7-pin and Solar diagram

[southboundsnakes]

Hello all,

Newb here, just ordered my first TTT. I want the electrical system to be able to do three things: charge from my tow-vehicle while hauling, charge from a basic solar panel, and connect to shore power.

For the TTT, the electrical system will be powered by 2 12v marine batteries connected in parallel, to increase the amp-hours but not the voltage.
I have several 110v appliances I want to use, and I've settled on a 3000w continuous/6000w peak inverter for these.

The battery "bank" will be powering the following:

- 3 12v outlets (12v cooler, 12v heater, 12v - USB for charging phones/computers)
- interior lighting LED array
- 3000w inverter powering various appliances

See diagram for the way I intend to charge the battery bank using my T/V and a solar rig.

Wiring v1 - New Page (1).png (94.54 KiB) Viewed 4309 times

Question 1: Does this arrangement make sense? Particularly, will a 40w solar panel and 7A charge controller work for this battery bank?
Question 2: Must solar power first be stored into the battery before being converted to AC? (I know this is kind of a stupid question, but I'm new to this )
Question 3: As for connecting to shore power, should I simply install a connection point, and have a power-bar attached to it (bypassing the 12v-based battery system) or is there a way to connect shore power to the battery system to charge the batteries (with a 120v - 12v converter?).

It seems to me that bypassing the battery by using shore power for the 110v appliances in the galley would make a charge last much longer and extend the life of the batteries themselves.

Any input will by much appreciated!!!

Taylor

[Shadow Catcher]

You might want to re think the marine battery choice, they are a compromise between a starting battery and a true deep cycle, one of the best battery faq for solar
http://www.solar-electric.com/deep-cycle-battery-faq.html

I have a Progressive Dynamics power center http://www.progressivedyn.com/all_in_one_pd4000.html which makes hook up and wiring relatively easy and I have a 30A DPDT switch to shunt the shore power to the converter or the 120AC circuits (You don't want the batteries trying to charge themselves through the inverter).

Question 1: Does this arrangement make sense? Particularly, will a 40w solar panel and 7A charge controller work for this battery bank?
Yes generally controllers, converters and the line from the TV play well together.
Question 2: Must solar power first be stored into the battery before being converted to AC? (I know this is kind of a stupid question, but I'm new to this )
Essentially your 40W panel will not add a great deal in the way of usable current and the output of the solar controller from the panel will not power much.
Question 3: As for connecting to shore power, should I simply install a connection point, and have a power-bar attached to it (bypassing the 12v-based battery system) or is there a way to connect shore power to the battery system to charge the batteries (with a 120v - 12v converter?).
The converter needs 120AC, you will be using a power panel with 120 circuit breakers keeping this separate from the 12V DC fuses.
It seems to me that bypassing the battery by using shore power for the 110v appliances in the galley would make a charge last much longer and extend the life of the batteries themselves
Yep purity much a must

[MtnDon]

How many watts are the 12 VDC cooler and heater? Is the cooler a compressor type or a thermoelectric? Thermoelectrics are inefficient; compressor types much better. A typical thermoelectric can consume more than your 40 watt panel puts out in direct sun.

Question 2: Must solar power first be stored into the battery before being converted to AC?

The answer is yes/no or it depends.

IF the sun is shining brightly and directly on that 40 watt panel you could have 40 watts going into the battery. For now we'll ignore the charge controller and battery inefficiencies. Once the battery is fully charged the 40 watts would normally be wasted, not actually processed from the panel to the battery. So in that case that means you could use up to 40 watts either directly with a DC light/device or via the inverter. And that is also ignoring whatever losses the inverter will cause.

