Best way to use inverter while camping

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Wxboy
Wxboy Solar Expert Posts: 70 ✭✭✭✭
in Solar Beginners Corner #1
Last year while camping I had my inverter hooked to the camper batteries and plugged things directly into the inverter. This year I would like to hook the shore power line to the inverter so I can use the outlets in the camper and keep the inverter out of sight. I have a Xantrex Prowatt SW2000 pure sine wave inverter and I was not planning to ground the inverter. I realize there can be an issue with the converter charging the batteries and creating a loop but I pulled a fuse in the camper and it was no longer putting voltage into the batteries so I think I solved that problem. My biggest concern is frying the inverter. I read other threads about the problems with using MSW inverters and using the shore cable but should I be ok using my PSW inverter?

I'll be using a small solar panel to replenish the power I use.
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #2
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    Re: Best way to use inverter while camping

    Good morning "Wxboy"
    Most important that you NEVER EVER have your inverter AND shore power both connected to your AC electrical system at the same time! Instant destruction of the inverter will result.
    Also, since this inverter has built in GFI at it's output, if it's connected to a breaker or fuse panel that has it's neutral bonded (connected) to ground, the inverter's GFI will see this as a fault and trigger off.
    Re: "I'll be using a small solar panel to replenish the power I use." This statement set off alarm bells. How small is the panel and how big are your loads? How much power will you be using? Just running the inverter (specs say 800 ma (0.8 amps) at idle) and with nothing else running, the inverter alone, if left turned on, will consume almost 20 amp hours every 24 hour day. That's roughly 270 watt hours per day. Nothing to laugh about. That alone would call for a substantial solar panel and a good battery.
    Do you need an inverter that large? If not, you might consider the Morningstar Suresine 300 inverter. It's pure sine as the name implies, very robust and reliable, and has an idle draw of roughly half that of your mentioned Xantrex, PLUS a stand by mode where it powers down until a load is applied, thus saving even more battery power.
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  • Wxboy
    Wxboy Solar Expert Posts: 70 ✭✭✭✭
    #3
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    Re: Best way to use inverter while camping

    Wayne, there is no power where I'm camping so no risk of having 2 power sources connected. If the neutral is bonded in the camper, and I have no idea if it is or how to tell, I assume it's safe to test it and if the GFI trips then it's a no go, and if it doesn't then it should be ok??

    I knew my comment about a small solar panel was going to stir things up. It's a 125 watt panel so maybe medium sized is a better description. I'm bringing my Trimetric with me so I'll be monitoring the batteries charge status. Loads will only be camper lighting(2-3), charging phones, drill batteries for additional lighting, other batteries for flashlights, running a small fan, etc. If the sun is out I should have plenty of power. On cloudy days I'll have to conserve. I also have a Duracell portable power pack with a built in battery and inverter that can charge off my car as backup power if the sun doesn't shine.

    By the way the inverter's spec says .8a draw but it really only draws about 6 watts according to the trimetric so it's not too bad. I wouldn't mind having a smaller inverter for camping but I don't camp enough to make it worth the money.
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #4
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    Re: Best way to use inverter while camping

    Easy way to check if neutral is bonded to ground in your camper, if you have a multimeter, is to disconnect the inverter and check resistance between the ground part of a receptacle, and the other two wires, hot and neutral. If only a very few (single digit) ohms max, then most likely it is bonded. As a last resort, although I wouldn't recommend you do it, I would connect the inverter, fire it up and see, like you said, if the GFI kicks out.
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  • Wxboy
    Wxboy Solar Expert Posts: 70 ✭✭✭✭
    #5
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    Re: Best way to use inverter while camping

    With no power connected to the camper I tested the resistance between ground and hot and ground and neutral. The meter didn't budge from 1 but then again it's hard to tell when you are making a connection. I did moved the leads around enough that I think I made contact with the metal though so it appears that it's not bonded? I did notice that the outlets in the camper are GFI because they have reset buttons. Would that cause a problem because the inverter and camper both have GFI? I don't know much about AC power so sorry for all of the questions.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #6
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    Re: Best way to use inverter while camping

    In general, an RV that is designed to plug into AC power at a camp ground will not have a Neutral to Earth bond in the RV. They use the bonding at the camp site AC power.

    For a large motor home/RV with a genset--They may have a switched neutral to earth (RV chassis) ground when running from the Genset.

    The short answer, for small off grid power, there is almost never any "need" to tie AC Neutral to RV Chassis (safety ground) for any inverter with less than 15 amps of 120 VAC output (if you have florescent tube lamps that are "hard starting", using a TSW inverter and a neutral to chassis bond can fix that--They may need the safety ground to help start the arc--one of the few reasons to have neutral+safety bond in a small system).

    And if you have a MSW (modified square/sine wave) AC inverter--Most of them will fail if there is a Neutral to Chassis ground (creates a short if the battery bank is also connected to chassis ground).

    Personally, I believe in GFI protection at the point of use (near a sink, external wall outlets, etc.) that are near water/places where people can get shocked.

    If you have a GFI at the power source and there is an ("a"?) GFI fault anywhere in the AC power system, it kills the AC power to the whole place... I.e., get a short by somebody working at the sink turns off the power/lights everywhere putting people in the dark--And making it more difficult to find where the ground fault is.

    Some people have reported more "false" GFI trips with series connected GFI's--But I don't know if that is true or not. Some appliances (like computer power supplies) do put RF filter capacitors between Hot and green wire ground--And if you have a few of those plugged into the same GFI outlet--It is possible to trip a GFI due to the combined "AC leakage current" through the filter caps.

    I think the "legal" AC leakage current to ground is something like 3 mAmps for plug-in 120 VAC appliances, and GFI's trip around 5-10 mAmps--So multiple AC appliances (typically larger computer/switching power supplies) on a single GFI outlet could "legally" trip it.

    GFI outlets (and even Arc Fault branch circuit breakers) are a pain if installed where not needed. One of the posters here said that his Arc Fault breaker (required now for new construction bedrooms in the US?) would trip when vacuuming (universal/brushed motor looked like an arc fault to the breaker). And GFI outlets are not the most reliable devices out there and can fail over time.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Wxboy
    Wxboy Solar Expert Posts: 70 ✭✭✭✭
    #7
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    Re: Best way to use inverter while camping

    Thank you for the responses. I'll be testing this out today. Hope it works.
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  • Wxboy
    Wxboy Solar Expert Posts: 70 ✭✭✭✭
    #8
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    Re: Best way to use inverter while camping

    Quick update. Things are working well. For some reason when I plug in the shore power cable to the inverter it adds a 6 watt load so add that to the 6 watt idle draw from the inverter and it's 12 watts all day and night in addition to the loads. Either way it's been sunny and there has been plenty of power. Batteries staying above 80%.
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