ME-ARC, ME-BMK upgrade with PCS

[dp7]

After procrastinating as long as I could, I finally decided to get on with upgrading my Magnum ME-RC to ME-ARC & add the ME-BMK. There is a Precision Circuits PCS & ME-AGS-N currently installed in the coach. After the first of the year I plan to add solar, but that can of worms will be sorted out later. For now I am interested in using the AGS based on SOC rather than voltage.

A search on the forum turned up a few posts that indicate Magnum recommends disconnecting the PCS from the data bus when used with the ARC & BMK. I really didn't want to lose the features of the networked systems so I called Magnum tech support to verify the issue. Tech support confirmed that these components will be problematic if networked together. I also contacted Precision Circuits but have not heard back from them yet. This is quite confusing since some posts indicate that others have left them networked, apparently without issue. Perhaps the key to the networking question is the manner in which the components were connected. Some used the star configuration while others daisy chained them. So after reading through the Magnum manuals, talking with Magnum tech support & reading many posts on the subject, I made a wiring diagram (attached) that reflects my interpretation of how the components should be hooked up.

For those that have trail blazed this upgrade, I have the following questions:

1. Is my attached wiring diagram correct?
2. Have you had any long term incompatibilities between the PCS & Magnum systems?
3. Did you add a cut-off switch between the inverter & battery positive terminals?
4. Is it advisable to run all +12v battery connections off the same battery post? (I assume the small voltage drop across the battery interconnect cables is insignificant)

I appreciate any insight you could share!

[NWIP]

I recently completed the install of BMK with the guidance provided by members of this forum. I did not disconnect the PCS and haven’t had any ill-effects to date.

I have a different coach so more batteries, and did move all positive to terminal opposite of my combined ground going to the shunt. Below I included link to Redbaron73 post in which he provides a link to an excellent document. He explains the need to do this better than can.

http://www.irv2.com/forums/f103/simp...73-441768.html

[tnedator]

Please let us know how you proceed and the results. I'll admit that I have a BMK in hand, as I bought an ARC, BMK and MagWeb, and while I initially didn't install the BMK as I was going to wait until things got a bit cooler, this is now the second thread I've read about it being incompatible with the PCS system.

Since I don't boondock and likely never would unless I had to stop at a Wal-mart with no other choice, or did a Harvest Hosts thing and couldn't run the generator, but still thought the extra info would be handy. However, if I have to choose between load shedding and the BMK giving me state of charge, I'm going to choose load shedding, as the Ventana generator can't handle all the on board electric.

I am correct in that if the PCS is removed, then load shedding is gone. Right?

[dp7]

Originally Posted by NWIP

I recently completed the install of BMK with the guidance provided by members of this forum. I did not disconnect the PCS and haven’t had any ill-effects to date.

I have a different coach so more batteries, and did move all positive to terminal opposite of my combined ground going to the shunt. Below I included link to Redbaron73 post in which he provides a link to an excellent document. He explains the need to do this better than can.

http://www.irv2.com/forums/f103/simp...73-441768.html

Thanks for the feedback & link. I will check it out. Did you use a buss bar for the negative cables or just connect them to the shunt bolt? Was the shunt installed in the battery compartment? Curious if there would be a problem with it getting wet.

[dp7]

Originally Posted by tnedator

Please let us know how you proceed and the results. I'll admit that I have a BMK in hand, as I bought an ARC, BMK and MagWeb, and while I initially didn't install the BMK as I was going to wait until things got a bit cooler, this is now the second thread I've read about it being incompatible with the PCS system.

Since I don't boondock and likely never would unless I had to stop at a Wal-mart with no other choice, or did a Harvest Hosts thing and couldn't run the generator, but still thought the extra info would be handy. However, if I have to choose between load shedding and the BMK giving me state of charge, I'm going to choose load shedding, as the Ventana generator can't handle all the on board electric.

I am correct in that if the PCS is removed, then load shedding is gone. Right?

As I understand it, separating the Magnum & PCS systems does not affect the PCS load shedding feature. But you will lose two of the combined system functions. First is cutting back charge current during times of shore power shortfall. The other lost function is inverter assist during shore power peak demands.

[DG86]

We have the all-electric option on our 17 Ventana so we have 8 AGM batteries (EVGC6A-B) and the higher wattage inverter (MS2812). Newmar agreed to install the ME-BMK for us at factory pick-up so we purchased it ahead of time and brought it with us. We have had no issues at all with the PCS system and we often use the coach when we only have 20A shore power. The load shedding and inverter assist work fine. We are able to run one air conditioner on 20A and the inverter handles the brief spike. However, if you try to use much of anything else while the A/C is running, the PCS will shed it. We have since added the ME-ARC (which is a simple drop-in replacement for the ME-RC) and we use the excellent AC-IN feature which allows us to essentially dedicate the 20A shore power to the air conditioner and then use the inverter for the remaining power needs in the coach.

[NWIP]

Originally Posted by dp7

Thanks for the feedback & link. I will check it out. Did you use a buss bar for the negative cables or just connect them to the shunt bolt? Was the shunt installed in the battery compartment? Curious if there would be a problem with it getting wet.

I installed on the shunt using a longer bolt. The shunt is installed on aft wall of battery bay just below the 350A fuse. I mounted the BMK controller in the next bay aft, which on our coach is the pass thru

[redbaron73]

Inverter assist does work with the PCS, arc, and bmk.

I am not sure about the charger cutback, as I have not seen this happening. It did work on my 2013 after the PCS upgrade with the same setup, so I assumed it would work on the 2019.

All other functions work as intended

[10 fan]

My system is now different than most or all. I didn't disconnect it and everything is working perfect. Mine load shares and to my surprise it cuts back on shore power to use all of the available solar.

[dp7]

Originally Posted by DG86

We have the all-electric option on our 17 Ventana so we have 8 AGM batteries (EVGC6A-B) and the higher wattage inverter (MS2812). Newmar agreed to install the ME-BMK for us at factory pick-up so we purchased it ahead of time and brought it with us. We have had no issues at all with the PCS system and we often use the coach when we only have 20A shore power. The load shedding and inverter assist work fine. We are able to run one air conditioner on 20A and the inverter handles the brief spike. However, if you try to use much of anything else while the A/C is running, the PCS will shed it. We have since added the ME-ARC (which is a simple drop-in replacement for the ME-RC) and we use the excellent AC-IN feature which allows us to essentially dedicate the 20A shore power to the air conditioner and then use the inverter for the remaining power needs in the coach.

Originally Posted by NWIP

I installed on the shunt using a longer bolt. The shunt is installed on aft wall of battery bay just below the 350A fuse. I mounted the BMK controller in the next bay aft, which on our coach is the pass thru

Thank you for the feedback. Did either of you install a cut-off switch for the inverter?

Any issues with the shunt being exposed to moisture in the battery bay?

Is my wiring diagram correct?

[10 fan]

Originally Posted by dp7

Thank you for the feedback. Did either of you install a cut-off switch for the inverter?

Any issues with the shunt being exposed to moisture in the battery bay?

Is my wiring diagram correct?

I installed a double pole disconnect on both and 12v feed. This way pos and neg are turned on or off at the same time. I ran the chassis ground thru the 12v D.P. disconnect, that way when you turn it off and work on the batteries if you touch the pos to ground no surprise. A double pole is about $5 more if I remember correctly. I would connect all positives to the battery which you have going to the bi directional relay for a better balance. This is what I did, doesn't make it right or better.

[DG86]

Originally Posted by dp7

Thank you for the feedback. Did either of you install a cut-off switch for the inverter?

Any issues with the shunt being exposed to moisture in the battery bay?

Is my wiring diagram correct?

In my experience, there is no problem with the shunt for the ME BMK being exposed to the "weather" inside the battery compartment. I ran that way for 2 years with no problems, though I have since sealed up the bay with black-painted sheet metal - i was tired of the road grime accumulation in there and didn't really need ventilation with AGM batteries.

I also at that time placed all my positives onto a 600A buss bar and then ran a 4/0 cable from the bar through a cut-off and then onto the (+) battery terminal furthest opposite where the (-) comes in from the shunt, similar to what "10 fan" said for balance. The cutoff therefore is not just for the inverter, but isolates the batteries entirely. I also installed a buss bar for the negatives instead of having them all piled up on the shunt which I had initially. The reason for adding the buss bars was only to make it easier to install solar in the future and to make things neater.

Your wiring for the RJ-11 lines looks correct to my recollection from when I inspected after Newmar did the initial install. Again, I have a different inverter than you do, but it's probably not that different in this regard.

Best of luck in your project. I am sure you will like having a true SOC for your battery bank.

[dp7]

Originally Posted by 10 fan

I installed a double pole disconnect on both and 12v feed. This way pos and neg are turned on or off at the same time. I ran the chassis ground thru the 12v D.P. disconnect, that way when you turn it off and work on the batteries if you touch the pos to ground no surprise. A double pole is about $5 more if I remember correctly. I would connect all positives to the battery which you have going to the bi directional relay for a better balance. This is what I did, doesn't make it right or better.

Thank you for reviewing the diagram and commenting.

I first considered a double pole switch. The concern is Magnum's caution about making sure that the positive connection is removed before the ground connection is broken. So I am now thinking that two independent switches would ensure the order that the connections are broken.

Regarding the pos cables all running to a single battery terminal: Were 4 cables a bit unwieldy? Were the cable lengths long enough to allow the battery tray to fully extend?

Originally Posted by DG86

In my experience, there is no problem with the shunt for the ME BMK being exposed to the "weather" inside the battery compartment. I ran that way for 2 years with no problems, though I have since sealed up the bay with black-painted sheet metal - i was tired of the road grime accumulation in there and didn't really need ventilation with AGM batteries.

I also at that time placed all my positives onto a 600A buss bar and then ran a 4/0 cable from the bar through a cut-off and then onto the (+) battery terminal furthest opposite where the (-) comes in from the shunt, similar to what "10 fan" said for balance. The cutoff therefore is not just for the inverter, but isolates the batteries entirely. I also installed a buss bar for the negatives instead of having them all piled up on the shunt which I had initially. The reason for adding the buss bars was only to make it easier to install solar in the future and to make things neater.

Your wiring for the RJ-11 lines looks correct to my recollection from when I inspected after Newmar did the initial install. Again, I have a different inverter than you do, but it's probably not that different in this regard.

Best of luck in your project. I am sure you will like having a true SOC for your battery bank.

Thank you for reviewing the wiring diagram & commenting.

It is good to hear that you did not experience any issues with water on the shunt. Since the sensing portion of the shunt works in the millivolt range, I wasn't sure if exposing it to road spray would be an issue.

The 600A bus bars sound like a good idea. The fuse to my inverter is 300A and the fuse to the coach is 150A. I do not see a fuse on the last pos cable (between battery bank & Bi-directional isolator). So is it safe to assume that a 600A buss bar & battery cut-off switch would accommodate the sum of the currents from all three pos cables combined?

[redbaron73]

on my 2013 DSDP the shunt was in the battery bay and never had a problem. Drove and used in all sorts of weather conditions. I put the shunt in the battery bay again on my 2019.