Breakaway Brakes

System

This discussion was created from comments split from: 400 is not operating at all on battery power.

Sharon_is_SAM

gooddogs74 - Safe practice and good sense dictates that you charge your battery with a smart charger before towing or replace it if necessary.  You will not have any break-away brakes without the use of your TaB battery and you will be liable in the event of a mishap - now having been discussed several times here on the forum.  No battery, you really should not be towing.  

gooddogs74

@SAM they said I did have some charge before I left.   I also just got the little plug in voltmeter and I will check on that as well before I go.  

dsfdogs

@SAM, I'm confused. I read somewhere on these forums, and took notes from the post, that said the electric brakes and breakaway brakes are powered before the switch on the battery, so the battery can be turned off while towing. And that the TV is still charging the battery, but just no power to inside of trailer. Therefore, wouldn't that mean the brakes would still work with a dead battery? Does all this depend on year of trailer? Thank you.

gooddogs74

@SAM, @dsfdogs just got off phone with Marvin, thinks bad cell in battery,  Harris battery will replace, have to work with them directly.  Also did say safe to drive,  breakaway brake power should cone from my tv. 

tabiphile

Hm....I'm with SAM on this one. If you "break away", you won't be getting power from your TV anymore unless you happen to get very lucky and the 7 pin doesn't get ripped from your 4 runner and the cable continues to reach the trailer as it goes bouncing down the road.
It's not likely but if you lose your 400 you will be out of luck. The brake away locks the trailer electric brakes when the brake away cable is yanked from it's socket during a disconnect. The electricity that holds the trailer brakes is provided by your 12 volt trailer battery.
If it were me I'd grab an old car battery (charged of course) and connect that to the trailer for the trip. That would provide the(required) voltage for the brakes..it would not run your camper and it is purely a band-aide but safer than going commando.

ScottG

@dsfdogs, SAM is correct with regard to the breakaway brake wiring on the 320.

Everything is connected to the battery via a junction box under the front of the trailer. If your cut-off switch is installed at the battery (as is standard on 2016 and later T@Bs) it will disconnect the battery from the converter, the tow vehicle, and the breakaway brakes.

The only way to circumvent this would be to have the breakaway brakes connected directly to the battery via a separate, dedicated line. I'm not sure if this is the case with the 400, but I would assume not unless proven otherwise!

ScottG

@gooddogs74, Marvin is correct, technically, but tabiphile makes the more important point.

Your tow vehicle is not going to power anything if it becomes completely separated from the trailer. That is why they are called "breakaway brakes!"

tabiphile

@ScottG ...yes, as you note, my presumption is that you would wire the brake-away directly to the car battery if you went that route. It's a complete but easy kludge that gets power to the brakes....

That aside, what is keeping his dealer from pulling a battery from another unit and getting him going safely? This has been a comedy of errors. Someone needs to step up and take care of doing whatever it takes to get the problem fixed before bad decisions are made...if the trailer is at a camping world, they have batteries they can install.

LSkrabut

Per Dexter axle, 2-12 Vdc to operate their electric brakes and approximately 2.5 to 3 amps per magnet. Single axle with small brakes, 5-6 amps. 
https://www.dexteraxle.com/docs/default-source/default-document-library/light-duty-electric-brakes.pdf?sfvrsn=2

Assuming there is not a major voltage drop from the trailer battery to each brake, 2 Vdc would give some braking, where 12 Vdc would give max braking, if the amperage is there. 

5-6 amps out of a 235 ah T@B 400 battery, even if discharge some or only charge to 11%, as long as it has close to 12 Vdc should slow down to a stop the trailer "If a breakaway" happen for a few seconds the breakaway being applied would be needed.

Would a mostly discharged battery work, maybe? As well as a fully charged one, no!

In this case being discussed, if the owner could charge the battery more, highly advised, just by connecting to shore power (30 amp preferred, 15 amp for a longer time). If not, but could jumper another 12 Vdc battery in the T@B, sure, but most points to attach/jumper (securely) one is not readily accessible. Take a chance nothing will breakaway, its a gamble and could be gambling with a life. Changing out a battery in the 400, not an easy, but possible task, best/safest option if the original one will not take a charge. Take it out, drive to the dealer, exchange with a new-fully charged battery, reinstall and be a happy camper. 

