Just finished the ultimate small trailer electrical system.

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Just finished the ultimate small trailer electrical system.

Postby tdhcsc » Mon Apr 24, 2017 5:48 pm

Just about finished installing what I believe may be the most advanced electrical system in a teardrop trailer. For more than 12 years the wife and I were cruising sailors. When making the switch to camping I felt it was necessary for me to have 2 things, sleep well and not sacrifice on our electrical needs. I could deal with everything else if I just had those two necessities.

The wife and I purchased a new/custom ‘Vistabule’ teardrop trailer last year. Not wanting to sacrifice anything electrical we had on the 50 foot boat and since the little teardrop was new I started from scratch and re-installed the electrical system leaving only the pre wired lights untouched.

My system consists of 2-100 amp hour Lithium Ion (LiFePO4) 12 volt batteries, a 1,500 watt pure sinewave inverter, 40 amp 120 volt charger, a high amperage feed from the Jeep alternator to the teardrop batteries for charging from the tow vehicle, Victron battery monitor & MPPT solar controller, iphone monitoring along with 2-100 watt semi-flexible solar panels (roof mounted).

We just returned from 10 days of dry camping in Joshua Tree National Forest here in Southern California and after a lot of trial and error including shorting out a Victron solar charge controller and purchasing a replacement the system is working great! We have all the power we want (at the moment, 50 amp hours in a 24 hour period) and can charge the batteries using either the 120 volt shore charger, the Jeep’s alternator or the 200 watts of solar panels. We can also monitor everything by bluetooth on our computers or smart phone. We have a refrigerator, make percolator coffee in the morning and can plug in anything that can be plugged into a household circuit at home (like a waffle iron). With our charging system we can re-charge the Lithium Ion batteries quickly with 120 or the Jeep alternator, or, (using the solar panels) re-charge the 50 amp hours we normally use in a 24 hour period by 2PM on a sunny day and can go 4 days 'dry camping' before needing to recharge by any source.

I’m impressed with myself, (sorry) and plan on making a website with detailed information on what I tried to do, what I accomplished and what I learned putting the system together. At the moment the wife and I are just enjoying the fact that the system works great! My approach was when in doubt, make the system bigger and it seems to have worked, from wire sizing to solar panel output.

If anyone is building an electrical system for a small trailer or RV and wants some input, send me an email, that is until I make that website. I did a lot of research online and found there’s nothing that starts from scratch and builds the ultimate system. Be warned though,,,, doing all the work myself it still cost more than $4,000.00 for the parts.

Approximate cost,,,

Lithium Ion batteries, $2,300.00
Wiring $ 500.00
Solar equipment $ 450.00
Battery/solar monitoring $ 400.00
Misc. $ 450.00

Email address: [email protected]
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We're X long distance sailboat cruisers logging more than 25,000 miles under the keel. After 13 years the 24/7 routine became just too much. On multi day passages someone always had to be in the cockpit and we took 3 hour watches. Even at anchor we had to be ready to head to sea even if it was 3AM. We miss it but using our experience of 'self accountability' the Jeep/teardrop idea appealed to us. Our idea is to camp mostly in the California dessert (we had the Vistabule teardrop set up for off-roading) and play in the dirt with the Jeep Rubicon.

It's all new but fun!
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Re: Just finished the ultimate small trailer electrical syst

Postby John61CT » Mon Apr 24, 2017 6:59 pm

Crazy money for a couple of batteries!

Sam's Club "Duracell" actually East Penn/Deka 6V x2 GC2s gives you 215AH for a tenth the price of the LFP bank, without having to worry about their specialized demands.

You could then monitor SoC when needed with a $6 hydrometer, but then that won't automatically alert you on your iPhone.

Yes LFP is half the weight, and if taken care of will last longer, and of course no one can tell you what to do with your money, just sayin'

OK OK I'm jealous 8-)

Do you have a warming system for when they get below zero?

If you have the option to keep absorption voltage to 3.45V max, and just end charging when current tapers to .025C (4A in your case), not do any float, you'll likely get a much longer lifetime than what the mfg intends.

Nice setup!
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Re: Just finished the ultimate small trailer electrical syst

Postby Aguyfromohio » Mon Apr 24, 2017 9:49 pm

Very nice system, thanks for posting the details.
What brand is your inverter charger?

The charging system from your tow vehicle, is it the standard 7-way low amp circuits from the Jeep alternator?
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Re: Just finished the ultimate small trailer electrical syst

Postby tdhcsc » Tue Apr 25, 2017 11:45 pm

The inverter is a Samlex 1,500 watt pure sine I purchased from Amazon. We had a Heart 2,500 watt inverter/charger on the boat but it's wasn't needed on the teardrop. The charger is spearate. A Progressive Dynamics (LiFEPo4) 40 amp charger for charging from 120. Oh yeah, the batteries are Stark Power 100 amp and have dropped in price since we purchased them.