People with off grid cabins or homes will often power "opportunity loads" once the sun has recharged their batteries. I had a friend who tries to do laundry on sunny afternoons as that will not draw down the batteries if the sun shines bright and the batteries are full. Sometimes he has to run the generator.

~~~~~~~~~~~~

40 watts is not a very significant amount of power, IMO. If you were in the SW on a summers day you might get 6 hours of full sun. 40 watts x 6 hours = 240 watt hours. Again, not accounting for equipment losses. If all you were powering were some 5 watt LED lights then you would be in good shape. But I see a 3000 watt inverter. The inverter itself could consume 300 watts just sitting there, turned on and idle. I said "could". A great inverter will have a low power standby mode. I don't know what you have. Let's say you plug in a coffee maker; mine is 800 watts. Add 300 watts consumed as work = 1100 watts. It takes my coffee maker about 5 minutes to finish, small machine. 5 minutes is 0.083 of an hour. 1100 watts x 0.083 hours = 92 watt hours. 240 watt hours coming in; 240 / 92 = 2.6 times the coffee maker could be run on the amount of power from the sun all day.

The 40 watt panel would be more than adequate to replenish the self discharge of the average FLA (flooded lead acid RV/marine) battery. Or if only low watt LED lights and phone chargers were the only loads. IMO, you are really pushing the batteries to and beyond their ability if the intent is to be able to power AC devices that draw 1200+ watts for anything longer than a minute at a time. Even then a load like example would likely set off the low voltage alarm, if the inverter has one. FLA batteries suffer large voltage sags under continuous (roughly more than a minute but that varies a lot depending on battery age/condition/state of charge) heavy loads.


Hope that helps you understand the ability of battery power better.

[capnTelescope]

Howdy, southboundsnakes.

Question 1: Does this arrangement make sense? Particularly, will a 40w solar panel and 7A charge controller work for this battery bank?

Yes, with nits to pick. Your charge controller can handle 7A * 12V = 84 watts of solar. You should be good to go for 40 watts. Others may have a more learned opinion.

The nit is that the solar panel connects to the charge controller separately from the connection from controller to battery, not panel to battery directly.

Question 2: Must solar power first be stored into the battery before being converted to AC? (I know this is kind of a stupid question, but I'm new to this )

It all kinda happens in one swell foop.

Question 3: As for connecting to shore power, should I simply install a connection point, and have a power-bar attached to it (bypassing the 12v-based battery system) or is there a way to connect shore power to the battery system to charge the batteries (with a 120v - 12v converter?).

What *I* would do, and YMMV, is connect a double pole, double throw switch or relay so you can switch between shore and inverter power and not have them both on at once. Also, mount your inverter so that the on-off switch is easy to access, so you don't run it when you aren't using it.

Charging from shore power would need a on-board charger or one of the Progressive Dynamics units. Others can help you with the PD units better than I can.

I don't have solar, but I do have an on-board charger. There's a good description of how I did basically what you want to accomplish, complete with photos, starting here in my build thread. There is also exhaustive discussion of the DC>AC>DC charging method starting here in the Charging While Towing topic.

I'm sure others will have some thoughts about your setup. Prepare to be overwhelmed.

[troubleScottie]

Although I believe you will find all of this in the other posts' references, I would also suggest the idea of separating the AC and DC circuits.

There are numerous DC appliances like water pumps, radios, televisions, refrigerators, water heaters, fans, usb power ports and of course lights. They save on the need to convert AC back to DC when running on the batteries. And has been stated before, going DC to AC then back to DC is wasting lots of power. In addition, the DC wiring is lighter weight and to some extent simpler. Generally speaking, the DC appliances are designed for lower power consumption or realize that the power is limited and designed to be physically smaller. In many cases, this might come a price increase. For instance, a DC Engel frig is considerably more than a regular AC refrig. LED on the other hand are really cost effective.

