Fazley RabbiThe problem: fuel you cannot account for
"We buy diesel every week, but the numbers never add up." Owners of factories, shops, clinics, apartment buildings and remote sites say this often. Fuel is a large running cost, generators often run without anyone noting the time, and when the logbook is filled in by hand, mistakes and sometimes theft are hard to prove.
Behind it are usually three questions. How much fuel is in the tank right now? Where did the rest go? How many hours did the generator actually run?
What a monitoring system tracks
- Fuel level, from a sensor fitted to the tank. Several types exist, and the right one depends on the tank's shape, material and access points.
- Running status, detected from the generator's electrical output, so the system knows when it is running.
- Mains power status, so you know when outages begin and end.
- Optional extras, such as a sensor on the fuel cap or the fuel store door, or the temperature of the generator room.
A small controller with its own battery combines these and sends the data over a mobile SIM to a dashboard on your phone. It should store readings while the network is down and send them later, and it should alert you if it stops reporting.
Before adding anything, check what your generator's own controller already offers. Some have run-hour counters or remote monitoring options built in, and the right solution may simply connect to those.
What the data shows you
- Refuelling events. A rise in level is recorded with the time and amount, so you can match it against purchase receipts.
- Sudden drops while the generator is off. The clearest sign of theft or a leak, and a reason for an immediate alert.
- Fuel used per running hour. If consumption rises with no change in load, something may be wrong with the generator or with the records.
- Running hours, so servicing is planned on time instead of guessed.
- Failed starts. An alert when mains power is off and the generator has not started within a set time.
- Low fuel, early enough to refill before a long outage.
Accuracy and safety
Fuel level readings are affected by tank shape, vibration and temperature. The system is calibrated by filling the tank in measured steps and recording the reading at each step. Expect small variations rather than exact figures.
Fuel tanks and generator wiring carry fire and electrical risks. Any sensor fitting or wiring should be done by a qualified technician following proper safety practice. Check with your generator supplier first, so the work does not affect your warranty or service agreement.
The people side
A theft monitoring system works best when staff know it is there; much of its value is prevention. If the data shows a problem, treat it as a question to investigate fairly, not as automatic proof against a particular person. A leak or a faulty reading is also possible.
Decide before you start
- Which generators and tanks to monitor, and who is responsible for each
- Who receives alerts for theft, low fuel and failed starts
- How refuelling will be recorded and matched to receipts
- Whether you need it for one site or several
The planning and record keeping can be done in-house. An IoT developer helps choose sensors that suit your tank, build the controller, set up connectivity and alerts, and design the reports. This is part of my IoT device development work, and it pairs well with electricity usage monitoring.
A first step
Choose the one generator whose fuel use worries you most. For two weeks, write down every refuelling and every start and stop by hand, alongside the purchase receipts. That baseline shows whether a monitoring system is worth it, and gives you something to compare against once it is installed. If you want to discuss it, get in touch.