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HHIDan · 12-07-2015, 05:26 PM

I recently upgraded my ME2012 to a MS2812 and my ME-RC to a ME-ARC50 and my ME-AGS to a ME-AGS-N. I now wish to install a Magnum ME-BMK to complement my setup and get a better read on my batteries' condition.
I know that I have to install a shunt which will measure the amps coming in and out of the battery bank. I was wondering about when the engine batteries are connected with coach thru the BIRD and solenoid and how this would affect the quantity of current going in and out… Through a search I think I have determined that the BMK system will treat both battery banks as one bank (negatives from both banks will run thru the shunt).
So when I drive or are on shore power both banks will eventually get connected together and will eventually reach 100% charged. When I stop driving or disconnect from shore power the BIRD disconnects the two banks (so engine batts don't drain) and the current available to the coach will be limited to the current from the coach batts. Thus the SOC might at some point indicate 75% which might represent engine batts at 95% and coach at 55%??
My next question before I dig in to install… On A side of shunt I must connect two new cables from neg side on both banks. And on the B side of shunt : all the cables that were previously connected to the Batts gnd (2Banks) from the coach 1) the – side from the MS2812 2) the – side from the Alternator and 3) the cable connected to FRAME. Does anyone know if the Alternator minus is connected to the frame directly or is it run to the battery engine GND?
Thanks in advance, additional comments welcome!
Daniel

HHIDan · 12-07-2015, 06:21 PM

I see that I may need to update my EMS?? I have:
Intellitec 50A Smart Energy Mgmt System Model 960 (load shed panel w/remote display)
Otherwise I have the following firmware in the Magnum parts:
Inverter 5.9
Remote 4.0
AGS 5.4

joes2901 · 12-07-2015, 10:25 PM

I have the BMK shunt wired to the house batteries negative terminal only; then I get accurate information about the SOC of that battery bank. I used a spare Xantrex Link-10 for the engine battery bank and as a result have accurate information about the engine batteries. The BIRD provides the charge either bank needs from solar panels, generator, or engine's alternator. I do not think Magnum would approve of using one shunt for 2 different battery banks. The battery temp. monitor should be connected to the house bank also so that the charger can compensate for the temperature of the house batteries when charging.

My AGS starts the generator when the SOC is below 70% and stops it at 90% during generator run time only. The solar panels usually bring the bank back to 100% by late afternoon.

Luv2go · 12-08-2015, 10:30 AM

I agree with joes2901. One shunt per bank is the standard, the state of charge meter depends on knowing the voltage and current through one bank.

As you have found out, having one shunt will only work if both house and chassis batteries are connected all the time, then the BMK will treat it as one bank. Having the BIRD disconnect the banks will confuse the BMK's state of charge calculation, as it will not know how much of the current is coming from the house and how much is coming from the chassis. Also, it will not know what the voltage on the chassis battery is.

Sky_Boss · 12-08-2015, 10:49 AM

There have been a couple threads on this subject. In my case I have the shunt located on the negative lead to the my MS2812. In hind sight I would relocate it to the battery bay and tie all grounds to it. PDRJohn has some good info on this.

The reason for tying all grounds through the shunt is to account for the alternator. If you had a solar system then that would also need to be put into the equation. Since my alternator is not tied into the shunt my system doesn't account for that charge when I am driving without running the generator.

HHIDan · 12-08-2015, 12:21 PM

So if I read you all correctly, I have two large GND cables going to coach batteries. I will disconnect those and put them on the LOAD side of the shunt. I will then put 2 new cables between the shunt BATTERY side and the negative posts on the coach batteries. (I also have three pairs (+and-)of smaller size cables hooked up to the coach batts, so I will run their GND end to the LOAD side of the shunt also). And then finally, I think that obviously the BATT temp cable remains on one of the batteries' gnd.

Nothing to do on engine side... And I also get how the alternator supply current will still be taken into account when the BIRD has the two banks connected together!

Thanks, a bit more confident now!

Luv2go · 12-08-2015, 01:33 PM

Quote:

Originally Posted by Sky_Boss

There have been a couple threads on this subject. In my case I have the shunt located on the negative lead to the my MS2812. In hind sight I would relocate it to the battery bay and tie all grounds to it. PDRJohn has some good info on this.

The reason for tying all grounds through the shunt is to account for the alternator. If you had a solar system then that would also need to be put into the equation. Since my alternator is not tied into the shunt my system doesn't account for that charge when I am driving without running the generator.

We're probably saying the same thing. Let me rephrase: One side of the shunt goes to ONLY the coach battery(s) negative. The other side goes to everything else that used to be connected to battery negative. This can include chassis (which will measure the alternator current), inverter, solar charge controller, house wiring, etc.

A second shunt (and energy monitor) will be necessary to measure the chassis battery current if desired, it's hooked up the same way.

Luv2go · 12-08-2015, 01:38 PM

Quote:

Originally Posted by HHIDan

So if I read you all correctly, I have two large GND cables going to coach batteries. I will disconnect those and put them on the LOAD side of the shunt. I will then put 2 new cables between the shunt BATTERY side and the negative posts on the coach batteries. (I also have three pairs (+and-)of smaller size cables hooked up to the coach batts, so I will run their GND end to the LOAD side of the shunt also). And then finally, I think that obviously the BATT temp cable remains on one of the batteries' gnd.

