Breakaway Brakes and Battery Disconnect Switch (T@B 320)

Omniphil

Hello folks,

It seem from what I can tell that the users manual might have some bad information in regards to the Battery Switch so I have a couple of questions....

When the battery disconnect switch is disconnected, are you getting power to...
     1. The trailer 7 way power feed to charge the battery.
     2. The factory solar option to charge the battery.
     3. More importantly, will the breakaway brakes function?

Basically does the battery disconnect switch basically disconnect everything?

For Towing, i'd obviously want the battery in the T@B getting charged from the car's alternator. But also for storage when its sitting outside for a week at a time I'd want the solar panel keeping the battery topped off as well.

Breakaway brakes, while 99.9% of the time they aren't going to be used, but certainly that one time it might actually breakaway i'd certainly want that to function as intended...

Sharon_is_SAM

While towing keep the battery switch turned on to allow power to the break away brakes and to charge the TaB battery.  I believe the solar connection is directly to the battery, so the switch will not impact solar charging.  

Omniphil

Ok, that makes sense. Might be a good word of warning for other folks that you need that switch turned on to have the breakaway brakes functioning in case of emergency.

MiquelCamo

I thought if the battery needed to be left on for the emergency brakes there would a clear note in the manual and a warning label near the cut off switch. This seems like a possible liability issue to me. Does anyone have confirmation from the factory that the switch must be left on?

Verna

@MiquelCamo, if you were to search on the forum for brake away brakes, there are many references to the fact that the battery switch must be turned on for them to work.

The T@B manual is always a work-in-progress as many changes and additions do occur during each production year. nüCamp is a small enough company that many changes are instituted during the production year to add features. 

ScottG

No confirmation from the factory is needed if you trace the actual circuits. On the 320, the breakaway brakes receive power from the battery via the second terminal in the junction box under the front of the trailer.

If the battery is disconnected, the breakaway brakes will still receive power from the tow vehicle via the same terminal. This works just fine, of course, unless the trailer is actually broken away. I'll let you ruminate on the logic of that statement...

If you want your breakaway brakes to function in all circumstances, then tow with your battery connected. Skeptics who don't want to take my word for it are strongly encouraged to examine the physical evidence for themselves.  ;-)

MiquelCamo

@ScottG , thanks. I see yours is a 2015 which didn't have a factory disconnect. Is there a chance that those with factory disconnects are wired differently with a wire that is not switched for emergency brakes? I do know there is a wire connected to my battery which is not switched. 

In the meantime, I did contact NuCamp this morning with the details of my trailer and this is the quote from an email I received... "If the car comes detached from the trailer a wire that goes from a little box on the tongue to the back of the tow vehicle will pull a little pin out and activate the the emergency brakes. The battery disconnect switch will not affect this".

Obviously, I wasn't satisfied with that answer so I asked. "...since the emergency brakes are electric, where do they get their power when the trailer becomes disconnected from the tow vehicle? Is there a separate connection to the battery that is not effected by the disconnect switch?" 

I'll post any additional details I get from NuCamp and I will be testing mine to ensure I really have emergency brakes. IMO, if the disconnect switch does indeed "disconnect" the emergency brakes a warning should be visible near that switch. If I find this is true, I will create a label so the next owner doesn't tow the trailer, as I have, with the battery off thinking I have emergency brakes.

Marceline

I have surge brakes, so I'm not familiar with how the electric brakes operate, but could it be that once engaged via the breakaway cable they would stay engaged even with no power? After all, don't you need to re-insert the breakaway pin to get them to disengage? 

ScottG

MiquelCamo said:

@ScottG , thanks. I see yours is a 2015 which didn't have a factory disconnect. Is there a chance that those with factory disconnects are wired differently with a wire that is not switched for emergency brakes? I do know there is a wire connected to my battery which is not switched. 
...

@MiquelCamo, when this issue arose previously I asked the same question regarding changes to the circuits in later models. IIRC at the time owners of newer T@Bs confirmed that the only change had been the insertion of the cut-off switch between the battery and the junction box. Also at the time I communicated with nuCamp and they did concede that if the battery was switched off the breakaway brakes would not be powered in the event of a total trailer separation. A correction was pending to the T@B manual, but I don't know if that has yet to be implemented.

