| Author |
Message |
Jon W.
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 31, 2005 - 4:09 pm: | |
For the first time I am adding a braking device to our toad. We are using a brake actuator that is operated off the air brakes on the coach.
That means everytime the coach brakes are activated the air cylinder in the toad pushes on the toad brake pedal. When that happens the toad brake lights work without any electrical connection to the coach. The bad news is on a long trip I can envision the toad battery being depleted.
On our other toads the coach is wired to the toad brake, parking and turn signal lights. The toad battery never has any current draw. If I wire the new toad the same way, then I assume that even though the toad brake lights are getting power from the coach as well as the toad battery, the toad battery will never drop to a voltage lower than the coach brake light current, unless I put a diode in the circuit to prevent coach power from backfeeding to the battery of the toad through the brake light switch.
( I get tired just thinking about what I just wrote.) An alternative is to install a relay in the brake light circuit, so that anytime the coach brake light circuit is energized, the circuit from the toad brake light switch is open and there is no toad battery draw.
This might be a silly question for this forum, but does anybody out there have any opinions on this? |
Lin
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 31, 2005 - 5:24 pm: | |
You still would have to wire the toad for turn signals and tail lights (unless you were going to leave the toad tail lights on when traveling at night. But anyway, even if you drove for 10 hours, how much of the time will your brake lights actually be on. There really might not be any significant affect on a good battery. I wonder if a dashboard plugin solar charger would more than make up for the draw assuming your are not driving all night. |
Jon W.
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 31, 2005 - 8:16 pm: | |
In case I wasn't as descriptive as I could have been, the toad will be completely wired.
It will have all lights, turn signals and brake lights operational.
To answer the question, I am concerned about towing for several days without starting or unhitching the toad. We have towed cross country several times. |
Stephen Fessenden (Sffess)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 31, 2005 - 9:14 pm: | |
LED replacement bulbs for the brake lights might reduce the current so that you still have no worries even with a week long trip. Or why not just put a battery disconnect on the toad battery for peace of mind, or pull the toad brake light fuse, or switch the brake lights to an ignition only circuit. My cars have the brake lights on only when the ignition is on, so it should be legal. |
Brian (Bigbusguy)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 31, 2005 - 10:51 pm: | |
What about a charge line to the toad that will keep the battery up.
Brian 4905 Klamath Falls Oregon |
NewbeeMC9
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 31, 2005 - 11:21 pm: | |
A six or seven prong trailer prong should have a 12V terminal to charge battery/supply accessories. Just hook it to the battery and make sure you have a good ground between the two vehicles. |
franz
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, April 01, 2005 - 8:30 am: | |
Just put a DPDT switch in the toad brake wires. Hook the toad brake wires to one side, and the bus brake wires to the other. Use this instead of the diode you would normally install.
Then, when you connect, set the switch to bus. When the brakes are activated, there's no connection to the bulbs. The brake lights are powered by the bus electrical system. When you disconnect, set the switch back to toad. |
franz
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, April 01, 2005 - 8:36 am: | |
BY the way, if you wire the bus turn signals into the toad brake lights as is normally done, then you won't have any turn signals on your toad when your brakes are activated because the toad brakes will override the coach turn signals. This is true, even if you use the relay setup you described in your original question because the relay will cycle when the turn signal cycles.
If your toad has independent turn lights on the rear, you could wire the turn signals (not brakes) from the bus into those, and then wire the bus brakes into the toad brake lights using the normal diode setup and it wouldn't matter if the toad overrides the bus on braking because they both do the same thing. |
Jon W.
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, April 01, 2005 - 2:49 pm: | |
franz, I like your idea of the DPDT switch. It is a more elegant and simpler way of dealing with it than the relay.
I have separate turn signals in my toads, so whatever I do with the brake lights will not affect the signals or parking lights. |
Rob King
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, April 01, 2005 - 8:34 pm: | |
Hi Jon W
We have the same setup on toad as you want and have never had any problem towing for 3-4 days without charging the toad battery. That being said, Franz post is a good fail safe wiring to make sure nothing goes wrong.
