Do I need 2 Shortstops?

[Thomas]

I have a 2017 Dutchmen Kodiak Ultimate.
I'm upgrading from 2 Group 24s to 2 Group 27 batteries.
I have to move the battery tray to accommodate the longer Group 27s and so I want to clean up the installation a bit. When purchased it had only 1 battery. We had the dealership add the second battery. Shore power is 50A (both ACs) that we break down to 30A or 15A as needed.

I have 2 Shortstops, 1 30A, & 1 50A;
The 30A Line side has main 12V line from converter/charger plus a purple wire that I have no friggin' clue about.
The 30A Load side splits off to the Load side of the 50A Shortstop.

The 50A Load side has pigtail from 30A Load side and pigtail to batteries.
The 50A Line side smaller gauge wires go to tongue jack and leveling jacks.

THIS DOESN'T LOOK RIGHT TO ME!?

Should the 50A Shortstop be first in line?
If not, shouldn't the Load from 30A go to the Line of the 50A? Otherwise will 50A trip if it's backwards?

Asking for some guru help!
Pics hopefully included

[dsol]

Way beyond my pay grade but plenty of electrical experts visit this forum all the time. I bet you have some good feedback in due time.

[persistent]

I agree, it does not look correct. Both the 30 amp and the 50 amp are connected to the battery. (The large wire goes to the battery?) Almost all the house loads are on the 30 amp breaker. Two small wires are connected to the 50 amp breaker. Those two small wires are not protected by anything in your picture.

I guess the purple wire supplies the electric emergency brake. Leave it where it is.

You can probably remove the 50 amp breaker altogether. It does not do anything.

Connect the large wire from the batteries that now goes to the 50 amp, to the 30 amp copper stud. Discard the jumper and the 50 amp breaker.

Connect the tongue jack and leveling jacks to any convenient stud if they each have their own fuse.

Add an appropriate sized fuse for each wire if there are no fuses now. Check installation instructions for each device for proper fuse size and type.

I wish you good luck and happy trails ahead!

[kimbo@alum.mit.edu]

From the picture and what you say it looks correctly wired to me. The only real question is are the breakers the right size to protect the wires. A 30 amp breaker protects a #10 or larger wire and a 50 amp a #6 or larger wire. Could be you've got the load wires reversed. Use breakers form auto parts if you want to replace tongue and leveling breakers otherwise you'll be buying fuses every time a motor stalls.


The other question is have you paralleled the batteries such that the paralleling wires are of equal length and one battery has the main positive lead and the other the main negative lead. Try and cover the connections in some way to keep water out.

The DC Power amperage has no direct correlation to the AC amperage except when running the converter and then you must convert such that 120V * A equals about 14v * B. Thats 120 volts ac times A ac amps equals 14 volts dc times B dc amps. (14 volts the real battery voltage).

[Thomas]

Here is a picture with the wires labeled for clarity.
I have a call in to the dealer service department as well.
I haven't changed anything here since we bought it. I don't know what, if anything, they changed or added when they installed second battery.

Battery cables are 6AWG. I've ordered some new rubber caps for the shortstops. Batteries are/were in parallel with Neg & Pos leads on different batteries. Batteries are/were in battery boxes, covered.

Tongue jack has an inline fuse, just beyond the picture.

The negative battery lead is much longer than the positive. At least to the shortstops. the negative lead runs into the floor under the front cap.
From where should that measurement be taken to ensure the same lead lengths to the batteries?

The reason I'm replacing the batteries is I had 2 batteries die with dead cells. Interstate 24s Marine Deep Cycle (yes that means they are also starting batteries and not true deep cycle). First time the battery was 13 months old, just past the 1 year Interstate warranty. :-( Second time (this time) was 2 years later.
Moving up to the Group 27s Deep Cycle only.

[persistent]

The labels make things clear. I stand by my analysis above. The 50 amp breaker is doing nothing.

Hopefully the tongue jack and level system have a fuse in each line unless they are at least 10 gauge. (10 gauge can handle 30 amps. The 30 amp shortstop covers that.)

Purple wire could be anything related to front harness and emergency brake. The purple wire may have another fuse as well unless it is at least 10 gauge.

[persistent]

Here is another possible solution:

6 awg can handle 50 amps. The three smaller wires cannot. Connect the three smaller wires to the 30 amp load side. Connect the 6 awg to the 50 amp load side. Leave the jumper between the 50 and 30 in place.

If any of the three smaller wires are smaller than 10 gauge, it will need a fuse of its own. The 30 amp breaker will protect wire 10 gauge and larger. Smaller wire needs a smaller fuse. From battery to the emergency brake needs a self resetting circuit breaker not a fuse.

You should inspect the house side of the 6 awg wire on the inside end. Make sure it does not drop below 8 gauge at the other end. The 50 amp breaker will protect 8 gauge and larger wire. Also ground wire to the battery and at the other end need to be 8 gauge or larger.

This method would support 50 amp battery charging and 50 amp inverter (600 watt). 6 gauge wire would be a bit under size for efficient operation, but should work acceptability.

