On 29/10/12 09:45, Chris Green wrote:
If the voltage measuring device has a floating/balanced/differential input there is not so much of a problem, a pair of wires to the battery terminals (or as close as necessary/needed) should work OK and if it's a twisted pair most electrical interference will be fairly well rejected.
Aye that would work, The AVR chip used in the arduino doesn't AFAIK have a dedicated differential mode on it's A2D though so some fiddling would be required.
Either that or you are only a handful of op-amps away from having nice stable differential inputs with ground isolation by default :)
Personally I would still go with just putting the A2D or micro-controller down near the things you are monitoring and then you only have to deal with a single low speed data connection up to the bridge or wherever your PC lives. If you are really bothered you could always stick RS-422 level shifters at each end rather than using RS232 and run it over twisted pair...a bit of cat-5 would do.