Let's talk TRAILER electrical systems

Dean

Adventurist
Founding Member
My current electrical system in the "Poorman's Teardrop" is, well, kind of poor. It's basic and functional, but it's hard to monitor and even harder to service. I recently scored a pair of Odyssey Group 34/78 AGM's that are going in the trailer. While I'm at it I figured I'd rewire the entire trailer.

Right now the primary load is my 47L ARB Fridge. Beyond that it's just little things like lights, some small USB fans, and USB charging for my iPad and iPhone. I'd like to add some exterior lights and maybe some g/fx lighting to help with walking around camp at night. Wouldn't mind an exterior 12v and/or USB socket. Beyond that, nothing crazy.

Charging is done by a 150w Overland Solar tri-fold, a trickle-charge off the Jeep while I drive, and (hopefully) shore power if I can get it set up.

So let's discuss trailer electrical systems and please share photos of your systems.
 
I lost my electrical system pictures to photobucket but this diagram helped me. The power wire in the 7 pin allows me to charge my trailer battery while I'm driving

7 pin.jpg
 
Trailers are kinda fun to wire! There are minimal "other" wires to worry about (required safety lights), sometimes plenty of room to work with, Tongue boxes work great for storing batteries and charge controllers, and allow a nice spot to put external ports (USB, Cig adapters) without compromising the integrity of the trailer.

The two of those batteries will provide you with a combined amp hour rating of around 130, that's plenty for a single bank. The solar you mentioned should have no problem keeping them topped off. Stay away from glitzy things like battery meters, ironically, they consume too much power just to show you your battery level, unless you put them on a momentary switch so that they're on only when you're curious enough to look. I use CTEK Battery Sense, you'll need one for each battery, and now your phone becomes your battery monitor, and can send you a notification if your batteries get too low!

One way to spruce up the charging from your vehicle while you drive, correctly isolate your batteries, AND has a built in solar controller, is to use the CTEK D250S. It's a DC to DC charger that will handle all of those things in a single device.

When mounting your batteries, don't play around, 65 pounds is a dangerous amount of weight, even in an accident at 35 MPH, they're heavy enough to destroy anything near them if they break free. Get a good PC1500 battery mount like Artek Industries makes.

That should get your gears spinning and keep you busy for a bit...

I thought I had some good trailer-related wiring photos, but none really worth showing off. You can check out my instagram accounts, @4runamok and @AdventureWired for some good wiring photos. The Adventure Wired account is new, but off to a good start, I just opened the business in June.

There's your other option by the way, go on a cross-country adventure and drag that trailer to CA and get it Adventure Wired! I'm not the cheapest option, but I know what I'm doing!

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Trailers are kinda fun to wire! There are minimal "other" wires to worry about (required safety lights), sometimes plenty of room to work with, Tongue boxes work great for storing batteries and charge controllers, and allow a nice spot to put external ports (USB, Cig adapters) without compromising the integrity of the trailer.

The two of those batteries will provide you with a combined amp hour rating of around 130, that's plenty for a single bank. The solar you mentioned should have no problem keeping them topped off. Stay away from glitzy things like battery meters, ironically, they consume too much power just to show you your battery level, unless you put them on a momentary switch so that they're on only when you're curious enough to look. I use CTEK Battery Sense, you'll need one for each battery, and now your phone becomes your battery monitor, and can send you a notification if your batteries get too low!

One way to spruce up the charging from your vehicle while you drive, correctly isolate your batteries, AND has a built in solar controller, is to use the CTEK D250S. It's a DC to DC charger that will handle all of those things in a single device.

When mounting your batteries, don't play around, 65 pounds is a dangerous amount of weight, even in an accident at 35 MPH, they're heavy enough to destroy anything near them if they break free. Get a good PC1500 battery mount like Artek Industries makes.

That should get your gears spinning and keep you busy for a bit...

I thought I had some good trailer-related wiring photos, but none really worth showing off. You can check out my instagram accounts, @4runamok and @AdventureWired for some good wiring photos. The Adventure Wired account is new, but off to a good start, I just opened the business in June.

There's your other option by the way, go on a cross-country adventure and drag that trailer to CA and get it Adventure Wired! I'm not the cheapest option, but I know what I'm doing!

View attachment 32402

Yeah, Already pinging Artec about their dual battery mount. One of the reasons I chose the 1500 series group 34/78 batteries. They have a very nice dual tray.

I'm checking out the CTEK Battery Sense now. I'm assuming I could have multiple of those linked to the amp for each battery?
 
Yeah, Already pinging Artec about their dual battery mount. One of the reasons I chose the 1500 series group 34/78 batteries. They have a very nice dual tray.

