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power distribution, paging Doug Well (and any others that know this stuff)

I have a Heart Interface, 240W of solar, and  a U280 being used as a house for a month, plugged into not enough shore power. Right now the drill is to turn off waterheater/air compressor/fridge when running roof AC. If the desktop PC that's in there is running, that is enough to trip the breaker in the house supplying said shore power if the roof air is running. I've gone through the manuals, and found some relevant threads here, but am not totally clear as to whether turning the inverter on and running say the PC on it would help or hinder. Is the amperage we're collecting off the roof going into the grid and reducing the load the charger would otherwise have to pull, such that turning the inverter on just increases the overall load on shore power? Or would running the inverter help to reduce the transient loads?
Jay
1989 U280 SE, 36', 3208T Cat, build 3292

Re: power distribution, paging Doug Well (and any others that know this stuff)

Reply #1 –
The answer depends on a few things. But no matter what, the power from your solar panels is not going out to the grid but simply charging your house batteries.

If you have a separate inverter and charger/converter then you can turn OFF the charger/converter, (at the circuit breaker), then turn ON the inverter and run your PC from the inverter without drawing any extra power from the inadequate external AC power. Make sure you don't leave the inverter on after you're done with the PC because it draws power even if you're not using anything connected to it (idle current). The solar panels should be able to replace the power used by the PC as long as the sun is shining on them.

If you have a combined inverter and charger/converter then it might be possible to turn off the charger/converter side (maybe at its circuit breaker) but still have the inverter portion work. If not, then there's probably no use trying the scheme of using the inverter because it will simply draw power from the charger/converter anyway.

Craig

1993 U225 36' Unihome GV with PACBRAKE exhaust retarder, Banks Stinger and Solar Panels.
Toad: 1999 Jeep Wrangler 2-door soft-top.

"No one has ever had to evacuate a city because the solar panels broke."

Re: power distribution, paging Doug Well (and any others that know this stuff)

Reply #2 –
Don't know what you have for batteries, but if you have 2 8D's 240 watts of solar is a bit wimpy to charge your batteries. If your Hart interface is an inverter/charger then it may be funneling the incoming AC to charge/help charge  your batteries. If you can, set your Hart interface power share to 15A, that will reduce the draw to charge the batteries. If your Hart interface is simply an inverter, then you have a converter somewhere that will provide a charge to the batteries whenever you have shore power. Disabling the converter would reduce the draw on the shore power but also reduce the charge to the batteries. If your inverter is wired correctly turning it on would provide you with additional AC to power your outlets but that power has to come from somewhere and that somewhere is your batteries. You really have to keep an eye on the batteries and make certain they are getting fully charged, they not be cheap to replace, a Trimetric battery monitor is a great battery monitoring device that tells you exactly how much charge your batteries are getting. As to whether you are feeding power back into the grid I would say that you are not, you just don't have enough shore power to run the AC and all the other systems on your rig. Hope I did not confuse you to much.

Roland

1993 U280 4341
2010 Jeep Liberty
The Pied Pipers

Re: power distribution, paging Doug Well (and any others that know this stuff)

Reply #3 –
Yeah I meant the bus' grid, not the outside grid. It sounds like there may be some advantage to running the PC off the inverter. We'll give it a try, and keep an eye on the batteries, thanks y'all.
Jay
1989 U280 SE, 36', 3208T Cat, build 3292

Re: power distribution, paging Doug Well (and any others that know this stuff)

Reply #4 –
By all means, run your computer from the inverter. A laptop will only use a quarter of the power available from a 240watt solar panel,however, a desktop will use most of that available power if left on all day (with bright sunlight every day).

Your A/C unit may require 20 amps at startup and about 15amps when running, so 15 amps shore power is inadequate for any additional loads.

I use the inverter to power the microwave when on 15 amp shore power, while using solar to charge batteries, leaving the 15 amp shore power for water heater, tv, computer. I can use the toaster by temporarily turning the water heater off. If I had to run an A/C, all the other stuff would have to be off. I would start the motorhome engine and drive to where the temperatures are more reasonable, ie Victoria, BC, Canada where I live during the summer.

