12V issues

[wetzk]

I am thinking about a couple changes to my wiring.
I have 4 AWG from the battery to a larger cutoff switch then into the converter. I picked up a pack of 60 amp fuses as I had changed the fuse wiring size to 4 awg and just stuck the original 40 amp back in. Now the battery side is 60 amp like yours., I plan to use the 50 amp thermal breaker in the converter circuit and go with a 40 amp fuse to the 7 pin plug circuit. I also am going to change the wimpy 12 AWG wiring from the converter to the breakout box to 8 AWG. Mine came with the large size fuse for the 40 amp that was originally in the battery box so I can move it to the trailer plug wiring. Which does not matter as my trucks 10 gauge wiring is protected by a 30 amp fuse and can't push even that to the rear. In the future I will fix that problem ( maybe ) .

[tdf-texas]

Originally Posted by wetzk

I am thinking about a couple changes to my wiring.
I have 4 AWG from the battery to a larger cutoff switch then into the converter. I picked up a pack of 60 amp fuses as I had changed the fuse wiring size to 4 awg and just stuck the original 40 amp back in. Now the battery side is 60 amp like yours., I plan to use the 50 amp thermal breaker in the converter circuit and go with a 40 amp fuse to the 7 pin plug circuit. I also am going to change the wimpy 12 AWG wiring from the converter to the breakout box to 8 AWG. Mine came with the large size fuse for the 40 amp that was originally in the battery box so I can move it to the trailer plug wiring. Which does not matter as my trucks 10 gauge wiring is protected by a 30 amp fuse and can't push even that to the rear. In the future I will fix that problem ( maybe ) .

Let me play devils advocate on the 40 amp - if it blows, then you lose your emergency brake as that is what powers it. That's why I used the thermal breaker there as it would reset itself. The problem that I see with the thermal breaker is that there is a time delay between sensing a high current condition and the breaker opening that may cause the 60 amp to blow - the fuse doesn't have that problem. MMM - I might use a fuse as well.

(edit) per your drawing, the 50 amp thermal breaker sets the current limit to/from the battery. The current to/from the TV connects at the converter fuse panel.

Turning off the battery disconnect switch kills all power from the battery. Since it should never be turned off except in storage, losing power to the brakes (emergency switch) shouldn't be an issue. I would make sure to not use that toggle switch the trailer came with as I have accidentally turned it off and that would be bad for a moving trailer.

Your schematic looks good!

[wetzk]

Originally Posted by tdf-texas

Let me play devils advocate on the 40 amp - if it blows, then you lose your emergency brake as that is what powers it. That's why I used the thermal breaker there as it would reset itself. The problem that I see with the thermal breaker is that there is a time delay between sensing a high current condition and the breaker opening that may cause the 60 amp to blow - the fuse doesn't have that problem. MMM - I might use a fuse as well.

The "converter" current going in feeds the fuse panel - the 4 AWG lands on the panel terminal lug and powers the panel fuses going to the trailer circuits so no additional fuse is needed. The converter charges the battery back through that wire as well but converter is already current limited to 55 amps and is covered by the 60 amp fuse.

I guess that the thermal breaker is not needed anywhere in this circuit.

Did not see that, may either remove the fuse or add a separate circuit. In my previous trailer the emergency system was not part of the converter wiring.

[Rossue]

We have inverter + solar + dual 6V and no fuses on any wiring going to batteries.

[wetzk]

Originally Posted by wetzk

Did not see that, may either remove the fuse or add a separate circuit. In my previous trailer the emergency system was not part of the converter wiring.

Per the wiring diagram on my previous trailer. The magnets will pull less then 5 amps each. For the 4 brake system they had it fused 40 amps and directly wired to the battery.. ( So that's where that came from in my head )



Glad I have time to decide how to do this so I do it right the first time I washed it today to remove 8000 mile plus of bugs and will wax it one day this week. Then I will fix the crack in the grey water tube from something that was kicked up. Wiring is a future project.
But one I do want to do as mine did blow the 40 amp back when I first was bringing it home. So it had no lights if not plugged into truck or on AC and the emergency brake away switch was inactive due to no battery power to it.

