Towing without a trailer battery or removal of the 30amp battery fuse - implications?

RetireeBC

Greetings all.  Wiring / batteries and such are not in my list of competencies.  I would appreciate input from others who have this knowledge.

My specific questions are:

 Towing a trailer without a trailer battery (for example - taking my trailer to the dealer for service, but without a battery)

1. Will I still have electric trailer brakes through the TV  7pin connection?
   
2. Am I correct that I will not have the emergency trailer brakes as they require the trailer battery to operate? If this is the case, I would need to purchase a battery before taking it to the dealer.
   

Towing my trailer with a trailer battery, but with the 30amp battery fuse removed (I want to isolate the trailer battery from the car alternator):                          

1. Will I still have electric trailer brakes through the TV  7pin connection?
2. Will the emergency trailer brakes still operate with the 30 amp battery fuse removed?

Thanks for your assistance,

pthomas745

Your vehicle and brake controller control the trailer brakes.

You will not have an emergency "breakaway" brake without a trailer battery or if you pull the trailer battery fuse.  Removing the battery fuse is the same thing as turning the battery switch off.  No breakaway brake.

When  you talk about "isolating the trailer battery from the alternator".....what exactly for?  The vehicle alternator may be able to charge the battery (your vehicle's capability may vary from mine).  There are stories of vehicles, when the trailer 7 pin plug is still connected, having their battery drained by the trailer electrical use or battery need.  Towing packages are ( or can be ) protected from having this happen by using an "isolation relay" in the vehicle, and it is easy to test to see if your vehicle is so equipped.  Here is a simple way to test for a charge line from the vehicle, and whether your vehicle has an isolation relay:

"I have an isolation relay that stops the connection from the truck to the T@B when the ignition is off. How to check: Turn off your T@B battery, plug in your 7-way. Crank your vehicle. Turn on a light in the T@B. If the light comes on, you have a charge line from your vehicle. Turn off your vehicle and remove the key. If the light goes out, you have an isolation relay, so no need to unplug. If the light stays on, you do NOT have an isolation relay, and you will need to unplug when stopped."

Tabnero

my trailer breakaway brake works without a battery

RetireeBC

Thanks so much for the information and the tip on how to tell if I have an isolation relay.  This is very helpful. 

The reason I want to isolate the trailer battery from the alternator is that I purchased a lithium battery that I will charge with a lithium charger and my solar rather than with the car alternator. I want to avoid the potential issues for alternators arising from lithium batteries. I know others use a DC to DC charger to address this which I will  look into.

Cheers 

pthomas745

@Tabnero what year is your trailer?

@RetireeBC what is the issue with "alternators and lithium batteries?" 

CharlieRN

@pthomas745 - the Battleborn rep I spoke with recently recommended that in the absence of a DC:DC charger, you isolate the trailer battery. Since I have solar that can be programmed to fully charge LiFePO4 batteries, he suggested simply disconnecting the TV charge line. I know that there is considerable debate on this forum about the likelihood - or not - of damage to the car's charging system from lithium batteries used without a charger and it may be that Battleborn is simply being overly conservative. Regardless, it is easy enough to do, doesn't really have a terrible downside and seems to be the recommendation and advice that @RetireeBC is reacting to.   

RetireeBC

@CharlieRN - yes, you're correct that I'm trying to address the "potential" issues concerning damage to the charging system from lithium batteries. Thanks for the suggestion concerning disconnecting the TV charging line. That is what I was trying to do by removing the 30 amp battery fuse.  I now understand, however, that I wouldn't have emergency trailer brakes as explained by @pthomas745 .  Your approach, I believe, ensures that I still have emergency brakes.

@pthomas745 - there is some debate / discussion about TV alternators overheating due to the draw of lithium batteries.

Cheers

Tabnero

RetireeBC said:

Thanks so much for the information and the tip on how to tell if I have an isolation relay.  This is very helpful. 

The reason I want to isolate the trailer battery from the alternator is that I purchased a lithium battery that I will charge with a lithium charger and my solar rather than with the car alternator. I want to avoid the potential issues for alternators arising from lithium batteries. I know others use a DC to DC charger to address this which I will  look into.

