@bjacobse Granted that is what he has, but it's a lot more effort reducing a Nano to pro-mini compared to the cost of a getting a pro-mini to begin surgery to start with... We all have devices bought with good intention gathering dust as we learn....
One of these days will get a Nano to play with, but had dismissed it for battery applications from the start of this adventure and have seen no reason to reconsider that conclusion since.. For testbed or PSU applications, fine, but for battery applications?...
As the Limerick man advised the driver seeking directions to Dublin, " I wouldn't start from here"