Forum Discussion

DIVE2XS's avatar
DIVE2XS
Explorer
Jan 02, 2019

Multi Inverter use

I have 3 inverters that I can use for my travel trailer. A 2000,1500, and 350 watt. Also 2-12 volt interstate batteries for storage.
It would be nice to use appliances en route or overnight. Use the refrigerator on electricity instead of propane while traveling from place to place or, microwave before disconnecting as long as the tow vehicle is connected and running to keep from having to connect and use my gas generators.
I can see using a small medical device for a longer period, say over night.The placement for this would be stationary in the bedroom.
Since using the refrigerator and microwave would be high usage, I'm guessing that the 2000 watt would be best for that as I would not be as concerned about energy usage. Placement for that would be in the kitchen area in the same area as the converter.
For the bedroom, I could run a 12 volt wire from the battery or hook into an existing 12 volt light and mount on wall in bedroom. I would use this separate as it uses less energy and would make the 2-12 volt storage batteries last longer.
I guess what I am asking is how to run/connect it all together and how to separate each inverter for the system for uses I envision.
Perhaps I have it all wrong and there is another way to do this?
Thanks for any help!
  • time2roll's avatar
    time2roll
    Nomad
    Jan 02, 2019
    350 watt is fairly easy install next to the power distribution and converter area. Use the main 12v power feed to get 12 volts from the battery and use a small transfer switch to power the branch circuit of outlets. 350W should power the absorption fridge heater.

    1500/2000 watts really needs more battery and needs short heavy wire direct to the battery. Then you pull 120v wire to the power center and again use a transfer switch to power the branch circuit of choice such as the microwave. Microwave far prefers a sine wave inverter.

    And yes my RV is wired like this.
  • BFL13's avatar
    BFL13
    Explorer II
    Jan 02, 2019
    The not very big Servel S630 fridge in our C pulls at least 360 watts on start up using 120v, and then as the heater warms up the watts drop off somewhat to under 350.

    A 350w inverter will have a continuous rating of maybe 300? So I wouldn't count on a 350 to run the fridge on 120.
  • ScottG's avatar
    ScottG
    Nomad
    Jan 02, 2019
    You say you like to run the fridge on ac on the road so I assume you have a two way.
    Running an elect/propane fridge on AC draws about 350 watts at a 50% duty cycle. So to run it overnight your going to need a lot more battery.
  • 2oldman's avatar
    2oldman
    Explorer II
    Jan 02, 2019
    I'd wire up the 2k whole-house and be done with it. The small amount of 12v you'd save with the separate installs is minimal. 2 12v batteries is not much when running the MW.
  • wanderingaimles's avatar
    wanderingaimles
    Explorer
    Jan 02, 2019
    A others have said, use the larger inverter and mount it near the batteries.

    https://www.altestore.com/howto/recommended-inverter-cables-sizing-and-breakers-or-fuses-a62/

    Cable sizes listed are for runs under 10 feet.
  • BFL13's avatar
    BFL13
    Explorer II
    Jan 02, 2019
    2oldman wrote:
    I'd wire up the 2k whole-house and be done with it. The small amount of 12v you'd save with the separate installs is minimal. 2 12v batteries is not much when running the MW.


    True about minimal savings from having both a big and small inverter. However, it can be convenient in some scenarios.

    I went all big inverter, but lately went back to using a small one as well. The big one is whole house, which includes the seldom used TV which stays on standby drawing amps unless unplugged. Meanwhile I want to leave some 120v on all the time for phone charger etc low draws.

    Easier to use a small inverter for phone charger etc, and turn off the big inverter except when needing it to do something temporary.

    In summer with lots of solar much of the time, you can afford to leave the one big inverter on all the time. It is all about scenario as usual.
  • wa8yxm's avatar
    wa8yxm
    Explorer III
    Jan 03, 2019
    One thing I found when running an Absorption fridger on the inverter (That is an option in this RV) is that the alternator does not provide the house batteries with enough current to maintain them at that high a load. Sorry.

    Most RV fridges are 300-400 watt on A/C (And I also have some parasitic loads like the TV/Radio/Sat receiver (no more) and so on) The alternator could not keep up. Run it on propane and be happy

    Residential run 100-200 watts now days That it can handle.

    Or a high effiency (50 watts and it runs on 12 volt).
  • theoldwizard1's avatar
    theoldwizard1
    Explorer II
    Jan 03, 2019
    wanderingaimlessly wrote:
    A others have said, use the larger inverter and mount it near the batteries.

    Better yet, get rid of your current converter, but keep the DC power distribution panel. Sell all of you inverters and buy a good quality inverter/charger/transfer switch. It will make your life SO MUCH SIMPLER !

    When your current batteries die, replace then with a pair of 6V golf cart batteries. They hold more energy and will last longer.

    If you take trips that require multiple nights on the road and you are NOT stopping at sire with electric power (like a Walmart parking lot), the you will need to run a generator for a few hours to recharge the batteries than have been running the inverter for your refrigerator.

    If you don't want to buy/use a generator, the you need a DC-DC battery charger to recharge your batteries when you ar on the road.
  • RLS7201's avatar
    RLS7201
    Explorer II
    Jan 03, 2019
    wa8yxm wrote:
    One thing I found when running an Absorption fridger on the inverter (That is an option in this RV) is that the alternator does not provide the house batteries with enough current to maintain them at that high a load. Sorry.

    Most RV fridges are 300-400 watt on A/C (And I also have some parasitic loads like the TV/Radio/Sat receiver (no more) and so on) The alternator could not keep up. Run it on propane and be happy

    Residential run 100-200 watts now days That it can handle.

    Or a high effiency (50 watts and it runs on 12 volt).



    Your alternator should be about 130 amps at 1500-1800 engine RPMs.
    If it won't keep up with 360 watts, you have a problem.
    Properly functioning gas coaches will keep up with running an absorption refrigerator on the electric heaters.

    Richard
  • SoundGuy's avatar
    SoundGuy
    Explorer
    Jan 03, 2019
    theoldwizard1 wrote:
    When your current batteries die, replace then with a pair of 6V golf cart batteries. They hold more energy and will last longer.


    The OP hasn't indicated just which 12 volt batteries he has but Group 31s wired in parallel offer roughly the same capacity as a pair of 6 volt GC-2s wired in series.

    theoldwizard1 wrote:
    If you don't want to buy/use a generator, the you need a DC-DC battery charger to recharge your batteries when you ar on the road.


    Agree, it's the only way to charge batteries effectively using the vehicle's electrical system.

About Technical Issues

Having RV issues? Connect with others who have been in your shoes.24,188 PostsLatest Activity: Jan 17, 2025