do it........not the same old same oh.

Monte


I agreed with your post - in principal, but you gotta look at the bigger picture some times. For instance, is the added weight of having to run a ground cable from a rear mounted battery to the front of the car off set by the better conductivity of the cable over the frame? Doubt if you could measure the difference. The reason that it is still done the way it was done 30 years ago is because nothing "practically" better has come along. Change for the sake of change is not better. Who ever coined the phrase "change is good" must be in sales. Who ever invented "scotch-locks" should be shot. Minimum wiring, minimum ( and clean ) connections, still the best bet IMO.


Wire a few EFI cars.....chase your ass for weeks with EMI "noise" and get back to me on if its "worth" it

Monte

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