The included directions are slightly confusing. The best way to understand the operation is to realize that the display has 2 voltage inputs. First is the 2 lower terminals in the picture. The power the unit and also provide the volts reading on the unit. If those 2 terminals are the only 2 connected then the screen will turn on and read battery volts with no current draw (amps). The best place to get the voltage reading is directly from the battery. These 2 lower terminals connected directly to the battery + and - (with a small fuse of course). Unfortunately this would bypass the shunt so the minimal (even possibly insignificant) current draw of the display would not register across the shunt. It's probably such high impedence that you'll never even seen the current draw from the display. I would wire it the lower 2 terminals "directly" to the battery + and - just to ensure the most accurate voltage reading. The shunt is uninsulated and as such creates an exposed electrical path. For this reason the shunt is always attached to ground. In most modern cases we have negative ground systems so this means attach the shunt "directly" to the battery neg post. At this point only 2 things should be attached to the negative post. The ground wire for the meter and the shunt. Ground buss wire should have been disconnected from the battery and attached to the free end of the shunt forcing ALL load current to draw through the shunt.
The top 2 terminals of the display are the second voltage inputs and detect the ever so slight voltage drop across the known resistance of the shunt. As load goes up, the current through the shunt goes up and the voltage drop across the shunt goes up. The display registers this voltage drop and correlates it to the appropriate current which is displayed as amps. You can inverse the top 2 wires to change the current reading from positive to negative and vice versa. I like the loads to read as negative current so make sure it reads the way you prefer. The charger should also be attached to the "free" end of the shunt. With a constant charge current applied the display should show positive current. As the boat system loads increase, less of the current flows through the shunt since it is being use for the loads. If the loads equal the charge then the display will read zero amps applied to the batter. If load is further increased then the current will begin to read negative current since the battery will have to start making up the difference between that of the loads and that of the charger. Long winded - I know. I hope you follow. Summary: - Bottom 2 terminals attached as directly as possible to the battery or power source "+" and "-". -Top 2 terminals used to detect the voltage drop across the shunt. Polarity selected to suit your needs. - Shunt is placed in line with the existing ground path such that the ground bus is connected to the shunt and the shunt is connected to the battery. Positive Load path remains unchanged. Josh Muckley S/V Sea Hawk 1989 C&C 37+ Solomons, MD On Sat, Apr 27, 2019, 9:28 AM David Knecht via CnC-List < [email protected]> wrote: > I bought one of these Bayite energy monitors ( > https://www.amazon.com/gp/product/B013PKYILS/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1) > at someone on the list’s suggestion and am planning to install it this > spring. I would like to mount it at the nav table. I am presuming I can > connect the positive where the main power comes into the panel bus bar from > the battery. However, I am unclear where to connect the negatives. The > shunt is connected on one side to the negative side of power. The other > side is to negative side of load. What does that mean in practice given > standard boat wiring? Thanks- Dave > > S/V Aries > 1990 C&C 34+ > New London, CT > > > _______________________________________________ > > Thanks everyone for supporting this list with your contributions. Each > and every one is greatly appreciated. If you want to support the list - > use PayPal to send contribution -- https://www.paypal.me/stumurray > >
_______________________________________________ Thanks everyone for supporting this list with your contributions. Each and every one is greatly appreciated. If you want to support the list - use PayPal to send contribution -- https://www.paypal.me/stumurray