The vehicle charge wire is a #2 battery cable running from the alternator to the rear of the jeep to a large female plug. The trailer cable plugs in and just keeps going to the shunt near the battery. We were putting out 70 amps at idle when I ruined the solar charge controller and had to charge by Jeep without breaking camp. The 7 pin only gave me about 6 amps. Not enought to charge the batteries when you use 50 a day. We'd need to run the Jeep for 7 hours every day. As it was, 1/2 hour in the morning and a 1/2 hour later in the day was fine.

Yes it was expensive but it was a project of discovery and retirement (I'm 72). On our sailboat we had 6 volt Trojan T-105's golf cart batteries (8 of them) Like the ones you mentioned. When one would go bad in Central America we replaced them with local cheap ones as they failed. Specs say we had 900 amp hours but with flooded batteries you can really only use 1/2 or about 110 amps per battery so we really only had about 450 amps available. At 18 lbs the lithium ion's were 1/3 the weight and can be charged fully from dead theoretically in 1 hour. Although stupidly expensive the LiOn batteries in the end average out to less than 1/2 the cost of flooded golf carts given the available usable amps (95% capacity and charge cycles of over 2,000 compared to golf carts which only give you about 400 if you treat them right and equalize once a month.

Lithium Ion has it all over any other battery type on the market. I was skeptical at first but reading the specs brought me over.

A lot of money but I achieved what I was setting out to do, an ultimate state of the art sistem in a really small space.

No warming system for below 0. At 72 if it's that cold we don't go camping.

Below, photo of our now sold crusing vessel/home in Oceanside Ca.for the weekend. Now that had a big electrical system.
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We're X long distance sailboat cruisers logging more than 25,000 miles under the keel. After 13 years the 24/7 routine became just too much. On multi day passages someone always had to be in the cockpit and we took 3 hour watches. Even at anchor we had to be ready to head to sea even if it was 3AM. We miss it but using our experience of 'self accountability' the Jeep/teardrop idea appealed to us. Our idea is to camp mostly in the California dessert (we had the Vistabule teardrop set up for off-roading) and play in the dirt with the Jeep Rubicon.

It's all new but fun!
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Re: Just finished the ultimate small trailer electrical syst

Postby John61CT » Wed Apr 26, 2017 8:18 am

Sweet, I bet you miss her.
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Re: Just finished the ultimate small trailer electrical syst

Postby tdhcsc » Wed Apr 26, 2017 8:53 am

She really was a princess and was designed in 1982 as a 'Performance Motorsailor'. Sold our house to get her. After 12 years I was in my 70's and it was time to move on.

The teardrop and Jeep appealed to us. We could go camping, sleep in comfort and take the Jeep exploring. Still trying to wrap myself around land traveling. We had a lot electrical power on the boat as it was our home, and neither of us wanted to sacrifice any of it in the teardrop. I became really involved in the research and beauty of designing an electrical system in such a small space. This last shakedown of the electrical system confirmed that I reached my goal.

Do I miss the boat? Yeah,,, but we have pictures and are doing something new.
We're X long distance sailboat cruisers logging more than 25,000 miles under the keel. After 13 years the 24/7 routine became just too much. On multi day passages someone always had to be in the cockpit and we took 3 hour watches. Even at anchor we had to be ready to head to sea even if it was 3AM. We miss it but using our experience of 'self accountability' the Jeep/teardrop idea appealed to us. Our idea is to camp mostly in the California dessert (we had the Vistabule teardrop set up for off-roading) and play in the dirt with the Jeep Rubicon.

It's all new but fun!
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Re: Just finished the ultimate small trailer electrical syst

Postby Aguyfromohio » Wed Apr 26, 2017 12:11 pm

Thanks tdhcsc.
For our build we also plan high amp power circuits from the tow vehicles .
Our goal is to run the air conditioners from the tow vehicle alternators out in the boondocks.

Sizing our wires, they get pretty big pretty fast at 100 amps.
Since wires are rated at ohms per foot, we learned right away to put the battery and inverter/charger on the A frame to save half the wire length.
For our build the only substantial DC load is battery charging also, but we really don't see any need for rapid high amp charging.
We'll probably set our AIMS inverter chargers for a 30 amp charging limit.
The AIMS Power units get mixed reviews, but I can buy a 2,000 watt, low frequency unit for $588.

The TV can supply 100 amps, but the air conditioners only draw 800 watts when running steady, which is 66 amps from the alternator (at 100% efficiency)
With the trailer battery online to assist the A/C starting load for a few seconds each start we should be OK with two #4 wires.
I like #4 because I can buy it at the local big box store.

