Installing Inverter Where One has Never Existed Before

[sjpotter]

I bought a 2005 26'RB that the owner advertised as having an inverter (a must for me), but it did not. I bought it (the motorhome) anyway. After all what else could I do after flying halfway across the country to pick it up? The previous owner was gracious enough to give me $1000 toward an inverter purchase, better than nothing.

My question is this, after I buy the Xantrex 2000 watt inverter (which I believe this is the one that comes from the BF factory, not sure though) how do I go about retro-fitting it to the coach so that it works correctly with the generator and the shore power. I wish the inverter to charge the coach batteries becuase it has a much better charger than the current converter/charger has. Of course I still want the alternator to charge the coach batteries when the engine is running.

Any help?

[al1florida]

With only 2 batteries you may want to install a 1000 watt inverter. It won't run your microwave though.

The issue with the 2000 watt is that when you run something like the microwave it will drain the batteries too quickly and you may drain them below 50%. In fact it is best not to drain the batteries below 25% for the longest life on your batteries.

I have the project, you have in mind, on my todo list for our 2005 26RSB we bought in May 2011. I plan on removing the converter & installing an inverter to run laptops, TV, satellite receiver, lights & fans as needed. I will also install a TriMetric power monitor to track the amount of 12 power I am using, as well as the amount of power left in the batteries.

Sorry, no help on how to do the wiring, other than looking closely at how everything is currently wired and figure out how to make it work. If you don't have experience with 120V AC power, 12V DC, how converters/inverters work in some detail, etc, etc, then this may not be something you want to try to do by yourself.

[whemme]

sjpotter,

If you want your new Xantrex 2000 watt inverter installed so that it is integrated into the existing power system including it to replace your existing Parallax 7345 charger/converter then I think you will need to have this installation done by an experienced professional RV technician.

You could also take your coach back to the Humboldt factory and have them do it but that is some distance to travel between Texas and Iowa.

[sjpotter]

Well you may be right, but don't write me off so easy. All I need is one person who has successfully done this before take me under his wing and tell me what to do (with pictures of course) and it will be a job well done. Hell, I've already got a multimeter, a circuit tester and a bunch of tools and some wire laying around. A schematic and a list of parts would help too. Of course if that RV tech would charge less than say oh, $500 I might just heed your suggestion. Trouble is lots of people don't take pride in their work and with my luck I'd end up with one of them.

[tomzleapin]

The question is do you need 2000 watts of AC power? My experience with inverters is that the high power units are quite inefficient when under low load. I wired in a cheap 400 watt inverter into the circuit for the electrical outlets. Almost all the outlets go to the GFI breaker in the electrical panel. After blowing up two inverters, I realized I needed to add some switching to totally isolate the inverter. I purchased a 30 amp 120 volt DPDT relay from Grainger:



http://www.grainger.com/Grainger/relays ... /Ntt-relay

I wired it so that the inverter output is disconnected when on generator or shore power.

Virtually all my camping is dry camping so power is a big issue. I have a 125 watt solar panel that serves quite well most of the time. For those cloudy days I have a separate Stanley 40 amp battery charger that I bought from Amazon for $75. You could opt to change out the guts of your existing converter. Here's a link to Bill Hemme's post:

http://www.bornfreervclub.org/bulletin_ ... php?t=2482

Please note there are HAZARDS involved.
1. If you leave the inverter on there is 120 volt at the outlets even when not plugged in to shore power or running on generator.

2. The cheap inverters are Modified Sine Wave out. The better approach is to use a Pure Sine Wave inverter. I have had no problems with the cheap inverters but know that people have had issues with interference and/or damaged or destroyed electronics using the cheap versions

[sjpotter]

I went ahead and ordered the prosine 2.0 after reading this post on rv.net:

The ProSine will charge the batteries whenever there is an external 115Vac power source available (generator, shore power, etc) AND the charger switch is ON. It can be programmed to charge ANY type of battery chemistry and includes dozens of built-in charging algorithms.

The ProSine has an ac IN and OUT. When it detects 115ac on the input, the inverter's transfer switch acts as a pass-through to the output. When external ac power is not available, the ProSine inverts power from the 12Vdc source.

Since you already have a generator in your camper, you (almost certainly) already have a transfer switch... so an inverter with an internal transfer switch would be installed after the one in the camper.

Yes, the Prosine 2.0 requires a 300A fuse and 4/0 cables... that's par for the course with a 2000W inverter.

So I'm thinking all I need to do is splice the wire coming off the auto transfere switch and send one lead to the breaker for the Air Conditioner, and the other to the in side of the prosine inverter, then from the AC output of the inverter I run a wire to power the other AC components, i.e. microwave and ac outlets. That way the air conditioner can only be powered by the shore power or the generator.

