Swapping of batteries

I am currently trying to create a circuit to swap between 2 battery source when one of it goes flat (1 lithium polymer, 1 lithium ion battery). Is that possible to do so with arduino and relays? if not can anyone teach me any other methods? Because the current draw might be huge. I am running 12 motors and it can draw up to 400A in total and relays might not be able to take that much current

You can certainly design an Arduino program that causes something to happen on its output pins when it detects a situation on some of its input pins.

I suspect you can get a relay for pretty much any level of current that you require - your just need $$.

Whether you can create a circuit that can reliably detect the low charge level on your batteries is something I don't know. With a suitable voltage divider you can probably present the battery voltage to one of the Arduino analog inputs. But is the voltage is a reliable measure of the state of charge?

...R

Hi, Welcome to the forum.

Please read the first post in any forum entitled how to use this forum. http://forum.arduino.cc/index.php/topic,148850.0.html.

What is the application, traction motors, 400A? Are you modifying an existing piece of equipment? Is there a motor controller in the circuit?

Do you want the batteries to change over while operating at even 100A? How big, Ah and voltage are the batteries?

Can you tell us your electronics, programming, Arduino, hardware experience?

Thanks.. Tom.. :)