A bay signed with the P sign and “opladen elektrische voertuigen” is for electric cars while they are connected, and Rotterdam sets no time limit — you may stay as long as you are plugged in, even after the charge completes. In a paid-parking area you pay the parking tariff as well: €6.42 an hour in the centre, €3.20 in the ring of districts around it, €2.24 further out, until 23:00 most nights and until 01:00 on Friday and Saturday in the centre, from 12:00 on Sunday. A car at a pole without valid parking payment, or one that is not plugged in, risks a fine. Cheaper: the P+R sites are free for up to 24 hours if you validate your parking ticket with an OV-chipkaart or RET chip ticket within an hour of returning by metro or tram — mobile tickets, barcodes and bank cards don’t qualify — and P+R Kralingse Zoom and Slinge have 42 and 44 charging bays respectively, with the charging paid separately. A free RFID card starts the charge at any of them without signal.