Electrical Planning Questions

[sincere01]

As I plan my build I definitely need some help with planning the electrical. I am scouring all the other posts in this section to learn as much as I can, but figured I'd also layout here exactly what I need for electrical and ask for any advice others have. For more information on my overall build plan see the build thread link in my signature block.

Here is what I feel I want to do:
1. Obviously need to install brake lights and turn signals. I want these to be installed into the hatch itself, not sticking out from the trailer frame.
2. All lights will be LED unless there is some weird reason I shouldn't do that.
3. Two inside lights for the sleeping quarters.
4. Two lights on the inside of the hatch to light the galley.
5. Deep Cycle battery (maybe two?) in the tongue box.
6. Fantastic Vent (sounds like this is the brand everyone uses and recommends). Also unsure on how much a fan will drain the battery.

I don't really plan on much else. I do not need an ac/heater. I wont be installing a fridge of any sort. I want to keep my electrical needs to a bare minimum. Originally I had planned on not wiring anything except the tail lights and not even having a battery in the tongue box, and just using push-on battery operated LED's for lighting in the sleeping area and using a lantern for the galley. I have since changed my mind on that and hope to wire the above things.

I am not new to wiring but am by no means an electrician. I have re-wired many things around my house (all 120VAC and 240VAC). I have also built a control panel for brewing beer based on Kal's design from theelectricbrewery.com. However, I have never really done anything with 12VDC or used inverters.

As I said I would like to have everything hooked up to a battery in the tongue box, but would also like to be able to plug in at campsites. One thing I don't know how to go about is:
-Do I have the power always drawing off the battery and use the campsite power to charge the battery? or,
-Do I install an inverter and a switch to go between battery power and plug-in power?

My apologies for my lack of brevity. Being concise has never been one of my strong suits.
As always, any advice, experiences, et cetera are greatly appreciated.

[sincere01]

Not sure if this is appropriate here, if not let me know and I'll remove the post, but if anyone is interested here are pics of the control panel(CP) I built that I mentioned above:

This is the initial fabrication of the box:


This is the box with the new paint:


Parts being installed inside:


Bottom view:


Components installed but no labels yet:


Here is the CP as it is being wired. I don't have one of the inside finished with the heat sink on, but I cleaned up all the loose wires and such.


First test:


Running the brewery for the first time. I am currently in the process of welding much nicer stands than those ones I just threw together so I could start brewing on the system:

[bobhenry]

While not exactly a tiny trailer wiring adventure I must admit you sir are an artist when it comes to correctly routing and forming the circuits. Any builder could take a lesson that a bit of care makes a wiring job , what ever it is, go so much smoother.

[sincere01]

While not exactly a tiny trailer wiring adventure I must admit you sir are an artist when it comes to correctly routing and forming the circuits. Any builder could take a lesson that a bit of care makes a wiring job , what ever it is, go so much smoother.

Thanks!

[tony.latham]

That's some serious brewing going on there...

Your trailer chassis lights (tail lights) and your 12V cabin/galley wireing are two different critters (systems). The chassis wiring should only be hot when it's plugged into your running tow vehicle and the appropriate switch is flipped (brakes, blinkers or headlight).

I'd suggest a fuse box like this to protect your 12V cabin system. A ten or twelve gauge negative and positive will come off your teardrop battery and then fourteen gauge neg/pos to your lights and fan:



http://www.amazon.com/Blue-Sea-Systems- ... ne+fusebox

Your Fantastic Fan will pull about 2.5 amps. I think LED lights draw about .25 amps per hour. So lets say you read for a couple of hours with the lights on, and run your fan during the same time period. That's about 6 amps. A Group 24 marine battery has about 40 useable amp hours. So in theory, at that rate you can go hang in the woods for a week without charging your battery.

As you've probably figured out, a properly wired tow vehilce will charge your battery coming and going. Thus if your on a trip... you'll start each night with a charged battery.

For me, an aditional 120v charger isn't needed. I do have an always-on 20 watt solor panel on my tongue box that maintains the battery and then some (along with a sixty watt folding panel inside the box that I find I seldom need).

I'd also throw one of these in the mix for charging your phone etc:




Tony

[Shadow Catcher]

An alternative to the Fantastic fan (which many folk try to slow down) is to use computer case fans which use much less power and do the job. I used two Antec 80mm three speed fans, seldom do we use them above low or medium.

[sincere01]

That's some serious brewing going on there...

Your trailer chassis lights (tail lights) and your 12V cabin/galley wireing are two different critters (systems). The chassis wiring should only be hot when it's plugged into your running tow vehicle and the appropriate switch is flipped (brakes, blinkers or headlight).

I'd suggest a fuse box like this to protect your 12V cabin system. A ten or twelve gauge negative and positive will come off your teardrop battery and then fourteen gauge neg/pos to your lights and fan:



http://www.amazon.com/Blue-Sea-Systems- ... ne+fusebox

Your Fantastic Fan will pull about 2.5 amps. I think LED lights draw about .25 amps per hour. So lets say you read for a couple of hours with the lights on, and run your fan during the same time period. That's about 6 amps. A Group 24 marine battery has about 40 useable amp hours. So in theory, at that rate you can go hang in the woods for a week without charging your battery.

As you've probably figured out, a properly wired tow vehilce will charge your battery coming and going. Thus if your on a trip... you'll start each night with a charged battery.

For me, an aditional 120v charger isn't needed. I do have an always-on 20 watt solor panel on my tongue box that maintains the battery and then some (along with a sixty watt folding panel inside the box that I find I seldom need).