I last ran the A/C in  my motorhome about 18 months ago.

If you have another 15 amp circuit available, use another extension cord to power some devices.

Supplying power to the grid from a solar system requires a very expensive ($4000.00) "grid interface" inverter (ie an Outback), so, while it is possible, it is very unlikely that Foretravel has ever installed such an inverter in any motorhome.


Wyatt
96 U320 40 WTFE, build 4943
84 Toyota Supra towd
2015 Jeep Wrangler towd
Victoria, BC, Canada

Re: power distribution, paging Doug Well (and any others that know this stuff)

Reply #5 –
I bought a 180 watt pure sine inverter. It works fine out of the bottom cig lighter on the dash.

It will keep my mifi and router going along with 2 laptops.

Since mifi and laptops have batteries, not all 4 have to be powered from the inverter at the same time to keep them going.

best, paul

Quote
By all means, run your computer from the inverter. A laptop will only use a quarter of the power available from a 240watt solar panel, however, a desktop will use most of that available power if left on all day (with bright sunlight every day).
1999 U320 40' 1200 watts on roof. 12cf AC/DC Cold plate fridge/freezer. VMS 240 CL Honda Element

Re: power distribution, paging Doug Well (and any others that know this stuff)

Reply #6 –
I did this mod' maybe 2 yrs ago and have found it to be very good. It now runs my res' fridge, tv and up front plug etc when boondocking. Uses far less wasted power than the Xantrex 2500 and therefore takes a lot less out of batteries overnight. I used a true sine inverter.
Additional Inverter
well worth the few dollars
John h
Coachless, now use aircraft. 2003 Ford Travelair TC280 class C. Super shape. Just for 1 yr .
1994 Ford E350 ClassC,total renovation inside and out. Now sold.
2000 U295  36' Cummins 350 c/w Banks Stinger, Resonator upgrade,Solar, LED lites.Residential fridge with slide out pantry. Build 5674. Sold
ex 92 GV 022C ored Cummins. Sold
ex 95 GV240 cat 3116. Sold
2017 Mini cooper s & 2016 land Rover LR2 HSE  LUX.
jhaygarth@aol.com    SKP #130098
treat everyone as you would like to be.

Re: power distribution, paging Doug Well (and any others that know this stuff)

Reply #7 –
Quote from: John Haygarth –
I did this mod' maybe 2 yrs ago and have found it to be very good. It now runs my res' fridge, tv and up front plug etc when boondocking. Uses far less wasted power than the Xantrex 2500 and therefore takes a lot less out of batteries overnight.
Additional Inverter
well worth the few dollars
John h

+1 on your solution, John... as well as another +1 to Paul. At this point in time (and, almost certainly, from now on) it has become undesirable to have one large (or very large) inverter to cover all AC power requirements in an RV. Using small (or very small) inverters as needed is economically feasible and even more efficient; depending upon the situation.

This is why I want to be just like you when I grow up. :P

Craig
1993 U225 36' Unihome GV with PACBRAKE exhaust retarder, Banks Stinger and Solar Panels.
Toad: 1999 Jeep Wrangler 2-door soft-top.

"No one has ever had to evacuate a city because the solar panels broke."

Re: power distribution, paging Doug Well (and any others that know this stuff)

Reply #8 –
Consider the value of true sine wave inverters over modified sine wave, whether they be small or large capacity.

Re: power distribution, paging Doug Well (and any others that know this stuff)

Reply #9 –
Correct Barry, I used a true sine one as noted.
John H
Coachless, now use aircraft. 2003 Ford Travelair TC280 class C. Super shape. Just for 1 yr .
1994 Ford E350 ClassC,total renovation inside and out. Now sold.
2000 U295  36' Cummins 350 c/w Banks Stinger, Resonator upgrade,Solar, LED lites.Residential fridge with slide out pantry. Build 5674. Sold
ex 92 GV 022C ored Cummins. Sold
ex 95 GV240 cat 3116. Sold
2017 Mini cooper s & 2016 land Rover LR2 HSE  LUX.
jhaygarth@aol.com    SKP #130098
treat everyone as you would like to be.