I wish you good luck and happy trails ahead!

[persistent]

"Batteries are/were in parallel with Neg & Pos leads on different batteries. Batteries are/were in battery boxes, covered."

Good to go. Wired properly.

"Tongue jack has an inline fuse, just beyond the picture."

Good to go. Wired properly.

"The negative battery lead is much longer than the positive. At least to the shortstops. the negative lead runs into the floor under the front cap.
From where should that measurement be taken to ensure the same lead lengths to the batteries?"

Good to go. The leads from battery box to house do not need to be the same length.

"The reason I'm replacing the batteries is I had 2 batteries die with dead cells. Interstate 24s Marine Deep Cycle (yes that means they are also starting batteries and not true deep cycle). First time the battery was 13 months old, just past the 1 year Interstate warranty. :-( Second time (this time) was 2 years later.
Moving up to the Group 27s Deep Cycle only."

I have a pair of 12 volt 100 amp hour Interstate Marine deep cycle AGM batteries. They are group 31 and are now 3 years old and working perfectly. They are possibly working better now than when they were new. They are indeed deep cycle. They are capable of starting small engines like small generators or small marine engines. They will not start my SUV engine.

My last pair was 10 years old and working perfectly when I sold the trailer.

I don't know if your batteries are AGM, but AGM can charge faster and deliver higher maximum current than deep draw flooded cell batteries. It all depends on the design. See battery manufacturers specs for actual capabilities. They cost about twice as much.

AGM batteries can be drawn down flat without significant damage to the batteries. AGM batteries do not spit acid or emit acid vapors or hydrogen gas when charging.

AGM batteries must not be charged at high voltages. For most, 14.4 for 4 hours and then drop to 13.8 volts is the maximum. 13.2 volts is best for long term storage. Check the specs on your battery charger to make sure it does not "condition" batteries.

All lead acid batteries must be stored with a full charge. A full charge means 14 to 18 hours using a high quality RV battery charger.

Long periods of time in a discharged state causes sulfation. That results in lower capacity.

AGM batteries can be stored for 12 months if disconnected. Flooded cell can be stored for 12 months if disconnected.

Storing connected with RV charger is OK. 13.2 volts would be optimum. 13.8 volts is OK. Higher voltages consume water. AGM batteries may vent which is permanently lost.

Battery University https://batteryuniversity.com/

How does the Lead Acid Battery Work? https://batteryuniversity.com/learn/...ased_batteries

Charging lead acid batteries https://batteryuniversity.com/learn/...d_acid_battery

AGM https://batteryuniversity.com/learn/..._glass_mat_agm

How to Charge and When to Charge? https://batteryuniversity.com/learn/...o_charge_table

How to Store Batteries https://batteryuniversity.com/learn/...tore_batteries

Summary of Do’s and Don’ts https://batteryuniversity.com/learn/..._battery_table

I wish you good luck and happy trails ahead!

[larrypride]

What is a short stop? I read the comments and the only correction I see, is the amperage rating of wire is also based on the insulation. #8 normally is 40 amps not 50 again depends on insulation. You also need to consider line loss if your running wires long distances, especially at 12 volts. Make sure your batteries are secured properly. If they got loose and shorted to each other or to ground you would have a big fire probably.

[Lagman]

Agree, they probably through the 50 because no 30 or the guy wanted to get to lunch.

[Thomas]

Ok, I got some conflicting answers.

Correct me if I’m wrong, but when I am connected to the 50 amp shore power, that’s not going directly to the batteries. That goes to the converter/AC panel. The converter then sends the appropriate charge, hopefully no more than 14.4 V when charging, to the batteries.

So the question is why do I need 50 amp protection, or even 30, going from the batteries to the coach? Even the first leg, off of the 50 amp shortstop, that goes to the front jack, Is only drawing power, not supplying it.

That’s what’s confusing to me. It seems that the shortstop should be where the shore power cord comes into the coach. That’s completely at the rear. The batteries are only connected to that, via the converter/charger.

Anyway, my main question is, do I need two short stops? I didn’t really get an answer which is OK. I’m going to have to check with the dealer I suppose.

I don’t have an inverter yet. So that’s not part of the issue.

[kimbo@alum.mit.edu]

The purpose of breakers and fuses is to protect the wire and from a fire caused by short circuit, overload, or insulation failure. They can only protect downstream of the power source. A breaker in the power pedestal protects the 50 amp cable to the trailer and the AC panel which has breakers to protect the wires going to the 120/240 volt appliances, converter and circuits. There should be additional fuses/breakers to protect the 12 volt lighting, and other 12 volt circuits in the trailer. Power from the converter is usually protected with a fuse labeled reverse polarity protection. So should a short occur after the shortstop but before the converter and both battery and converter are powered both ends will go off. If the converter is not operating (shore power off) than only the shortstop will trip.

[kimbo@alum.mit.edu]

If you're unhappy with the replies than you can buy a book on basic electricity and educate yourself on the subject otherwise get the dealer to do your work. If something goes wrong a lawyer is who you're looking for not advice.