Yes, you got it, nothing except battery negatives go on the BATTERY side of the shunt

And yes, the temp cable goes on one of the battery terminals.

Quote:

Originally Posted by HHIDan

Nothing to do on engine side... And I also get how the alternator supply current will still be taken into account when the BIRD has the two banks connected together!

Thanks, a bit more confident now!

Scottybdivin · 12-08-2015, 09:26 PM

I know the Bird charges both house and chassis batteries, but don't they remain seperated unless you use the "boost" switch? I'm installing a ME-BMK also. My plan is to use one ground cable from the batteries to the shunt and then connect all the grounds to the load side of it.

HHIDan · 12-08-2015, 10:22 PM

Quote:

Originally Posted by Scottybdivin

I know the Bird charges both house and chassis batteries, but don't they remain separated unless you use the "boost" switch? I'm installing a ME-BMK also. My plan is to use one ground cable from the batteries to the shunt and then connect all the grounds to the load side of it.

When the BIRD is charging both banks, it does so by connecting the + sides of the two banks using a large relay/solenoid. This is the same thing as pushing the BOOST switch.

With regards to the BMK monitor, you can measure the current going in on + side or going out on - side, same difference, just easier to use the GND side mostly because of the BIRD setup.

Only the coach battery bank is monitored so yes you can connect the battery side of the shunt to the - side of the batteries and the LOAD side of the shunt to all the cables previously connected (to batt gnd). This will measure the current going in and out of the batteries as all current eventually goes thru the GND. Note that when the BIRD connects the two banks the charging device (converter or alternator) "pushes" current on the + side of each bank but the BMK only measures the current coming out of the coach bank which is what we want...

In another thread someone had mentioned to connect wires from the GND on the engine batteries to catch the amount of current from the alternator, which is not correct (and not necessary)...

Grwalker · 12-09-2015, 10:55 AM

I have a 2005 MADP. I'm also installing an MS-BMK to better monitor my 4 brand new Trojan T-105 house batteries. I'm going with connecting the two large ground cables from the inverter and house panel side to the shunt and from the shunt to the battery negative. Can I also take the 6 volt panel ground to the house side of the shunt as well? My big question though is where do I mount the shunt? Not much room, very awkward access and those BIG battery cables are a bugger to twist and turn. Thanks for the help. I watch this forum all the time.

HHIDan · 12-09-2015, 02:02 PM

Quote:

Originally Posted by Grwalker

I have a 2005 MADP. I'm also installing an MS-BMK to better monitor my 4 brand new Trojan T-105 house batteries. I'm going with connecting the two large ground cables from the inverter and house panel side to the shunt and from the shunt to the battery negative. Can I also take the 6 volt panel ground to the house side of the shunt as well? My big question though is where do I mount the shunt? Not much room, very awkward access and those BIG battery cables are a bugger to twist and turn. Thanks for the help. I watch this forum all the time.

Do you mean the 6 "watt" solar panel?
If so yes, in fact anything connected to GND side on your coach batteries should move to the LOAD side of the shunt. You may have a BTS (battery temperature sensor) (cable looks like phone cable), that one stays on the battery.

I am mounting my shunt on the back wall of my battery compartment and I plan to run 3 new cables (on the Battery side) as I have 6 6 volts (3 GND connections). Because I will use 3 cables I will use a little smaller gauge so they can move more freely when I open/close the tray.

joes2901 · 12-09-2015, 02:12 PM

Grwalker, it sounds like you are planning changes to a 10 year old system. So I would recommend going to the Magnum site and download the installation and owners manuals for the Magnum inverter/charger you own and the controller and the BMK. They will have valuable information about the firmware versions you need for them to play well together. Then read and reread the instructions and it should become clear what the better way to do the installation will be.

I would not put the shunt in the compartment with batteries that emit hydrogen gas and the resulting corrosion of connections and shunt plates. Also, have professionally made cables (I used 4-0 or 4 ought gage) with fine wires and lead tinned if available with weather tite plastic boots over where the cable is joined to the terminals. It is more expensive but cheaper to do it right the first time than replacing them after a few to several years.

Depending on the power of your inverter you can pull up to 350 amps from the battery bank when the batteries are low in the morning and you turn on the coffee maker and toaster in the morning.

HHIDan · 12-09-2015, 02:54 PM

The shunt needs to be near the batteries and the Sense Module needs to be about 4 feet from the shunt (cable is supplied and you can not replace it). I have looked at my options and I still think the best place is behind the battery tray, at the same level as the top of the batteries. Good venting. I also think that if you use a BMK and the ME-ARC50 remote you will be better handling the charge cycle and so you get less gassing... I have a small enclosed space in my battery compartment where the Spartan Bus Box is located that will be a good spot for my Sense Unit...

From the manual:
CAUTION: Do not mount the ME-BMK Sense Module in a closed
battery compartment, or in an area where water or any other liquid
can enter the ME-BMK Sense Module and cause shorting or corrosion.
The internal circuit board is conformal coated to help prevent
corrosion, but this failure is not covered by the warranty.

Info: Shunts should be mounted in an area where freely circulating
air is available. For continuous operation, it is recommended that
shunts are not used at more than 2/3 of their rated current. If this
is not possible, adequate forced ventilation should be provided to
keep the shunt operating temperature below 60°C.