I'm checking out the CTEK Battery Sense now. I'm assuming I could have multiple of those linked to the amp for each battery?
Yes, you can have many Battery Sense devices. They must attach directly to the battery its monitoring.
 
Stay away from glitzy things like battery meters, ironically, they consume too much power just to show you your battery level, unless you put them on a momentary switch so that they're on only when you're curious enough to look. I use CTEK Battery Sense, you'll need one for each battery, and now your phone becomes your battery monitor, and can send you a notification if your batteries get too low!

Um, whaaa. My system for example with a 7 inch LED color screen is around 0.7 amps idle with a second display and propane monitor. I like having plenty of power on tap.

That CTEK looks interesting. Wonder if the shunt is built into it or not...

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Um, whaaa. My system for example with a 7 inch LED color screen is around 0.7 amps idle with a second display and propane monitor. I like having plenty of power on tap.
Yes, very nice, not a typical install, but I think you and I have had that convo before.

What kind of battery bank is behind that system? Because 0.7 amps is enough to drain a single average battery in a 12-24 hour time period. My personal opinion is that battery monitors are bling and pointless. More focus should be placed on charging processes so that you can relax and not worry about your battery levels :D

In short, your average camper doesn't have the money nor the necessity for a system like the one shown in your photos. Now I'm not always dealing with the average camper, but I will still motivate towards solid need vs. glamorous want. Save that money for the suspension or armor! :)
 
Hmm, @Dave, I can't seem to edit my posts.

So.. EDIT: Wait, I think I'm looking at your battery bank, is that a bank of 4 lithium batteries?
 
Bling. :rolleyes: What's the point of charging systems if you don't know what's going on or what your usage habits are at any given point in time? The battery monitor is a crucial part of a system. Not having one is basically making decisions based on GUESSESTIMATES. The average camper, who has solar could benefit from something like a Trimetric battery monitor. If it's not thru a shunt, it's guessing games.
 
Do I need to isolate and monitor both batteries separately, or can they be linked and monitored together? Obviously in a vehicle I'd want to isolate a starting battery from a house battery, but is that necessary in a trailer where both batteries are serving as house batteries?
 
Do I need to isolate and monitor both batteries separately, or can they be linked and monitored together? Obviously in a vehicle I'd want to isolate a starting battery from a house battery, but is that necessary in a trailer where both batteries are serving as house batteries?
No.

There is a right way and wrong way to wire multiple batteries in an Auxiliary Bank. You should link the batteries in Parallel (Connect each Positive together, and each Negative together), but draw all the Positive connections from one battery, and the negative connections from the other. Like shown in the photo below. This will allow each battery to drain equally. Drawing from only one of the batteries in a bank will cause that battery to drain faster than any other battery in the bank, larger banks the batteries furthest from the draw won't see any draw at all. This will burden not only that first battery, but your charging method as well.

If you use the CTEK Bluetooth monitors, each battery gets it's own monitor, and they connect directly to the battery. If you use a battery monitor meter (the worst way IMHO) I would just attach that at my fuse block (that's connected to the battery bank drawing from opposite ends of course).

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I lost my electrical system pictures to photobucket but this diagram helped me. The power wire in the 7 pin allows me to charge my trailer battery while I'm driving

View attachment 32393


Question: Has anybody here used an ammeter to measure the actual current delivered to trailer batteries by way of this 7 pin connector?

I have heard that, because of the length involved from the alternator back to the trailer, as well as the fact that the wires involved are very thin - 14 gauge?, 12 gauge? - there is so much voltage drop that very little current flows.

I have heard that the purpose of that power pin is to serve as a trickle charger to keep the little emergency battery topped up - the one that activates the electric trailer brakes during a break-away situation.

I have heard that some people run a separate circuit from their tow vehicle to their trailer battery using Anderson Power Poles and much heavier wire - 8, 6 or even 4 gauge, which allows far more current to flow.

There are a lot of "I have heard"s there, so I ask again, anybody got any hard numbers as to what is going on?

Thanks
 
Any of you use 6 volts in series or series parallel for your aux batteries? Basically two 6 volts to get to 12 volts for deeper discharge rates. On average 6-volt batteries have better amp hour life. Was curious why I've never seen that outside of RV applications in overlanding setups. Two golf cart batteries for example.
 
"Any of you use 6 volts in series or series parallel for your aux batteries? Basically two 6 volts to get to 12 volts for deeper discharge rates. On average 6-volt batteries have better amp hour life."


I've been debating doing that for my pup trailer with some solar, I just don't really want to buy more batteries and have to figure out new mounts. If I do I'll relocate them to the rear bumper probably due to the size and weight.
 
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