[persistent]

"Correct me if I’m wrong, but when I am connected to the 50 amp shore power, that’s not going directly to the batteries. That goes to the converter/AC panel. The converter then sends the appropriate charge, hopefully no more than 14.4 V when charging, to the batteries."

This is correct.

"So the question is why do I need 50 amp protection, or even 30, going from the batteries to the coach? Even the first leg, off of the 50 amp shortstop, that goes to the front jack, Is only drawing power, not supplying it. "

The 12 volt system is separate from the 120 volt system. The shortstop thermal self resetting circuit breakers protect the wires that they are connected to. Those wires carry 12 volt power. They are bi-directional. They protect against too much current flowing in either direction.

The size of the wire from the battery bank to the shortstop and the wire from the shortstop to the house fuse panel determine the size of the breaker.

The 30 amp shortstop may have been in place when the RV was delivered. The 50 amp breaker may have been added when a second battery was added. In any case the configuration in your picture does not make sense electrically. The 50 amp breaker serves no purpose the way it is wired.

Any time the wire size gets smaller, like to the jacks, an additional fuse or breaker is required to protect the smaller wire. So, the front tongue jack should have its own fuse because it uses a smaller wire.

"That’s what’s confusing to me. It seems that the shortstop should be where the shore power cord comes into the coach. That’s completely at the rear. The batteries are only connected to that, via the converter/charger."

The 12 volt 50 amp DC shortstop has nothing to do with shore power. Shore power is 50 amps 240 volts AC. The shore power cord is protected by a circuit breaker in your main service entrance.

"Anyway, my main question is, do I need two short stops? I didn’t really get an answer which is OK. I’m going to have to check with the dealer I suppose."

You do not need the 50 amp shortstop circuit breaker. The way it is currently wired it does nothing. You have been using the RV and everything works fine without it doing anything. However, you can leave everything exactly the way it is. There is no safety or functional issue with the way it is.

If the 30 amp shortstop switches 12 volt appliance "off" then after a brief moment switches things back on, it is indicating overload. In that case the wires and connectors from the battery to the house fuse panel need to be evaluated to see if they are large enough to use the 50 amp short stop. In this case increasing wire size and rewiring using the 50 amp short stop would be useful.

Generally you should not have a problem unless you install a larger converter charger, or an inverter. However, rewiring would be required. a 1000 watt inverter would draw 90 amps from the batteries. Nether the 30 nor to 50 amp shortstop would be enough. Existing wire is way too small.

[kimbo@alum.mit.edu]

Not to put words in Paul's mouth but when he says the 50 amp short stop is not doing anything he means to say it is not providing the proper protection for the downstream wire. It won't click off at 30 but only 50 amps more than what the downstream wire is rated for. We can't read the minds of the original installers and any assumptions about how the 12 volt fuse panel is wired are just assumptions. It could be the wire gets smaller at the 12 volt panel or it could be the same size

[Thomas]

Originally Posted by kimbo@alum.mit.edu

If you're unhappy with the replies than you can buy a book on basic electricity and educate yourself on the subject otherwise get the dealer to do your work. If something goes wrong a lawyer is who you're looking for not advice.

Unhappy? No. Where did I say I was unhappy?
From your reply it seems that you are unhappy.

I have educated myself on electricity. That’s why I know that I needed to ask questions.

You seem to be making a lot of assumptions in what you said so I leave it to you to own the electrical information.

Thank you for your rather unhelpful post.

[kimbo@alum.mit.edu]

Electricity is dangerous some people will not understand it no matter how many books they read and classes they take. I have worked with people who passed the same exams as I have and they can't make a light bulb light.

https://www.youtube.com/watch?v=aIhk9eKOLzQ

[dsol]

In my experience most engineers struggle with practical applications like this. While there are some exceptions of course, working a calculator or computer to figure out resistance forces of physics is far different than turning a wrench or or just thinking practically.

And by the time someone gets an engineering degree the odds that they will work in a capacity where they actually use their hands is very slim.

[kimbo@alum.mit.edu]

If you attended a university where you are not immersed in a culture of math and science are not required to take a physics course on electricity and magnetism then not being able to make a light bulb light would be more understandable. The same goes for electricians and technicians. Somehow certain people pass their exams but need to be told every move to make.No matter how many times you explain something they are unable to take that knowledge and generalize it.

In the case of engineers you can't be expected to have an original thought and have any idea how to solve a given problem with your specialized knowledge. In the case of technicians you have no idea why something which should work isn't working. In the case of electricians someone else has to run the job because you have no idea why you would do anything other than follow someone elses directions.

Despite what seems to pass for common knowledge today we aren't all born equal. Because of the way capitalist economics works people who should be doing a different job end up in jobs they can't do where they then can then pose a problem for everyone else despite their education.

[kimbo@alum.mit.edu]

A certain number of people hired as engineers are not engineers but people hired as supervisors. Their job is to watch others work and report back to the hire ups. Others are hired to calculate costs or in technical sales.