12 volt system inventory

[shawnjr22]

I’m looking to get a list of things I need to get a 12 volt system run in my teardrop (lil red is her name) below is what I think I need
-A deep cell battery
-On/off control switch
-12 gauge red wire (for positives)
-12 gauge black wire (for negative)
-a grounding block
-fuse panel
Please let me know if I need anymore haha I don’t know anything about power

[lfhoward]

Battery terminals for + & - cables
A set of wire ends to connect wires to your fuse block & lights etc.
A wire stripper tool
Heat shrink tubing or black electrical tape

It would be good to draw out the map of your system & circuits to see how much wire you need.

Also, here is a good chart for determining wire thickness you need for particular amp loads at different distances. The wires between your fuse block/grounding bus & the battery need to be heavier duty than what goes to individual devices from the fuse block.

[shawnjr22]

awesome thank you! now my only other concern is charging the battery. Id like to charge while tow but I have no clue how to wire the deep cell battery to the towing plug. would another option be to just make sure I charge the battery before we leave for a weekend with a regular battery charger? electricity is all a foreign language to me haha

[troubleScottie]

Just a note on wire size. The power/ground pair in a 7 pin trailer connector is generally too small to effectively charge the battery and/or run appliances.

You would be wise to run a separate pair of cables -- something to handle at least a 20A load. I cannot recall the gauge. Most likely something between 4 and 8 gauge depending on the length. Think big audio amplifier power cables. Use the previously given chart to determine the load and length and gauge to reduce loss of potential.

The TV to trailer connection is often an Anderson connector. Nice solid connectors, idiot proof. Again, look around. Lots of variants with covers, attachment points, handles, etc

This can/should be keyed ie add an solenoid to allow charging only when the engine is on. Also remember fuses.

Obviously this cable has to go all the way to your battery/charging system. That might mean creating additional holes into the trailer. Probably do not want to have this cable in the living space.

If you browse the electrical section, there are numerous discussions on how to connect to charge your battery eg "charge while towing" or "dc to dc" Everything from a direct connection, relays, ACR and DC to DC chargers. The technology is improving. As is mentioned above, some serve both solar and vehicle charging. Your design is generally only limited by your pocket book.

[shawnjr22]

Ok so I have a deep cycle marine battery with 8 gauge wires running from the positive and negative to the fuse panels positive and negative terminal all in the battery box on the tounge of the trailer Then I’m running 14 gauge wires from the fuse panel to 3 led lights and two fans. A couple of lights and fans is all I need and want so does this work?

[troubleScottie]

Yes for the discharge part of the solution.

You can go lower on the wire gauge. Assume you want a 3% voltage drop, for a 10A line, you can use 10awg for 20-30 feet run. For a 5A total amperage usage, you can use 12awg for 25-30 foot run. Look at the devices. DC devices will list their amperage usage directly or by dividing the wattage by 12. Sum them up and you get your power demand.

You might consider what else you are thinking about adding. Your selection is very minimalistic. You might want usb ports for charging. People do add fans, frigs, brighter lights, water pumps, heaters, tv, radio, disc players, exterior lighting, safety meters. LED lights are generally low power, but can be very power hungry. A final item is an inverter to generate AC from the battery. Read some of the electric systems.



The other half of the system is to recharge the battery. You need some mechanism to recharge the battery: a battery charger, a converter, a solar regulator, connection to the towing vehicle battery, a generator or a combination of all of them. Again the question is how often do you need to recharge. If you can always wait till you get home, less of an issue. Or your always camping with external power available. My previous suggestion is a DC to DC charging system from the towing vehicle.

Again the question is how much usage. Lots of articles on how to determine usage and power consumption. Last resort is just try it and see when it fails. When computing usage, remember rainy days when you are inside all day. Or camping at a site that should have power, but does not for some reason. You have a reservation, but you may not get what you want (a Seinfeld car rental gag). For the great NW, summer may not require lights due to late sunset (9-10PM), where winter camping means dusk at 4-5PM and sunrise at 8AM.