Electrical Schematic Ideas

[gonemissin]

This is a plea for the electrically gifted among us to get me on the right path.  I'm mechanically inclined, but electrons generally leave me scratchin my head...   However, if I've got a good plan, I'll be able to knock it out. 

I'm in the process of buying a slide in truck camper, a Capri Rodeo (It's being built, delivery in Dec '10) that is fairly basic.  It is lightweight and comes without frills.  I'll be able to taylor this to my needs and tastes.  The biggest change will be upgrading the electrical system.  After digging around the web and our library, I'm having difficulty finding schematics of electrical systems that include inverter/converter/chargers, on board aux batteries, solar panel(s), fuse panels, etc.  Once I find a suitable schematic, I can get down to sizing components.

It is prewired for 120VAC for fridge, microwave, and overhead A/C.  DC is available for lights, water heater piezo starter and demand water pump.  My basic concept is to have two 6V deep cycle batteries in series for 12VDC, an inverter/converter/charger, shore hook up (20A or 30A, although shore power will be rare), an EU2000i Honda generator for topping batteries and running heavy loads such as A/C and voltage gauges.  I'll add solar as money allows with the intent being trickle charging batteries. 

What I need are ideas and particularly schematics that will put me on the path to sorting this out.  Any help would be appreciated.

Yes, I've been to the RV Forum library and looked around the web with little success.

Thanks, Rocky

 

[rsl]

Well you wont be able to run the AC without well AC and unless it is an extremely small AC unit the Honda 2000 wont run it.

 

[gonemissin]

That's correct.  I've got a very small insulated space and anticipate having a very small A/C unit.  I anticipate running one appliance at a time if only on 2KW genset.  With battery only power, I'll run appliances one at a time AND sparingly.  Like running the 650W coffeemaker in the morning.  I can always use the stove and the percolator, but the small coffeemaker is a real convenience.

We also tend to be in Northern climates throughout the entire year, so the cooling load would not be very high.  I plan on using the A/C similar to the way we use the A/C in the TT and the stick house-it is used as much to wring humidity out as it is to actually cool...

Add: I just looked up a small 5000 BTU window unit and the draw is listed as 515 Watts.  Even with starting surge the 2K surge capacity of my 2K genset can easily handle that.  Even 5K BTU is gonna be gobbs plenty.  I may end up having to get a window unit vs an overhead just because of availability of very small output.

 

[Gary RV_Wizard]

If you can install a 5000 btu window unit, that's great. But most RV roof a/c units are larger than that - the smallest I know of is a Dometic Brisk Air at 11,000 btu.

Other than the size of the generator vs the a/c, your plan sounds fine.

 

[gonemissin]

Thanks, Gary. 

What I really need is a schematic or three for something like I've outlined.  I could eventually figure it out, but not being 100% up to speed electrically, I'll take a while to reinvent the wheel and I will be prone to some preventable errors.

 

[yfx4]

It may help....on the winnebagoind.com site>

http://www.winnebagoind.com/resources/manuals/

there are wiring diagrams for most of the WB products. You could pick a simpler model, download the diagrams/schematics, and pick out the parts you want to copy or use as a model for your plan. Just a thought.

 

[Bob Flight]

I think the attached block diagram is what you are asking for.

We have (2) AC circuit boxes.  The AC comes into the main box to fed the A/C, refrig, and hot water heater directly.  A leg from the inverter feeds the second circuit box to feed the kitchen, microwave, TVs and some outlets.  We have (4) 12v batteries to support our 2000 watt inverter.  A transfer box is not needed if you are willing to plug your RV power cord into shore power or into the generator manually.

The block diagram is from our XANTREX manual from XANTREX

 

[gonemissin]

Thanks Bob, this is a good start.  8) With my TC, I'll have a miniature version with emphasis on boondocking.  More what folks tend to call an expedition type unit.  Low loads=low demand=small inverter/converter=small battery pack = more effective solar charging = quicker genset charging.

Yes, the overhead A/C units tend to be a bit large and wow do they pull juice!  Our TT has 30 breakers and will trip if the A/C is on full and we run the microwave at 100% power.  A/C will be one of the last things I do and will likely be a micro wall unit in the 3K BTU to 5K BTU range.  To help keep the system small, I may just count on using it with the genset or shore power.

At this point, I really need to sit down and pencil out my loads and how they'll be used so that I can begin sizing components.  As I look at appliances and loads, I really start to question the need for some of the bigger loads, such as a standard RV propane furnace.  It works great in our TT since we are hooked up to shore power 99% of the time, but doesn't seem real energy efficient if the super hot exhaust grill is any indication.  Keeping this TC project small and light is part of the objective.  Given the remoteness of some of the areas and the altitudes I'll be at, running the batteries down in a night or two due to poor system design on my part is not an option.  Sure, I can fire the genset up, but it's a gas unit and gas storage is necessarily limited so that's a very short term play.  Sometimes the weather can prevent leaving when planned, so longer stays will be inevitable.  (aw shucks  ;D)

As I put this together, I'll be happy to share the results.  Initially, I'm just going to have to depend heavily on shore power until I get all this sorted out.  Since this is completely custom, it's gonna take a while to sort out unless I can run into an electrical genius or two.