I too have an additional unswitched wire running to my battery, but it goes directly to the Zamp port on the side of the tub. I believe models with factory solar also have the controller wired directly to the battery.

Which brings us back to my original point. If you are comfortable doing so, I would encourage you to trace the circuits in your own camper and definitively determine the source of power to the breakaway brake system. Given the history, I for one am just not going to take anybody's word for it, including nuCamp's.

MiquelCamo

@ScottG , NuCamp responded to my additional questions by stating the emergency brakes are not electric. I know that's not correct. "The emergency brakes are not electric. The are triggered by the pin being removed from the sensor".

I then went out to my trailer, pulled the cover off the junction box, took my meter and verified that the battery disconnect switch must be "ON" or the emergency brakes have no power. Thanks for your help and your patience. 

I am disappointed that you can easily bypass a safety function such as this unknowingly. I'm suggesting this be the first thing to tell any new owner. I appreciate this forum more than ever. 

ScottG

@MiquelCamo, thanks for the quick followup and for confirming what I understood to be the case regarding the power supply to the breakaway brakes. I have no idea why getting clear correct information regarding this relatively simple technical detail seems to be such a bugaboo...

MiquelCamo

Here's the last response from NuCamp:

"Yes the emergency brakes are electric and they are powered by your battery. However, the emergency brakes are hardwired directly to the battery so the battery disconnect switch does not affect the function of the emergency brakes."

ScottG

Okey dokey.

I don't know if that means they actually have made a change on recent models, but it doesn't seem to apply to your 2016.

Did you determine what the other unswitched wire to your battery is? Does yours have the Zamp port installed on the driver's side of the tub? I know that feature was discontinued at some point.

MiquelCamo

It does have the Zamp port, that must be it. I'll chase it down later. 

MiquelCamo

MiquelCamo said:

It does have the Zamp port, that must be it. I'll chase it down later. 

As I'm an old man with not much else to do I took a quick look. It is the Zamp. 

Sharon_is_SAM

@MiquelCamo - welcome to the club:) I think you have a great idea to place a sticker on or near the battery switch to indicate how it impacts the break-away brakes!  Maybe have something on the break-away hitch hook as a reminder, too.  

ScottG

With so much stuff regulated these days, I'm a little surprised that it isn't a requirement to have breakaway brakes wired to the battery without interruption.

lkc001

I was always of the understanding that if a trailer (any brand or model) of trailer had electric brakes and a cutoff switch, that the cutoff switch needed to be in the "ON" position so that in the event of a breakaway that act of the pin coming out of the breakaway box automatically triggered the electric brakes to lock up??  Also thought it was an industry safety standard.  There are electrical wires going into the back of the breakaway pin box.  If it was just dependent on only the pin coming out there would be no need for electrical to go to the box.

Sharon_is_SAM

I don’t know if there is a formal, written industry standard, but I have read that the break away brakes should be wired directly to the battery so they would always be available.  Our current set up allows for human error (towing with the battery switch off and the break away brakes disabled).

Tundra57

Wow what a nest of worms that stirred up. You have a 2019 tab 400 and have never towed with the DC switch on. So now I'll go check if I have power at the emergency brake with it off. I have come accross a number of incorrect entries in my manual so I don't trust my expensive fun home to a misprint. I'll post what I find here.

tybladesmith

I suggest if in doubt, with the TV connected, 7-pin cable disconnected, and the battery isolation switch off, pull the breakaway pin out. Then pull the camper forward to determine if the trailer brakes locked up. If the brakes don't come on, repeat test with the battery switch on. The brakes should come on if the trailer battery is charged. 
 Don't forget to reinsert the breakaway pin after this test as the brakes remain energized until the breakaway pin is reinserted.
 https://www.youtube.com/watch?v=kPTHIsOKnjs

ScottG

Do whatever test you need to do to convince yourself, but the breakaway brakes in a 320 will not receive power if the factory disconnect switch is turned off. The standard wiring configuration has been confirmed by several owners.

It's possible the 400s are wired differently but as of yet there has been no indication that is the case. It would be helpful if someone with some electrical know how could check and confirm the circuit in those models.

Regardless, I do think checking your brakes as @tybladesmith suggested is a good idea. Brakes can fail for reasons other than lack of battery power and this would confirm that the entire system is operational.