[Jim Bennett]

Originally Posted by Rossue

We have inverter + solar + dual 6V and no fuses on any wiring going to batteries.

Did you not install a fuse from the batteries to the inverter? I put one in for safety sake, though doubt it will be needed. I put breakers on both sides of my charge controller too, not just for safety but to provide an easy disconnect if needed.

[wetzk]

Here is the info from the Dexter brake manual. Notice the breakaway switch is hardwired to the battery. The amps drawn by the magnets normally will be 12 amps. If the 40 amp fuse blew the system would not be functional anyway. So my old stick build might have done something right. The rubber roof, leaks in the windows and almost non functional refrigerator and such they did lousy at. But the emergency brakes would work.

[tdf-texas]

Originally Posted by wetzk

Here is the info from the Dexter brake manual. Notice the breakaway switch is hardwired to the battery. The amps drawn by the magnets normally will be less than 12 amps. If the 40 amp fuse blew the system would not be functional anyway. So my old stick build might have done something right. The rubber roof, leaks in the windows and almost non functional refrigerator and such they did lousy at. But the emergency brakes would work.

After staring at the wiring diagram, it came to me that with a fuse in the circuit going to the brakes - if it popped, you wouldn't know it until you needed the emergency brakes. Without a fuse in that circuit, the 60 amps would be the one to blow and it would be obvious that it had.

Now, should the wire to the tow vehicle be powered from before or after the battery disconnect switch?

[rubicon327]

Originally Posted by tdf-texas

After staring at the wiring diagram, it came to me that with a fuse in the circuit going to the brakes - if it popped, you wouldn't know it until you needed the emergency brakes. Without a fuse in that circuit, the 60 amps would be the one to blow and it would be obvious that it had.

Now, should the wire to the tow vehicle be powered from before or after the battery disconnect switch?

Agreed the breakaway switch should be wired around any disconnect switch and unfused (direct to the trailer battery). I believe the tow vehicle charge line should tie in before the switch as you show. This treats the disconnect as a true service/isolation switch that kills power to the power center DC board (all loads except breakaway) no matter if tow vehicle is hooked up or solar is connected on the other side. It looks like Oliver has a 40 amp on the tow vehicle charge line. Their schematics starting at pdf page 103 with circuiting and wire gauges look well engineered. Wish Escape had these.

https://olivertraveltrailers.com/wp-...l-03252018.pdf

[tdf-texas]

Originally Posted by rubicon327

Agreed the breakaway switch should be wired around any disconnect switch and unfused (direct to the trailer battery). I believe the tow vehicle charge line should tie in before the switch as you show. This treats the disconnect as a true service/isolation switch that kills power to the power center DC board (all loads except breakaway) no matter if tow vehicle is hooked up or solar is connected on the other side. It looks like Oliver has a 40 amp on the tow vehicle charge line. Their schematics starting at pdf page 103 with circuiting and wire gauges look well engineered. Wish Escape had these.

https://olivertraveltrailers.com/wp-...l-03252018.pdf

Thank you for the Oliver manual! Very interesting to see their wiring diagram - they run separate wires for the TV charge line and the emergency brake. That allows having a 40 amp circuit breaker on the charge line and no fuse on the emergency brake line. Having separate circuits would be optimal but a lot of work to implement on our trailers.

They also show no battery fuse which means a short would melt the wires. So their wiring has some issues as well.

It's starting to look like this schematic is the one I'm going to go with.

