One of our customers used an energyShield 2 Pro to build a device that measures the height under a bridge, which lets him know if there is enough space for his boat to pass under the bridge. The best part is that a single battery charge lasts 4-5 MONTHS! If you are wondering how this is possible, read his complete project description/review (below) and take a look at the energyShield 2 Pro to better understand its power-saving capabilities:

Customer Review

Green Pond Bridge Clearance! Battery works outdoors for 4-5 months without recharge

on January 19, 2018

This battery is great. The complete project is explained below, but the features of this battery that make the entire project possible are: a) it turns the Arduino on every 15 minutes, then the Aruduino takes a couple distance measures from an ultrasonic sensor, sends those measures vi an RF24 radio, then cuts the power to the Arduino. b) it sends remaining-voltage, so battery state can be monitored remotely. c) my tests in outdoor environment indicate it can operate on 15 minute cycles for about 4-5 months!

Green Pond Bridge Boat Clearance

At ‘very low tide’ the clearance under Green Pond Bridge in Cape Cod is 6’6” or less and that is too low for the boat I use. The tide charts for Falmouth, MA are theoretical and can vary as much as 18” from what is actually happening at the bridge. This system monitors the clearance and transmits the information on the internet.
All of these parts were purchased from Amazon.


An (Arduino) Elegoo UNO R3 board is connected to an Elegoo HC-SR04 Ultrasonic Distance Sensor. The UNO and the sensor calculate the distance from a fixed dock to the sea level, then transmit that data using a MakerFocus NRF24L01 Wireless Transceiver to the Receiver described below. The Transmitter sits on the end of a dock where there is no power, so the UNO, Transceiver and Distance Sensor are powered by the energyShield 2. This battery has special capabilities – it wakes everything up every 15 minutes. The system takes a couple readings of the distance to the water then transmits that data, then the battery shuts it all off. The data transmitted includes information from the battery – time, date, and voltage.

I have been testing this unit at home (in Dallas) and it has been operating outside, for about 20 days. Based on battery drain it looks like it will operate for about 4-5 months before it needs a recharge. When the temperature drops below zero the system still works fine but the voltage reported in the battery seems low.

All of this is housed in a plastic box printed for the purpose with a FlashForge 3d Printer Creator Pro, using eSun White ABS+ filament

Picture below.


An (Arduino) Elegoo MEGA 2560 R3 is connected to another NRF24 Transceiver to receive the data. The MEGA does the math to convert the distance from the dock to the water, to the bridge clearance. Then the information is displayed on an Elegoo UNO R3 Touch Screen (that also works fine on the Mega).

Picture below. A small plastic frame for the Receiver was also printed on the 3d printer

Web Server

Finally, the information in the MEGA is transmitted over a serial bus to a Hiletgo ESP8266 NodeMCU ESP-12E Internet WIFI Development Board (Also operates using Arduino IDE programming). This board is connected to the MEGA via the XCSOURCE Logic Level Converter and powered by a UCEC MB102 Breadboard Power Supply Module. All mounted on an Elegoo Breadboard. The ESP8266 is programmed to be a web server. It connects to the internet through the modem/router provided by AT&T.

Picture of my cell phone below.

We love to see our customers succeed with our products. Nice job, Frank!

You can read the original review here.