Copyright 2019 Discovery Owner's Association, Inc.

Replacing the 1,000 Watt Inverter

The following article is by John Veach. He details his addition of a new 2000 watt inverter (to replace his original 1000 watt inverter) and also the wiring changes necessary to power everything in his coach from the inverter, except for the roof air conditioners. I recommend that you read Ed Kennedy's article first, as I have included some pictures there that are not included here. Click here to go to Ed's article.

Remember, if you do not understand basic electricity, do not try this. Get a qualified electrician to do this job. You can be severerly injured or killed, or damage your rig. if you do not do this job correctly.

Following Ed Kennedy's instructions for his coach on the DOA tips page and with several daily e-mails back and forth between us, I now have all my circuits except for the air conditioners on my inverter.

Over the last year, I have installed 4 solar panels on the roof of our D. I can generate 250 watts of power in direct sunlight in the middle of the day with these panels. In order to utilize this solar energy, I installed two more six volt batteries. Since I have all of this power available to me, I replaced my 1k Heart Inverter with a 2k Trace inverter. I simple removed the Heart and rewired the compartment with the Trace. The major difference in this installation is that the cables coming from the battery bank is much larger than the ones that came with the coach. When doing a replacement like this, you need to also change out the battery cables between all four batteries. I used #1 size cables. I believe the ones from the factory were either #4 or #6. If you are pulling 20 amps at 120 volts ac, then you are drawing approximately 200 amps at 12 volts across the batteries. This would tend to make small cables fusable links.

After installing the solar regulator and a new inverter controller, I moved on to the actual coach rewire job.

As the 99 37V comes from the factory, there are 8 branch circuits and the main 30 amp circuit in the power distribuition panel. Ed Kennedy suggest using a 30.20 amp double circuit breaker in place of one of the 20/20 breakers in the panel. I could not find one of these, so I just bought a single 30 amp breaker that fit the panel. My panel uses Cutler Hammer breakers, but the one I put in is a universal 30 amp breaker from Ace Hardware. If you are located near a larger do it yourself store, you will probably be able to find the correct breaker a lot easier than I did in a small north Georgia town.

I carfully removed the bus bar from the circuit breaker panel and cut it into two pieces. Since I had a double breaker 30/20 amp and a 20/20 amp in the top of the panel, I just cut the bus bar after allowing enough room to replace these two double breakers and adding my single 30 amp breaker. I left about a half inch gap between the two pieces of the bus bar.

In the bottom half of this bus bar I reinstalled the original double breakers for the regular branch circuits. This gives me a 20/20 amp breaker and a 20/15 amp breaker for those circuits.

I feed the single 30 amp breaker in my top panel into a new 10 gauge romex wire I pulled from the circuit breaker panel under the refrigerator to the electrical bay where the inverter lives. I tried to neatly pull this through the wiring trays that run under the floor of the D, but the main one in the bathroom, goes from under the furnace cold air intake to under the shower. There was no way to pull this wire across. Then I tried to pull it through a plumbing tray that crosses from under the pantry to the refrigerator. Apparently, there are braces in this tray that prevented me from snaking the romex across under the floor. Finally, I just went up from the inverter bay into the channel that runs down the street side of the coach. This wiring tray has a piece of wood and carpet that is just lightly tacked to the floor of the bedroom and can be carefully lifted up. I ran the romex into the bathroom under the carpet covered box that runs down the street side next to the commode. In the bathroom, I again went through the floor into the bay where the dump valves are. I fished the romex across these tanks to a position under the refrigerator. Then I went through the floor under the refrigerator to the circuit breaker panel. The romex is fastened to the frame of the D as it crossed between the two subfloors.

The old inverter circuit from the breaker panel to the inverter now becomes one of the inverter output circuits. The Trace 2k inverter has two 20 amp outputs. One of these is connected to this old wire and feeds the bottom of the circuit panel and all the branch circuits for the coach except the one that was originally on the old inverter.

The original inverter circuit is now attached to the second output of the Trace and feeds the outlet under the table and the two TVs.

Under the pantry in the 99 37V is a transfer switch that is now totally redundant. The inverter has its own built in transfer switch. I removed the Fleetwood installed transfer switch under the pantry and wired the load and line wires together. White to white, black to black and ground to ground. I just cut off the third wire and taped the ends. This third wire is no longer needed in this configuration. It used to go to the circuit breaker panel.

On the top of my now modified panel the breakers are as follows.
First breaker, top of panel

Top 30 amp shore power/generator power main breaker
next 20 amp circuit to front ac unit

Second breaker
Top 20 amp circuit to rear ac unit
next spare 20 amp breaker

Third breaker
Single 30 amp breaker that feed the #10 wire to the inverter input.

Gap in Panel

Sub Panel
First breaker
20 amp breaker for house circuit
15 amp breaker for house circuit

next breaker
20 amp breaker for house circuit
20 amp circuit from inverter output #1

The panel lable states that only 9 branch circuits are allowed in this panel. As you can see, I have 9 branch breakers, but one is a spare. Ed and I discussed that this might be good place to run a circuit for a light bulb placed in the water utility bay for subfreezing nights. Just a thought.

The two circuits coming off the inverter are protected by built in circuit breakers on the inverter itself.

This configuration lets us utilize the entire coach electrical system, except the AC units, when boondocking or when the power fails. I even got rid of my UPS on my computer since it is now backed up by the coach batteries. The refrigertor will run on the inverter in this configuration while parked and while traveling. The alternator on the engine can handle this load, but if boondocking for an extended period, I would put the refer on lp. With our 4 solar panels and 4 batteries, we are pretty independant of power connections. Just as an added bonus, my inverter controller will remote start the genset if the battery voltage falls below a level that I preset and program into it. I have not yet wired the remote start function to the generator, but plan to do so this winter. The inverter controller can also be programmed for quiet hours so it doesn't remote start the genset at 3 am thus annoying the neighbors.

Thanks to Ed Kennedy for all of his help and support.
Submittedy by John Veach


The DISCOVERY OWNERS ASSOCIATION, INC, was formed to promote the sharing of information and the camaraderie of fellow Discovery motorhome owners. Membership in the club is limited to owners of Fleetwood Discovery motorhomes.


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