[strawbarry]

If a fuse blows it needs investigating. It could be repeated surges that have weakened the element of an older fuse, or a real short. If a new fuse blows you have to find a problem. Using the attached time current curve for Bussman fuses. Note the 40 A fuse will stand around 45 amps for 100 seconds before clearing the circuit, and will clear the circuit in .01 seconds at 1000 Amps. Coordination of downstream devices should be considered when making changes to any electrical system. You can create a situation where a larger fuse blows when a smaller downstream device should have operated.

[tdf-texas]

Originally Posted by strawbarry

If a fuse blows it needs investigating. It could be repeated surges that have weakened the element of an older fuse, or a real short. If a new fuse blows you have to find a problem. Using the attached time current curve for Bussman fuses. Note the 40 A fuse will stand around 45 amps for 100 seconds before clearing the circuit, and will clear the circuit in .01 seconds at 1000 Amps. Coordination of downstream devices should be considered when making changes to any electrical system. You can create a situation where a larger fuse blows when a smaller downstream device should have operated.

Here are the criteria for the battery/converter circuits.

1. The converter charge output to the battery can be up to 55 amps. Fusing the converter to battery circuit to less than 55 amps could cause the fuse to blow under low battery charge conditions.
2. The circuit to the emergency brake circuit should minimize failure points and if the circuit fails, it should be readily noticeable.
https://www.researchgate.net/publica...e_1oo2D_voting
3. The positive wire leaving the battery should have overcurrent protection as close to the battery terminal as possible. A short in the battery lead has a very high current capability and could cause the wire to melt or potentially catch fire.
http://www2.schneider-electric.com/d...s/page_019.pdf
Charge Controller to Battery.. do I need a breaker or fuse?? — northernarizona-windandsun

Explanation:

For number 1, this is a reliability issue. You don't want to design a system where failure can happen operating under normal conditions. Having a low battery charge and requiring the converter to charge it should be considered a normal operating condition and should not cause the circuit fuse to blow.

For number 2, this is a safety issue. The circuit supplying power to the emergency brake system should have high reliability and minimized failure modes. And if it fails, you should immediately know it. By having the circuit wired direct to the main battery fuse, the circuit has minimal failure points and if the main battery fuse were to fail, it would be detectable.

For number 3, this is a safety issue. The battery in your trailer can discharge a great deal of current if shorted requiring the wiring to have overcurrent protection. Since the location of a short could as close as within the battery box, it is recommended that a fuse be installed as close to the battery terminal as possible.

Hope this help explain the "why" as to our redesigning these circuits.

[MBA80]

Fred,
Do you have any updates concerning your 12-volt issue?

[MikeS]

Originally Posted by tdf-texas

Here are the criteria for the battery/converter circuits.

1. The converter charge output to the battery can be up to 55 amps. Fusing the converter to battery circuit to less than 55 amps could cause the fuse to blow under low battery charge conditions.
2. The circuit to the emergency brake circuit should minimize failure points and if the circuit fails, it should be readily noticeable.
https://www.researchgate.net/publica...e_1oo2D_voting
3. The positive wire leaving the battery should have overcurrent protection as close to the battery terminal as possible. A short in the battery lead has a very high current capability and could cause the wire to melt or potentially catch fire.
http://www2.schneider-electric.com/d...s/page_019.pdf
Charge Controller to Battery.. do I need a breaker or fuse?? — northernarizona-windandsun

Explanation:

For number 1, this is a reliability issue. You don't want to design a system where failure can happen operating under normal conditions. Having a low battery charge and requiring the converter to charge it should be considered a normal operating condition and should not cause the circuit fuse to blow.

For number 2, this is a safety issue. The circuit supplying power to the emergency brake system should have high reliability and minimized failure modes. And if it fails, you should immediately know it. By having the circuit wired direct to the main battery fuse, the circuit has minimal failure points and if the main battery fuse were to fail, it would be detectable.

For number 3, this is a safety issue. The battery in your trailer can discharge a great deal of current if shorted requiring the wiring to have overcurrent protection. Since the location of a short could as close as within the battery box, it is recommended that a fuse be installed as close to the battery terminal as possible.

