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Old 08-22-2015, 12:02 PM   #1
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Magnum Charg/invert problem

Arrived at the boat last night to find the refrigerator warm and no 120v systems running. The panel for the Magnum Charger/Inverter (ME 2512) is flashing and displays "AC Backfeed". This happened one other time in early June. At that time, we cycled through shutting everything down and unplugging/restarting shorepower a couple times and the system reset and had run fine for the past couple months. Last night, no joy. I did get it to reset and start charging the batteries a couple times, but after a minute or so, it would shut down and resume the same error. A conversation with the PO indicates he had this problem previously, but thought it was solved. (boat new to us + 6 mo). He has no idea of what was done last time. A brief search online last night based on other folks problems indicate it may be a circuit board issue.

The frustrating thing is it appears that most of my power runs through the Magnum before hitting the panel. Meaning, I could not use most routine power items on the boat on the 120v side. I even disconnected the shorepower and fired up the Genny and still had the same problem. I also disconnected the battery bank going to the unit to see if it was somehow involved. No resolve.

What concerns me is that my ability to use 120v power on my boat is tied to the functioning of an electronic device.

Depending on what I find and the cost of fixing/replacing - I may do away with this combo unit. I really have no great need for an inverter anyway. I'd rather have the power from shore or gen hit the panel, be distributed, and then have a charger (or 2) running to charge up batteries when needed.

So, back home stewing. Any input welcome.

Anybody know a good Boat electrician in San Diego/SoCal?
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Old 08-22-2015, 12:50 PM   #2
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Call Magnum on Monday, they are very helpful.

I suspect the thing wasn't installed correctly . AC Backfeed means there is another AC source tied in somewhere downstream of the inverter's AC output. What kind and configuration of AC source switching does the boat have?

The fix should be very simple.
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Old 08-22-2015, 01:30 PM   #3
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It has been on the boat roughly 4 years (of course after the 3 year warranty! ) and the previously very intermittent nature, I'm not sure if it is an installation issue - but could be. Also, after resetting and attempting to run with nothing turned on makes me wonder if it isn't internal to the unit. Being so new to the boat and with electrical/electronics being my very weakest point... not sure how much I can do without getting a well-paid professional electrician on board. Doesn't help that she's 2 1/2 hours away!
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Old 08-22-2015, 01:44 PM   #4
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That's why I asked about switching, I suspect there is a link to the original panel somewhere. Don't worry about the warranty, they can still help you and probably recommend a tech in your area. If we had pictures of your service panel(s) it might help us help. I'd guess that the least likely source of the problem is the Magnum unit itself.

Out of curiousity, what model is your inverter and remote?
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Old 08-22-2015, 02:08 PM   #5
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Quote:
Originally Posted by caltexflanc View Post
SNIP...
Out of curiousity, what model is your inverter and remote?
ME 2512 with I believe an ME-RC remote.
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Old 08-22-2015, 06:00 PM   #6
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I have the 3000 watt model of your unit. First thing to understand is that the units brain runs off 12 vdc not 120 vac. So the fact that your battery is flat may have something to do with it not restarting properly. I had one hiccup with mine that was similar but different. It wouldn't go into charging mode and gave me an error code. Tried restarting it several times by pushing the restart button on the main box not the remote display, no joy. So I turned off / discounted the battery bank and shore power for 15 minutes. This wiped all of the memory that was volital (may not have said that correctly). Turned the battery on and the shore power. Held the power on button on the main unit in for 1 minute even though the green light came on. Unit it functioned normally and no reoccurrence. The 15 minute power off and holding the button for 1 minute were on the advise of a Magnum Energy dealer as I seem to remember. Not sure if this will work with a battery near dead.

The other recommendations would be to try the above with all the breakers off except the one for the charger inverter. If that works, after 10 minutes try turning on one additional breaker at a time to see if there's something the inverter doesn't like.

If your getting an AC back feed code, maybe there is something a miss in the boat grounding setup. Do you have a galvanic isolator in the boat between the shore power receptacle and the breaker panel?

Ted
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Old 08-22-2015, 06:20 PM   #7
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I had to bypass my inverter completely on the maiden trip aboard our boat (equipped with Magnum Energy MagnaSine MS2812.) The knucklehead diesel mechanic had left a hose clamp loose, generating a nice stream of saltwater right into the top of the inverter. Of course, that let all the smoke out of the MagnaSine.

I bypassed the inverter completely by first killing the 120V power to the inverter at the panel then removing all the in and out 120V cables from the inverter. Twisted the matching pairs together and turned the breaker back on. I was now powering all the 120V appliances directly from the generator or shorepower without using the inverter's "pass-through" feature. Only took a few minutes to bypass, but allowed us to continue on our 3-day trip using the big alternators on the diesel mains to keep the 12V system charged.
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Old 08-22-2015, 06:24 PM   #8
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If the battery bank is too low, then the low voltage cutoff will be what turns the inverter off and that would be the fault code on the remote. First step here in my opinion is to make 100% sure there is no AC backfeed, which is fairly easy to suss out.
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Old 08-22-2015, 07:17 PM   #9
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Thanks for the replies. I wish I had the knowledge to better answer your questions (and help you help me trouble-shoot this). Wish I had more time with Calder's book! I'm going back and forth between reading your questions and responding. So, in no particular order:

Caltexflanc - In regards to switching. Not sure which switching you refer to. On the Mainship's electrical panel I have breakers that allow me to take power from the shorepower, or the generator. Sorry if I am not clear on your question.

O C Diver - In regards to the depleted batteries, I had a similar concern, and ran the engines for a while in order to charge batteries from the alternators. This brought the house bank just up to 12v (based on panel gauge). (don't like dock running... but trying to resolve.)

I did disconnect everything and waited several minutes before retrying. I also held the power button in on the main unit as the manual says until the power light flashed rapidly for a reset.

All attempts were made with everything (all breakers) off to ensure there were no backfeeds.

Several times the system would reset, and I would actually enter a charging mode... whereupon it would fault and show AC back feed after anywhere from 30 seconds to a couple minutes. Other times, it would go immediately to fault.

kraftee: I thought about bypassing the Magnum and getting power so we could continue our weekend. But, I didn't want to disrupt anything that may be the causation. Rather let it sit unmolested until someone knowledgeable can walk through it.

Re: Galvanic Isolator. Hmmm... wish I knew. Even if I was on the boat today, I wouldn't know what it looked like. Again... I have a very basic understanding of 12v/120v systems. I do pick stuff up quickly. Just have not had the chance to go through the boat with someone who knows all this stuff and can explain it. Or specifically how my boat is wired.

There has been no work done on the boat. Nothing modified or added to the electrical system. Nothing plugged in. Apparently it has had this intermittent problem for some time according to what I now understand. I had no problems from December to June before I first saw it happen. Reset at that time after some playing with it. Had I better known the history, I would have had it worked on a couple months ago! But sometimes we hope it is a fluke and all is well. I should know better.

Need a good electric guy or knowledgeable guru to sort it all out, then explain it to me!
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