I invite you to visit Bob at https://handybobsolar.wordpress.com/. Read his blogs carefully and as you get through his rants you will learn quite a bit about RV 12 volt systems and especially solar 12 volt.
As Bob points out, without the battery monitor to tell you what is happening in your system you are basically driving blind (which some of us can do, but most of you cannot). No point in spending gobs of money on great batteries, good wiring, a decent converter if you don't know how the system is performing.
With this in mind I chose the Bogart Engineering Trimetric TM 2030 battery monitor. http://www.bogartengineering.com. I selected this monitor because it gets excellent reviews, has great capabilities, and is built in the USA. Also, I had decided to use Bogart's solar charge controller which is designed to work with the Bogart battery monitor to maximize solar charging performance. There is a lot of literature and videos online on these products and so I felt confident using them.
I purchased the battery monitor from AM Solar, http://amsolar.com, whom I highly recommend. Along with the monitor I purchased the shunt and the installation kit. AM Solar provides you with all the parts you need for a complete installation. They are very knowledgeable and friendly. I called them several times with installation questions and got a prompt, and correct, answer.
I purchased the battery monitor from AM Solar, http://amsolar.com, whom I highly recommend. Along with the monitor I purchased the shunt and the installation kit. AM Solar provides you with all the parts you need for a complete installation. They are very knowledgeable and friendly. I called them several times with installation questions and got a prompt, and correct, answer.
I wanted to place the monitor in an area where it was easily visible but did not want it to stand out too much. Here you see its location, on the front of the electronics compartment under the driver side seat. Easily viewable and accessible but not in your face. High enough off the floor that it wont get kicked.
The electronics compartment vent on the right of the monitor was originally one of the sides of the old converter. Cut it to size, treated it for rust with Corroseal, painted it, and voila!
The monitor works by measuring the current through a gizmo called a "shunt". I had no idea what a shunt was until I saw a photo. Basically a shunt is a bridge across which all the current in the system runs and the monitor measures that amount. The shunt is incorporated into the system on the negative side of the wiring. In order for the battery monitor to work properly all (and I do mean ALL) negative current has to pass through the shunt. Here is a closeup of the shunt with the negative bus bar sitting above it:
I connected all grounds (negatives) to this bus bar. The bus bar is then connected to one side of the shunt. The other side of the shunt is connected to the battery negative through a 2-gauge wire. This wire is the only connection at the battery negative post. You don't have to use a bus bar to connect all the grounds but with all these large gauge wires coming together it would be impractical to tie them all directly to the shunt. Much cleaner and easier installation using a bus bar.
In my first 12 volt blog I pointed out that I had a separate 6-gauge wire running as chassis ground from the negative bus bar out to the tongue area. This means that not only the chassis but the entire trailer is grounded through the bus bar first. So the shunt is measuring anything that is grounded anywhere to the trailer shell and frame. I am then getting accurate values on the monitor.
It so pretty!