Hope this help explain the "why" as to our redesigning these circuits.

This is great info, thanks for sharing along with the previous diagrams. Which rallies will you be performing this mod for the rest of us?

[tdf-texas]

In my research of my trailer wiring, I came across something that I should pass along. It seems that the electrician who made the crimp connections in the breakout box near the front of the trailer for the 7 pin wiring doesn't know how to properly do this.

Look at the picture below. The crimp connectors are the wrong size for the wire so the tech just doubled the wire back on the insulation, shoved insulation and wire together into the terminal, and crimped the whole thing. In a number of the crimp connections, the crimp is made on the insulation - not the wire. I could take a pair of needle nose pliers and pull the wires out of the crimp - the only thing holding the wire in the terminal was the insulation!

Look at the red and yellow top connectors - they are the most obvious! The wire in those connections is just touching the inside of the terminal - no crimp! But they were all done this way which means for me - new correctly sized crimp connectors and a redo of the breakout box.

Fred! Will there be an end to this? I'm getting leary of opening anything else!

[Greg A]

Oh my, never seen anyone crimp wires like that in all my years! I hope this is being done by someone that wasn't there in 2015, but I'm going to inspect mine this week when I do some work.
Much of this convinces me they are not really doing QC or someone in that role is not up to snuff. Each step of the build should be passing QC and this is a pretty obvious catch. It will be interesting if more have wires crimped like this or was it just a handful that slipped by?

[NCBill]

Wow, worst crimping job by a manufacturer I have ever seen. Hopefully that is an outlier. I'll be checking mine for sure!!!

Sadly, when the "quality" you can easily see is substandard, I worry about the quality that is harder to inspect.


In my own personal manufacturing career, there were two approaches to quality. One is to inspect the heck out of it, the other is to make the process very robust and high quality. No level of inspection can catch every manufacturing defect. So IMHO, its best to have a robust process.

The RV industry in general is not noted for robust processes.

[thiggins]

Oh jeez...





I sure hope I don't find that in our new 21' next week.


I guess I'll be packing my crimper now.

[wetzk]

Originally Posted by strawbarry

If a fuse blows it needs investigating. It could be repeated surges that have weakened the element of an older fuse, or a real short. If a new fuse blows you have to find a problem. Using the attached time current curve for Bussman fuses. Note the 40 A fuse will stand around 45 amps for 100 seconds before clearing the circuit, and will clear the circuit in .01 seconds at 1000 Amps. Coordination of downstream devices should be considered when making changes to any electrical system. You can create a situation where a larger fuse blows when a smaller downstream device should have operated.

Unless you are using an active charging system you probably will not fully charge the trailer battery from your tow vehicle. I know mine won't, I have at least a 3% voltage loss and between that and the wire resistance the vehicle charging system is not going to fully maintain the remote trailer battery.

I suspect what happened when I blew the fuse was we had stopped and used a trailer a few times at rest stops with the fans and lights and such. So the battery was down a bit. When we plugged into the park power the current rush into the depleted battery blew the fuse. Since we were on park power I had no hint the fuse was blown. I discovered it later when we were traveling back and were trying to turn on lights at a rest stop.

The original probably was a fast blow fuse, I do not have it anymore so no way I can tell. Since then we have had no further problems, I think I am going to remove the 60 amp fuse and go back to the 40 amp slow blow fuse that I installed after we arrived at home as it was working fine.

Also, maxi fuses may not be real common in small towns so you might want to toss one into your parts kit. I had to wait until I was near Atlanta before I found a auto parts store that carried the larger maxi fuses and when I got back replaced the 80 amp they had with a Bussmann 40 amp slow blow.

[John in Santa Cruz]

the voltage loss due to wiring is proportional to the current, due to ohms law (volts = amps * ohms, where the ohms is the resistance of the wiring). as the charging current approaches zero, the voltage drop also approaches zero.