Battery monitor

A wee update on the mobile workshop.

Somewhat late as i’ve been running with this for about 2 months now.

As the mobile workshop is battery powered it is useful to know how much energy is left in the batteries so I can work out if I need to switch over to mains or start up the towcar to charge the batteries.

Previously I had been working off voltage and guess work on how much is left in the batteries. This is somewhat inaccurate as all batteries suffer from sag. This is when you are pulling power from the battery the voltage drops which would give you an impression they have far less energy in them than there is.

To solve this i did a wee bit or research and there is a few solutions on the market. One of the best being a Victron but as budgets are tight i went for a cheaper solutions. Amazon link

A review of the battery monitor I am using

When you first install it you tell it what the size of the battery bank is and you also tell it when you are fully charged and then it counts energy in and out of the battery. from this is should be able to give you a pretty accurate account of the battery bank state of charge. It can’t compensate for temperature which can make some batteries especially flooded lead acid some problems.

It will display

• Battery percentage

• Volts

• Amps

• Amp hours in the battery

The battery monitor showing the shunt and the display

As all of this info is very useful i wanted the display to be just above the workbench so i could keep a good eye on it.

Of course this meant a 3D printed housing which gave me a chance to fit in the control panel from the inverter instead of it hanging on a screw.

The shunt which actually has all the current flowing through it and does the measurement bit is hiding under the cover for the battery isolator. Seeing that it is using a home made connector strip made from a big piece of scavenged lightening conductor you aren’t getting a picture of that.