The on-line calculators show just under a half volt drop for an 18 foot run of double #4 carrying 100 amps.
Since we don't really expect to ever use more than 70 amps we should be OK.
Of course the connector from TD to TV is a separate high amp connector.
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Re: Just finished the ultimate small trailer electrical syst

Postby tdhcsc » Wed Apr 26, 2017 1:55 pm

MY MISTAKE,,,,, :? it was (and is) #4 cable to and from the tow vehicle. A total of almost 35 feet (round trip).

On our boat we had air conditioning but we had to run the generator to power them. Even though we were in the tropics we opted for a lot of 12 volt fans. Had 2 of them in every area except the heads which had 1 each (2 heads). We just didn't like the noise of the 10K generator running and could charge our house batteries in 2 hours so the air was only running while charging the batteries, the aircon worked well for keeping the boat dry in humid conditions and if we got too hot we could always jump in the water.

The fans worked really well and were less than an amp each. On the boat we used about 225 amp hours a day just for general electrical use.

Here's the high amperage connector we used on the Jeep and trailer https://www.etrailer.com/comparison.asp ... c2=PK12801
Last edited by tdhcsc on Wed Apr 26, 2017 2:35 pm, edited 2 times in total.
We're X long distance sailboat cruisers logging more than 25,000 miles under the keel. After 13 years the 24/7 routine became just too much. On multi day passages someone always had to be in the cockpit and we took 3 hour watches. Even at anchor we had to be ready to head to sea even if it was 3AM. We miss it but using our experience of 'self accountability' the Jeep/teardrop idea appealed to us. Our idea is to camp mostly in the California dessert (we had the Vistabule teardrop set up for off-roading) and play in the dirt with the Jeep Rubicon.

It's all new but fun!
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Re: Just finished the ultimate small trailer electrical syst

Postby John61CT » Wed Apr 26, 2017 2:05 pm

Have you **measured** actual continuous amps output from your Alt?

Very few stock units will output anywhere near their rating for more than a few minutes without getting too hot. And some stock setups drop voltage rather than amps when things get hot.

If I wanted actual output over 70-80A for hours at a time, I'd put in a large-frame Leece-Neville or Delco designed for big trucks, rated for at least 160A, higher capacity the better really, cooling designed to handle it over long runtimes.

Make sure the belts could handle the torque at full output, and get the pulley ratio set so the Alt was capable of putting out 70+% at a low "high idle" rpm.

An external alt with separate remote voltage sensor and temp sense wires helps a lot, Balmar MC-214 ideal for custom programmability, essential for LFP longevity.

If that's charging a big TV house bank, then a Sterling DCDC would be ideal for charging from there to the trailer's. I think 120A is currently the biggest model, 180A "coming soon".

And yes big fat heavy expensive wires, robust connectors, top-notch fuses all essential.

With lead banks, you'd want solar to do the long tail last 15-20% low-amp stages, silly to burn fossil fuel for 3-4 hours for that part.

But with LFP, no need to top up full, 1-2 hrs runtime would be plenty even for a very large bank.
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Re: Just finished the ultimate small trailer electrical syst

Postby Aguyfromohio » Wed Apr 26, 2017 3:07 pm

John61CT wrote:Have you **measured** actual continuous amps output from your Alt?

Very few stock units will output anywhere near their rating for more than a few minutes without getting too hot. And some stock setups drop voltage rather than amps when things get hot.

If I wanted actual output over 70-80A for hours at a time, I'd put in a large-frame Leece-Neville or Delco designed for big trucks, rated for at least 160A, higher capacity the better really, cooling designed to handle it over long runtimes.

Make sure the belts could handle the torque at full output, and get the pulley ratio set so the Alt was capable of putting out 70+% at a low "high idle" rpm.

An external alt with separate remote voltage sensor and temp sense wires helps a lot, Balmar MC-214 ideal for custom programmability, essential for LFP longevity.

If that's charging a big TV house bank, then a Sterling DCDC would be ideal for charging from there to the trailer's. I think 120A is currently the biggest model, 180A "coming soon".

And yes big fat heavy expensive wires, robust connectors, top-notch fuses all essential.

With lead banks, you'd want solar to do the long tail last 15-20% low-amp stages, silly to burn fossil fuel for 3-4 hours for that part.

But with LFP, no need to top up full, 1-2 hrs runtime would be plenty even for a very large bank.


Thanks John.
You might be right that I'll need a bigger alternator.
The way I see it, it doesn't cost me a penny extra to burn up the OEM alternator before I throw it away and install a bigger one.
I'm hopeful that all my calculations are conservative and the tow vehicle alternator will live through a few air conditioning nights.

First, we won't use the air conditioner often, or for longer than six or eight hours sleeping.
When there's shore power at the state park campgrounds, we'll just use that. We only ask the alternator to step up when we're boondocking and it's too blazing hot to sleep with the windows open. We are hardy tent campers at heart.