Rob |
Al Newell (Peregrine)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, April 01, 2005 - 11:37 pm: | |
A lot of the folks are now adding an extra lamp socket in the rear light housing and feeding that from the bus. That way you have a completly independed system and don't worry about the toad batteries or diodes burning out.
Al Newell |
John that newguy
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, April 04, 2005 - 8:01 am: | |
Jon-
Re:
"every time the coach brakes are activated the air cylinder in the
toad pushes on the toad brake pedal. When that happens the toad
brake lights work "
Assuming you have the towed electrically connected to the bus
and are using the bus turn, parking and brake light circuits to also
control the towed vehicle's lights..... And you're just having trouble
with the towed brake lights being illuminated by it's own system.....
I'd move the towed vehicle's' brake light lead from the "always on"
fuse (circuit) it's now connected to, to a fused circuit that's only on
when the ignition's on. Some vehicle's brake lights work regardless if
the ignition's on or not, for whatever reason they chose to engineer
it that way... Changing it isn't a sin.
I would not add any "switch" that would prevent the brake lights from
working normally, since one forgetful moment can totally ruin your
otherwise perfect day. |
Brian (Bigbusguy)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, April 04, 2005 - 10:08 am: | |
New guy,
That will not work as easy as you say then every time the coach powers the brake light circuit then the switched side would have power to it from the coach and everthing in the toad would come on like the key was on.
I think if the toad has a good batt having the brake lights come on from its batt would take a week of driving to run down the batt anyway.
Brian 4905 Klamath Falls Oregon |
Jon W.
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, April 04, 2005 - 4:42 pm: | |
I got to thinking about the switch and realized that if forgotten the brake lights won't work. The good news is when I am running from the law I can switch them off (just kidding)
I'm going to see if my concerns are unfounded. He re is my thinking and if it is wrong I trust some of the more erudite contributors to this forum will slap me up side the head.
I will not use diodes for the brake lights which are independent. I will have coach power to the toad brake lights so when the coach brakes are applied, the toad brake lights will get power from the toad as well as the coach.
My theory is that once the surface charge is removed from the toad battery, the voltage should be around 12.7 volts. With the coach running, the brake light circuit is going to be about 13.4 volts. I expect the coach power to feed back to the toad battery upon every application of brakes, so there should be no drain, and in fact each application of brakes, in a round about way will actually supply a miniscule charge to the toad battery. |
John that newguy
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, April 04, 2005 - 7:33 pm: | |
As posted earlier by Al, it's 100% easier, and fail-safe to your
automobile's electrical system, to simply install extra bulbs in
the car's taillight assemblies.
http://www.aemfg.com/Accessories/wiring.html
You're lucky that your bus is 12 volts! That really simplifies things. |
Tom Caffrey (Pvcces)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, April 04, 2005 - 9:53 pm: | |
Jon W.,
In a post above, you said "I expect the coach power to feed back to the toad battery upon every application of brakes".
If you are to avoid trouble with a setup like that, you should think about what it takes to make it safe.
If the wiring is good, the only limit to the current flow from the coach to the toad will be the resistance of the entire circuit, limited by whatever you use as a fuse.
I would guess that most of the time the current will not be enough to damage anything, but what if something fails in the toad, like the alternator? You could go from a few amps to maybe 50 or more.
With two sources to a single circuit, you actually need fuses or breakers on both sources. If I really wanted to do something like that, I probably would add a small resistance to the circuit to prevent failures, but I think there are better ways.
For what it's worth.
Tom Caffrey PD4106-2576
Suncatcher |
Jon W.
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, April 05, 2005 - 7:41 am: | |
John the new guy, It is a 24 volt coach, but the toad light circuits from the coach are 12 volt. Thanks to you and Tom. Because of your comments I am going to give serious consideration to going with dedicated light bulbs in the toad brake light circuit. |