I still have to research what to do with the charger/converter. I won't need it to charge the coach batteries anymore because I will be charging them with the much more fast and efficient charger in the prosine inverter, but I don't want to send AC power to the converter from the inverter. Maybe I will will wire it so the converter can only recieve AC power from shore or generator like with the air conditioner.

Remember my goal is to power only the ac outlets and the microwave from the inverter. I want the inverter to charge the coach batteries if the engine is not running and I am conected to shore power or the generator is running.

Is my plan valid? I have to do this myself for 2 reasons: 1. Camping World wants $700 to do this and 2. It's good to know how things work in your RV in case something goes wrong in the future and you need to troubleshoot the cause, and there is no better way to learn then by doing it yourself

[al1florida]

Steve,

Your plan sounds doable (is that a word?) I'm sure it won't be nearly as quick and easy as your outline shows.

On real fun part will be running the 4/0 cable from the inverter to the batteries. Two cables will be needed, one for positive and one from ground return. Including the insulation the cables are 5/8 to 3/4 inch thick. An you need to mount the 300A fuse near the battery.

Keep in mind, using the microwave with the inverter very much at all will not leave you much battery power for other uses. Four batteries would be much better for using the microwave. Not sure where you would put them.

What are your plans for the fridge? If it is wired to the inverter, it will be easy to forget to switch the fridge off of auto and quickly deplete your batteries.

When I install my inverter I doubt I will even wire the microwave to the inverter. Also the microwave (TV as well) will use a good bit of elect just by being plugged in and not used (phantom load).

If you plan on dry camping or boondocking you really need a way to monitor your 12V usage and equally or more important how well charged the battery is as you run your generator to recharge your battery. The inverter will recharge your battery from 75-80% to 90% in an hour or so, but it will take several hours to charge it to 95% or higher.

The Trimetric monitor is an excellent battery monitor. Here is a link to their site:

http://www.bogartengineering.com/products/TriMetric

[sjpotter]

When I installed an inverter in my 4x4 pickup 2 years ago I used 2/0 cable and had to run it about 20' from the switch in the engine compartment to the battery bank in the truck bed, then about 2' to the inverter, routing cable this thick is not fun. I shouldn't have to do much of it for the inverter install on the RV though as I plan to mount the inverter directly above the batts in the storage compartment under the sofa bed. Maybe 3 ' of cable.

Regarding the microwave..., I see no problem using it during times when you're driving and the alternator is charging the batts. I have used the microwave when camping with my 4x4 lot's of times, as long as I drive the vehicle for a half hour or so the batts get charged back up. When dry camping in the RV and I am shutdown for the night with no further intention of starting the RV's engine I will of course start the generator to power any high load appliance..common sense prevails here.

regarding the fridge I might also wire it to bypass the inverter

I am still researching how to modify the wiring from the converter. My BF owners manual doesn't have a schematic, or am I looking in the wrong place?

Steve.

Thanks for the input, appreciate it.

[al1florida]

Sounds like you have it well planned. There are wiring, plumbing & propane routing diagrams in my owners manual, about 20 pages or so if I remember right. I don't have access to my BF right now to look to be sure. I don't recall if there are any details on converter/battery wiring.

[sjpotter]

I completed the instal of a Prosine 2.0 hardwire inverter. It was a pretty involved job that took a good 2 days but it was not difficult technically. I just finished a 3 day trip with it and it is fantastic. It has a smart charger that charges your batts in no time. It has "pass through" AC input so whenever you're plugged into shore power or the gen is running it passes that power through the inverter to power whatever you have wired to the inverter, at the same time charging the batts. When you open up the electric panel on the coach you'll be able to easily figure out how to wire the thing up. The good instructions that come with the Prosine help. Here's what I did: Remove the GFCI breaker (which powers all the outlets in the coach) from the coaches electric panel and in its place put a standard 15 or 20 amp breaker from any hardware store. This breaker is now the AC input for the inverter, which will power the inverters battery charger, as well as providing the "pass through" AC power. Use standard Romex indoor wire and connect the black lead to the breaker, the white lead to the neutral block and the ground to the ground block. Route that wire to where you'll be installing the inverter. Connect those leads to the inverter's input. Run Romex from the output of the inverter into a GFCI circuit breaker which you'll instal yourself. I reused the GFCI breaker that I took from the coaches electric panel and wired it identical to how it was there. Route Romex back to coaches electric panel and connect to the romex black wire to the black wire serving power to all the outlets in the coach, this wire used to be connected to the GFCI breaker we removed earlier, connect also the white wire and ground to the appropriat blocks in the electric panel. Route and connect the DC cables from the coach batteries, through a high amp disconect switch and into the inverter. Keep your DC cabling length to a min. Also use a 175 amp inline fuse directly at the battery's positve post. Viola, you now have ac power available at all times to power all the coach outlets. If you start the generator or hook into shore power the inverter allows that power to pass through to the outlets and your batteries begin an intelligent charge cycle. The inverter's control panel tell you how much current is being drawn from or being sent to the batts. Great piece of gear. Cost of the inverter at Digital Oasis is $1250. This is a simpfied explanation, I can provide pictures on request.

