Magnum inverter Battery Monitor

[Jerry Emert]

I replaced the xantrx inverter with a Magnum 2800 watt pure sine.  In my ignorance I ordered the battery monitor kit (ME-BMK-NS) without shunt thinking that the xantrex must have had one.  Further research seems to indicate that the shunt used by the xantrex is internal to the inverter which makes a lot of sense, not so with the Magnum.  There are several shunts in the locked electrical compartment above the batteries.  Does anyone know if one of those would be suitable to tie in to?  The DC shunt is a 50mv/500 amp shunt.  
Thanks in advance.
Jerry

[Edward Buker]

Jerry,

I think the shunts that you are seeing are actually the main house and chassis battery bank fuses. They are strip types that look like shunts. I have not installed a Magnum, my Xantrex is still chugging along. Others who have had the Magnum put in may be able to comment on this. I have not heard anyone comment on adding an external shunt as part of the Magnum install (yet).

Later Ed

[Karl Welhart]

Jerry,

I recently install the Magnum MS-2012 and did not install the external shunts you have described in your message.  In reading the notes in the Magnum Installation manual, my interpretation is that the external shunt is optional. I did wonder about other protection afforded in the system with the Xantrex ProSine installation from the factory.

[Dick Simonis]

I replaced my Xantrex with a Magnum PSW and did not have to install a shunt but the battery temp sensor for the Xantrex did not work with the Magnum.  No problem and the switch was easy.

[Jerry Emert]

The battery temp monitor was easy but it only controls the charge level coming out of the inverter.  It doesn't give you a state of charge level such as 50% full, 80% etc...  As I understand it, and my understanding could easily be flawed, you need a shunt to get a current reading to the inverter.  So I was hoping there was already one I could use in the beaver.  Still hoping someone will know.  Thanks.
Jerry

[Edward Buker]

Jerry,

I cannot imagine that the Magnum does not have circuits within it that provide voltage and current measurements being provided to the battery bank. As the voltage rises and the current tapers off you would know the charge state. The only reason that I can rationalize where there would be the need for a shunt is to watch the current being pulled from the house bank when you are no longer plugged in (boon docking) given the charger is no longer supplying current to the bank and therefor cannot measure it. That may not be such a big issue in my mind.

Later Ed

[Jerry Emert]

Ed, I couldn't imagine it either, which is why I ordered it without the shunt!  My mistake, they do not have an internal shunt like the xantrex does according to a tech that I just talked to who is an authorized repair tech for xantrex and magnum.  So thats another lesson learned.  I also learned that the xantrex is repairable if you find the right guy.  About 1100 dollars for a new board which does not make it very attractive though.  The guy I talked to has a shunt attached to his bench that he is going to let me use until I can get one.  Seems like a real good guy.  The RV Tech that I have coming tomorrow will install the one I borrowed and I can replace it when the new one comes in in about 2 weeks.  So all's well that ends well except it cost me about 50 bucks to learn this lesson.  Thats ok it will stick better if I have to pay for it, I'm just that kind of guy.  I'm not sure if I will boondock much but I want to have the option.  Thanks for your help.

Jerry, quickly becoming an experienced RV Tech.!  (LOL)

[Edward Buker]

Jerry,

I had installed a Magnum unit in a boat for a friend a couple of years back and it had the external shunt arrangement as well as the separate battery combiner. As far as needing a shunt I am still in the camp that its main purpose would be to see the discharge rate in case something was left on while running the inverter off the battery bank. I have always used voltage to determine the charge level of the batteries and your Magnum panel readout will give you that without the shunt. For lead acid batteries 12.65V is 100% charge, 12.45V is 75%, 12.24V is the 50% level which is where you would want to start considering providing a charge to prolong the life of your battery bank. 12.06V is 25% and 11.89 is 0% charge. The only trick is to stop pulling current for a bit, let the voltage settle with no load, in order to get an accurate measurement.

The Magnum unit that you chose will go to bulk charge and hold constant current until it reaches the absorb voltage at 14.6V and then it will taper the current. The absorb cycle starts at 80-90% of battery charge capacity. That last 10 to 20% of capacity can take several hours before going to float charge state. The panel LEDs and readout will tell you what is going on. In a practical sense you would start the genset to enable charging at the 12.1 to 12.2V with no load and take it through bulk charge and maybe 20 to 30 minutes of absorption if you have time. After that there is diminishing returns and the genset is no longer worth running.

The ME-ARC remote panel will provide DC current as well as DC Voltage, and what mode of charge the unit is in on the display, when charging is being done. It actually uses the AC current level being pulled by the charger to give you an accurate estimate of the DC current being put into the battery charge/coach load. The only time the shunt would come into play is when you do not have an AC source and then the DC current due to voltage drop across the shunt provides the estimate.

So living without the shunt is not a big deal but if you want it all, let no man stand between you and your shunt :-) Hope this helps.

Later Ed

[Gary Wolfer]

Onestopcustomshop.com best electric inverter man in the country. He is in Colorado Springs. Not cheap but best there is in my book.He works on all colorado county and state fire and police wiring. He does Motorhome everything.

[Jeff Watt]

As some additional info, I too had thought of getting the battery monitor kit. I figured for $170 it would be a nice addition for minimal work/cost. However when I contacted Magnum, it turned out my Magnum remote ME -RC needed a software upgrade. To get that I'd have to send it to them, not too big of an inconvenience. Then, the tech also asked about my inverter (MS2812) circa 2006. He suspected it needs a newer control board in order to properly work with an upgraded remote and battery monitor. The inverter would need to be removed from the coach, board removed and sent for a new one.

Needless to say that I didn't bother to buy the battery monitor. Someday if I am I Everett I may upgrade the equipment but since everything works well now, I don't see a lot of urgency.

One final thought, the ME-ARC remote is more advanced and combined with the network auto gen-start allows more precise starting protocols, I.e. at specific charge levels say 75%. This is in contrast to the AGS (ME-AGS-S) like the one in my coach where the starting voltages range from 10-12v; not effective as at 12v, which I think is too low, since at that point batteries are discharged to the point that potential harm may be done if repeatedly discharged to that level. Also since on my coach the genset starts from the house batteries, whether there is enough voltage left to start is questionable.

Jeff

[Jerry Emert]

Thank you all for information.  I found an authorized magnum/xantrex service guy here in Orlando, actually Sanford, who had a shunt on his bench for troubleshooting.  He took it off and gave it to me to install until mine comes in.  Great guy.  Scott at Sanford RV Repair.  What a PITA running those wires!  Everything seems to be working so far, I'll worry about the new auto gen start later.  Thanks again
Jerry