Sharon_is_SAM

LSkrabut, the owners battery is so discharged that even the battery inline fuse replaced with a 40 amp circuit breaker trips with attempts to charge it via the converter.  She says she has a DC plug in voltmeter to assess the charge, but the last status when the trailer was picked up over a week ago was at 10% charge and who knows what the charge is now.  She does not want to purchase additional equipment in the form of a smart charger which has been suggested.  No one really knows if the battery can be charged at this point.

Concerning only requiring 6 amps, think about the voltage drop on the way to the brakes coupled with limited amperage.  May get lucky and those magnets will come together for a short time, but they need constant current, so I suspect with limited amps, it would be very easy to quickly deplete the remainder of your amperage bank.

I wish it was a simple matter of switching out the battery, but I suspect the 400 battery is special order.  I know ours was and it is only 150 amp.  

Dsfdogs - It is ideal to have the break-away brakes wired independent of the battery cut off switch, but the TaBs are not wired in that manner.  To tow a TaB safely you need an adequately charged trailer battery with an attached and functional break-away switch and you must keep the cut off switch in the “ON” position to allow the TV battery to charge and to allow power to reach the break-away brakes.  

dsfdogs

Thank you @SAM and @ScottG. I'm trying hard to understand. I re-read your posts from another thread about this very question and I must have misunderstood.

It makes sense the break away brakes would not work if there is a dead trailer battery and the trailer becomes detached from the TV/7way. 

RE battery charging while towing, my manual states that when connected to the TV, the battery will charge regardless of the battery disconnect switch position. 

The electric brakes seem to work from the 7way as I recently drove w/battery switch off and they worked.

Are you saying, if my battery is charged up, battery switch off, and while towing my trailer detaches, the break-away brakes would not work? 

Thank you.

Sharon_is_SAM

Debbie, we believe the manual has a misprint.  The TaB battery will not charge when the cut off switch is turned OFF which effectively isolates the battery.  Here is a picture of the junction box that Scott posted that may help.  The battery wire, pigtail that
carries power from the TV to the junction box, and the breakaway brake wire are all connected on one post.  

1.  Removing the battery wire from the post is just like placing the cut off switch to OFF.  You can see then that power from the pigtail would not flow to the battery - there is no communication and hence, no charging.

2.  Now with the battery wire intact, disconnect the pigtail wire (what would happen if the trailer breaks away from the TV) and you can see how the breakaway brakes receive their power from the TaB battery.  So, if the cut off switch is OFF while towing or the TaB battery is dead or undercharged, in the event of a detachment, you will not have emergency breakaway brakes.

3.  The TaB electric brakes receive their power via a brake wire that is part of the 7 pin and works along with a traditional dash-mounted  brake controller.  They are not dependent on the TaB battery.   (A non-traditional brake controller that works using radio frequency and a trailer mounted controller only requires a charge wire as part of the 7 pin.  That’s another story.)

So, the battery cut off switch should be ON when towing to allow for charging and breakaway brake operation.  Keep in mind that if you tow with the 3 way frig on battery and stop for lunch, your frig will draw down your TaB battery as the cut off switch is in the ON position and the battery is not isolated.  If you turn the cut off switch to OFF during lunch to protect your TaB battery, you need to remember turn the switch back ON when you resume towing or you will not have breakaway brakes and be unable to charge.

I hope that answered your questions.

Sharon

dsfdogs

Thank you Sharon! Very helpful explanation and yet disturbing the manual appears to be wrong. I will reach out to nuCamp to ask. (I need a 2018 manual as well, mine came with 2017. I asked in November and was told it is still in edit). 

Thanks again, Debbie

Sharon_is_SAM

I think the manual is a work in progress and it will eventually be corrected.  Our administratiors keep nuCamp aware of these issues as they come up and hopefully corrections will be made.  When I created a newbie “winterization” tutorial, I noticed some clarity issues with the content of the online/thumbdrive manual.  Required some sleuthing to figure out the intent.  The forum member exchange is invaluable in that way

ScottG

dsfdogs said:

Thank you @SAM and @ScottG. I'm trying hard to understand. I re-read your posts from another thread about this very question and I must have misunderstood.

