Connecting a magnum 2012 inverter/charger

dcwettstein

Well-known member
I have a MS 2012 Magnum Inverter/charger. In my 3160 Big Horn the Shore power is right next to where I want to mount the Magnum. I will be removing the existing charger and using those wires for the DC side. My question is If the wires were good for the present charger why would I have to increase the wire size for the new inverter/charger.
 

Jim.Allison

Well-known member
Because you are doing both, the same wires that power the inverter are the same wires that are being used to charge the batts. The DC feed into the rig (the existing wires that feed the DC fuse box and other DC component) will remain the unchanged and should attach to your battery the same way as before. The wire size is determined not for the charging so much as what the inverter requires to make the AC electricity to 2000 watts or really the max load that can be achieved by the inverter on a temporary basis. Do I have the idea of your question correct?

I have a MS 2012 Magnum Inverter/charger. In my 3160 Big Horn the Shore power is right next to where I want to mount the Magnum. I will be removing the existing charger and using those wires for the DC side. My question is If the wires were good for the present charger why would I have to increase the wire size for the new inverter/charger.
 

dcwettstein

Well-known member
I think you have it correct. There are 2 wires from the existing Charger that go to the DC distribution Panel then go to the battery. I would like to use these same two wires to hook up to the DC side of the inverter/charger. I know the AC side can be the same wires it is the DC wires I am wondering about. I feel if the existing wires were good enough for the charger why would they not be good enough for the inverter/charger.
 

scottyb

Well-known member
He has a Magnum MS 2012, which is probably what I am leaning toward. The manual says max current of 267A and recommends #2/0 for runs up to 5', #4/0 up to 10', and 2 x #4/0 10' - 15'. If you place it where the converter sits now, you are going to be close to 10'+.
 

Jim.Allison

Well-known member
Does it not use the same cables to charge as it does to power?

I capped and taped the leads from my charger, bundled them up and taped them to my black tank pipe to secure them. I removed my charger altogether. It's in my garage at home. Since then, I realise that I could have left it in and hooked up as an aux charger. His new magnum will not have any place to hook up such batt charging leads anyway. This is supposition on my part.
 

scottyb

Well-known member
Correct, it does charge through the same cables. I would leave the Converter where it is and just unplug it. If anything happens to the Magnum, everything is still in place. Then find a better location, hopefully closer, to install the Magnum. Here's their simple wiring diagram.
 

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Jim.Allison

Well-known member
I was thinking about reinstalling mine and assigning a separate breaker with a switch, but yes just unplug it, bundle up the cord so that you can get to it in the event you need it. I think I will put mine back in.

I notice that my progressive has a special chord on it, a vertical, horizontal and a ground. What is that about?


Correct, it does charge through the same cables. I would leave the Converter where it is and just unplug it. If anything happens to the Magnum, everything is still in place. Then find a better location, hopefully closer, to install the Magnum. Here's their simple wiring diagram.
 

marvmarcy

Well-known member
I have a MS 2012 Magnum Inverter/charger. In my 3160 Big Horn the Shore power is right next to where I want to mount the Magnum. I will be removing the existing charger and using those wires for the DC side. My question is If the wires were good for the present charger why would I have to increase the wire size for the new inverter/charger.

For an excellent explanation of inverter/charger installation look at this website.

Why would you have to increase the wire size? Because you are now pulling much more power from the batteries, not just charging them. The PD Charge Wizard used in Landmarks and Bighorns charges at 80-90 amps but the MS2012 can pull over 250 amps from the batteries and charge at much more than 90 amps. The long wires in your Bighorn will also restrict power draw, and the original one or two batteries will be inadequate to handle the capacity of the MS2012 for more than very brief use.

I installed a MS2812 in my Landmark with a large battery bank, subpanel, monitoring/control panel and solar charging. The original 12v batteries and charger remain untouched as they are inadequate for my 120vac needs but still handle all house 12vdc needs.
 
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Jim.Allison

Well-known member
Yes I have 0000 cables on a 3012 and run a little less than 10 feet, but I have two fuses and a selector switch. My microwave will pull down significant current. I have to set the xantrex cutout to accept 5 minutes at 11.7 V or else the inverter will shut down thinking the batts are under charged. They are not, but the xantrex thinks they are because of the resistance of the cables at that current level is only providing that much at the xantrex. Run long AC and short DC.