Second, there are three DC power sources hanging on that 12VDC high power bus -the alternator, the car battery, and the trailer battery.
I'm a mechanical engineer, not electrical, and don't know how to quantify how each source will participate.
But when the air conditioner draws the start-up surge, I expect the batteries will assist the alternator significantly.

Further, I don't know what the duty cycle will be for the air conditioner, but the trailers are well-insulated and a small volume.
My guess is off for 20 minutes, on for ten minutes through the night.

The OEM alternator is rated at 110 amps.
So the alternator will be loaded down only 1/3 of the time with chances to cool off every half hour, and never loaded above 65% of rated max output.

I'm hopeful the alternator can survive that a dozen times over the next 3 years.
If not, well, it burns out and I install a bigger one.
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Re: Just finished the ultimate small trailer electrical syst

Postby H.A. » Wed Apr 26, 2017 4:48 pm

FM
Last edited by H.A. on Thu Jul 06, 2017 4:16 am, edited 1 time in total.
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Re: Just finished the ultimate small trailer electrical syst

Postby John61CT » Wed Apr 26, 2017 6:00 pm

If your engine compartment doesn't allow for the modifications required to mount a large-framed alt, there are companies that do custom winding of stock bodies to create high-output alts. With a good external VR as mentioned, the de-rating due to heat gives you as much as possible for the conditions.

But they don't last as long as the large-frame units.
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Re: Just finished. For Ohio guy

Postby tdhcsc » Thu Apr 27, 2017 9:42 am

I'd give fans some serious thought. I like the idea of being able to run the air at night but using fans you can simplify your electrical system significantly. We were in Panama for 2 years and only used the air conditioning when in a marina. When we were at anchor we alway used the fans. I'm sure Ohio gets pretty darn warm and muggy but it can't be much worse than Panama.

Moving air really keeps you pretty comfortable (most of the time) and it's a lot quieter than running the air conditioner.

How big is your trailer?
We're X long distance sailboat cruisers logging more than 25,000 miles under the keel. After 13 years the 24/7 routine became just too much. On multi day passages someone always had to be in the cockpit and we took 3 hour watches. Even at anchor we had to be ready to head to sea even if it was 3AM. We miss it but using our experience of 'self accountability' the Jeep/teardrop idea appealed to us. Our idea is to camp mostly in the California dessert (we had the Vistabule teardrop set up for off-roading) and play in the dirt with the Jeep Rubicon.

It's all new but fun!
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Re: Just finished. For Ohio guy

Postby Aguyfromohio » Thu Apr 27, 2017 11:32 am

tdhcsc wrote:I'd give fans some serious thought. I like the idea of being able to run the air at night but using fans you can simplify your electrical system significantly. We were in Panama for 2 years and only used the air conditioning when in a marina. When we were at anchor we alway used the fans. I'm sure Ohio gets pretty darn warm and muggy but it can't be much worse than Panama.

Moving air really keeps you pretty comfortable (most of the time) and it's a lot quieter than running the air conditioner.

How big is your trailer?


The trailers (a friend and I are building a pair together) have inside floor dimensions of 65 inches wide by 100 inches long. Just a bit bigger than a queen size mattress. We do plan a standard powered roof vent fan on top and one screened window that opens on the drivers side.
We expect that will be good enough for most nights. If we find ourselves in Arizona or get the odd Ohio night with 98 percent humidity and 96 degrees Fahrenheit temps, then we will fire up the air conditioners from the tow vehicle, if we are out in the boondocks with no shore power.

Since we and our wives are seasoned tent campers, we are used to sleeping in summer with just the available warm breeze to cool us.
But we always want the option available to turn on the air conditioning, shore power or not.
Inside we'll have one duplex outlet for 120VAC, powered by the inverter from the trailer battery, that could run an extra little fan or two.
The roof vent fan is 12VDC from the same battery , permanently wired into the 12VDC system.
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Re: Just finished the ultimate small trailer electrical syst

Postby tdhcsc » Thu Apr 27, 2017 12:16 pm

The Vistabule teardrop we purchased came standard with one of these 'MaxxFan' rooftop fans. A bit gimicky but has a lot of features and works really well.

https://www.amazon.com/Maxxair-0007000K ... DTSS8M0KWW
We're X long distance sailboat cruisers logging more than 25,000 miles under the keel. After 13 years the 24/7 routine became just too much. On multi day passages someone always had to be in the cockpit and we took 3 hour watches. Even at anchor we had to be ready to head to sea even if it was 3AM. We miss it but using our experience of 'self accountability' the Jeep/teardrop idea appealed to us. Our idea is to camp mostly in the California dessert (we had the Vistabule teardrop set up for off-roading) and play in the dirt with the Jeep Rubicon.

It's all new but fun!
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