Monitoring multiple 12v batteries?

I have been trawling some some threads, mostly fairly old and have not found
a complete solution to me needs.

Looking at using an arduino to monitor a bank of 12v batteries, these will vary
between 4Ah and 100Ah in capacity. Approx 6 or 8 batteries currently.

Each battery is charged from the same solar cells but independant from each
other. So if power is drawn from one battery it will not affect the others.

Ideally i would like to monitor the level from 12 feet away and keep an eye
on each battery to ensure the voltage does not drop below the level
where it affects the cells ability to recharge.

This varies as some cells have different chemistries.

Anyone know of any working and completed projects?


Resistor divider to drop each voltage down to 5V max, then a part like DG406 to mux the signals for analogRead() by an Uno.
Or use a Mega with up to 16 analog inputs.

Any advantage or disadvantages to either option?

I have several UNO's and just bought a MEGA 2560 with a ramps shield
so i can test with either.

Although the standard voltage will be 12.8 i presume i need to be careful
because on a day full sun the solar panel maybe putting out 20v (not tested)

Thanks for the quick reply.

Mega costs more.
Since you are wiring up resistors anyway, one more chip is not painful.

Plan so that voltages Never exceed 5V, readings will just return 1023 if it does and tell you nothing.