adding solar to Travel Trailer

[completelyhis]

I'm going to be adding solar to my travel trailer. at present it has two batteries, which are charged by the shore power. I'm pretty sure they are also charged by the trailer towing wiring. 


I am going to add a 5000 watt continuous power inverter as well. I'd like to be able to plug my shore power into the inverter, which would be powered by the batteries connected to the panels. The problem is that the shore power charges those batteries as well, so I'm sure there is a loop issue that would need to be dealt with.

Should I have two separate battery banks? What do most people do?

Ian

 

[B and C]

You have to wire in another relay like this: https://www.amazon.com/dp/B00MJVSCY...olid=13VYN7BHCGYSP&psc=0&ref_=lv_ov_lig_dp_it to get rid of the feedback loop. I don't know if you have 50 amp or 30 amp service to your trailer but will need one based on what you have. This will be in addition to the existing relay you have.

I don't know how many amps or type of batteries you have but that is a really large inverter for two batteries. Living off grid means you are your own power provider and unless you have a LOT of solar and a large battery bank, you won't be running a lot of you 120V household appliances (at least not very long).

 

[completelyhis]

You have to wire in another relay like this: https://www.amazon.com/dp/B00MJVSCY...olid=13VYN7BHCGYSP&psc=0&ref_=lv_ov_lig_dp_it to get rid of the feedback loop.  I don't know if you have 50 amp or 30 amp service to your trailer but will need one based on what you have.  This will be in addition to the existing relay you have.

I don't know how many amps or type of batteries you have but that is a really large inverter for two batteries.  Living off grid means you are your own power provider and unless you have a LOT of solar and a large battery bank, you won't be running a lot of you 120V household appliances (at least not very long).

Thanks! I'm adding 400w solar, and plan on having a total of 4 batteries - I just wasn't sure if I'd be able to add 2 to the existing 2, or if they should be a separate bank.

My system is a 30 amp system. My main goal is to be able to run air conditioning and microwave. when those aren't needed, we'll be on the 12vDC system. are there any wiring diagrams that illustrate how that relay would be integrated?

Thanks!

Ian

 

[B and C]

There are wiring diagrams right on the cover.  400 watts of solar and a small battery bank will not run your air conditioning at all and maybe your microwave for a very few minutes.  In reality new batteries should not be added to old batteries as the old ones will drag down the new ones. JiminDenver (member here) has I think 1100 watts of solar for his 5000 BTU air conditioner and only runs it during the day so it can be powered by the solar.  I don't remember how big his battery bank is.  If your air conditioner is a 13,000 BTU one, good luck.  When I run mine I use the generator.  I have a 350Ah AGM battery bank and my big inverter is only 750 watts.

If you move with the weather, you won't need air conditioning.  I only run mine when trying to get out and then back into HOT Texas.

Edit to add:

You will be better served with a generator when you need air conditioning or to run the microwave.  Buy an inverter generator (quiet) and not an open frame contractor generator (loud).  Everyone (including yourself) will be glad you did.  This will also be useful on those days when there isn't enough sunshine.

 

[Gr8ful]

What are you running you need an inverter that big for? I have a 1000 watt pure sine wave & a 2000 watt cheaper one for power tools. My ambulance has a 250 amp altonator & 2 vehiicle batteries as it's a diesel & I have 4 golf car batteries & an auto switch where the alt charges all when driving but only discharges the golf car batts. I plan on 4 325 watt colar panels which I can buy new for 34 cents a watt local.

 

[completelyhis]

What are you running you need an inverter that big for? I have a 1000 watt pure sine wave & a 2000 watt cheaper one for power tools. My ambulance has a 250 amp altonator & 2 vehiicle batteries as it's a diesel & I have 4 golf car batteries & an auto switch where the alt charges all when driving but only discharges the golf car batts. I plan on 4 325 watt colar panels which I can buy new for 34 cents a watt local.

I'm sure I could have gone smaller, but this one was given to me by someone that had a previous installation. I tested it, and it works - in my conversion van i had a 1600w inverter that couldn't power my kureg, so i figured "bigger is better." My understanding is that the inverter won't waste unused electricity - it will only convert enough to meet the demand. 

I should have stated that the two existing batteries are toast, and that when i replace them i'll be upgrading to a total of 4. I do have a 4k generator that I can use if it's really hot and we are in the trailer all day long, but I want solar to be our first option, given noise, gas, etc. 

We are going to take our TT out on a "maiden voyage" for 5 weeks - end of June to beginning of August. We'll be starting in Northern Oregon, going down to southern CA, then across to TX, then up to Cody, WY, then across back to northern Oregon. I'm just wanting to make sure that my princess is comfortable .

Ian

 

[completelyhis]

My assumption is that I will be able to run the air conditioning off of the 5k inverter, even if just for a short while (definitely not all night long!)

thoughts?

 

[B and C]

I'm sure I could have gone smaller, but this one was given to me by someone that had a previous installation. I tested it, and it works - in my conversion van i had a 1600w inverter that couldn't power my kureg, so i figured "bigger is better." My understanding is that the inverter won't waste unused electricity - it will only convert enough to meet the demand. 

The bigger the inverter the greater the loss in the conversion and the higher the drain rate on the batteries.  The inverter is probably at best 85% efficient.  Your battery may have not been able to deliver the amps to the inverter fast enough for that big of a draw.  I have about 160 usable Ah's and my big inverter is 750 watts but I normally only take my bank down to about 80% for longevity.  

I should have stated that the two existing batteries are toast, and that when i replace them i'll be upgrading to a total of 4. I do have a 4k generator that I can use if it's really hot and we are in the trailer all day long, but I want solar to be our first option, given noise, gas, etc. 

What voltage and how many Ah at 20 hours?  4 - six volt golf cart batteries at 230 Ah would give a total usable 230 amp hours.  You don't discharge batteries below 50% capacity without significant harm.  You give no indication of air conditioner size or power draw.  At 2000 watt draw you may get 20 minutes of air conditioning.    Just a guess.  I pity you and anyone anywhere near you when you run that loud contractor grade generator.  They will not let you run it in any national park.

We are going to take our TT out on a "maiden voyage" for 5 weeks - end of June to beginning of August. We'll be starting in Northern Oregon, going down to southern CA, then across to TX, then up to Cody, WY, then across back to northern Oregon. I'm just wanting to make sure that my princess is comfortable .

You may want to take a maiden voyage to work out kinks closer to home for a weekend or two in the earlier part of the summer.  It might prevent you from ruining a perfectly good trip.

Ian

 

[highdesertranger]

you won't be able to run the AC off of batteries for a meaningful amount of time. for AC you either need a generator or significantly more solar and more batteries. highdesertranger

 

[Gr8ful]

Completelyhis, can't beat free but most do use current at idle or no load. I built many remote systems for way off grid hunting camps with Onan 2500 watt gen sets that only ran under 1/2 an hour a day, long enough to make a pot of coffee with a Mr Coffee. Onans are great as the run 1/2 speed 1800 rpms, use real mufflers, use bell wire to remote start as far away as you want & last forever. Had a roll around 65 amp charger, a switch that let the gen set warm up one minute before before swithing to the gen set. Had 6 golf car 6v batteries that lasted an average of 12 years per set. Only had 1 solar panel for the long cold winters when no one was there. If you have gen set without a remote start a ford old style fender mounted solenoid will convert one easily. My deleima is do I need solar panels or just use the 250 amp altonater? I can get new 325 watt panels, several different brands for 34 cents a watt so I'll probablt buy 4 & haul them on the trailer as I want to park in the shade & set them up in the sun. Good luck! Eric