Anyone here wire in the servo supply (Vs) to an A to D input (AX0-AX3) to monitor the power of the servo battery?
I imagine a divider circuit would be necessary for any analog voltages exceeding 5V?
If I am not mistaken there are already jumpers on the bot board to do that… it would be good to look in the manual at page 2 item 8 in the description. 
haha that’s already built into the Bot Board II. 
All you need to do is install the jumper and read the input. We routed VS to AX0 and VL to AX1. There is a voltage divider that drops the voltage by 25%. So a 9vdc battery (assuming it’s 9vdc) will leave 2.25vdc at the input of the regulator.
Yeah, that’s what I was thinking of doing on the bot board. That pair of header near AX0 and AX1 where you can feed in VS and VL into those A to D ports.
I was looking at the schematic of the mini-ABB, this header is “J2” I presume? The header with the 30k and 10k voltage divider? The reason why I’m asking is because you mentioned bot board II but I’m using its precursor, the venerable mini-ABB… This divider would indeed give you a 0.25 Vin (where Vin is VS or VL) since it’s 10k/40K*Vin. This feature is quite nice, I believe I will jump in the VS supply into the botboard and make the mini-ABB chime a tone through the speaker when low voltage is detected…
I’ve also been using the LED-based battery checker as well, which works really nice, I recommend this to everyone. The “meter” effect and what you see visually under load is quite interesting (like when all 18 servos are commanded, the level dips down a bit, thus indicating the heavy current pull on the battery)…
Now what would be interesting is interfacing the bot board with an LCD to give you a poor-man’s voltmeter to show the status of the on board batteries…
The ABB is the same as the Bot Board II as far as the battery monitor circuit is concerned.