Electrical system: ways to ground

[Frontranger]

A question for y'all today: is taking your grounding connections straight off the battery (+) post the wrong thing to do? I'm hooking up a tail light power converter (Modulite HD) AND an electronic brake (Tekonsha P3) on my 95'Chev 3/4T pickup. There are several GM Ground points in the engine compartment and at the back end too, but many of them, more than I want to clean up right now, are kind of crudded up, apparently not badly enough to keep anything from working for the time being. I'll get to them later. I've already cleaned up the main one at the battery to the frame. I could clean and use one of them closest to the under hood fuse box, but I'm wondering if there is any advantage/disadvantage to just running say a #10 or #8 wire directly over to the (+) terminal on the battery. Or am I asking for trouble in some way I don't yet know about?? Looking for max/best possible ground to reduce future difficulties. Thankin' you in advance for your help here!
BTW Reason for the question: I'm upgrading the Tow Vehicle wiring to the trailer plug (all bigger wires and 7 instead of 6) and adding a new Electric Brake to accommodate my "new" 1977 Trailer-Eze 8X20 12,000Lb. cap. trailer. Gonna make that pup shine like new, don'tchaknow! Might even run it bare(nekkid)in the 4th of July parade if it comes out as good as I want it to. It'll likely get more whistles than the gals down at the farm store!

 

[rustyfarmall]

Nuthin' wrong with grounding directly to the battery, but DON'T EVER ground the positive + post. All 12 volt systems are negative - grounded.

 

[John T]

Ranger, didnt you mean grounding from the battery - post?????? and tapping hot feeds off the + post of course????

When I want a sure fire trailer and brake connection I use for the hot feed a 30 amp circuit breaker tapped from the + battery terminal connection then use 10 gauge stranded insultated (well DUH) wire to my loads such as the trailer connectors auxiliary hot voltage feed terminal and to the input feeder for an electric brake controller etc etc. Of course, there are hot feed terminals under the hood which would be about as good provided alllllllll connections are good and Id still use the 30 amp circuit breaker

As far as grounding a trailer via the connectors truck mounted receptacle, I like to weld a stainless steel bolt to a main frame member and use it as the grounding terminal for a wire to the trucks receptacle. Of course, one could run a 10 gauge wire allllllll the way back to the trailer connector from the batterys - post, but if the connections are all good (like my welded SS bolt) using the frame as a conductor should drop less voltage then a 10 gauge wire.

Grounds are soooooooooo important as far as trailer lights and its electric brakes which is why I like a dead grounded frame member take off (my welded bolt) for connecting ground wires like to the trailer wiring receptacle. Similar, I like a stainless steel bolt welded to the trailers frame for its ground and ground wire connections.

As far as wiring, I like to use the cripmed on connectors BUTTTTTTTTT then also solder them for a super good electrical connection. I DO NOT LIKE OR TRUST any of those cheap scotch lock type push/crimp on wiring connections for trailer wiring, its best to butt splice n solder or even use twist on wire nuts with silicone sealer versus those push/crimp connections.

Its not really all that much work or expense to do it right (soldered connections and welded ground frame bolts etc) the first time on BOTH the truck n trailer (you want perfect grounds everywhere) and then have trouble free use for a long time. I try n keep my trailer receptacle n plug clean n sealed where necessary also.

Good luck

John T

 

[Anonymous-0]

Crimps done right (with a matching ratchet crimper to mil specs) are better without solder. Solder done right is good except it wicks into the strands away from the lug and makes a rigid stress point so the wire breaks at the end of the solder when vibrated. Also the heat of soldering tends to reduce the pressure of the crimp.

Scotch taps will corrode and go open. Had to hot wire my 4020 one summer to make hay because it had a Scotch tap in the ignition circuit. Its not there now. I won't allow any more used for anything.

Gerald J.