Re: power distribution, paging Doug Well (and any others that know this stuff)

Reply #10 –
Quote from: Barry & Cindy –
Consider the value of true sine wave inverters over modified sine wave, whether they be small or large capacity.

I'm at a significant advantage here because my little old U225 did not come with an inverter at all so even though I had to design my own system, I didn't have to worry about whether to keep an old system or match the rating of an older system that really didn't have any bearing on how I would use it.

I have one "central" pure-sine inverter installed in the vacuum cabinet (under the refrigerator and directly above the battery bank). I sized this according to what I figured would be the most likely load; 1600 watts (for about $300 from Amazon). This corresponds quite closely to a 15-amp household circuit (ok, it's 13.3 amps but who's counting?) and would run our microwave. The cable run of 3 feet is good, too.

I then bought a 180-watt cigarette lighter plug pure-sine inverter (for $79) and use that for HDTV and DVD playbacks, charging laptops, tablets, hand-held radios, etc. I think I'll buy another and install it under the dash with an AC outlet somewhere up there.

We also have several "modified sine wave" cigarette-lighter style inverters for appropriate tasks. These are typically only good for up to 180-watts (but much less is better).

With the pricing of pure-sine-wave inverters coming down quickly it makes a lot of sense, now, to just buy them and reduce the worry about whether some device will fry itself when you plug it into your inverter.

Craig
1993 U225 36' Unihome GV with PACBRAKE exhaust retarder, Banks Stinger and Solar Panels.
Toad: 1999 Jeep Wrangler 2-door soft-top.

"No one has ever had to evacuate a city because the solar panels broke."

Re: power distribution, paging Doug Well (and any others that know this stuff)

Reply #11 –
very nice John, can you give us a source for the inverter or recommend one?

Thanks
Tim Fiedler    2025 LTV Unity MBL on Order
2000 Chevy Tracker 2 Door Convertible 4WD Now lifted 4.5"
1985 Citroen 2CV6 Charleston
Murphy Rebel on wheels with 175HP Titan
Cessna P337
1980 48' Westport MY (!/4 Share)

Re: power distribution, paging Doug Well (and any others that know this stuff)

Reply #12 –
Sounds like you may want to  consider running the main engine on cross connect (boost) to help maintain the batteries during peak usage.  Wouldn't be a good solution if you were in that mode for a long time.
Fritz & Kathy Johnson
1991 36'

Re: power distribution, paging Doug Well (and any others that know this stuff)

Reply #13 –

Tim, this is the one I have but looking at the web it does not give you the fact it is a Pure Sine. I just looked at mine and it is marked on the case--Pure Sine--- I got it from Amazon but do not remember the price then. Has been working great. The model # of mine is HP1000.
Amazon.com: Royal Power PI1000-12 Power Inverter 1000 Watt 12 Volt DC To 110

John H

As an Amazon Associate Foretravel Owners' Forum earns from qualifying purchases.
Coachless, now use aircraft. 2003 Ford Travelair TC280 class C. Super shape. Just for 1 yr .
1994 Ford E350 ClassC,total renovation inside and out. Now sold.
2000 U295  36' Cummins 350 c/w Banks Stinger, Resonator upgrade,Solar, LED lites.Residential fridge with slide out pantry. Build 5674. Sold
ex 92 GV 022C ored Cummins. Sold
ex 95 GV240 cat 3116. Sold
2017 Mini cooper s & 2016 land Rover LR2 HSE  LUX.
jhaygarth@aol.com    SKP #130098
treat everyone as you would like to be.