Cheers 

2021

Sharon_is_SAM

@RetireeBC and @Tabnero - the factory wires the cut off switch between the battery and the junction box where the electric brake away brakes receive their power. You can have a separate battery for the break away brakes or rewire the battery cut off .  Isolating the TaB battery via battery switch or fuse removal  will disable your break away brakes.  I suspect Tabnero has modded his system beyond the factory standard.

pthomas745

Seems that the actual cost of the lithium is 1000 for the first 90 amp hours and 1000 for the next 10 amp hours. 

CharlieRN

@RetireeBC - don't know how the power connection on your 7-pole is wired but if it's through a breaker or fuse (and it really should be), you can disconnect it there. If it's fused, you can simply remove the fuse and be done with it. If it's a breaker, there's an additional step needed. The connection to the trailer battery will carry current, so you'll need to use insulation & tape on the cable's proximal connector to prevent it shorting - and likely playing real havoc as it welds itself in place.

Next time around, I'm going to use switched breakers that will make it much easier to shut things off if needed . . .

Marceline

pthomas745 said:

Seems that the actual cost of the lithium is 1000 for the first 90 amp hours and 1000 for the next 10 amp hours. 

Seems like the value of information learned via the internet is exactly what one pays for it. I’ve towed a few thousand miles since dropping in my lithium battery and have not experienced any issues with my alternator. As far as I can tell this issue only arises with a huge lithium battery bank drawing an enormous amount of power. 

RetireeBC

@Sharon_is_SAM - thanks for the confirmation.

@Marceline - good to know - this seems to be the experience of others as well.

Thanks to all for your input,

Cheers

dragonsdofly

@RetireeBC, @Marceline is correct about the potential damage to a tv electrical system (alternator) being proportional to the size of the battery bank AND the depth of the battery bank discharge. If you are beginning your journey with a near to fully charged battery, there will be virtually no draw through your tv electrical system, and therefore very little to no potential for damage. Only if your tv alternator has a very limited amperage capacity and your battery charge is moderately to severely depleted do you run the risk of damage.

Usually, for a single 100 amp hr LiFePO battery, even moderately discharged, any alternator rated 150 amp or above will not only charge the battery, but suffer no damage in the process.

We have a relatively large solar system on another larger trailer. We tow it with a 2015 chevy silverado 2500hd equipped with a standard 220 amp alternator. Our battery bank consists of 6 (100 amp hr battleborns) and our truck had to be outfitted with interruptive software to protect the alternator. In other words, if my battery bank is discharged below less than 40% power remaining, and we hook up the truck to charge or tow, the thirsty batteries are allowed to draw charge from the truck for only 15 minutes, then the charging circuit is  interrupted for 20 minutes and then charges the batteries another 15 minutes and is interrupted for 20 minutes, etc. This protects the truck's alternator from overheating or the electrical system of the tv from being damaged due to excessive draw.

Again, I want to stress that if your single battery is not severely discharged, your tv's electrical system should be up to the challenge. Good luck.

RetireeBC

@dragonsdofly, thanks so much for the further explanation. Very helpful.

Cheers

Tabnero

Sharon_is_SAM said:

@RetireeBC and @Tabnero - the factory wires the cut off switch between the battery and the junction box where the electric brake away brakes receive their power. You can have a separate battery for the break away brakes or rewire the battery cut off .  Isolating the TaB battery via battery switch or fuse removal  will disable your break away brakes.  I suspect Tabnero has modded his system beyond the factory standard.

Tabnero said:

RetireeBC said:

Thanks so much for the information and the tip on how to tell if I have an isolation relay.  This is very helpful. 

The reason I want to isolate the trailer battery from the alternator is that I purchased a lithium battery that I will charge with a lithium charger and my solar rather than with the car alternator. I want to avoid the potential issues for alternators arising from lithium batteries. I know others use a DC to DC charger to address this which I will  look into.