 

[buickanddeere]

This would be a good time to upgrade with a 2nd battery that supports only trailer electrical loads.
Use an oil pressure switch and a relay to isolate the trailer battery from the starting battery when the engine is shut down.
Technically the - goes to chassis. Connecting to ground would require driving a 10ft copper rod into the dirt below the truck.

 

[55 50 Ron]

Please be careful when using the word "all". My John Deere two cylinder tractor IS positive ground on a 12 volt system.

 

[55 50 Ron]

I think I'm a bit confused. So your point about the second battery supporting only trailer loads means it's just doing that when the truck engine is not running, right? And the batteries are in parallel when the truck engine is running?

 

[Oldmax]

Not all are Neg ground some large trucks still use Pos ground if you remember the flow is Neg to Pos . I ground all my Trailers to battery post Saves a lot off trouble after a few years and you lose ground due to corriosn of a nut and washer .

 

[Frontranger]

Correctomundo fellers! I had a 50-50 chance to say it right and I said it just exactly the opposite, dadgummit, six kinds of hello! I'm gonna call it a premature senior moment, dislexia, or bi-polar or somethin'. (-) terminal to the chassis (a tip of the hat to buickanddeere) and (+) terminal for the hot feed. I'm now scratchin' my chin and working over the double battery idea. John T I'm with ya on the dedicated stud welded to the frame. Gerald J. I get what you're saying about the milspec crimp, and the rigidity/potential for breakage of the soldered connection. I've been avoiding a good crimper out of sticker shock avoidance, but I may just have to get over that temporarily.

 

[jose bagge]

Negative- errr, incorrect. All American 12 volt is negative ground, I guess, but Some brit stuff- triumph for instance- is 12V positive ground.
That's the reason british drink warm beer...they can't figure out how to hook up the refrigerator

 

[jose bagge]

Don't see any problem grounding straight to the negtive post of the battery. Most "aftermarket" battery cables have a spare lead that will allow you to do just that.

 

[Brian Jasper co. Ia]

The stainless bolt sounds for a ground sounds like a good idea. All of my wire connections are soldered and sealed with heat shrink tubing. Soldering the wires to the terminals in each light has made them trouble free.

 

[MarkB_MI]

The mistake a lot of folks make when connecting directly to the battery is to do something that interferes with the original battery connection. If you using a battery cable that has both a heavy wire and a smaller one, tapping in to the smaller one is unlikely to cause problems. But if, for example, you stick a lug under the bolt head of a side-terminal battery you're asking for trouble.

 

[dave guest]

Being a lectrician and havin a lotta extra split bolts, you know how all my batt taps look. Just like the splices on your o verhead edison wires. Tighten them brass babies on that cable with a little grease, tape em real good. Never look back.

 

[Frontranger]

Hey Jose B, Brian, and MarkB_, (and the rest of y'all) input is much appreciated! Brian, you're a feller I'd be trackin' right after. The soldering is kind of a PITA, but I figure, scratch that, I am certain the reliability of the conection(s) is more than pretty durned important (we're talkin' brakes here). Gerald J. had some good commentary on the subject of crimp vs. solder (I'm leaning hard his way). I'm also adding all the conductive and non-conductive di-electric grease appropriately where I can and when I need to. I'm also working, for my first time, with "Weatherpak" (TM) connectors, without the benefit of the $78 crimping tool they so like to sell with that system. So far, so good. Can't really pull them apart on just the crimp without a pretty good fight. After a drop of solder in there....forgetaboudit. The double crimp required is not impossible to accomplish with the normal low-tek wire stripping/crimping tools. Supposedly bullet proof, I'll report on that later after the trial run if requested. You fellers are all doin' me proud. Thanks!!

 

[buickanddeere]

Yes.
The + to + tie between batteries has to be opened when the alternator isn't turning.
No use trying to tell people in the trailer not to run down the truck starting battery. It's like trying to get a dog to understand card tricks.
Just install the axillary battery and be done with it.

 

[Frontranger]

Hardy, har, har! Dogs and card tricks! Good one and so true.