Completed 2500 watt Magnum Inverter/Charger mod

szewczyk_john

Well-known member
The planning of this mod started during our last camping trip last year. During the fall Martinsville race my 2 6 volt batteries would not hold a charge overnight forcing me to start my generator by jumping it with my truck. I decided that for our needs a small inverter was needed. We boondock at a bunch of NASCAR events yearly so anytime we wanted AC power we would run our generator. I started doing my research and made my mind up to use a Magnum product because of the reviews and other info I had found out. This plan started with just a small inverter to power our entertainment wall and maybe another outlet to charge cell phones. I found a 2500 watt mobile unit model 2512 on Craigslist and inquired about the unit. This unit was installed into a brand new airstream only a month before I saw the ad by a professional solar installer. Seems that the airstream owner wanted more power so he went back to the installer and asked for more wattage and agreed to eat the cost of the 2500 watt unit. When I called the installer and learned about the details, I was still reluctant to purchase a new from factory unit but then the installer offered me the used 2512 modified inverter/charger with brand new remote control unit and the cable going between the two along with everything that came from the factory, all for less than half of what I would pay for a new unit alone. I drove 2.5 hours to Wadsworth, Ohio to complete the transaction. Then over the next few months, I added one or two other pieces needed to complete the mod every pay day, spreading the costs over 4 months. I was originally planning on doing solar with this mod but decided that I could not justify that expense as we are not full-timers yet. I know that I can easily add solar at this point.

On March 22nd, I went to the storage unit and cleaned out the basement, removed the walls and cleaned out the battery compartment. Each night after working 10 or 12 hour days at the job that pays the bills, I would go down to the trailer and spend a few hours working on this. So what I ended up with is the Magnum hanging on the wall of the basement opposite the battery compartment. I sandwiched the stock basement wall with 3/4 OSB flooring on either side and bolt that together giving plenty of strength to hold the weight of the unit. I also wrapped the area under the unit with a piece of sheet metal to dissipate the heat generated by the unit.

I added a 30 amp breaker to the main panel to power the AC side of the unit using #8 wire. I then ran the AC output from the unit using # 8 wire to a new sub panel installed inside a small cabinet in the entertainment wall. We removed the 2 15 amp circuits from the main panel that were labeled bedroom and GFI by the factory and ran them to junction boxes directly below the sub panel box. While I was in the main panel box, I purchased a 20/20 breaker and installed a 20 amp outlet at the bottom of the entertainment wall for a space heater and then ran another outlet from there to the basement. The unit has a transfer switch to detect AC power and also allows for pass through meaning these 2 circuits can be feed at all times.

On the DC side I went with 4 crown batteries 260s 6 volt batteries. Wired in series and parallel. This gives me 520 amp hours. Using all 4/0 SAE rated J1127 welding wire. I installed a 500 amp shunt on the negative side. On the positive side, I installed a 600 amp rotary on/off switch ( this was necessary as the unit does have a milliamp draw even when off, and my batteries would be dead each trip as I do go months between usages of the camper) and then the 400 amp type T over-protection fuse. I left the stock 12 volt system hooked up as installed, just moving the rotary disconnect to a more accessible location then the factory installed position. This allows me power either one or both depending on my needs and or service of either side. I left the stock converter in place put unplugged in case I may ever have issues with the inverter branch.

In order to get the new battery boxes installed, I had to cut and bend the installed brackets that hold the hydraulic pump and lines. I connected the venting out of the boxes with 1 1/2 inch fittings and ran swimming pool hoses inside the fittings.

I installed the Magnum remote control and Trimetric 2025 battery monitor to a location above the TV on the entertainment line to complete the mod. I ran the suggested test of the system and all worked correctly Saturday 3/26. On Monday we removed the plumbing to the washer/dryer location as we will never install that option, cleaned up the debris left from the factory, tidied up the factory wiring, and ran a new 12 volt outlet to the UDC to power the carry out satellite antenna. Before replacing the walls, I opened up the transfer switch just to make sure everything in there was tight. Mine were still very tight with no movement. The only issue we encountered was that the wiring going into and out of the 15 amp outlet in the basement all fell out of the outlet. I replaced that outlet with a new box and outlet but the cut out such a large hole for the outlet that I had very little wood left to screw into. I ended up having to run one screw though the outlet cover to hold the bottom of the plug to the wall.

We are leaving later today for our first trip of the season, heading to Martinsville for the race. I will be using the system and learning how our different appliances use the up the battery power. I am looking forward to not having to run our generator as much as I have had to in the past.

Pic # 1 shows the original wiring of the battery compartment
# 2 shows the new junction boxes and the white outlet in front of the wall is the new 20 amp outlet
# 3 new sub panel
# 4 main panel after changes
# 4 & 6 remote and trimetric installed
# 7 unit hanging in basement
# 8 new DC lines in the battery compartment

I apologize for the pictures but I took them as I remembered to do so with my smartphone.
 

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Diamondjim

Well-known member
I'm tired just reading all the work you've done after a FULL days work.
Awesome looking install. Seems you have the bases covered, knowing how much juice the unit draws when not in use etc.

Being electronically challenged, I marvel at those that dive right in and get the job done. Good find via Craigslist as well.
 
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