Re: power distribution, paging Doug Well (and any others that know this stuff)

Reply #14 –
And now for a different opinion on "which is better?" several small inverters OR one large one:

I have one 1800 watt "pure sign wave" inverter by Xantrex because:

1. I can use the existing ac wiring to power whatever I need from one central inverter. I control what is receiving ac power at the power panel and also at other (added) ac switches which control power to the front or rear TV. For example, the front TV can have no power while the duplex receptacle beside driver seat can power my computer even though they are on the same circuit.
Note: I removed the inverter ac power panel by moving the breakers to the main ac panel and completely rewired the main ac panel. I split circuits and my main ac panel now has 15 breakers. 

2. Modern inverters are far more efficient than the 2500 inverter/charger that was installed by Foretravel. My Xantrex 1800 requires 1 amp in standby and 250 milliamps in sleep mode. Left on all the time this uses 24 or 6 amphours a day, however, the control panel for the inverter is in the kitchen so that it is convenient to just turn it on when required. I will at times leave it on all day (powered by solar), but never at night. I do not use sleep mode because it makes the microwave do stange things.

My experience on inverter efficiency:
Do not be fooled by the 90% on the side of the inverter packing box because that only tells half the equation. My way of measuring efficiency is to measure the number of watts required from the 12volt batteries to power an appliance. There was an obvious difference between my old Canadian made "modified wave" inverter and my "pure sign wave" Xantrex inverter. The Xantrex "pure sign wave" inverter required about 95% of what the "modified wave" inverter did with the same ac load. I also tested a cheap ($100), 2000 watt, chinese inverter labeled "modified sign wave" which was 10% less efficient then my old inverter. My scope revealed what was labeled "modified wave" was really a "spikey square wave". The Xantrex 1800 "pure sign" inverter is priced at $1000, however, I paid $500 for a refurbished one at Quartzsite.

If you are interested in the technical numbers on the side of a "pure sign" inverter box, look for "Total Harmonic Distortion" or THD. Mine is 3%, which is excellent, 5% is good, 7% acceptable, 10% is too high. A good modified wave inverter will have THD of circa 25%.

My experience on powering a laptop from a dash socket.
I had a 125 watt inverter which was in the car to power my laptop. It worked well, only if the laptop battery was fully charged. Squawked "overload" if not. Obtained a 400 watt inverter with a lighter socket plug, squawked because car wiring was too small. Installed under dash socket with #10 wire directly to the battery. Works well even with a dead laptop battery. With a dead laptop battery, inverter squawkes "low voltage" after 30 minutes, and I have to start the engine to continue.






 
Wyatt
96 U320 40 WTFE, build 4943
84 Toyota Supra towd
2015 Jeep Wrangler towd
Victoria, BC, Canada
 

Re: power distribution, paging Doug Well (and any others that know this stuff)

Reply #16 –
Quote from: P. Wyatt Sabourin –
...
Note: I removed the inverter ac power panel by moving the breakers to the main ac panel and completely rewired the main ac panel. I split circuits and my main ac panel now has 15 breakers. 



How far did you have to go to identify what wire was what, Wyatt?  I headed back to the bed area to do some modification to one of the three circuits (circuit 5) that feeds more outlets than I'd like.  I was really surprised to see the three SINGLE wires in the inverter sub-box for the three circuits that feed MANY things eventually.  From what it appeared to me, FT used RV junction boxes/outlets as 4-wire splices and mounted them upside down (not that I am sure there are outlets on the bottom) as the backs (now tops) come off.    Hope that makes sense.

Is all the splicing being done in that bed area?  In other words, if I take apart the junction/outlet boxes and separate the wires (and track them for continuity with an ohmmeter), will it be a simple chore to add more 110 breakers?  Or are there junctions that are too buried elsewhere in the coach to allow me to find them and separate out new circuits?
The selected media item is not currently available.Brad & Christine Slaughter
Was:  1990 U280 36'
Was:  2002 U270 36' (With a bathroom door) Build #5981
Is:  2021 Leisure Travel Van Wonder 24RL
2015 Jeep JKU, 2003 S10 QC 4x4 or 2017 C-Max
Lake Havasu City, AZ (or Gillette, WY)