I though it was simple to change out the inverter

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I though it was simple to change out the inverter

December 11, 2020, 06:45:41 pm

I am in the process of getting ready to change out my freedom 25 inverter to my newly acquired Magnum 2812.
Investigating the unit bracket, which I have been told requires significant modification (I am NOT a welder so this should be interesting) I noted the unit mounted behind it on the same bracket.
Can someone advise what this is as it is mounted in such a way that I may have to remove it to get at the inverter.
Help would be appreciated.

Re: I though it was simple to change out the inverter

Reply #1 – December 11, 2020, 06:47:33 pm

one more pic..

Re: I though it was simple to change out the inverter

Reply #2 – December 11, 2020, 06:57:29 pm

Looks to me to be your 12 volt air compressor.

Re: I though it was simple to change out the inverter

Reply #3 – December 11, 2020, 07:31:14 pm

is it common for this to be installed on the same bracket as the inverter???

Re: I though it was simple to change out the inverter

Reply #4 – December 11, 2020, 07:49:29 pm

The compressor is behind the inverter but I don't remember it being on the same bracket as I know I didn't take the compressor
out when I modified the old bracket. Check closely as their may be two brackets.

Re: I though it was simple to change out the inverter

Reply #5 – December 11, 2020, 08:44:40 pm

looks like it is on the same bracket

Re: I though it was simple to change out the inverter

Reply #6 – December 12, 2020, 10:34:27 am

Quote from: dicksop – December 11, 2020, 06:45:41 pm

I am in the process of getting ready to change out my freedom 25 inverter to my newly acquired Magnum 2812.
Investigating the unit bracket, which I have been told requires significant modification (I am NOT a welder so this should be interesting) . . .

A professional welder will have a truck with everything he needs mounted on it. Id est, he'll come to you.

Or you can pay $850 for a reasonable arc welding unit and take a course.

Re: I though it was simple to change out the inverter

Reply #7 – December 12, 2020, 12:11:43 pm

You can save yourself some hassle and just mount it on the wall.
jor

Re: I though it was simple to change out the inverter

Reply #8 – December 12, 2020, 03:33:30 pm

the wall installation sounds interesting...do you have any more info on that...will the wall support it? what modifications etc are nesseary. can anyone offer up any pics of a Magnum wall mount??

Re: I though it was simple to change out the inverter

Reply #9 – December 12, 2020, 05:51:15 pm

Quote

can anyone offer up any pics of a Magnum wall mount??

Here's a photo of a Magnum wall mount in a 99 320.
jor

Re: I though it was simple to change out the inverter

Reply #10 – December 12, 2020, 06:41:34 pm

Here is another wall mount option that shows it in a vertical orientation. Note that a hood needs to be added to protect the area overhead. This location kept the battery cables as short as possible and allowed room for the Magnum Mini panel which includes an inverter A/C bypass switch and a 250 amp DC circuit breaker, A Midnite Solar Classic 150 controller is mounted on the side of the Mini Panel. The white fiberglass covered DC circuit breaker panel has been moved to the basement ceiling.
Don

Quote from: dicksop – December 12, 2020, 03:33:30 pm

the wall installation sounds interesting...do you have any more info on that...will the wall support it? what modifications etc are nesseary. can anyone offer up any pics of a Magnum wall mount??

Re: I though it was simple to change out the inverter

Reply #11 – December 12, 2020, 08:42:11 pm

I was wrong the inverter and the compressor are both in the same frame. I must of undone the four bolts holding the compressor frame to the inverter frame and then hung it up to remove the inverter frame to rebuild it. I widen the front and welded taps on the
side. You now have different options on how the hang the inverter.

Re: I though it was simple to change out the inverter

Reply #12 – December 13, 2020, 07:53:19 am

I have a friend who is a retired welder who modified my bracket-it just needs to be an inch wider. Easy job-look for a local welder.

Re: I though it was simple to change out the inverter

Reply #13 – December 29, 2020, 12:06:57 am

So in checking my battery connections to buy the correct ones for my Magnum 2812 (they state 4/0 are correct)
I discovered some strange wiring done on my coach. The Magnum manual is fairly straight forward with the connections from
the Inverter to the batteries (negative and positive) with the directions saying the wiring is direct to a shunt (installing the Magnum ME-BMK)then to the negative from the inverter. The positive is the same thing with cable from inverter to fuse then to positive on battery.

As you can see from the first AND second picture on my Freedom 25 inverter I am replacing, the positive cable (3/0) comes out of the inverter then goes towards the aqua hot then loops back (4-5 feet) and then into the fuse block. It then comes out of the fuse block and loops down into some sort of positive "DISTRIBUTION BLOCK" and THEN on to the battery. (another 5 feet)

The negative come off the inverter, goes out and towards the aquahot and then loops back (4-5 feet) to a "shunt" of some sort and
then on to the battery (another 4-5 feet) third picture

It looks like the power distribution terminal by the fuse handles ALOT of power cables etc

My questions are should I be using the same distribution block as it seems the power goes through it and then to the fuse.
also the shunt shown for the negative.....does that replace the shunt included the Magnum ME-BMK??? OR do I use that block..

It seems that I am going to have to purchase MANY different lengths of each positive and negative cable with different terminal ends for each.

Seems like a mess...considering the manual for installation is fairly straight forward...
Any help would be appreciated..

