The BMK works in conjunction with a Magnum inverter to give a remote display battery monitoring capability.
Installation Conceptualization: Electrical current always flows in a loop from the positive side of a battery bank through cables, through loads, through more cables and eventually back to the battery bank through the negative side. Different loads create alternate routes in the loop but they all end up going back to the negative. In order to determine total current flow (which is used to determine remaining battery capacity and a number of other things) ALL of the current has to pass through the shunt. The easiest way to ensure that you capture all of the current, and not just some that went on an alternate route, is to install the shunt right before the negative side of the battery bank and make sure that all alternate route cables connect on one side of the shunt and the battery negative goes to the other side.
How a shunt works: When current flows through a load the voltage is reduced. This reduction is proportional to the amount of current passing through that load. A shunt is like a very low power load. There is a slight voltage drop between the terminals of the shunt. This voltage drop is measured and translated by a microprocessor to determine current.
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AM Solar Part Number: MONITOR-BMK