Bayliss

UPDATED POST (12-21-2019) - NEW WIRING DIAGRAM AND PHOTOS

After reading through this discussion, I decided to spend some time checking the wire connections at the junction box under the front end of my 2019 320S Boondock Lite.  Other year/model trailers may vary from what I found, especially if they do not have a battery disconnect switch.  However, on my trailer, I was able to confirm that IN THE EVENT THAT the trailer and 7-way electrical connection should become detached from the tow vehicle while towing, the trailer battery MUST be connected and the battery switch MUST be "ON" for there to be power available to the electric brakes.

[NOTE and a WARNING:  You will have power to the trailer electric brakes, even without a battery, as long as the 7-way plug is properly connected to the tow vehicle.  HOWEVER, you should never tow the trailer without the battery connected.  The whole idea is to have a power source available to activate the trailer's electric brakes in the event the trailer becomes detached from the tow vehicle while towing.  It CAN happen, so don't take chances!!] 

Below is a wiring diagram of my junction box, plus photos of the junction box and the interior 12V (DC) ground wires bus bar.


As depicted in the wiring diagram, the seven-way plug wires (from the tow vehicle connection) enter through the lower right corner of the box.  The emergency breakaway brake control wires enter through the lower left corner of the box.  The wiring back to the electric brakes exit the box at the same lower-left corner.  Additionally, there is a ground wire (white) that connects between terminal #7 and a ground lug located just outside of the lower-left corner of the junction box.  (I learned from @klenger that the purpose of this particular ground wire connection is to make the chassis the same "voltage potential" as the negative side of the battery.  He informed me that no current actually flows through that outside ground, because the common ground point for all 12V (DC) systems is the inside ground bus bar - - - see photo below.)

The terminal connections identified in the diagram are as follows:

#1 - Electric brakes.
#2 - Right turn and stop light.
#3 - Tail and marker ("running") lights.
#4 - Left turn and stop light.
#5 - Back-up/Reverse lights (none are present on my T@B.)
#6 - 12V (DC) connections.  [Battery cut-off switch is b/w #6 & battery.]
#7 - Ground wire connections.

The 12V wiring generally enters the junction box from the bottom openings and those wires connect at the bottom of each terminal.  Wires that continue on to the trailer 12V systems (including the 12V battery and WFCO Power Center/Converter) generally connect at the top of each terminal and exit back to the trailer through an opening in the upper right corner of the junction box.  For example, for terminal #3, one green wire from the 7-way plug attaches to the bottom of the terminal; from there, two green wires (one for each side of the trailer) continue on to the trailer electrical connections for the right and left side tail and running lights.

The above photograph depicts the main 12V electrical connections inside the exterior junction box.  The junction box is located at the front of the trailer on the frame.  You have to get under the A-frame area of the trailer to see it, but it is generally located below the propane storage tub.

As depicted in the above photograph, there are at least five ground (white wire) connections to Terminal #7: 

Green Arrow  - Ground wire from interior ground bus bar.
Brown Arrow - Ground wire from Seven-Way plug.
Red Arrow     - Ground wire from exterior ground lug (yellow arrow.)
Blue Arrow    - Ground wire from the trailer electric brakes.
Not Visible    - Ground wire from the trailer 12V battery.

If you look at the blue arrow, you can see (just to the left of the tip of the arrow) the black wire from the electric brakes, which leads to Terminal #1.  Because the wiring is so tightly fitted, I could not visually 100% confirm the connection to Terminal #1 without unscrewing the terminal.  I elected not to do that.  However, it makes sense that it goes to that terminal, because it is the only way the electric brakes would get power from the tow vehicle when the tow vehicle brakes are applied.

Also, as best I can visually determine (without removing the protective covering over the wires), the blue (curved) wire that is connected to Terminal #1 (which you can trace back through the lower left corner of the junction box), presumably connects at some point (out of view) to the black wire from the emergency breakaway switch.  In the above photo, you can also see the red wire from the breakaway switch, which enters through the lower left corner of the junction box.  That wire leads to Terminal #6, which supplies power to the emergency breakaway switch.  Further, if you look at the left-center of the above photo, you can see a red Romex-like wire covering.  It contains two wires, which connect between the electric brakes and the junction box.
  