Re: I though it was simple to change out the inverter

Reply #14 – December 29, 2020, 01:23:43 am

I stayed with 3/0 wire 4/0 is better. That extra wire that loops back and forth I shortened as I want the wires to be as short as
possible. The rest of everything else I think I used. I will take some pictures tomorrow afternoon and post for you.

Re: I though it was simple to change out the inverter

Reply #15 – December 29, 2020, 01:36:56 am

Seek professional help, one bad connection could let the smoke out. Just sayin.

Re: I though it was simple to change out the inverter

Reply #16 – December 29, 2020, 09:48:12 am

On the two I've done, I switched to 0000 but if my setups were like yours I would have stayed with the 000. Many here have replaced the factory unit with a Magnum and have not upgraded the cables.
jor

Re: I though it was simple to change out the inverter

Reply #17 – December 29, 2020, 10:49:13 am

If Magnum says use 4/0 cable between the battery and the inverter then use it. Usually they give you some length specs as well. For the purposes of determining cable size you need to know maximum amps and the total length of cable from the battery tomthe inverter/charger and back to the battery.

Wiring diagrams often make the task look simple but cables need to go around everything else to get from point A to point B. Foretravel probably followed best practice at the time but today the maximum number of power lugs on one post is three. And when you go from 3/0 to 4/0 the lugs get bigger and thicker. Often to the point where the post will not be long enough.

You can add a post or two with short jumper cables between them to get more post capacity or replace the post with a high amp capacity bus bar. Verify that the big lugs will fit on the spacing of adjacent posts.

Here is a 3 stud 650 amp bus bar
BEP Marine Pro Installer 650 Amp, 3-Stud Heavy Duty Bus Bar
And a 4 stud 500 amp one
BEP Marine Pro Installer 500 Amp, 4-Stud Heavy Duty Bus Bar
Marinco makes link bars to make close connections between devices without having to make a very short cable.
Marinco Link Bars - Pro Installer

You can make two cable leave a post going in the same direction if one lug is down and the next up.

Use a very thin coat of electrically conductive grease on the posts and lugs to keep then free of any corrosion.
NO-OX-ID "A Special" Conductive Terminal Grease

Use a torque wrench to tighten to spec.

You can see the link bar between the bus bar and switch. I used two stacked based on cross section area and maximum possible current. Link bars to fuse block as well. I used a short cable to the shunt because it was significantly different in height than the adjacent switch. Since everything is mounted on a panel I could have made the panel thicker under the switch and other parts to match the thickness of the shunt. Mounting parts on a panel and them mounting the panel in the coach is an easy way to do this.

Re: I though it was simple to change out the inverter

Reply #18 – December 29, 2020, 12:14:46 pm

When I changed my inverter from the old Freedom to a Magnum 2812, I only changed the connections into and out of the inverter. I did not change/upgrade the wires between the battery and the inverter.

I am sure my wires may be under sized, but as long as I am not pulling maximum amps, they are probably ok.

Re: I though it was simple to change out the inverter

Reply #19 – December 29, 2020, 12:45:20 pm

Unless you plan on running your microwave and coffee maker all at the same time on your inverter, 3/0 will be fine. A lot of folks have done some wonderful upgrades to the DC systems in their coach to fit their needs. But keep in mind what you had worked for 30+ years.

Re: I though it was simple to change out the inverter

Reply #20 – December 29, 2020, 02:17:18 pm

Can I use the same shunt that is there for my ME-BMK I am installing?

Re: I though it was simple to change out the inverter

Reply #21 – December 29, 2020, 03:21:18 pm

Update on my 99 the DC cables feeding to original freedom inverter are 2/0, so insufficient for a 2812, at full output. With that said I suppose you could still use them with the fuse that is currently protecting them. That would of course limit the output of the 2812. But unless you
Plan on living on your inverter you will rarely use its full output. I think my microwave pulls 145 dc amps. Upgrading to 4/0 from the batteries would be the proper way to do it.

Re: I though it was simple to change out the inverter

Reply #22 – December 29, 2020, 05:29:34 pm

Bruce, if you already have 2/0 cables run a second set along side of them to increase total wire cross section. They should be pretty close to the same lengs to inimize differences in resistance. If younhve to use a 4/0 into the Magnum, run the 2/0 pair to a post nearby and a short 4/0 into the inverter.

Re: I though it was simple to change out the inverter

Reply #23 – December 29, 2020, 06:08:40 pm

Quote from: dicksop – December 29, 2020, 12:06:57 am

The negative come off the inverter, goes out and towards the aquahot and then loops back (4-5 feet) to a "shunt" of some sort and
then on to the battery (another 4-5 feet) third picture

...
Any help would be appreciated..

The "shunt" is a precision resistor, in your case calibrated to handle 500 Amperes because running more at more than 50% of capacity makes it get too hot.

When you run electricity through a resistance, a voltage develops across the resistor. This voltage is directly related to the amount of current, measured in Amperes and that tiny voltage is what your device uses to tell how much current is flowing.

You're overloaded trying to understand everything at once. Take it one circuit at a time and it will soon seem easy. And yes, you will "discover some strange wiring done on your coach."

Re: I though it was simple to change out the inverter

Reply #24 – December 29, 2020, 06:36:31 pm

Hear are the pictures I said I would send. The shunt I changed as I had a new one but the were exactly the same. When I bought
my coach All the inverter and all the solar came with it but not installed. I don't know if you are changing your batteries but the
silicone batteries is what I choose as they work the same at 40 below as they do in the summer. They are sold out of Calgary and
the guy I dealt with is Gordon at 403 240 2400

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