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Topic: I though it was simple to change out the inverter (Read 1555 times) previous topic - next topic

I though it was simple to change out the inverter

Reply #25 –
My project shortly is to swap the Heart Freedom 25 to a Magnum 2812 (possibly install MBK Battery monitor with it)

I AGAIN discovered some strange wiring done on my coach.

In rechecking the wiring yesterday I discover that the pos and neg wiring coming from the inverter are both 2/0 wiring....the positive going towards the aqua hot and then looping back (4-5 feet) and then to the fuse. It then comes out of the fuse block and loops down into some sort of positive "DISTRIBUTION BLOCK" and THEN a 3/0 cable goes to the battery. (another 5 feet) (Pic attached with (red arrow)going into the fuse and (blu arrow) out .

The negative 2/0 cable comes off the inverter, goes out and towards the aquahot and then loops back (4-5 feet) to  a "shunt" of some sort and then a 3/0 cable on to the battery (another 4-5 feet)  (green 2/0 arrow in and purple arrow 3/0 wire out)

SHOULD I BE CHANGING OUT THE 2/0 CABLES TO MATCH THE 3/0 CABLES??
This does not look like s PO change. This looks like it came straight from the factory like this.

It Seems like a mess...
Any help would be appreciated..
Peter    Alberta Canada
'98 U320 40'  Build 5359 M11 450 HP, Aqua hot, Blu Ox

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

Reply #26 –
Looks about like mine. I'm following closely as a change will be in my future. With that said I think your newinverter recommends 4/0, instead of new 4/0 cables you may see if you can just run another 2/0
Bruce, Linda, and Macy
Zoey RIP 1/20/19
1999 U295 40' build #5400
2017 silver Jeep Wrangler, 1260 watts of solar on top
Moving around the country

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

Reply #27 –
Foretravel was never generous on cable sizing. Cable sizes are based on how much current is going (can go) through them and how long the cable is there and back again.  In this case tor 2/0 cables went to inverter (provide power to invert going one way and to charge going the other way) and back.  For the power consumption of the Freedom 25 and it's charging capacity a 2/0 cable was probably sufficient when it was built.  The Magnum can probably pull more power to invert and push more to charge.

From the MS2812 manual...

https://www.magnum-dimensions.com/sites/default/files/MagDocs/64-0007-Rev-D-MS-Series_Web.pdf

Use Table 2-1 to select the DC overcurrent device needed based on the recommended minimum wire size.
Use 4/0 cable and a 400 amp time delay fuse. Use a #6.

2 2/0 cables of equal length will work in place of a single 4/0 cable.  Slightly bigger total cross section of wire.  They should be about the same length so their resistance is about the same and they each carry an equal load.  What's equal?  Maybe within a half inch in 5 ft?  About 1%.  This assumes that you will have no more than three cables per post which is the current standard.  It was likely different when our coaches were built based on what FT did.

Follow the recommended installation insteuctions.  See Table 2-2 if your cables re longer than 5 ft. If longer than 5 ft, they require 2 4/0 cables.
Roger Engdahl and Susan Green
2001 U320 3610 #5879 (Home2) - 2014 Jeep Cherokee or 2018 F150
Hastings, MN

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

Reply #28 –
I'm in the process of changing out my dead Prosine to a new Victron Multiplus 3000. 
I thought I'd be finished by now but had to order 2 sets of 2/0 short cables to extend the battery cables going into the new inverter.  BUT, a really big BUT, when I was installing one of the new cables the wire pulled out of the terminal.  While I was looking at the bare wire dumbfounded the other terminal fell off!  I took another cable and gently tugged on the terminals and they fell off also.  They were NOT crimped properly and could have caused major problems.  I contacted the manufacturer who claims these are made in USA and they admitted these were defective crimps from their factory.
So check your wires before you install them.  New cables from a different supplier should be delivered today.
Forest & Cindy Olivier
1987 log cabin
2011 Roadtrek C210P
no longer 1999 36' U320 build #5522
2013 Rzr 570 & 2018 Ranger XP1000
2006 Lexus GX470
2011 Tahoe LT 4x4
Previous 1998 45' 2 slide Newell, 1993 39' Newell

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

Reply #30 –
Quote from: folivier –

So check your wires before you install them.  New cables from a different supplier should be delivered today.


I'm working on the Foretravel now, having finally accepted that I will never reach the top of my to-do list.  I had a broken battery terminal on the Studebaker, on a #2 cable.  I went to order one from a specialist and the description said that it was soldered.  I bought a cable 5" too long at NAPA and when I went to install it saw that it was a #4.

I'm waiting for this to arrive:

https://www.foreforums.com/index.php?action=dlattach;topic=40720.0;attach=101103;image
1992 Foretravel Grand Villa
U225 SBID Build No. 4134
1986 Rockwood Driftwood
1968 S.I.A.T.A. Spring
1962 Studebaker Lark
1986 Honda VF700C
1983 Honda VF750C
Charlie, the Dog was broken out of jail 24 Oct 2023
N1RPN
AA1OH (H)e who must be obeyed.

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

Reply #31 –
When I installed the 2812 into my coach I had 3/0 cable right through and the cables from the inverter where way longer than
necessary so I shorten them. 4/0 would have been better.
Peter and Frieda Morin
1999 36ft. U320 Foretravel
Build # 5436
1998 Suzuki Sidekick Sport

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

Reply #32 –
Cable Making Hints

Whether you use an FTZ crimper or a hydraulic crimper get several lugs of the size you are going to use and make a half dozen or so practice crimps.  I hve both types and think it is easier to over crimp with the hydraulic crimper.  There should be pictures of correct crimps.  An over crimp will pinch the lugs between the dies and the result is obviously not uniform and symmetric.

With an FTZ crimper if you use the right die set you get consistent, uniform crimps. I usually rotate the crimp 90° and crimp it again to press down any edges the might come through the heat shrink tube.

I like to use two pieces of adhesive lined heat shrink tube.  One about a 3/4 inch longer than the first.  Slide the longer one on the cable first and then the second one.  Crimp on the lug.  Slide the first tube onto the lug so that it covers the tube of the lug, the end of the cable covering and about a half inch of the cable cover.  Shrink, cool. Slide the other longer piece over the first one so that it extends past the ends of the first tube on either end. Heat and shrink.  You will see adhesive ooze out around the end of the tube.

When making your own cables you can make the ends oriented the best way for your application.  Rather than twisting the cable to make it fit, rotate the lug before you crimp it on so that the orientation is right without twisting the cable.  Lay the cable flat on the bench with a lug at each end, mark the cable and the lug to get the orientation right.

Two cables with lugs rotated 180 degrees from each other will fit on a post with the cables aligned. 
Roger Engdahl and Susan Green
2001 U320 3610 #5879 (Home2) - 2014 Jeep Cherokee or 2018 F150
Hastings, MN