check the voltage at the dash voltmeter when this happens and then you will know the actual battery condition. If you ave a voltmeter check the actual battery when this occurs
Make the graph end wires as short as possible.
If you are now seeing this on your other graphs then you battery is getting tired possibly. It could be dirty terminal posts and loose connections. Use Vaseline petroleum jelly on connections to reduce corrosion issues.
The wire is enough to carry the amperage, though the graph wires are all too small in our opinion. Make those short and keep travel low on those lines.