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nayther's avatar
nayther
Explorer
May 21, 2018

Inverter Help

Gathering up the materials/devices to start installing in our new rig which we'll have in a couple of weeks. Base line will be 2 T-105 GC 6 volt and 3000I Honda with remote start. Trailer is "solar ready" meaning wired from roof to charge controller location to battery compartment (at least I think that's what they mean, it's not the stupid little plug for a portable panel wired direct to the battery) so a 3 panel solar system is down the road shortly. Now my major question is do I get a super duper all in one inverter/charger with auto transfer or a less expensive inverter with a manual switchover? I'd like to keep the inverter on 24/7 when boondocking to maintain satellite settings, etc. I think the converter is a 3 stage but probably low amps

We dry camp in the desert most of the time but usually only a few days at a time so battery capacity should be OK with the 2 GC's and running the generator morning/evening for a couple of hours

I'm looking at 3,000 watt inverter so we CAN run the coffee pot if we're in a place where we can't run the generator early.

I've read a lot of threads here regarding this, separate components and ATS, all in ones with multistage chargers, etc. and some negatives about having both inverter and shore power connected simultaneously.
Seeking Advice

38 Replies

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  • nayther's avatar
    nayther
    Explorer
    May 21, 2018
    Maybe I'm better off just getting a small inverter to run the TV/Satellite on its own then? Assuming the converter is a decent size (I upgraded my last unit and it made a HUGE difference plus no more boiled batteries).

    I don't have the trailer yet so just contemplating where I'd put the "jars" and to keep them isolated from the rest of the pass through; I think they put the one measly 12v group 24 in a vented box.
  • ktmrfs's avatar
    ktmrfs
    Explorer II
    May 21, 2018
    pianotuna wrote:
    Nayther,

    There is no point in having more than 150 watts of panels per 100 amp-hours of storage. In your case that would be about 340 watts.

    The reason is that at 85% state of charge acceptance rate of the battery bank is 12.5 amps per 100 amp-hours of storage.

    225 amp-hours may only support a 1000 watt inverter. Six volt jars exhibit greater voltage drop under load. Larger loads on a 3000 watt may drive the input voltage so low that the inverter cuts out to protect the battery.

    Lead acid cells are "happy" up to about 25 amps of load. 25 X 12 = 300 watts. They may support 75 amps or about 900 watts. Anything over that may push them HARD.

    If real estate is a problem then if you have deep pockets move to LI jars. It solves the capacity problem, too. Caveat is not using the RV in cold weather.

    There is no way I could boondock with a 225 amp-hour battery bank. Mine is 556 and I wish it were 1000 amp-hours.


    I second the comment on inverter. With 2 GC I could run my 1000W inverter drawing about 900VA only if the batteries were in the 80% SOC or higher. With 4 GC, I can do it down to 50% SOC.

    As a baseline, 1000W draw is around 90A from a 12V battery bank!

    And I have very short wiring to the batteries from the inverter with #0 wire. very low cabling drop.

    Solve the coffee problem the way we do. Use a teapot to heat water on the stove, DW makes her tea, I use an Areopress for coffee. A french press w/o the mess of cleaning a french press, and great coffee.

    If you want/need to draw over 1000VA often you have two choices.

    1) use 4GC
    2) use 12V deep discharge batteries. they have much lower internal resistance and when paralleled each battery only needs to supply a portion of the total current.

    But then for low current draws (25A or less) and dry camping, GC wins.

    Now we boondock quite a bit, but have 4 GC and 500W solar. That has been plenty for us, but 2 GC would be an issue.
  • pianotuna's avatar
    pianotuna
    Nomad III
    May 21, 2018
    Nayther,

    There is no point in having more than 150 watts of panels per 100 amp-hours of storage. In your case that would be about 340 watts.

    The reason is that at 85% state of charge acceptance rate of the battery bank is 12.5 amps per 100 amp-hours of storage.

    225 amp-hours may only support a 1000 watt inverter. Six volt jars exhibit greater voltage drop under load. Larger loads on a 3000 watt may drive the input voltage so low that the inverter cuts out to protect the battery.

    Lead acid cells are "happy" up to about 25 amps of load. 25 X 12 = 300 watts. They may support 75 amps or about 900 watts. Anything over that may push them HARD.

    If real estate is a problem then if you have deep pockets move to LI jars. It solves the capacity problem, too. Caveat is not using the RV in cold weather.

    There is no way I could boondock with a 225 amp-hour battery bank. Mine is 556 and I wish it were 1000 amp-hours.
  • nayther's avatar
    nayther
    Explorer
    May 21, 2018
    Thanks for the advice. I'm not ready to have huge battery bank, don't really want to give up that much real estate or $$$.

    I like that Samlex and thought just that it was "easy peasy" and you answered my other question without asking, "Do i take the entire input to the 12 v panel off or just a couple of circuits?" I read "12 volt side of life" and I see that's what he did. Also looked at http://www.rvsolarelectric.com/index.php?route=product/product&path=37&product_id=108 but think I need more panels/power no?
  • pianotuna's avatar
    pianotuna
    Nomad III
    May 21, 2018
    Advantage of independent units is more flexibility and the ability to do "double conversion". I used to do that often before I had the load support of my current unit. Separate components may also be much less expensive.

    If I were starting over, I would jump right to 48 volts.
  • theoldwizard1's avatar
    theoldwizard1
    Explorer II
    May 21, 2018
    nayther wrote:
    Now my major question is do I get a super duper all in one inverter/charger with auto transfer or a less expensive inverter with a manual switchover?

    Pay the money and get the deluxe inverter/charger/transfer switch. My choice would be one of these Samlex. The spec on the 3000W unit say it has a 130A 4 stage charger.

    Check the installation manual. They make it SO EASY !!
  • GordonThree's avatar
    GordonThree
    Explorer
    May 21, 2018
    I prefer my high end inverter for a few reasons. Don nailed the first one, it has a fast charger... 125 amp capacity, so it replaces my AC/DC converter for the rare times I'm on shore power, and makes the most of generator time when I'm docking.

    Secondly, I like the integration. Charger + Inverter + ATS all in one compact box. It's wired "whole house" so my entire RV is powered through the inverter. Shore power cord goes in the input, existing circuit panel wired to the output, easy peasy.

    My only regret on my system is not spending the extra $1000 to buy the 48 volt model. The 12 volt version is working fine, with its massive cables, but it's lame duck technology. It's never (from my engineering opinion) going to adapt to a lithium battery technology, where the 48v is better suited.

    Look long and hard at going with a higher voltage system. It makes a lot of things easier. Solar is easier at high voltage, inverting is easier, cabling is easier, the only hiccup is a 48v to 12v DC-DC converter to run lights and appliances, and that's not really a big deal.
  • pianotuna's avatar
    pianotuna
    Nomad III
    May 21, 2018
    Advantage of a high end inverter charger is the ability to charge FAST.

    2 six volt jars may have a tough time powering a coffee pot. With only 112.5 amp-hours available the generator may need to be run lots.

    This series of articles may help with the solar planning.

    https://freecampsites.net/adding-solar/

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