Holy cow this is confusing. For years I have been trouble shooting and helping owners try to use these devices in a smarter and more accurate manner. This is certainly not difficult but requires some level of precision, access and can be a tad tedious. Like what you saw or read? This is complicated, time consuming, and very few boaters are willing to do this. The only thing different in this photo is the location of the chargers negative lead. As always choose your fuses based on the wire gauge you are protecting. There is a slight voltage drop between the terminals of the shunt.
There are other gotcha scenarios that can rear their ugly head too. Again, these are not difficult to wire just more tedious. I actually photographed this quite a while ago, on a boat, and decided not to use any of the photos. Many boats these days have a battery or systems monitor permanently installed. When energy conservation is critical, a battery monitor is very helpful in educating you on the electrical consumption of your various devices as well as the charging potential of your solar array. Inaccurate assumptions can lead to erroneous data: You had 100Ah programmed into the Ah counter.
I actually photographed this quite a while ago, on a boat, and decided not to use any of the photos. It is equipped with an internal programmable alarm relay, to run a generator when needed or to turn off devices when the battery voltage exceeds programmable boundaries. Actually if you threw Peukert's exponent into the mix you may actually be lower or higher depending upon the actual load at which it was drawn. It will let you discover if your charging systems are charging to the proper voltage, which is important for maximizing your battery life. When the two units are used together, it increases the performance of the charge controller and can adjust the output to a level that is better suited to your batteries current state of charge.
These are just rough guesstimates and on many banks tend to correlate ok, but never perfect. The biggest problem with traditional Ah or Coulomb counters is keeping them accurate with the batteries physical condition. After the battery receives a full charge this readout resets to 0. Schematic If you click the image it will make it larger and easier to read. Please be aware of this.
These fuses are meant to protect the wiring from dead shorts and are easy to install. ! If you click the image it will make it larger and easier to read. This sample happens to be properly calibrated. If you want to know the charge level of your battery bank and how much current is entering or leaving your batteries, you need a battery monitor. While I much prefer an isolated ground for alternators many boats just do not have alternators with this feature and they use the case as the ground. This is explanation is just far to difficult to illustrate on a boat.
This includes inverters, alternators, battery chargers, bilge pumps or stereo memory wires. This is complicated, time consuming, and very few boaters are willing to do this. The Trimetric will help you keep track of how charged or discharged your batteries are. The Xantrex monitors do not come with the wire to hook it up, just the shunt. This voltage drop is measured and translated by a microprocessor to determine current. From left to right I have three generations of battery monitor represented. Keep in mind that many marine alternators are case grounded and thus the system ground, which on most boats is the engine block, is the ground path for the alternator.
I now have complete tracking of all the ah into my pack from the solar panels, wind turbine and backup generator, as well as outflow to my inverter and dc loads. Knowing this the monitor manufacturer can make the display correspond to any load from 0 to 500 amps or 0 to 50 mV. 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. They both will monitor the voltage of a second bank but the Victron is costs less and does more. This is just one example where an Ah or Coulomb counter can become inaccurate in relation to the actual battery bank. The latter shunt delivers 10 times the voltage for a given current flow through the shunt, so the meter can show an extra digit of current resolution down to 0.
The shunt needs to be placed near the batteries; since these wires carry very high currents the wires from the batteries must be kept short to minimize electrical losses. The only way to accurately know your actual battery capacity is to perform a physical 20 hour load test. Would you like to see more articles like this? 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. The resulting drop in current is then measured by the monitor and multiplied to give the correct current reading. How a shunt works: When current flows through a load the voltage is reduced. I tried to wire this up on the bench to replicate what one might see on-board a boat. A trick many of us in the industry use is to start with a lower programmed Ah capacity than the bank is rated for.
When owners understand how an Ah counter works, they can be very useful. Therefore, the Battery Monitor can only see and record what goes in and out of the battery, but not the different sources of those amps. They are actually easy to install but there are a couple of gotcha traps that you may find your self falling victim to. This shunt is a 500 amp 50 millivolt shunt. Is so feel free to donate, support the site and keep it growing. When owners understand how an Ah counter works, they can be very useful.
If you need all the individual parts that make up a complete system, including a charge controller, please see the kit or the kit. The essential function of a battery monitor is to calculate ampere hours consumed and the state of charge of a battery. This product is called a battery terminal fuse. . Please be aware of this. Your donations help keep the content coming and also help keep it free. An experienced sailor and electrical engineer on SailboatOwners.