Expedition Trailer Electrical Layout (1 Viewer)

[barefoot]

I am starting to plan my first 12V electrical system where battery endurance without recharging is a major consideration. This will be built from the ground up and I would much rather save and buy quality the first time than skimp and regret it later. I feel very comfortable with assembly, but would like some input on component selection. At this point I "think" I need batteries, charger/inverter, a distribution/fuse panel,and conductor.

Goals:
-Charge via shore power or from the vehicle
-Use the electrical system while charging
-I would like to be able operate…
- a freezer/fridge more or less constantly (I am undecided between the Engel mt45 and the ARB 50)
- an electric blanket
- LED lighting (for reading etc.)
- pump for water system
- phone charger
- small radio
- ????

Constraints:
-I have room for multiple batteries, but do not want to carry more than 100 pounds in battery weight.
-I would like to leave room for future expansion.
-I want this to be weather tight.

Thanks in advance,

 

[barefoot]

Try try again...
What battery (size, style, manufacturer, etc.) is preferred when longevity between charges is the primary objective?

 

[titanpat57]

I think this may fair better in the trailer section, but I'll give it a try.

First off I think you need a good, deep cycle battery, one that is designed to be drawn down and charged up many times. That brand thing is a whole nudder ball of wax...but any Die Hard, Insterstate, etc. will fair well. If you want to do a higher end there is Trojan, and a few other popular amongst the big RV crowd.

I actually have 2- 6v batteries wired in series, mostly for longevity, but it also has a lot wallop, and I have yet to run them down. They run the Engel 45, LED lighting and the pump.. This year it will have to run the cpap through the night. I also carry a 12v sleeping pad, and use it below 30. Both sides have 12v plugs, protected from the weather by the RTT overhangs. I have one up high, to run power in the tent to charge my phone and watch movies...I mean really...how can you Expo without movies?

Here's a quote from an article..

"6V vs 12v is not the issue - it's the quality of the deep cycle battery involved. These days 6v's are golf cart batteries, designed from the ground up to be rugged and deep-cycled repeatedly. Most 12v's you can buy are essentially 12v starting batteries, perhaps with some improvements for better deep cycle performance, but not fundamentally different in design.

But amp-hours is what you need so 3 x 12v is the way to go in your case. Trojan and Lifeline make some pretty darn good 12v deep cycles, but they are really pricey. The Minnkota brand 12v deep cycle, made by Johnson Controls, isn't too shabby and the price is far better (available at Walmarts). They probably won't last 5 years like your 6v golf carts, though. "

Here's the Gospel according to Mark, for all things 12v....

The 12volt Side of Life (Part 1)


I currently run a 45 amp IOTA converter, which a quick charge, and a trickle charge option. It charges the battery bank off shore power or generator. I also carry a Honda ie2000, which has a 12v charging as well as 120v. I keep two, 2 gallon Rotopax on the nose, and the generator holds a bit more than a gallon. Running it a few hours a day, the gas would last 10-12 days. If you just want to top off the batteries, and run it an hour, you'd have a 20 day supply. I keep a Group 31 AGM Sears DieHard under the hood of the 4Runner.

I used a leftover alarm panel mounted on the inside of the trailer as a "power distribution" box. The front of said panel houses the light switching, a 120v GFI, a 12v plug. Right below it is the IOTA, with a shore power waterproof plug outside. There is a also 120v in a waterproof box on the outside. The wires go from the converter to the battery bank, then back to panel to distribute power. Electrical is not my strong suite, but my insurance is paid up.

So there you have it...good luck

 

[Offroads4x4]

I would look at Blue Sea systems for marine use.
bluesea.com

 

[Bogo]

something to think about. How much will it be used? Deep cycle batteries are often rated by how many 80% DOD cycles they can withstand. A mid line one may handle 300 to 400 cycles. 2 cycles per trip, 10 trips per year is 15 to 20 years. Most batteries die from old age or lack of maintenance before then. On the other hand if it is to be used continuously, then spending on a very high quality battery may be justified. Also if you over capacity, then the average depth of discharge can be less. Only discharging to 50% DOD may double the life of the batteries.

