Towing w/o T@B Battery

John_and_Kris

We want to take our T@B to a hitch facility to try some different hitches to level the T@B out.
QUESTION Our battery is at home being maintained. Can we hook the 7pin connector to the TV and will the brake, brake lights and turn signals work ww/o the T@B battery.
We would like to do this w/o having to haul the battery down connect and then disconnect and brig it home I know its not that much work except I am recovering  ( late May) from total knee replacement . John

SweetlyHome

We do this regularly.  Installing the battery is part of the packing or unpacking process at home before we move Dulce Domum from or to our storage location.  And, yes, the interior lights etc will function as well being supplied by the TV alternator and battery.  We highly recommend that you do not operate a frig in this situation!!!  

John_and_Kris

Thanks Dave & Katie. We just want to tow it to the Hitch dealer 20 minutes away. Thanks again John

jdargis

Just no brakes on the trailer, if the trailer separates from the tow vehicle.

Sharon_is_SAM

Yes, your break away brakes are powered by the Tab battery.  

SweetlyHome

I had over looked the brake issue.  We have surge brake.  Sorry.

John_and_Kris

Not going very far and speed limit all way is 35 so chains should hold

ericnliz

Have a safe journey!

Photomom

I really wonder how often the breakaway brake is actually used. The coupler would have to fail AND two chains would have to break, OR the hitch would have to totally come off the car. 

ericnliz

Don't think I'd want to find out Photomom!

rfuss928

The break away cable should engage the brakes before the safety chains pull taut.

ChanW

@rfuss928, that's one way to look at it. But there seem to be as many opinions in one camp as the other (so to speak). I don't know either way, myself, but I tend to agree with you. I bet that discussion can go on forever. B-)

Ratkity

Photomom said:

I really wonder how often the breakaway brake is actually used. The coupler would have to fail AND two chains would have to break, OR the hitch would have to totally come off the car. 

It would have been helpful when that U-haul 6x12' trailer (without surge brakes) broke away from my receiver (hitch and all fell off), the chains broke and the trailer was gaining on me when I looked in the rearview mirror! Fortunately, I was going less than 25 mph and didn't slam on the TV brakes despite my insane urge to do so. The solid steel hitch was so heavy, it acted as a brake before releasing from the coupler and the mostly empty trailer coasted to a stop. No one was injured. This was in the late 90's, btw. Not on any modern U-haul trailer.

SweetlyHome

Now I have to ask the question.  Since the charge line from the TV is connected to the battery as are the electric brakes why wouldn't the TV provide power via the charge line to the brakes when there is no T@B battery? This assume there is only one wire attached to the battery connections themselves.  

ChanW

I think it would, until the trailer went free from the TV, disconnecting the 9 pin connector, which is probably when you most need your breakaway brakes!

Sharon_is_SAM

My understanding is the break away brakes receive their power exclusively from the Tab battery.

ScottG

On my 2015-S, the TV charge line, battery, and emergency breakaway switch are all linked together at the junction box. So, technically, the TV can power the breakaway switch...but only if it isn't broken away. Kinda makes the argument moot...

Note that the normal operation of the electric brakes is controlled by a different circuit from your TV.

ericnliz

ScottG, Actually kinda' redundant! 

ScottG

Yep. I think it's just a side effect of how all the wires are hooked together. Since hitch failure can occur in a variety of ways (including the whole darn thing falling off) the safest approach is to rely on the T@B battery to power the breakaway brakes.

ericnliz

That's what I rely on Scott. Just make sure the battery has a good charge and leave the cut-off switch ON.

SweetlyHome

ScottG has described the VDC system in a great way and think along those lines when trouble shooting the 12 VDC system.  All the 12 VDC "+" are tied together and all the 12VDC  "-" are tied together on the T@B and TV when the 7 pin plug is connected.  

With this in mind I do a simple check of my 7 pin connector every time I start out (the physical position of the T&B battery cut off switch will impact if this works)  With my T@B battery cut off switch in off position I connect the 7 pin to my TV with TV not running.  My voltage meter installed in a 12 VDC outlet with in the T@B shows 12.?? VDC the voltage of my TV battery at its current charge level.  I know the 7th pin connection within the 7 pin connector is good.  Proceed to check brake lights, running lights, turn signals, emergency flashers, and, if, I had them, the electric brakes.  The connection of all 7 pins have now been verified.  I also often start the TV at this point and check that the voltage goes up to 13.?? VDC with in the T@B to verify the car alternator is working as expected.  This last step is very OCD on my part.

rdstrain49

This is just too simple.  Have the wife bake a dozen chocolate chip cookies, then bribe a neighborhood teen to do the heavy lifting, always works for me.

ericnliz

Cookies, someone say cookies?

vanderado

Does anyone know if the emergency brakes will work if the battery switch is OFF or is there a direct dedicated wire for the brakes?

wizard1880

If the battery cutoff is disconnected, then no you would not have emergency braking on the trailer.  If you ran a separate wire for that, it would kinda defeat the purpose of a battery cutoff, though it can be done.

Sharon_is_SAM

Vanderado,  the emergency break-away brakes should be wired directly to the positive terminal of the T@B battery.  The break away brakes should not be wired within the battery cut off switch wiring.  In this way, use of the battery cut off switch will not impact the break-away brakes.  So, if you forget to turn the switch to "on" while towing, you will still have power to the break-away brakes - as long as you tow with the battery intact and charged.  

Sharon_is_SAM

I believe someone shared an example here on the forum in which they had turned off the battery cut off switch- effectively isolating the battery from the T@B 12 V circuit.  They later returned to a dead battery because they had accidentally pulled the break-away cord that activated the break-away brakes.  Good example of how the wiring should be separated.

Nomad

I just replaced my battery a couple weeks ago - Only two things connected directly to the battery - The Zamp port and the main connection to the T@B. It would appear that on my 2015 that if you had a cutoff switch on that main feed, you'd have no power to the emergency brake - Unless there's a feed tied into the Zamp connection down below my view.

ScottG

On mine (2015 S) the breakaway switch is connected to the battery via the junction box under the front of the camper. So yes, a cutoff placed at the battery would need to be "on" for the breakaway switch to function as intended.

A cutoff placed at the converter (i.e., between the junction box and the converter) will leave the breakaway switch powered regardless of whether it is on or off.

Sharon_is_SAM

For those Tabbers with a new Tab with an installed battery cut off switch, where does the wiring for the cut off switch enter?

ScottG

What I understand from previous discussions is that the dealer installs the cut-off switch at the battery. Unless they are doing something fancy with the wiring (not likely...), that almost certainly places it on the leg between the battery and the junction box mentioned in my previous post.

Hopefully someone with a newer T@B can confirm this.