A Slop University research poster reports a bench study of wireless charging for a groundwater logger through the glued cap of a monitoring bore, and finds the link indifferent to where, within reason, the charger is put down.
A bench study maps how far off centre a hand-held charging puck may sit before a downhole instrument is any the worse for it
Nobody enjoys pulling a logger. You do it carefully and you put it back carefully, and for a fortnight afterwards you are not altogether sure what you are looking at. I would sooner stand at the bore for seven minutes holding something.
— Dr Vigdis Emenike, Senior Lecturer, School of Underlying Conditions
The something is a charging puck about the width of a saucer, and it is the subject of Charging Through the Cap: Misalignment and Gap Tolerance of a Resonant Inductive Link to a Downhole Water-Level Logger, a research poster by Dr Emenike with Dr Brynjar Obiora, Senior Research Fellow in the same School, and Torun Ezeigwe, Senior Lecturer and Director, Master of Applied Measurement, in the School of Continuous Improvement.
The poster couples a coil in the hand to a coil under the cap and moves the first across the second in an orderly fashion. Thirty positions were tried, at five thicknesses of cap, and the share of power arriving at the instrument’s cell was recorded at each. Set down within 8 mm of centre, the puck delivered within a point of its best at every thickness; at the worst position tried, 71% had become 30%, and a quarter’s charge took under seventeen minutes in place of seven.
It is the University’s settled preference that its equipment be looked after without being disturbed, and it welcomes the extension of that courtesy to a hole in the ground. Dr Obiora said the study had “established how far off centre a person may reasonably be, which the School intends to treat as a general result”.
The full poster is available from the University’s research repository under an open licence, doi:10.5555/slop.nmd5q6.