Wire Nuts, Parallel Batteries and other thoughts

[ZendoDeb]

In looking for info on batteries, I have seen a few things that may or may not be an issue. Your mileage may vary.

1 - the use of solid-core wire. In the early 1980s, the use of solid core wires was basically "outlawed" in the construction of boats. Solid-core wire when subjected to continued flexing, would crack, and short. Several fires resulted. Everything uses stranded wire today.

When I buy wire from my favorite wholesale, I have to watch because they always try to sell me automotive-grade, not marine-grade. (Marine grade wire is smaller individual strands and tinned over 100% of the run) This seem to imply that for automotive and RV applications people should be using stranded wire, but I have seen many photos of solid-core wire in AC electrical systems.

Now my 1979 sailboat was built with solid core wire, and had no problems, until my insurance company refused to cover it until it was rewired.

2 - Wire Nuts. The don't work with anything but solid-core, so see item 1. Crimp connectors are easy and secure, and if you have any question about exposure to the elements it is easy to cover them with heat-shrink tubing.

3 - Batteries in parallel. There is a lot written on this, but batteries in parallel are fairly common in the marine industry. I have six 6-volt batteries in my boats house bank, and separate starting battery. Everything - except air conditioning - on my boat is 12 volt DC, including the refrigeration. The last set lasted 6 years, and I admit they were neglected. (I installed a battery watering system when the new 6 were installed last year.) Everything is fused, and I have cut-off switches so I can isolate bad pairs. (660 amp hours of power lets me run refrigeration and autopilot... it isn't too much.) Is it the perfect set up? No, but I don't have to fiddle with it constantly and the electronics manage it pretty well.

[Miriam C.]

In looking for info on batteries, I have seen a few things that may or may not be an issue. Your mileage may vary.

1 - the use of solid-core wire. In the early 1980s, the use of solid core wires was basically "outlawed" in the construction of boats. Solid-core wire when subjected to continued flexing, would crack, and short. Several fires resulted. Everything uses stranded wire today.

My how times have changed. I used romex for the 120vac and automotive for the 12v.

When I buy wire from my favorite wholesale, I have to watch because they always try to sell me automotive-grade, not marine-grade. (Marine grade wire is smaller individual strands and tinned over 100% of the run) This seem to imply that for automotive and RV applications people should be using stranded wire, but I have seen many photos of solid-core wire in AC electrical systems.

Now my 1979 sailboat was built with solid core wire, and had no problems, until my insurance company refused to cover it until it was rewired.

2 - Wire Nuts. The don't work with anything but solid-core, so see item 1. Crimp connectors are easy and secure, and if you have any question about exposure to the elements it is easy to cover them with heat-shrink tubing.

Solder anything you want to stay and cover in a wire nut or some of the new connectors. Shopping spree will give all sorts of ideas.

3 - Batteries in parallel. There is a lot written on this, but batteries in parallel are fairly common in the marine industry. I have six 6-volt batteries in my boats house bank, and separate starting battery. Everything - except air conditioning - on my boat is 12 volt DC, including the refrigeration. The last set lasted 6 years, and I admit they were neglected. (I installed a battery watering system when the new 6 were installed last year.) Everything is fused, and I have cut-off switches so I can isolate bad pairs. (660 amp hours of power lets me run refrigeration and autopilot... it isn't too much.) Is it the perfect set up? No, but I don't have to fiddle with it constantly and the electronics manage it pretty well.

Can't wait to see the pictures You are right 6 batteries will be very heavy. A small TD will need very little power unless you are refrigerating and heating. Have fun

[Kelly Coker]

Something I've learned about in just the last few years (and was a practice I used to do extensively) is using solder with "crimp on" connections. Again I'm just talking about using solder on "crimp on" type connectors after the crimping has been done. There was a belief that this would bring about a more complete electrical connection. Turns out that it causes corrosion and brittlenes to the wires and connectors. So, the bottom line is let the crimper tool do all the work and DO NOT use solder on the connection.

I hope that didn't cause any confusion.

[mechmagcn]

2 - Wire Nuts. The don't work with anything but solid-core

Try to tell that to the RV industry, most RV wiring systems are connected with wire nuts,both 12VDC and 120VAC. I always wrap a round of quality electrical tape around them to keep them from loosening.

[Arne]

I am not an expert... I use wire nuts on everything... sometimes on stranded, I will solder the tips on stranded.

Sometimes I won't.

[ZendoDeb]

Won't have 6 batteries on my tear. The 6 batteries are on my boat. I can run refrigeration, stereo, recharge the laptop, etc. for about 2.5 days without recharging. (Depends on temperature, as the refrigeration isn't as well insulated as it could be.) I also have solar, so that would be 2.5 days with little or no sun. That isn't a long time, when you consider a trip from Tampa to Key West is at LEAST 2 days. Throw in the autopilot and I would have to recharge more than every 2 days. (But then running the engine heats the water in the water heater...)

[Steve_Cox]

Old boat guys and gals don't believe in solid wire, wire nuts, or soldered connections. All of the above are weak links in the system, but "good enough" for some people in a lightly used road warrior, it just isn't the same as a boat.