For example, I'm struggling with the heat option right now.  A good idea seems to be a catalytic heater (typically platinum as the catalytist metal) , but I'm reading horror stories about folks not waking up while using these.  I am certainly not interested in pushing daisies before my appointed time.  This seems odd since the heat is created by a catalytic reaction that takes place below the combustion temp of propane, so CO should not be an issue?  However, the reaction does consume O2, so oxygen depleting sensors must be used.  Hypoxia will kill ya, whether it's due to direct O2 depletion or CO substitution.  Yes, as a measure of safety, I'll have CO and gas sensors. 

A consideration for a catalytic heater that seems to allay any potential harmful gas buildup is one that actually exhausts 'fumes': http://www.ventedcatheater.com.  Does anyone here have experience with this unit?

I'm also looking at a diesel fired unit like the Espar Airtronic.  A simple air to air heat exchanger.  This would be slick from the standpoint that it has a proven track record, uses very little fuel and electricity and all combustion gases can be piped well away from air infiltration points.  The D2 would be quite handy since that's what is in the truck's tanks.  They are pricey at over $1000, but quite effective and safe.

 

[gonemissin]

This is a little more specific as I'm making progress building a schematic(s) and determining loads.  The load determination is not easy as it is a series of compromises to come up with a correctly sized system.   Keeping things lightweight and within reasonable cost parameters is of prime importance. 

Inverter/Converter/Charger.  Can anyone please steer me to some good sources on these units?  As well as some good reading materials that are beyond basic, please?  Preferably someone who has gone to the trouble (and angst) of replacing the standard Converter/Charger with a three way unit and has gone through the research end of this.  I could put a patchwork of components together, but at first glance it will likely cost as much or more than simply getting a three way unit to begin with. 

I'm beginning to see that if you want any convenience items like a microwave (even a small one), boondocking can start to get rather expensive as compared to just hooking up to shore power...  compromises...

Thanks!

 

[Gary RV_Wizard]

What sort of inverter/charger resources are you looking for? Xantrex, a major manufacturer of them, has a helpful inf int ehri install manuals, which are available online.

http://www.xantrex.com/power-products-support/document-downloads/document-type/installation-manuals.aspx

You really don't have to know much beyond your expected loads, to size both the inverter (peak load) and the battery bank to run it for the time you desire.

Some tips are available online, but we can probably tell you what you need to know right here. For starters, there is a good article in our Library.

http://www.rvforum.net/joomla/index.php?option=com_content&task=view&id=260&Itemid=41

http://www.ehow.com/how_5078518_install-power-inverter-vehicle.html

 

[gonemissin]

Thank you Gary!  I'll go check out those resources.  Study time.

 

[gonemissin]

An experienced RV'er pointed me to this this: http://www.windsun.com/Photovolaic_Systems/RV_Systems.htm

I'm beginning to lean toward using solar as my primary charge system and either not having a converter or leaving it unhooked/switched off...

The experienced hand is using two 135W Kyocera panels, Solar Boost 2000E MPPT Solar Charge Controller, 25 Amp, four deep cycle batteries and a 1700W inverter.  He says he runs coffee pot, toaster, TV, furnace, etc. All except his electric water heater element and his A/C.  He says he never runs out of power.  Batteries don't dip below 12.5V.  The solar typically recharges the batteries by 10AM.

Anybody running a similar system?  Any comments on how well it works and what kind of components you have?

 

[Terry A. Brewer]

Rocky

I have two 135W Kyocera panels, one 120W Kyocera, Solar Boost 2000E MPPT Solar Charge Controller, RS3000 pure sine wave inverter, 750 amps of batteries..... The solar won't even give me two extra hours of use.

I use 50-55 amps an hour & stay up until 1-2 am....Solar doesn't work for me.

 

[Gary RV_Wizard]

Your friend is either a real energy miser or likes to brag. A fully charged battery is 12.6v, and 12.5v is at least 90%. Either he isn't using any power to speak of, or he is parked in a sunny desert near the equator 100% of the time.

You must have batteries sufficient to store your daily power needs, because the sun doesn't shine 24/7.  And you should have multiple sources of battery charging, so you can take advantage of whatever external power is available - sunshine, campground hook-ups, or generator. They all have their place and time. There is no drawback to having a converter charger installed and connected - it doesn't use power by itself.

