"increasing bank reserves decreases the cost of lending" Only if there is a net margin between what the central bank pays on reserves and what the bank has to

"increasing bank reserves decreases the cost of lending" Only if there is a net margin between what the central bank pays on reserves and what the bank has to pay out on the matching deposits. Once central bank renumeration gets low, the cost of unsecured deposits matches or exceeds the central bank remuneration because of the draw to cash.