6 volt batteries in parallel. If you were building a self contained motor home it is a pretty good application of boat technology. In a tear drop where the dominant feature is light towing weight with a minimalist attitude, it is way over the top. Sometimes just because you have the know how doesn't mean it's application is necessary. Now if your objective isn't being a step above tent camping and you have specific needs, perhaps lot's of Amp hours is your desire. It is possible to be off the grid and have microwave meals, keep the crockpot stewing and have the ability to blog late into the night with the reserve power to jump start a 747. Myself, if I was on a power trip like that I would go high tech and add a couple of high end 55 amp marine solar panels, great for the desert although not much help in the forest.

And for Deb since you started this thread, here's a picture of my teardrop (marine) electrical panels.


PS - what happened to Zendo?

[asianflava]

A crimped terminal is a superior connection. It is the preferred connection in many applications.

The reason they get such a bad reputation is because people don't use the proper sized terminal for the wire they are crimping to. Another reason is because of those crappy crimpers that can be found anywhere.

[Steve_Cox]

A crimped terminal is a superior connection. It is the preferred connection in many applications.

The reason they get such a bad reputation is because people don't use the proper sized terminal for the wire they are crimping to. Another reason is because of those crappy crimpers that can be found anywhere.

This is what I use, not a crappy crimper. Although I do have several crappy crimpers

[vrooom3440]

I have a hard time believing that soldering *causes* corrosion, that is if the proper flux is used. It *may* cause a stress fracture point... but I have never seen this in practice only in discussion/theory.

What most people get wrong is that solder does not improve the electrical connection. What it really does it seal the elements out of the connection as well as provide a mechanical lock to the connection. I would solder any connection I want to be permanent.

I also would NOT use romex in a TD AC electrical system. I agree with the use of stranded wire for handling vibration.

[asianflava]

Here are my strippers and crimpers, I think I posted this before. I have some of the crappy ones too. Steve's crimpers are better, I only have 2 positions versus his 3. Mine can't do yellow (at least it isn't supposed to) terminals.

[48Rob]

I also would NOT use romex in a TD AC electrical system. I agree with the use of stranded wire for handling vibration.

I'm not trying to get too nit picky or start anything, but really, to announce that YOU wouldn't use Romex in a td to all the people here in a tone that suggests it is unsafe, and improper is going a little far...

You're certainly welcome to your opinion, and I'm not out to change your mind with regard to your wire choice, but gee!

I suppose if you have a td with no springs, and a couple bent wheels, the vibration over time might cause problems...if the connections in the system were poorly made to begin with.

Unless there are really prominant issues with the build, the wire and fixture installation, or serious damage to the suspension, wheels, or tires, vibration to a degree that would cause failure in the electrical system is non existant.

Please, think about it? The average teardrop...
Unlike in a boat, there are no engines running constantly to cause any vibration.
No pumps running constantly.
No bent or out of balance props.

About the worst vibration you'll get in a td is a young couple who left the kids with grandma for the weekend...

I think sometimes we, while meaning well, get a little too serious trying to pass on knowledge and or protect others.

Rob

[bobhenry]

And I gotta take all the wire nuts off of my stranded wire connections.

Like Hell

[brian_bp]

...I suppose if you have a td with no springs, and a couple bent wheels, the vibration over time might cause problems...if the connections in the system were poorly made to begin with.

Unless there are really prominant issues with the build, the wire and fixture installation, or serious damage to the suspension, wheels, or tires, vibration to a degree that would cause failure in the electrical system is non existant.

Please, think about it? The average teardrop...
Unlike in a boat, there are no engines running constantly to cause any vibration.
No pumps running constantly.
No bent or out of balance props.

If this is a valid line of reasoning, then it should apply to modern cars as well, since their engine vibration is almost undetectable and their suspension is better than a typical trailer. It seems that the automotive practice is still to use stranded wire...

It would be interesting to see an NVH (noise, vibration, and harshness) comparison of a car and the teardrop being towed by it. Okay, interesting to some of us, if not to normal people.

I agree that solid conductors are not the best choice in a vehicle (for AC or DC), but at the same time RV trailers (including mine) generally get away with using them. I think the fact that the average RV gets very little road time/distance compared to an average motor vehicle lets them get away with a lot.

[vrooom3440]

I also would NOT use romex in a TD AC electrical system. I agree with the use of stranded wire for handling vibration.

I'm not trying to get too nit picky or start anything, but really, to announce that YOU wouldn't use Romex in a td to all the people here in a tone that suggests it is unsafe, and improper is going a little far...

You're certainly welcome to your opinion, and I'm not out to change your mind with regard to your wire choice, but gee!

I understand where you are coming from Rob. I understand that Romex has been used in quite a few TDs without problems. And being realistic, the chances of actually breaking a piece of solid copper wire are probably quite slim. And I conceed that makes it just fine for a lot of people. But perhaps I should elaborate on why I stated it as I did to make the picture more complete...

The most likely failure mode with Romex and regular house electrical outlets would be a poor connection from the typical method of inserting wire into outlets. The design of 'stick it in' connections was never intended to handle potential movement of the wires. This movement could be caused by road vibrations or even just thermal expansion. Given a low power connection it would probably still never be a problem. But hook up an electric heater and that may change... remember that heating in a circuit is proportional to the *square* of the current multiplied by the resistance. So a 1500W heater pulling 12.5A with a 1ohm resistance in a connection generates over 150W of heating. That is enough to cause some issues

The other part of my thought here is that there are other types of wire out there which are much more suitable to TD usage than Romex. They are not hard to find nor much more expensive. A person could just cannibalize a decent extension cord and have a cable that is much easier to route. So why not just avoid the potential for problems completely by using stranded copper rather then Romex?