...

If I said or implied that it was in error. If you could point me to the post(s) in question I'd appreciate it so I can correct or clarify my remarks regarding this important safety issue.

I have commented (including earlier in this thread) that my particular configuration retains power to the breakaway brakes when the disconnect is off. That is because my disconnect is installed at the converter rather than the battery. Borrowing SAM's approach from above, it would be like removing the "converter" wire from the post (as opposed to removing the "battery" wire).

While the distinction my not seem immediately obvious, it's a point worth belaboring as it makes a critical difference in how battery power is distributed. The important thing is to cultivate an understanding of how your own equipment works. Not all campers (not even all T@Bs) are configured the same way.

It's a lot to swallow, especially if you are new to towing/electrical/plumbing/carpentry/auto repair/RVs/camping/whatever. You are on the right track by reading, asking questions, and not necessarily believing everything you read or hear! 

Ron

The problem I see with the picture is with the converter wire being fed from the breakaway terminal in the trailer light and brake junction box.  Two different systems are being mixed here that shouldn't be combined.  The only thing they have in common is that they are both 12 volt systems.
One system powers the vehicle part of the RV.  These are turn signals, brake lights,running lights and BREAKAWAY BRAKES.  The other system is the RV living space and it's 12 volt requirements.  Interior lights, fridge, radio, ect, and the charger output from the converter.
These are different systems that can have different requirements for wire size and fuse size.  The 400 changed the way things work by going from a 35 amp to a 55 amp charger.
I see the fix as running the converter wire through the battery disconnect directly to the batterey with the appropriate size fuse and wire for 55 amps.  The brakes terminal would only have power from TV, power from the battery, and output to breakaway switch.  The house battery would still trickle charger from the tow vehicle.  The battery lead for the breakaway brakes already has it's own disconnect switch at the end of the breakaway cable.
If someone doubles their battery capacity for boondocking or discharges to 11 volts the charger will send the full 55 amps to the battery bank when pluged into shore power or if they power the charger from a generator.  Any 12 volt draw inside the RV could reduce this to less than 55 amps to the battery, but not by very much.
In a properly sized 12 volt system the wiring and fuses should always handle the load that they are connected to.  The only way the charger fuse should blow would be a short circuit to ground or an overload for too great of a demand from a defective converter.

ScottG

@Ron, I agree that common sense dictates that the breakaway brake system should not be powered by a switched/fused line. However, I assume that nuCamp is required to meet certain industry standards in their products, and are doing so with the configuration they employ. Ultimately, the responsibility falls on the vehicle operator to understand their equipment and use it properly.

If someone were really concerned about this, rewiring the breakaway brakes directly back to the battery would be a relatively easy modification.

gooddogs74

Update on battery.  The voltmeter I purchased is plugged in.  It is staying around 12.61 to 12.68.  The battery button when pushed says full.   The lights work.  The fridge runs and the fans work.  I was plugged into 30 amp over the weekend.  So I'm not sure if it was just finally able to finish its charging process?  Should I take it somewhere for them to run any more tests on the battery?
   

Ratkity

@gooddogs74, see how long the battery holds a charge. Forgive me. I can't remember if you are on the road or not.

If you are parking it and flip the battery cutoff, then meter daily. Lead-acid batteries should hold a charge and slowly go down and need charging in about a month. I also can't remember if your batteries are AGM or lead-acid batteries. If they are AGM, they don't discharge like lead-flooded batteries. AGMs should be able to sit all winter (ok.. 3 months, not MN winters!) with a full charge and have barely a small detectable decrease in voltage.

I'm glad you have battery power!! 

ericnliz

@gooddogs74, Sounds like you finally got a good full charge on your battery. Like @Ratkity said though, I'd monitor it pretty close until you're satisfied it's holding & maintaining a good charge though. Happy days are here again!

gooddogs74

@Ratkity @ericnliz thank you.  It is an agm battery   I will try to check it a couple times per week.  It is stored on property near my house,  no electric out there.  We are planning on a 1 night camping trip in 2.5 weeks.