Cheers 

2021

I have not done anything to the system. You can check your own system and verify that the brake away emergency brake works without a battery installed at all

Tabnero

I have not done anything to the system. You can check your own system and verify that the brake away emergency brake works without a battery installed at all

Denny16

If the trailer is wired like a 2019 TaB320 shown below, the emergency brake switch, TaB Battery and 12VDC feed from the TV are tied together on the wiring buss in front of the trailer, so as long as the TV is connected to the TaB, brakes  will work with the TaB battery switched off, and the TV connected to the 7-pin cable.  The yellow line highlights the 12VDC connection on the buss bar:
 

However, if the trailer becomes disconnected from the TV during a hitch failure (Jack knife event or ?), the trailer brakes will not work.  This is the situation most state highway towing regulations want addressed with emergency break-a-way brake systems.  So be safe, and always have the battery installed and switched on whilst towing your trailer.  In most states this is the legal requirement for trailers with electrical brakes.  

Cheers

Bayliss

@Tabnero, it would be helpful if you can describe how you have determined that your trailer's emergency breakaway switch will receive electric power (without a trailer battery) in the event that your trailer becomes forcibly detached from your tow vehicle while towing.

As described by @Denny16, in the rare event that your trailer becomes forcibly disconnected from you tow vehicle (e.g., a serious vehicle collision), your trailer's emergency brake connection (i.e., the breakaway switch) needs its own source of electric power.  It is true that, while towing, the tow vehicle battery provides power to the trailer brakes.  However, if the trailer becomes detached from the tow vehicle and is no longer receiving power from the tow vehicle, the trailer brakes need an independent power source.  That source is the trailer's 12-volt battery.

As the trailer becomes detached and pulls away from the tow vehicle, the 7-way power cable will also likely become disconnected, thus cutting off all electrical power between the tow vehicle and trailer.  At the same time, the separate wire cable leading from a pin/plunger secured inside the trailer's emergency breakaway switch, and connected at the other end to the tow vehicle, will forcibly pull the pin/plunger from the breakaway switch as the trailer rolls/slides away from the tow vehicle.  That opens the electric (12V) circuit between the trailer battery and trailer brakes.  Without that independent electrical connection, I can not see how your trailer brakes would be activated.

It's an important point, which has been discussed previously on this forum.  I agree, as others have stated, that you should not tow your trailer without its battery connected and the isolation switch set to "on," so that the battery can provide independent emergency power to your trailer brakes.

Mouseketab

I'm in the process of installing a DC-DC charger and bypassing the 7-pin by putting Anderson connectors in. We are going to go in the junction box under the trailer and disable the charge line there. I don't have a Lithium battery, but don't want to confuse anything with two charging sources.

Tabnero

Bayliss said:

@Tabnero, it would be helpful if you can describe how you have determined that your trailer's emergency breakaway switch will receive electric power (without a trailer battery) in the event that your trailer becomes forcibly detached from your tow vehicle while towing.

As described by @Denny16, in the rare event that your trailer becomes forcibly disconnected from you tow vehicle (e.g., a serious vehicle collision), your trailer's emergency brake connection (i.e., the breakaway switch) needs its own source of electric power.  It is true that, while towing, the tow vehicle battery provides power to the trailer brakes.  However, if the trailer becomes detached from the tow vehicle and is no longer receiving power from the tow vehicle, the trailer brakes need an independent power source.  That source is the trailer's 12-volt battery.

As the trailer becomes detached and pulls away from the tow vehicle, the 7-way power cable will also likely become disconnected, thus cutting off all electrical power between the tow vehicle and trailer.  At the same time, the separate wire cable leading from a pin/plunger secured inside the trailer's emergency breakaway switch, and connected at the other end to the tow vehicle, will forcibly pull the pin/plunger from the breakaway switch as the trailer rolls/slides away from the tow vehicle.  That opens the electric (12V) circuit between the trailer battery and trailer brakes.  Without that independent electrical connection, I can not see how your trailer brakes would be activated.