For an excellent explanation of inverter/charger installation look at this website: www/jackdanmayer.com.

Why would you have to increase the wire size? Because you are now pulling much more power from the batteries, not just charging them. The PD Charge Wizard used in Landmarks and Bighorns charges at 80-90 amps but the MS2012 can pull over 250 amps from the batteries and charge at much more than 90 amps. The long wires in your Bighorn will also restrict power draw, and the original one or two batteries will be inadequate to handle the capacity of the MS2012 for more than very brief use.

I installed a MS2812 in my Landmark with a large battery bank, subpanel, monitoring/control panel and solar charging. The original 12v batteries and charger remain untouched as they are inadequate for my 120vac needs but still handle all house 12vdc needs.
 

marvmarcy

Well-known member
Jim, I put my MS2812 as close as possible to the batteries (4 large 6v). My longest 4/0 run is less than 3 ft of high-grade fine-strand welding cable. The batteries are in a vented box and there is a metal wall between the battery box and MS2812. I also used conductive "grease" to improve each connection and prevent corrosion. It would be better if I had 6 or 8 batteries and more solar charging power, but I can leave the inverter on during the day when dy camping and stay around 90% as long as I don't use the microwave too much. I kept all other high-current draws off the inverter subpanel. I have the inverter programmed to shut off below 12.2v, and it seldom drops below 12.4v. On a sunny day I'm solar charging at 15-18 amps off two 100w panels aimed at the sun, so two more panels would help. The batteries get topped off each night by the generator.
 

branson4020

Icantre Member
Guys,
Remember that voltage drop is not just about the cables. Its a fact of life inherent in the physics of the battery. I've attached a chart showing battery voltages at different discharge rates.

Jim, as an example, let's say you have a 90% charged 300A battery pack. If you put a 100A load on it, the voltage will instantly drop to about 11.7V. You should measure the voltage drop across your cables under a heavy load and see how bad they really are.

View attachment Graph.pdf
 

Jim.Allison

Well-known member
My system works perfectly, but I have been looking for that conductive grease. What brand, how does it work and where did you get it. A lot of resistance can be eliminated by making good, solid connections. I have 2 12v in parallel, so for the whole circuit I have about 14 connections. The wire is nothing compared to the connections as far as resistance is concerned.

The panels I use are shade tolerant and do not need to be pointed at the sun, I have them glued to the top of my rig. They will keep up with anything I use during the day. A microwave is not typically used over 5 minutes in any meal preparation, perhaps 8 min if you are preparing two frozen TV dinners, of course my panels have to put back that usage but they have no problem doing it, I can get back to 100% easily. All the other AC appliances can be run appropriately and the solar charger can keep up with power usage and still be 100% all day long. Then at night I start with 100%. I don't know how many days I can go without sunshine, I could use 240 amp hours in that circumstance. I would rather only use 50% or 150 amp hours, but I understand that you can deplete 80% now and then without harming the batts to much. I recently tweaked the system and will be taking it out this fall, I will see how it performs then.

Jim, I put my MS2812 as close as possible to the batteries (4 large 6v). My longest 4/0 run is less than 3 ft of high-grade fine-strand welding cable. The batteries are in a vented box and there is a metal wall between the battery box and MS2812. I also used conductive "grease" to improve each connection and prevent corrosion. It would be better if I had 6 or 8 batteries and more solar charging power, but I can leave the inverter on during the day when dy camping and stay around 90% as long as I don't use the microwave too much. I kept all other high-current draws off the inverter subpanel. I have the inverter programmed to shut off below 12.2v, and it seldom drops below 12.4v. On a sunny day I'm solar charging at 15-18 amps off two 100w panels aimed at the sun, so two more panels would help. The batteries get topped off each night by the generator.
 

marvmarcy

Well-known member
Jim, There may be others but I use NoALOX. It is primarily for coating a copper/aluminum connection to prevent electrolysis and assure a low resistance connection. I used very large aluminum connectors on the 4/0 copper cable to get a large-area connection. This required coating the copper wire and rubbing the NoALOX into the strands. I also coated every conductive surface. I use it on all my vehicle batteries - tractor, two cars and two trucks. You can get it at HD, Lowes and any electrical supply.
 
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