What's going on at A1 ?
You say you are losing 2.5V through the transistor, it's connecting to ground, so are you measuring from the E pin to ground? (after the 5V has passed through the relay coil)..?
I wonder if the current to initially pull the relay in is too great? And 42mA is the current to hold it in?
Yep. And it had nothing to do with the problem whatsoever. Turns out I forgot to set pinMode(dirPin, OUTPUT). Oops.All is well now. I guess the lesson is, don't give a pin a name that sounds like derpin'
I was thinking of trying to connect the transistor base directly to 5v
Where do you see a 1K resistor?