You might want to have a battery switch to select either battery or both and possibly an automatic charging relay to distribute power draw and charging paths. Also, it is useful to have chargers for the batteries. Then the AC when available is converted to DC and either used for the batteries or the DC appliances. My observation is multiple bank systems are more complex and more difficult to build.

Reading on the solar systems -- there is a need for at least a solar controller which is between the panels and the battery. They have various types and cost up to the MPPT type.



A large amount of electrical is based on what you are doing with your system.

Are you always camping with AC hookups or always boondocking.
Are you expecting to sell this at some point? So what would others want.
If you are not using air conditioning, the AC need is greatly reduced. This is camping.
Some people are more glamping -- coffee makers, microwaves, AC, etc. I would suggest a more structured AC system with a power distribution box, 30 or more amp inlet, etc. More expensive, more work, but safer in my opinion.

[OverTheTopCargoTrailer]

Dear Southboundsnakes

Please don't get upset with my advice , but i'm known here to be #1 on the admin watch list, brutally honest, politically incorrect,
socially insensitive, loud mouth & most all here don't like to hear my advice, they block me & love to FLAME ME

LETS BE HONEST ......Being Green really is not cheap

1.) You really need min 200 watts in solar to get on the map, you can use some flex panels & MPPT CC on your trailer. cost $600+
2.) min 200 amp hr Flooded deep cycle batteries. Cost $250+
3.) "MAX" Moringstar 300 watt pure sign inverter. Cost $225+

this set up gets you enough power to keep an ARB or Engle 50Q fridge running, cost of fridge $800+ new

Charging 3 batteries while driving works "maybe" if you have a 160+ ah alternator.

Cheers OTTCT

http://overthetopcargotrailer.blogspot.com/

[dales133]

Dear Southboundsnakes

Please don't get upset with my advice , but i'm known here to be #1 on the admin watch list, brutally honest, politically incorrect,
socially insensitive, loud mouth & most all here don't like to hear my advice, they block me & love to FLAME ME

LETS BE HONEST ......Being Green really is not cheap

1.) You really need min 200 watts in solar to get on the map, you can use some flex panels & MPPT CC on your trailer. cost $600+
2.) min 200 amp hr Flooded deep cycle batteries. Cost $250+
3.) "MAX" Moringstar 300 watt pure sign inverter. Cost $225+

this set up gets you enough power to keep an ARB or Engle 50Q fridge running, cost of fridge $800+ new

Charging 3 batteries while driving works "maybe" if you have a 160+ ah alternator.

Cheers OTTCT

http://overthetopcargotrailer.blogspot.com/

I tried to send this by pm but you have them disabled.
Reluctantly i post it here ,peace love and jelly beans,Dale
Just some advice from someone in a similar situation in a different forum on a different continant.
I, as you have ,have pissed alot of people off by careless comments or things i find funny or important that others aparantly dont.
Its easy to get off side with people and harder to get back on side but perfectly doable.
Try just being a bit less opinionated for a few weeks and offer advice where you can.
Use less caps....it sounds rediculous and it is but its seen as ofensive to some of the more precious types.
You offer some good advice and know what you know and it would be a shame for you to walk away from this comunity.
Please dont take anything i said as critisim its mearly advice.
Id like some help with lithium baþeries sometime if your able too.
Wish you well bud,
Cheers dale

[OverTheTopCargoTrailer]

Cheers Dale

I'm a branded man , no hope for my salvation.
Go to my blogspot and send me e mail with questions about "L" word , I'm banned from using it here, glad to help if you need it.

Cheers ottct

[southboundsnakes]

Thank you all for your replies!!! Everything is working just fine and all your input has been very helpful.

sss

[noseoil]

One thing I would add to this conversation would be to just work backwards from the loads. First figure out how many amps you need to draw at any given time, the amount of power you will need in a day for 24 hours, & then how much solar is necessary for keeping the system running & charged to full each day. This will tell you what type of battery capacity is needed to supply power to the trailer, then you can fine tune it for what you think is worst case, best case scenario stuff.

It sounds like there's a lot of power being used in your trailer, can it be reduced a bit, or is it really necessary? It's all a compromise, as we know too well.