Thats a cool idea ALAN

RICH on you divider circuit looks ok.,i would add protection,put that me i look at very high precision ,mostly i use to it and safety I use alot of it at work in inhose tester i design and make and calibrate with even much higher precision equipment ,last peice i finish last week was very hard 4000 amp tester for clamp-on meters for FPL

My divider circuit doesn't just look ok it is ok, it's been installed and working without a single glitch for the past 6 weeks or more, without R3, accurate enough for it's purpose.

Others dont also look at the time the battery is is going dead and depending where you have you need juice to get it back to the charger.

SO you need to add that to you low battery voltage,best way is move your robot to far away point in your house and check to see how much current is used ,kinda hard with a voltage monitor design

Only other way is to wait until is dies and re-adjust the divider again and may again You dont want to charge a half dead battery on gel cells ,main reason is called memory effect ,on LI-POLY it doesnt have that problem

If only the script had a variable like $vmin for adjusting the low voltage alert level... whoa, it does... But we should really have said about figuring out how much power may be needed to get to the dock... holy cow Batman, would you look at that, it's already been said...

Is my sarcasm too much?

RICH yes its a very common circuit its used in almost every type of voltage design and have made voltage divider latters using 9 to 10 resistors in series with tap off points

,i guess you read me wrong on what i said about it when i said it look ok,it meens ok, just i work for company that looks for better more safer design ,6 weeks is a short time for precision test equipment where we look at many years or more

and accuracy is not needed for robots ,mostly just a toy

Why overcomplicate things when they don't need to be overcomplicated?

I'm guessing that if I said I went on holiday to tenerife you would have been to elevenerife...

Expand on this protection, these improvements, be clear, part numbers, values, where in the circuit it should go and why it's needed. It's all very well saying "you should have protection" but how does that help anyone? What protection, put a seatbelt around it?

I apologise to everyone for my sarcasm tonight. It's now either laugh or cry I think...

About protection for it if a resistor goes bad,(very unlikely) or cold solder point over time (very likely ) seen many of customer returns wth this A TO D will be fried full 12 volts from R3 and R1 and i am talking about R2 going open may be not your but still more time is needed ,but other maybe this post is for everyone

i never ever use sacasm or ever get mad,but that me

But back to the fix its easy a zener diode so voltage never goes higher at the A-D THEN 5.2 volts it a very common resistor ,only about $.20 so doesnt cost much and at A-D at ad to ground or at R2 TO GROUND

price is lower $.15 each for 5.1 volt zener at 400ma can even go lower its not used as a regulator anode is always gnd and cathode is is always postitive on zener its black line on top 5.1 volt 400 mw zener

If too hard i can easy make it,so much work ,plus on forum to help others, sometimes have problem with what i write ,because of caps or spelling or peroids and others looking me to fix it