@bjacobse Because of available pins I'm using pins A2/D16 as digital In and A3/D17 as digital Out, no internal pullups are disabled. This is one of a pair of identical Nodes, with onboard RTC initiating an hourly update (usually<1 sec). The other is fairly recently converted so too early to see if the problem is replicated. This one lost 0.9v in 16 days compared to 0.26v on the other, and one of the US boards has the LED butchered, but cannot recall which. It's a bit tricky to measure the current as would need to insert meter then reprogram the RTC again, but the Arduino is specced low microAmp sleeping, the US is specced at < 8mA running, but leakage appears to be during sleep when all power is cut to the US. May just try connecting the Echo for a week via the spare relay contact to see if that affects it, then Trig if that fails. Curious why disabling internal pullups would make any difference?