Battery-powered level sensors are a growing trend, and for good reason – they’re much easier to deploy. However, there are a few things you need to know when looking for battery powered remote tank level sensors. Here are five tips that will help you align your expectations and plan effectively:
1) Know Your Application
Let’s start with our first tip. You need to know the ins and outs of your application before you can pick the right level sensor. Specifically, you need to know your goals.
Perhaps you want real-time tank-level information. Well, what does real-time mean? How often do you want a refresh on the level sensor’s data?
I ask, because every time you want the level sensor’s data updated, it means the level sensor has to turn on, pull a reading, and transmit it to you via whatever connection you have set up (e.g. satellite, cellular, etc).
And all that level reading and transmitting takes power – battery power. The frequency with which you want to update your level sensor’s data will directly affect how long your batteries will last.
Hazardous areas require even more meticulous planning, as the battery pack may not be certified for hazardous locations. You may need to house your battery outside of the hazardous zone and run wires to your tank level sensor.
Some companies can integrate a solution for hazardous locations, but not very many. We can discuss a few options with you if you would like to contact us directly.
2) Know Your Equipment
To accomplish your application goals, you may need to power more than a sensor. Perhaps you are also powering a local alarm or a solenoid valve. These little extras can add up fast, so you’ll need to be very cautious to keep cost and complexity down.
Adding a small solar panel may be necessary to achieve the expected battery performance. This adds cost and a bit of complexity, but it’s still a relatively simple and inexpensive way to get important level data.
3) Know Your Sensor Current Draw
If you’re figuring this all out for yourself, you’ll need to know how much current your sensor and other equipment draw. This will tell you how big of a battery you need and approximately how long it will last.
For example, an average ultrasonic sensor will pull around 50 mA. It also takes time. Several seconds can pass by the time you boot up an ultrasonic sensor, take a qualified reading, process it, and transmit the data through the modem.
A typical pressure transmitter, on the other hand, takes much less current and time to operate. This makes them popular in the world of battery powered remote sensors.
Get to know the sensor intimately. Details matter, and can make the difference of a few years of battery life.
4) Know Your Output
One of the contributing factors to battery life is the output of your sensor. Low current draw sensors use low current outputs. Sensors with a 4-20 mA output are typically not great choices for battery-powered applications. When on, the lowest current draw possible is 4 mA.
Look for a voltage or a digital output such as Modbus. These can have a higher current draw than a 4-20 mA sensor, so be careful – it depends entirely on how the sensor was designed. But they can also use much less current. If the sensor is a good fit for battery power, then it will use either a digital or voltage output and have a current draw of less than 4 mA.
5) Know Your Limits
I once had a remote controlled car that was really fast. It was a lot of fun. But the batteries ran out in about 20 minutes of play, and required several hours to recharge. It was a major disappointment, and I traded it for something a little slower, but a lot more reliable.
Batteries offer new possibilities, but they have limitations – a lesson I learned at a tender age. If you exceed those limitations you’ll run out of juice far too often, which isn’t an option for many whose remote tanks are distant.
Most of the people we talk to want a battery life of at least a few years. Keep that in mind as you plan for your remote data acquisition and control projects. Contact us and we’ll help you wade through the information and find a solution that will last a while, giving you the ROI you’re looking for.
top photo credit: RTD Photography via photopin cc
