Chrysler did it that way because of the type of neutral safety switch they use, and also apparently due to load (note the #10 wire from the starter to the relay that's called out). If you're not using their neutral switch (or any switch at all), you could eliminate the relay but the load on the ignition switch may exceed it's rating. I'd recommend retaining the relay....
If you’re using a connector that s designed to be crimped, crimp it with the correct crimper. If you’re splicing wires, you can solder them if it’s done correctly, or use a butt joint connector crimped correctly. Strain relief is always a good idea, regardless of the type of joint. Sent from my iPad using The H.A.M.B. mobile app
There is an astounding amount of aircraft, commercial and military, flying over our heads all day & night that have thousands of crimped connections in them. Of course every tool is calibrated and the personnel are trained, pull test samples are required at times.
Has anyone had experience with a contactor? I saw some 200 amp Tyco 12V contactors on ebay for around $50, seems pretty reasonable for the load it can take. It should last longer than a relay wouldn't it? Really appreciate this thread, exactly what I needed.
A contactor is just a multi-pole relay rated for large currents, so yes these can be used. About the only questions I'd ask are one, is it rated for continuous duty? Some aren't, and coil failure can result if they're not. Second, does it have a replaceable coil? Not a deal-breaker if it doesn't, but this can make later repairs cheaper.
They look to be sealed, probably not replaceable. I confirmed they're rated for constant duty, but only for around 175F temp, so I I'd have to bring it into the passenger compartment, near the panel. I also looked up the one you listed, and I found a White Rogers 586-105111 that seems to be identical, but takes 12v input. On my 64 Riviera, I've switched to a mini-starter, and a ford solenoid in place of the horn relay junction. I wanted to mount the contactor there, but it probably makes more sense bringing it inside. Do you see a need to fuse the line coming into the car? The lead would be about 4 foot long, and 120amp peak (thank you for the formula listed above!)
Unless you're using 1/0 cable, you can't really fuse it properly. Using diversity will allow a smaller wire than what calculated for a continuous load would be, but you have to fuse it for peak load to avoid nuisance tripping. So while that will give you catastrophic short circuit protection, you have little or no overload protection. A fusible link can work, but I've never seen one that big. The only thing you're doing is for that short circuit protection, and very careful routing and physical protection will prevent that. Every time you break a wire for a connection, you introduce another possible fail point or points. A well-designed system will eliminate all of those it can....
Ok, cool. I've got basically a blank sheet to work with, the only thing in place is the battery and starter solenoid. I was considering running 4AWG from the battery, put a 130A breaker right at the battery, and then run the cable back into the car to the contactor under the dash. Years ago, I miswired my ponycar, and a gauge shortout burned about 20ft of various wires (no protection from battery to ignition switch). I really, really don't want to repeat that mistake.
Seems like now-a-days with readily available automotive relays, fuses, breakers, etc; there should be no need to use industrial relays and components instead.
The key word here is miswired; it won't be an issue if it's wired right. The OEMs do this all the time, have for years, for pretty much the reasons I give. It's more common than you think; the wires coming to your house from the utility are unfused, again for the same reasons. A 130 amp fuse or breaker will probably be too small; if peak current is 125 amps, multiplying that by 125% (to give adequate headroom to avoid nuisance tripping) gives you a fuse size of 156 amps. You could safely drop that to 150, but that's still about 200% of #4 wires continuous rating so you don't have overload protection. When the automotive aftermarket quits selling over-rated components with snake oil, at that point there'll be no need for actual rated bits. Remember, ANY plug-in relay, regardless of it's so-called rating, is actually only good for 30 continuous amps max as that's the rating of the largest connector available. Your system will only be as good as it's weakest link...
Ok, makes sense. I noticed that about the Riv's original wiring, and thought it was odd, but it adds up now. I'll just run power in from the solenoid and keep that wire short. If you have time, could you check out my breaker panel, and see if everything looks ok before I put power on it? I have pics in this thread: https://www.jalopyjournal.com/forum/threads/replaced-my-fuse-box-with-a-breaker-box.1068031/ I realized the other day, I never tested those breakers. If I unplug everything, and put 12 volt across the poles, would it be a good test? I have a DC power supply with a meter, it does up to 15V, and 45A (adjustable) so I could tell at what level they trigger
There's a variety reasons... and remember, I'm coming from an electrical industry background. I'm retired, and field-installed solder connections have been illegal since before I got in trade. Solder connections are ONLY allowed on 'approved factory assemblies', i.e. components that have passed muster with UL, CSA or one of the other fire-safety testing labs. The 'why' is simple, and consists of basically two things. One, solder withstands heat poorly. Apply enough heat (and it doesn't have to be enough to fully melt it either) and it will migrate out of the joint, sometimes enough that the wire will literally come out. Overloads and/or poor/loose connections can easily generate enough heat to damage a solder connection; having a possibly-energized wire flopping around is never a good idea. A purely mechanical means of connection won't do this. Two, soldering destroys the annealing of the copper wire, making it brittle and very much more prone to breaking. If vibration or wire movement is present, this is a real issue. In vehicle applications, this is the number one cause of failures. This can be addressed with 'proper' strain relief, but I very seldom see it done 'properly' in automotive uses. Basically, you need to support the wire within 6" (or closer) of every solder joint to prevent ANY wire movement. You should also install a heat-shrink at each joint, but this will only be effective if the shrink is as stiff or stiffer than the wire insulation (so your paper-thin cheap heat shrink won't do the job). The idea is to transfer any strain from the wire insulation to your connector, preventing any movement at the wire/connector joint. This is why factory automotive connectors crimp to both the copper wire AND the wire insulation. Crimps got a bad reputation when the typical plastic-insulated crimps came into use. Used as designed in a dry, low-vibration environment and/or with close-in strain relief, they work fine; I've installed thousands of them. But automotive use IS NOT what they were designed for, and the crimpers designed for them work poorly in an automotive environment. You can't get a 100% crimp without destroying the plastic sleeve, and worse yet, this allows room for corrosion to get into them. They also lack the ability to properly install strain relief with the sleeve in place. I use uninsulated crimps ONLY. If need be, I cut the sleeves off insulated crimps to get them. Using a proper crimp tool to get a 100% crimp, I get: 1. virtually the same strength as the un-cut wire. 2. About 95% of the un-cut wires resistance to breaking from vibration or flex (and this is before installing a shrink). 3. As good resistance to corrosion as a solder joint because there's no room for corrosion with a 100% crimp. 4. Joint resistance so close to a solder joint that you won't be able to measure the difference with anything short of lab equipment, and maybe not then. What's a 100% crimp? When you cut the crimp in half at the crimp point, you'll see zero gaps between the wire strands and the connector barrel; it will look like a solid piece. And avoid the 'inline' tap splices like the plague; these are the crimps typically used by trailer places to install a pigtail. These should be used as temporary only; again, I've probably installed thousands of these too, and a 10% failure rate under good conditions is typical.
Steve, good info. For 33 years it was my policy in the shop to crimp uninsulated connectors, then solder and then cover with a good quality thick heat shrink. When I took over the shop, the little blue boxlike connecter were everywhere on the trucks from the previous mechanic. Spent most of my time early chasing bad connections because of these. This is why I installed my policy of solder “every” connection. To connect two wires I would twist inline,solder, heat shrink. If feasible I would replace the whole wire, but not always doable. All this was implemented before the information highway, as we know it now, was available. So I shot from the hip and did it my way and got excellent results.with no problems ever related to my connections. I was not aware that soldering was against the “rules”. The internet has become a mechanics best tool, it gives us easy access to other people in the industry and lets us share our knowledge. Some guys, such as yourself, have more knowledge than others. I’m retired now, so I won’t have to change my policy lol. I included a pic of my old terminal box, I used the uninsulated connectors the most, the others just came with the box and I could throw them away. I used this onthe job years ago. In your travels in the electrical industry, did you ever meet Dennis Litchinstien (mispell maybe) out of Ohio? Again, thanks for sharing with us, Steve/ Bones
There's plenty of cars out there with soldered wire connections; I'm not insisting that they need to be removed posthaste, but given the additional hassle involved with soldering, why would you want to? You're doing more work for a demonstrably inferior result.... You'll need to spring for a proper crimper for whatever your using, but costs on these have dropped sharply in the last few years. I will make one exception for a type of joint I'd never solder; very high current wires, battery cables in particular. These can easily generate enough heat to 'de-solder' the joint, and having one of those flopping around and possibly burning a hole in a fuel or brake line could be a major catastrophe...
Well.. Steve, you got me again! I always made a mechanical connection, ie crimping, then I soldered every connection. I used the best crimpers I thought where available, the red and black handles Klein and I had a large cable crimper for the battery cables that had four different dies. It was the one that pushed an indentation in the terminal. Then I would solder, they would never come apart even if the solder melted. I never had any formal schooling on this subject, just learned in the trenches. I had SO much trouble with crimps, even “factory” crimps, I thought soldering was better, anyway, that’s all in the past. I guess you never ran into Dennis? Bones
Thought maybe you might have. I had the privilege of attending one of his seminars. One of his last, he’s retired now. He ,too, was a learned man in electrical things, and would share his knowledge. Bones
I've recently discovered that Cole Hersee and others make a Bosch cube style relay with 60/70 amp capacity. Steve said pages ago that relay capacity is limited by the push on style terminals used: these higher capacity relays use a 3/8 quick disconnect on the secondary side. Google this: RC-700112-NN, it's a Cole Hersee part number. They can be had sealed or unsealed, with or without suppression. The 3/8 terminals can be harder to find than the more common stuff, here's one source for just about any connector you're liable to need when wiring a car: http://www.ferrulesdirect.com/ Edit: And beware ebay rubbish relays that are not rated for continuous duty.
What I said still applies, unless you can find a rated terminal that accepts wire larger than #10. And by rated, I mean UL/CSA approved, not some vendor 'rating'. I looked hard and had zero luck. Not to say these have no legitimate use; they do. But not at those continuous loads because of the terminal limitations. Where you'd want to use these is motor loads that are under the limits of the push-on connector when running, but have high inrush currents (think cooling fans) when starting. You can see instantaneous inrush current of up to 1200% of running current, but generally a figure of 300% is used when calculating circuit design. So a motor that has 20A running current will have inrush current of at least 60 amps. Most harnesses can take very brief overcurrents like these, but switch contacts don't like it. Using an 'oversize' relay will extend contact life.
Agreed, 100%. I know the relays I've mentioned would not sustain a 60 amp circuit. I was hoping to find 3/8 quick disconnects for #8 wire with 40 amp capacity, no such luck. Apparently bolt on lugs are the only option above 30 amps. Ebay has many sellers peddling "battery isolation" cube style relays up to "100 amps" with ring terminal posts on the secondary side. Most don't mention duty rating, the odd auction says intermittent use only. Scary... guess where they come from?.. I'd also like to thank you for taking the time to share your knowledge and experience, this is a very informative thread.
After 4 and 5 times reading that thread all over each time ,It's getting more understandable,even if it's complicated,but I'll be fine for some practice on my Ford 51 with a lot of stuff going on ...Thanks Steve for knowledge...Don
I just learned there is such a thing as desoldering braid! My usual desoldering method is holding the part in one hand, the iron in the other and the wire in my teeth until hot enough to pull apart. Anyone use this stuff?
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