Tony

Thanks so much for the thought and advice. That makes sense and simplifies things about not needing a 120v connection. And if I ever ran out of juice and wasn't going to drive anywhere I could still just hook up the connection to the TV and turn it on for a while to charge it. Or just carry a trickle charger and plug it in to an outlet.

Also, thanks for the reminder about the 12VDC plug-ins for phones and such.

An alternative to the Fantastic fan (which many folk try to slow down) is to use computer case fans which use much less power and do the job. I used two Antec 80mm three speed fans, seldom do we use them above low or medium.

Thanks for the heads up. I'll look into using those. I used a computer fan to build a stir plate for a yeast starter. That was a fun little project.
What is/are the reason(s) people try and slow down the fantastic fans? Are they too loud? Does it just move too much air and cool things down too much?

[capnTelescope]

OK, Scott, let us know when the beer is done and we'll hold the next meeting at your place.

I think you can handle this one:


This is the DC-AC-DC charging method discussed at some length in the Charging While Towing topic. You can also find pix and more at this post in my build thread. After seeing your nice wiring job, I won't post mine here.

This circuit charges while towing or charges while plugged in to shore power, and you don't have to remember to flip any switches or forget to do anything.

The solenoid connected to the TV battery sends 12V to the trailer when the ignition is on. On the trailer, the 12V goes to an inverter that supplies AC to the on-board charger. Power from the inverter also energizes the 115VAC relay to complete the power to the charger while towing. When the ignition is off, the relay de-energizes, allowing shore power to power the charger.

You will need to tap into a circuit in your TV that is live when the ignition is on.

Remember, ...

[pchast]

There are several ways to skin the cat....

Since I'm also using Solar primarily, we wired from the same ignition controlled continuous solenoid set up
to a connector for the trailer. From there I used a Solar Charge Controller to control the battery charge.
I have a fuse at each battery positive connection( all 3 ). The TV and the 2 identical SLAs in the trailer
battery box. This seems to work quite well also. When not towing I plug in a 30w panel.



The load center.... I thought I had one of it all wired. I'll get one tomorrow.

[capnTelescope]

Since I'm also using Solar primarily, we wired from the same ignition controlled continuous solenoid set up
to a connector for the trailer. From there I used a Solar Charge Controller to control the battery charge.

That's interesting. So a solar charge controller will handle any 12-voltish DC input? Sounds like a SCC could replace the smart charger in my setup and eliminate the inverter. You could add another relay on the trailer side of my circuit and have 3-way charging: Shore power, DC-AC-DC or basking in the sun.

[H.A.]

.....

[capnTelescope]

But one thing may be of concern & it probably varies with different charging control models / manufacturers.
The 'alternate' DC input may have to be very clean no ripple, filtered DC. It may be a good idea to check this alternate source is clean or place a suitable filter on the controller input for good measure.

A typical electrolytic capacitor would do that job. Those are the ones with + and - marked terminals. You could probably find one of a suitable size in an old computer power supply.

'Scuse the thread hijack, Scott. Are you thoroughly confused yet?

[sincere01]

'Scuse the thread hijack, Scott. Are you thoroughly confused yet?

No worries, Sometimes thread hijacks bring out a lot of useful information.

Not too confused, I track most of it and can research a bit to get caught up on the rest. I'm going to end up keeping things a bit more simple though.

[MtnDon]

Since I'm also using Solar primarily, we wired from the same ignition controlled continuous solenoid set up
to a connector for the trailer. From there I used a Solar Charge Controller to control the battery charge.

That's interesting. So a solar charge controller will handle any 12-voltish DC input? Sounds like a SCC could replace the smart charger in my setup and eliminate the inverter. You could add another relay on the trailer side of my circuit and have 3-way charging: Shore power, DC-AC-DC or basking in the sun.

I have to wonder how much actual charging is happening at the trailer battery with setup running down the road behind the TV?

Reason I wonder is that I did not think there are any solar charge controllers that do not have some internal voltage drop. As well simple charge controllers can not boost the output voltage to be higher than the incoming voltage.

When my Tacoma battery is charged I have a voltage reading of 13.7 to 13.8 volts when running down the road. That is pretty much the float voltage of the batteries in the trailer. If I have run the TV battery down some the TV voltage rises. The voltage also rises if I connect the partially discharged trailer batteries to the TV charging system. I can see 14.4 and even higher then. This is where some "bad" things may be going on... with a direct TV to trailer connection, if the depleted trailer batteries have best voltage for charging the TV battery is being overcharged.

In this example of using a solar charge controller I do not understand how the solar charge controller is going to come up with a voltage high enough to actually push a charge into the trailer batteries if the TV system is running at/near the float voltage? Maybe someone with experience can explain? Also can you tell us just what controller is being used?


As much as it bothers me to see the power path from DC to AC to DC as apnTelescope has done, I do see the good side of that system. That being it keeps all the batteries at whatever voltage the battery manufacture deems best (assuming proper hardware selection and programming).


As an aside I do use small PWM charge controllers to maintain my ATV and bike batteries in an off grid situation. There though, the charge controller is being fed a nominal 24 VDC and bucking that down to a nominal 12 VDC.

[Dale M.]

While not exactly a tiny trailer wiring adventure I must admit you sir are an artist when it comes to correctly routing and forming the circuits. Any builder could take a lesson that a bit of care makes a wiring job , what ever it is, go so much smoother.

Why is that so typical of a Volkswagen...

Dale