It's an important point, which has been discussed previously on this forum.  I agree, as others have stated, that you should not tow your trailer without its battery connected and the isolation switch set to "on," so that the battery can provide independent emergency power to your trailer brakes.

the trailer was up on blocks with free wheeling tires, plugged into TV, battery in off position, spinning tires and pulled ER brake line. Tires stopped. My ER brake pull is short coil attached to TV. it will engage before the power plug pulls out in the event of the trailer hopping off the hitch. The event described where the trailer hops off the hitch and the plug disengages prior to the ER brake engaging is unlikely in my view

Sharon_is_SAM

It is important for new and seasoned owners to understand that the factory installed system requires a charged TaB battery and the battery switch turned on for the break away brakes to deploy in the event of a complete disconnect including the 7 pin.  None of us can predict how a break away will occur, so, for everyone’s safety, keep your battery charged and your switch turned on.  

Bayliss

Your call, @Tabnero.  I suppose the next question is what is Plan B when the "unlikely" event happens and there is no power being supplied to the trailer brakes? 

QUESTION FOR THE GROUP:  

If the breakaway switch, powered by the tow vehicle only, engages and locks-up the trailer brakes, will the trailer brakes remain fully engaged in the event the tow vehicle power is lost (e.g., the trailer and its connections separate in their entirety from the tow vehicle and the trailer travels some distance unimpeded behind the tow vehicle)?  OR, will the loss of any source of electrical power cause the trailer brakes to then release their grip?

Sharon_is_SAM

@Bayliss - if power is lost, via a disconnected battery AND  7 pin, the break away brakes fail.  

The break away brakes will engage with power from the TV 7 pin right up until the 7 pin gives way.  Having the break away cable shorter than the chains so the break away brakes deploy before a complete disconnect is all well and good, except you can never know if a complete disconnect will happen or not.  Isn’t there a law that requires that a break away brake has a power source on the trailer?

pthomas745

And, to return to an oldie but goodie, the Purdue "Keep the Trailer Connected To The Truck" brochure.

The breakaway brake chapter starts on Page 58.  Interesting that the breakaway brake cable length is one of the few places where there are differing opinions in the brochure, and there is no definitive answer.  (There are arguments on both sides, apparently.)  

https://www.extension.purdue.edu/extmedia/ppp/ppp-92.pdf

ScottG

@RetireeBC, you asked some important and specific questions in your OP regarding the operation of the breakaway brakes without a battery, or with the battery disconnected. The discussion wandered a bit from there, but I hope your original questions got answered.

At various times this has been a hotly debated and controversial topic involving no small bit of misinformation (some of it even coming from nuCamp). The operation of the electric breakaway brakes is not a matter of opinion--their function is dictated by the laws of physics and they will not engage if they are not connected to a 12V power supply.

Tabnero

some e brakes have their own 5 to 9 amp hour battery installed with the system that is then charged via TV or shore line. I dont think ours is set up that way but if any one knows for sure one way or the other and the manufacturer of the brake system that would be nice to know. I may change my mind here. Talked to Battleborn yesterday and they said I do not need DC-to-DC charger. the 150 amp alternator on my truck is enough to keep up with the battery without damage to the TV system. So I may look at running with the battery in the on position, pending discovery of specific manufacture. Thanks to everyone

ScottG

The brake systems are part of the axle assembly provided by Dexter (or AL-KO on earlier models, but AL-KO is now part of Dexter and the differences are negligible). There are no batteries or other rechargeable power sources installed as part of the axle assembly, and there are no additional batteries installed anywhere on the T@B chassis as delivered from nuCamp.

While a dedicated battery to operate the breakaway brakes in the event of a total separation would be a nice feature, I am as certain as anyone can be that it is not a feature of T@B trailers. 

Tabnero

ScottG said:

The brake systems are part of the axle assembly provided by Dexter (or AL-KO on earlier models, but AL-KO is now part of Dexter and the differences are negligible). There are no batteries or other rechargeable power sources installed as part of the axle assembly, and there are no additional batteries installed anywhere on the T@B chassis as delivered from nuCamp.

While a dedicated battery to operate the breakaway brakes in the event of a total separation would be a nice feature, I am as certain as anyone can be that it is not a feature of T@B trailers. 

got it, thank you

RetireeBC

I've just returned from a wonderful camping week with the grandchildren and am catching up on the many responses to my question. I want to thank  everyone for your input which makes it very clear that a trailer battery in good condition with the battery disconnect turned on & 30 amp fuse in place is an absolute must!  I know understand what is required and why. Thanks again.