 

[Ken & Sheila]

You can simplify your wiring by using an inverter with dual output protected by there own circuit breakers. Magnum Energy makes a pure sine wave version,2000 watts model (MS2000-20B, this is an inverter and a 100 Amp 3 stage charger). Magnum and or Xantrex also should make a modified sine wave version, this would be cheaper. Using this type eliminates the need for a sub-panel after the inverter, but it does limit you to just 2 circuits but for your sized unit that should work just fine.

Since you are only going to put in 2 batteries you might want to consider a smaller inverter/charger. Magnum makes a 1200 watt modified sine wave or a 1000 watt pure sine wave. The 1200 watt is the MM1200 (also a 70 amp charger), a Factory re-furbished one costs about $480.00 from Wholesalesolar.com. They sell refrubs of several Magnum inverters. Using the MM1200 would require a small sub-panel after the inverter.

To get the best use out of Magnum or Xantrex you will need a remote Controller Panel. For the above Magnum products that's about $180.

Any of these products completely eliminates the Converter as they include a high quality charger. These model also include an internal transfer switch to allow shore power to "transfer" through the inverter when you are on shore or generator power. (this is a 30 amp transfer for most 2000 watts models and 20 amps for the MM1200)

BTW, I am not promoting Magnum. Xantrex make excellent products, I just happen to be more familiar with Magnums products.

General Inverter info: Most inverters with a charger will also have a transfer switch, this simplifies wiring both on the 12 volt and 129 volt sides. If you get a straight inverter you will need to keep your Converter (or add a separate charger) and a transfer switch to move the loads that you want to run on the inverter from inverter to shore/generator. If you leave these loads always on the inverter you will shorten the life of your batteries and you will limit your actual charging capacity because some of the capacity will be used by the inverter to run those loads even when on shore power.

ken

 

[Jammer]

For example, I'm struggling with the heat option right now.  A good idea seems to be a catalytic heater (typically platinum as the catalytist metal) , but I'm reading horror stories about folks not waking up while using these.  I am certainly not interested in pushing daisies before my appointed time.  This seems odd since the heat is created by a catalytic reaction that takes place below the combustion temp of propane, so CO should not be an issue?  However, the reaction does consume O2, so oxygen depleting sensors must be used.  Hypoxia will kill ya, whether it's due to direct O2 depletion or CO substitution.  Yes, as a measure of safety, I'll have CO and gas sensors. 

I don't like catalytic heaters on safety grounds but many people do use them.  CO becomes a problem with them as the catalyst degrades, which it does over time with age, use, and exposure to atmospheric contaminants.

Here are some alternatives:

1) The Dickinson Newport propane fireplace. 7500 and 9700 BTU/h output versions available, $700 street price for the 7500 BTU/h including vents. Vents vertically using tri-wall pipe. Outside combustion air is drawn from the concentric area. Requires no electric power though there is 12v blower for air circulation that can be used if desired. Cearance to combustibles - top 18", other 5 surfaces 2", vent pipe 2" (http://www.go2marine.com/product.do?no=98187F&WT.mc_id=gb1)

2) Propex heater. Popular with the Westfalia crowd because of the installation flexibility it provides. Imported from the U.K. This is a ducted heater that mounts inside. 1" clearance to combustibles. Unlike Atwood and Suburban heaters, which have rigid vents limiting the installation possibilities, combustion air and exhaust are vented outside through 1" flexible tubing. 6000 and 9600 BTU/h (output) versions are available, drawing 1.4A and 1.9A respectively. $800 street for either size from U.S. dealers. (http://www.propexheatsource.co.uk/pdf/Heatsource_A3_brochure.pdf)

3) Atwood Everest Star 8012. This is an unducted furnace with a smaller, lower current blower than the duct versions. Zero clearance, direct vent. Draws 1.8A. 9100 BTU/h output. $500 street. (http://www.ducktec.com/itmidx14.htm)

The Everest is widely used as original equipment for production truck campers.  The others are niche products.

 

[Jammer]

Many of the solar and alternative energy sites will have information and example schematics.

http://amsolar.com - RV-centric solar panels and charge controllers (dealer)
http://magnumenergy.com - inverters (manufacturer)
http://bestconverter.com - inverters, converters, battery monitors (dealer)
http://xantrex.com - inverters, converters
http://www.trojanbattery.com/ - Battery specifications.  Call your local Batteries Plus for pricing, they're dealers.
http://vintagetrailersupply.com/ - Inlets for detachable shore power cords

Some suggestions:

1) Use a battery configuration that provides the power you want and fits the space available.  If you have room for two group 31s, use that.  If you have room for two golf cart batteries, use that.  If you have room for three group 27s, fine.  Or a single 8D.  Any of these combinations will perform the same.  If that's not enough power then double or triple it or whatever bearing in mind that if you use 6v batteries you have to have an even number of them.

