Battery Monitor Shunt

[Sam 4106]

I am installing a Magnum MS 4024 inverter, remote control, and battery monitor. The manual for the battery monitor(PN: 64-0013 Rev A) tells you to put the shunt between the battery bank and the inverter so all input and output current passes through the shunt. I would like to install a second shunt between the batteries and the solenoid combining the house and start batteries so the monitor will see the current going into the batteries from the 50DN alternator. Can I parallel 2 shunts to the monitor to accomplish that? Or do I need to make up new battery cables for the alternator so I can feed the current through the inverter shunt. I'm trying to avoid making new battery cables since I have the shunts.

Thanks, Sam

[Sean]

Usually, shunts for monitoring battery SOC go between the negative battery terminal and the ground, with all DC returns connected to the ground point (i.e., across the shunt from the battery).

In this position, the shunt will see ALL the current into and out of the batteries regardless of source or sink.  The two most popular SOC meters, from Bogart Engineering and Xantrex, both use this method.

I am not familiar with your particular monitor or shunt, so I can't say whether it can be installed in this position.  If, for example, the monitor is using the shunt wiring to also detect voltage, then this would not work.

Is this a part provided by Magnum?

To answer your specific question, no, you can not parallel shunts.  Each shunt needs to feed a separate meter (or a meter designed for monitoring two different banks), and then, of course, neither meter would know the actual SOC of the batteries.  In order to monitor a single bank with multiple sources and sinks, you need to have all of them go through a single shunt.

If your shunt needs to go on the positive side, then everything other than the batteries themselves goes on the side of the shunt opposite the batteries.

-Sean
http://OurOdyssey.BlogSpot.com

[Sam 4106]

Hi Sean,

Thanks for responding. As usual I didn't provide enough information. The shunt goes between the negative battery terminal and the inverter. The two sensing wires from the shunt go to a sense module that also has a wire from both the negative and positive terminals with the wire on the positive battery terminal also going to the DC positive distribution. Then there is a four conductor communication cable (telephone cord) from the sense module to the network port on the inverter. There also is a communication cable from the inverter to the remote control. The battery monitor must be used in conjunction with the remote control. All of these components are supplied by Magnum Energy Inc. The remote control allows you to set the parameters of the charger among many other functions which I am not yet familiar with. This system is probably more complicated than I will ever understand.

I was able to reconfigure the existing battery cables to match the diagram in the battery monitor manual. There was a Vanner 5000 Watt, 24 VDC inverter and separate Vanner charger in the bus when we got it but the inverter failed last fall. Vanner no longer repairs that 20 year old inverter so I had a local guy repair it and it was working fine. It failed to work last weekend when we first tried to use it so I ordered the new Magnum MS 4024 inverter/charger to replace the old Vanner. The guy who fixed the Vanner was able to get it working again, but I felt uneasy about how reliable it would be for our planned 1 month trip in June. We rely on an inverter for our 120 VAC only refrigerator and A/C when driving. Our trip includes a rolling rally in North Dakota and Montana with some dry camping planned. Life is better with a working inverter.

Thanks again for your help, Sam