 

[Bogo]

On battery weight. Figure roughly 80ish usable Amp hours per 75lbs of battery weight. This is from deep cycle AGM batteries.

On battery chargers. Look at the ones made for installing in RVs. They are made for recharging a large battery bank as well as supplying a load at the same time. Ask around the RV sites for who makes good ones for the type of battery you choose.

A small solar panel battery maintainer with charge controller or plugin battery maintainer that actually gets plugged in is a wise idea. They could save the cost of having to get a new set of batteries at the last minute before a trip. Think of them as insurance protecting the investment in the batteries.

As for how much capacity you will need. Add up the daily Amp hours used and multiply by the number of days. You also wanted an expansion buffer for future increases in use. Multiply by 1.5 to 2 to get the total usable Amp hour capacity needed. Take that number and divide by .8 (80%) to get the battery bank capacity needed. There are some threads that already mention average uses for compressor based refrigerators. The electric blanket you choose should have it's Amp draw rate on the label.

Lets say your daily amp hours adds up to 40. You want 3 days use before recharging. So, 40 * 3 = 120. You want a 1.5X buffer, so 120 * 1.5 = 180. 180 is the number of amp hours the battery bank needs to be able to supply. Multiply that by .8 and to get 225 as the minimum size of the battery bank. Now remember we had that 1.5X over sizing. If just a bit smaller over sizing is used, then it will fit within a pair of Group 31 deep cycle batteries which would have around 100 to 110 Amp hours total capacity each. BTW, a pair of group 31 batteries should weigh around 150lbs.

 

[Bogo]

My thoughts on recharging a big battery bank. It'll take forever to recharge a large battery bank when driving. Also it will really tax your stock alternator. They weren't designed to output full amps for hours and hours. If you want to go with recharging from the vehicle, a second alternator on the engine is a good idea.

The method I think is best now is to get one of those 1000 or 2000 Watt inverter generators. Use it to power the RV battery charger. Figure out how much gas it takes to run the RV battery charger for 1 hour at full charger output Amps. Lets just say it uses 1 liter per hour. Now lets say we are at 80% DOD on a 220 Amp hour battery bank. That means we need to recharge 176 amps into the battery bank. The RV charger we have is a 45 Amp output one. Ideally that is 3.9 hours recharging time, but the last few percent always takes longer and is inefficient. So, lets go for 3.5 hour recharge. We only put in the amount of fuel needed for 3.5 hours run time, 3.5 liters. That should put back in roughly 157 Amps back into the battery. Given batteries are not 100% charge efficient, likely only 140 amps really got charged into the battery.

This short charging can be done for a number of cycles in a row, but at some point a full recharge will need to be done to prevent sulfation of the battery. Doing a full recharge every month should be all that is needed.

Part of the reason I came up with this idea for recharging is a fuel limited generator will only run so long then shut down automatically when the fuel runs out. I do this with stock tank pumps on the farm. 12 oz of fuel will fill my 1000 gallon stock tank from near empty. Second is the final few percent of the recharge of a battery is really hard on it and takes a long time in comparison. Charge rates drop off allot toward the end of recharge. Also allot more damage is done to the structure of the battery recharging that last few % than is done recharging the middle 50%. So, lets just avoid recharging back up to 100% while the battery is in heavy use. Yes it may mean recharges will need to be done more often, but with a fuel limited generator we can go off and do something else while it runs. Only fully recharge the battery bank when back at home where a smaller output charger can be used to recharge at a kinder rate.

 

[titanpat57]

you ain't gettin' jack done on the farm.....



too busy typing....





I do like the "fuel runout idea"...makes perfect sense....

 

[Bogo]

you ain't gettin' jack done on the farm.....



too busy typing....





I do like the "fuel runout idea"...makes perfect sense....

It's frigging winter. My time to goof off. I'll be back to doing 16 hour days soon enough.

 

[alia176]

"battery endurance w/o recharging..."

- lose the inverter, electric blanket, phone charger for starters.
- stick to all 12vdc appliances

Just some ideas I'm throwing out!