2) It's not worth it to have separate generator wiring unless the generator is going to be permanently bolted to the truck.  Just use the shore power connection.

3) Put fuses or breakers on everything

4) You will want 30A shore power if you have an air conditioner or electric heat.  20a shore power is fine if you don't have either of these

 

[gonemissin]

Had the Rodeo about a month now.  Workmanship reasonable.  It is a functional spartanesque camper.  Not a full time rig by any means but great for back country excursions and cross country jaunts sans motels.   Good for a starting point to build up to suit my needs.  Good bang for the buck.  It would have cost me about the same as I paid for it to simply get the materials and do it myself-and that's not counting my labor.  Quite a list of small items to knock out, as with any newly aquired RV, particularly a new 'spartan' model.  Plenty of time right now...

The electrical systems, 12VDC and 120VDC are about as rudimentary as you can get.  There is no fuse box nor are there fuses of any kind for the system input.  Obviously, I'll remedy the fuse issues right away while I sort out the new system design.  The only exception is a 30 amp fuse for the A/C option.  I didn't get A/C so I've pulled the fuse.  I thought the 30A fuse was interesting since the input is limited to 20A max by way of a standard three prong plug.    I've got my work cut out for me.  That's ok, it's more or less what I expected.  Acutally the challenge will be fun.

I did decide to get an Espar Airtronic D2 heater.  They are certainly expensive, but it sips D2 and has a low current draw.  With the altitude kit(necessary for my use) and tax for the guvna, it broke $1600.  Eeek!  It's also a very small unit (about 4.5 square x 12- inches long.) that I've been able to 'hide' in previously unused space.  It's certainly more work to install than a standard RV heater.  The biggest issue was thinking through the best place to put it while considering wiring, fuel line, combustion air in/out, heat exchanger air in/out and ducting.  Space is particularly precious with this small of a camper (8.5ft long+54 inch overhang x 80 inches wide x 78 inches high).  The Espar Airtronic units have a long track record in Class 8 trucks and offroad equipment.  Since I'm diesel powered with a 35gal stock tank and a 45gal auxiliary tank, I'll not be worried about running out while in the back country.

Secondly, a standard RV heater, while initially less expensive is inefficient and has quite a current draw.  That current draw would pose an additional challenge for boondocking.  Also, I only have room for one 20# tank and don't want to have to carry a spare due to space constraints.  It's not the cost of propane rather, running out of propane in below freezing weather in the boonies well away from a refill is bad juju for my water system, not to mention inconvenient.  So, I'll leave the 20# tank duties to heating service water and cooking.  If I happen to run out, it's not terribly consequential.  I'd like to be all diesel and leave the propane behind (like marine apps), but for now this arrangement will suffice.

I had a bad experience with a 'Portable Buddy' Mr. Heater ceramic catalyst propane heater.  The vented propane heaters won't be available until 2Q11 which won't ruled that out.

I can't say this loud enough. Unvented propane heaters, even the catalyst type are *dangerous*.  The 'Portable Buddy' catalyst heater did put out CO.  Not only did it set off the CO alarm, but it worked me over.  I had it set up in the camper, all closed up with no one inside.  The objective was two fold: get the water lines lines fully thawed ASAP so I could blow them out (close call on that one) and test the indoor pollution of the heater.  Well that test only lasted 20+ minutes.  With the CO alarm blaring, I went in to shut it and the heater off.  The CO level was so concentrated that I got groggy just trying to turn it off.   I finally had to take the batteries out to shut it down.  My exposure time was only a few minutes.  I came inside and sat down, feeling like a rag doll and with my judgement noticably impared.  It took a few hours in good air to get me back to normal.  I can absolutely see how these things can KILL people.  No question.  Sure, they say these things are 'safe' if used in a ventilated space.  I'm not buying any level of safe without an actual flue or combustion gas vent.  I took it back to the store and will never use one again.  It ain't worth the risk.  I'd rather shiver than be dead.  And I didn't even mention the *large* quantity of water vapor as evidenced by a significant build up of ice (not frost) on all windows.  Yuk.

Literally a LIFE lesson learned.  The low cost and convenience is a real temptation.  Glad I read the warnings here and decided to experiment before actully using the thing.    Thank you!  The threads here and elsewhere could well have kept me above room temp a little longer! 8)

 

[boatbuilder]

Most people forget that the byproducts of complete combustion of a hydrocarbon fuel are carbon dioxide and water vapor.

 

[gonemissin]

Indeed, boatbuilder.  I really have to wonder how these companies are getting away with even hinting that these things are safe indoors.  I should have paid more attention to my scientific 'ejumakashun'.  Lesson learned. 

Back to electricity.  Somehow it seems a whole bunch safer.