I forgot, as far as the converter goes, you can just unplug the leads that come off the converter and go to the battery buss. you can remove the converter from the coach it if you want to, it is now powering nothing. I left mine in place.

[Bill Dodgen]

Steve,

I installed a Xantrex Prosine 3.0 in my boat and it worked flawlessly for over two years. Was a big fan until I got an error when charging the batts. Shut everything down for a minute and then plugged shore power back in. Another error message and the AC pass through failed. Within a few seconds, it warned me that the unit was overheating. Tried it again 15 minutes later and poof, the magic smoke came out. Unit fried. Most likely the relay that senses AC power and passes it through failed. Of course, this all took place 4 months after the warranty had expired. In my case, I replaced the Prosine with a Samlex 2000 watt inverter that did not included a charger. That way, I could simplify things and guarantee that I would always have shore power. However, it meant that I had to use a standalone charger to charge the battery bank.

Hopefully, such a relay failure is a rare event and you'll have years of reliable service from your Prosine 2.0.

Bill

[Mike Jean Bandfield]

Steve,

I toyed with the same idea for a couple of years and finally decided I needed a generator for the air conditioner as well as the microwave. Also, the inefficiencies of the large inverter when running at 50 - 150 watts didn't seem practical for us 95% of the time. I ended up with a 600W unit that works well enough and we make popcorn on the stove.

I'm curious about how you handled a couple of things. First, does the Prosine unit you used force you to isolate the AC neutral from the coach's neutral? Second, did you run the AC feeds to the air conditioner, refrigerator and water heater to the AC line in front of the Prosine so they'd work on shore power or generator but not off the inverter?

I'd also like to hear from those who have used their microwave off an inverter. I'm curious as the the affect of the battery's internal resistance might have when drawing high currents like this. It would seem that some types of batteries or having only one or two smaller batteries might have an initial voltage drop that would cause the inverter to shut down or go into alarm. ...or only run for a short time before before dropping below the 10.5 VDC cutoff voltage. In this case the internal resistance slows the battery's ability to provide high currents or instantaneous high current while the battery's chemistry is catching up. Then shortly after the demand goes away the battery chemistry recovers and voltage returns to quiescence. In other words, the batteries have the amp hour capacity but can they provide enough throughput to run the micro to nuke cup of coffee or pop a 3 minute bag of popcorn?

I don't know anyone who has actually tried this and have always wondered wheether the practical and the theoretical aspects of this issue might be in conflict.

Mike

[sjpotter]

Mike:
The prosine I installed in the motorcoach is wireed to only power the coach's outlets. I start the generator if I need to use the microwave or airconditioning. Also the prosine has a great intelligent battery charger. As soon as I start the gen or plug in shore power an intelligent charge starts. It charges fast too, normally starting the charge at 63 amps.

Regarding your other question, I own a 2005 toyota tacoma which is my off road expedition vehicle, I equiped it with a 2500 watt inverter so i have AC power in the boonies. It is supplied by 2 75 amp hour batts and it has no trouble powering the microwave in my truck, or the 1500 watt kettle. I only wish it had a charger like my prosine.

I see you have a diesel like me....6.0 judging by the year of your coach. I love the power, I worry about the 6.0 powerstroke with it's reputation but the power is great.

[Mike Jean Bandfield]

It is supplied by 2 75 amp hour batts and it has no trouble powering the microwave in my truck, or the 1500 watt kettle.

I'm happy to hear that. It's good to know smaller 12v sources and inverters can work with high amp appliances.

I see you have a diesel like me....6.0 judging by the year of your coach. I love the power, I worry about the 6.0 powerstroke with it's reputation but the power is great.

I've been very pleased with my diesel's performance and have had zero problems but couldn't say whether that's due to technique or luck. Going for economy over speed, I tend to really baby it while squeezing mpg's so maybe that's a factor. I monitor a Scan Gauge and will let it slow to 45 or 50 (when traffic allows) to keep it out of passing gear and we usually drive about 60.