The best and recommended way to power the beacons of the indoor positioning system is to have a fixed external power supply.
For Super-Beacons, we recommend regular AC to USB converters or USB chargers.
Notice! Newer Super-Beacons are +5V power supplied – not +12V power supplied. Applying +12V to newer batches of Super-Beacons (produced in 2022 and later) will kill them.
Our converters and chargers support ~110V and ~220V. Thus, you can easily use them in Europe, Asia, and the Americas. Remember about different plugs, though.
Some converters come with external plugs. However, some come with open wires on the input side and are designed to be connected to your warehouse’s and factory’s electricity grid.
External power supplies give peace of mind and freedom to focus on other aspects of the system.
Though we strongly advise using an external fixed power supply, different battery options are available if the fixed power supply is not feasible. Even more exotic options, like solar panels, could also be helpful in some special applications.
Before we go deeper into the power supply variants, let’s discuss what to pay attention to and why.
First of all, notice that we don’t discuss powering of modems. Modems are nearly always active. They typically don’t sleep. In the majority of cases, they are even computer connected. Thus, powering them is typically not an issue: either they are USB connected and powered via USB, for example, Modem v5.1 or the power is readily available via ~220V to +5V (+12V for older batches) converter for the Super-Modem.
Stationary beacons (anchors) have fixed locations. See more in the Placement Manual.
At first glance, one may think that providing power to them is not a problem, and the primary focus shall be on the mobile beacons. Thus, there are claims of 1-year, 3-year, and 5-year battery lifetime for tags in UWB or BLE systems…
But in reality, it is the opposite in the majority of cases:
Mobile beacons, on the other hand, are typically either powered by the electrical grid of a robot, drone, or forklift or charged often (daily, weekly) because, unlike stationary beacons, their easily accessible and people used to charge their devices: phones, cameras, players, lights, etc.
Therefore, it is important to very clearly understand that powering mobile beacons (tags) is typically not a problem. But powering of stationary beacons could be due to the cost or limitations of wiring or size and costs of required batteries and associated battery replacement/utilization and recharging costs.
Like the majority of other modern electronic devices, Marvelmind beacons sleep most of the time. They wake for a very short time, do the job, and go to sleep immediately in order to save energy.
Beacons have a duty cycle with highly irregular power consumption: some milliseconds of relatively high current during the active phase are followed by tens or hundreds of milliseconds of nearly zero current during the sleep phase. The difference in current consumption between the modes is 1000:1 or even more.
Typical power consumption pattern:
As a conclusion:
As discussed above, the beacons sleep most of the time. Thus, it is possible to calculate a required energy for a single location update. By knowing that energy and by knowing the battery capacity, it is possible to calculate the number of location updates the battery can provide before it will depleted.
As it can be seen, the difference is drastic.
In reality, the difference is less dramatic, because there is a current in sleep mode as well, which is not zero after all. Thus, if the sleep time is long, the sleep current starts notably contributing to the total power consumption. For a 1-year battery lifetime, the sleep current consumption may prevail over the active current consumption.
External fixed power supply is the best and most reliable choice.
External DC-DC power converters are the best and most reliable choice for mobile beacons:
In many cases, an external USB power supply is available. You can connect a micro-USB connector to the beacon and get both power and the data stream to and from, for example, Raspberry Pi or Nvidia Jetson.
Similar can be done with an Industrial beacon or modem, if external +5V (for older batches – +6V…+15V) is available from the onboard sources of the mobile vehicle/drone/robot.
The majority of Marvelmind devices have internal LiPol batteries. Typically, it is a 3.6V cell. For example:
Some devices have additional external batteries; for example, the Headlight has two larger-capacity external LiPol cells that extend the capacity of the internal battery by a factor of 3-5 – depending on the chosen external cells.
Other devices, like robots, have massive internal batteries – up to 96Wh for Boxie and expandable; and 740Wh and expandable for Robot v100. Those batteries supply the robots’ motors, electronics, and beacons on board.
Industrial beacons intentionally don’t have internal batteries:
USB power banks are the simplest and the most straightforward way to expand the battery lifetime of Super-Beacons or other USB powered beacons. Notice the following though:
External Battery-3.7V-15Ah-IP67 is the simplest battery supply option for Industrial beacons and Super-Beacons. With default settings and an 8Hz update rate, it provides about 15 times longer working time than the embedded battery (depending on the mode and size of a submap). With different settings and with a slower update rate, it can last for a year if needed.
For those he really need batteries, we are offering customized external LiPol batteries. Then can be literally any capacity, voltage and and size. You need a 1 year battery lifetime – not a problem! 5years? – not a problem either.
Though possible, it is rather difficult to calculate an expected battery lifetime mathematically because:
Besides, pure mathematical calculations leave too much room for uncertainty and a design to measure in practice to prove the validity of the results.
It is possible to measure the current consumption of each element of a cycle and integrate it. It is possible but challenging, and still not very reliable because:
The best option in practice is to measure the actual battery lifetime and extrapolate it keeping in mind the underlying physics:
There are many factors affecting the battery’s lifetime. The most affecting – the location update rate – was already covered earlier. What else: