I really should have been working on this over the winter, but Ham radio took over, between work, snow activities and HR, I was kinda swamped.
While doing some spring cleaning I found a voltage regulator I ordered last year in hopes of making the arduino run more efficient from the batteries. The vreg on the arduino itself is not very happy bringing ~13V down to 5V without making tons of heat.
This adjustable regulator DE-SWADJ seems to be working rather well, stays cool and so does the arduino.
I've set it about 6.3V, anything less and the LCD starts to become hard to read, with the onboard regulator.
I've now dropped it down to 5.5v and used the vin, any lower and agin the lcd becomes faded.
Planning to order some voltage sensors to replace my dividers, and maybe a sensor shield to clean up a bunch of the wiring.
I've also found a bunch of proper stand-offs that I can set into the plastic sheet and mount everything better.
More progress as time allows.