Thanks, that makes sense. I'll add a real battery monitor to my Christmas wish list!
04-20-2013 10:59 PM
Re: Blue Sea Battery meter with two banks
None of this really matters with a simple ammeter/voltmeter as it is not counting Ah's or keeping track of Peukert/SOC. They simply show what is happening at a specific point in time (a snap shot) across the shunt..
If you had a true battery monitor then yes the position of the aux battery on the shunt would matter because it is actually doing something other than displaying the "at a glance" current.. With a simple ammeter is is not critical where the AUX batt is wired. Just wire an A/B to see voltage of a second bank..
I still prefer to have an aux battery on the load side of a house bank shunt but in this case it is not "critical"..
04-20-2013 07:17 PM
Blue Sea Battery meter with two banks
I'm replacing the high current wiring on my boat -- two banks, primary and reserve. The boat already has a voltage/amp meter (Blue Sea 8248).
There is a good thread about installation of a shunt with two banks at this thread, but that's for a Victron meter, which is designed with two voltage inputs.
The Blue Sea meter only has one voltage input, so measuring voltage on two banks requires the installation of a switch on the voltage sensing lead. Blue Sea has a nice tutorial here.
But here's the rub: Blue Sea says that to measure voltage on two banks, the banks must share a common ground (that is, both connected to same side of shunt). But as described in the Victron thread, connecting both banks to the same side of the shunt will prevent monitoring of bank-to-bank current (although this would seem to complicate consumption calculations).
Since the voltage drop across the shunt is so small, I'm inclined to ignore the Blue Sea direction, and connect the bank negatives the way Victron describes.