The above photograph depicts the inside ground wire bus bar (silver), which is the main common connection point for all of the 12V (DC) system ground wires.  The bus bar is located adjacent to the WFCO Power Center/Converter.  In the photograph, the wire that curves upward is the ground wire that connects to Terminal #7 inside the junction box.  (NOTE:  the actual connection point for this wire likely varies with each trailer since it can be connected anywhere along the bus bar.) 

Finally, if you look at the lower left corner of the above (third) photograph, you can see the bare copper wire that is the main ground wire for the 120V (AC) system.  That wire originates inside the WFCO Power Center and connects to the trailer's metal chassis below the floor.  Per Creed at nuCamp (11-14-2019), that bare copper wire is also the MAIN ground connection for the trailer (per RV electrical code) since the 12V (DC) systems ultimately connect back to and run through the WFCO Power Center.

MiquelCamo

Yep, I had my doubts as I mentioned above but the factory chose to isolate the breakaway brakes when the switch is off. I still think this is a potential liability issue for NuCamp and I'm glad I know now. I did add a label by the battery cut off to warn any future owner. 

Bayliss

@MiquelCamo and @ScottG, et al, I presume that nüCamp wired it the way they did, because without the cut-off switch between the battery and the #6 terminal, there would always be 12V power going to the trailer whenever a battery is hooked up (because ALL the hot wire connections are made to that terminal.)

ScottG

I suspect the brake wiring scheme more reflects the ongoing nature of T@B improvements rather than a deliberate design choice. Early PV/nuCamp T@Bs did not have a battery disconnects; this maintained power to the breakaway brakes at all times, but also resulted in phantom drain that killed many batteries when trailers were sitting parked. As @jkjenn liked to say, ruining your first battery was almost a right of passage.

The installation of battery disconnects was the hot topic when I joined the forum in late 2015--sometimes to the point of contentious disagreements that included how to maintain power to the breakaway brakes.

When nuCamp started supplying disconnects as standard equipment, they were installed at the battery. Not only was this the most logical and common location, but it also minimized additional modifications to the basic design. However, the side effect of this location is that when the switch is off the battery is not only disconnected from the converter, but also the tow vehicle charge line and the breakaway brakes.

Personally I'm a little surprised that a continuous connection between the trailer battery and the breakaway brakes is not legally mandated on trailers so equipped. Regardless, it's ultimately up to the operator to ensure that equipment is being used in a proper and safe manner.

ScottG

Also, nice diagram @Bayliss.  It looks like those junction box connections have remained pretty standard over the years. I see a few extra ring terminals but I think it's because previously two wires were sometimes crimped on a single terminal (as shown in the photo of my 2015 posted in a previous comment).

GatorEgg

  This is easy folks.  Go out to your trailer, turn off the battery, pull the emergency brake pin out.  If trailer won't move, brakes are on.  Turn switch on, let battery recharge, try again.

   We used to perform this on our company trailers on monthly maintenance check,  because we all know batteries go bad over time and may need replacement.

SweetlyHome

@Bayliss, ditto the nice wiring diagram.  There have been several posted on the forum over the years and the first I remember that notes that the system is grounded to the trailer chassis.  Always wondered about that but didn't take time to verify it.

mjwaldner

I know this post is getting old but I'm now looking at this on a 2021-400. Does anyone know where the fuse is for the breaks? If the wiring diagram listed above is accurate there would need to be a fuse some place.

MuttonChops

mjwaldner said:
. . .  a 2021-400. Does anyone know where the fuse is for the breaks?

If the wiring diagram listed above is accurate there would need to be a fuse some place.

The fuse for the Trailer Electric Brakes in located in the Tow Vehicle.
That is standard on all trailer brands/vehicles.
The 'Brake Voltage' comes to the trailer via the 7-pin connector, then connects to the trailer brake circuit at the trailer junction box . . . there is no fuse in/on/at the trailer.

The 2019 Honda Passport Owners Manual page 632 states the fuse is located in the Engine Compartment Fuse Box, fuse location 3 "Trailer Brakes  20A"

Your Passport electric brake controller is aftermarket not factory installed.  Honda includes a connector under the dash for an aftermarket controller.
That connector is wired to the Fuse Box fuse 3.
Passport OM pages 443 & 444 example the connector usage.