1. Battery Water Level Monitoring System
Team Members:
Jonathon Reimer
Joseph Sara
Ryan Estep
Faculty Advisor:
Dr. Rashmi Jha
Industry Sponsor:
Drew Barrett – Flow System Inc.

2. Presentation Outline Introduction The Battery Monitoring Problem
The Battery Water Level Monitoring System
System Architecture
Hardware Design
Software Design
Progress Completed
Future Outlook
Q & A

3. Introduction
The Battery Water Level Monitoring System is a system comprised of both hardware and software.
It contains embedded code, database software, PCB technology, and wireless transmission.
We will be outlining all aspects of the system

4. The Battery Monitoring Problem
Used in many different solutions – from providing power to fleets of golf carts to providing storage banks for wind farms
Their low cost combined with their high current output make them widely available and widely used.
The biggest problem, however, is maintenance

5. The Battery Monitoring Problem
Lead acid batteries contain a series of plates submerged in a mixture of water and sulfuric acid
Over time, water is lost from the recharging process and evaporation
As the water level diminishes, battery efficiency decreases

6. The Battery Monitoring Problem
Typically, the water level is monitored by a probe submerged in the battery cell
The probe utilizes the voltage of the battery cell.
When the water reaches a critical level the circuit is broken and the LED turns off
Unfortunately, the LED must be monitored by visual inspection, requiring extra manpower for the maintenance process

7. The Battery Water Level Monitoring System
Our proposed system seeks to streamline the battery maintenance process.
By monitoring the battery wirelessly we can eliminate the visual inspection from the equation
This eases battery maintenance

8. The Battery Water Level Monitoring System
The system is comprised of three parts:
The Client Node
The Server Node
The Data Display Module

9. System Architecture
The wireless network is assembled in a mesh network configuration
Client route messages though other Client Nodes
This extends the range of individual Client Nodes

10. System Architecture
When data transmission is finished, the network enters SLEEP MODE
The Server Node broadcasts a SLEEP signal to the entire network
The Client Nodes enter a low power state for an allotted amount of time

11. System Architecture Why Is This Important?
This system allows a single central user to monitor the water level of a potentially large number of lead-acid batteries
The mesh networking allows each device to use a very small amount of power while transferring data over a long distance
This makes the system useful in a large number of applications

12. Constraints and Assumptions
System should be able to function in outdoor environments
Appropriate housing must be made for Client Nodes
Probing lead acid batteries should not compromise surrounding environment with leaked acid
The Data Display Module should run on Windows XP/7/8
PCB board should be as small as possible while still allowing for the mounting of the FTDI board
Wireless communication should not interfere with other wireless systems

13. Non-Technical Issues 2.4 GHz is a busy Wifi frequency
Due to the low range of individual Client Nodes it is unlikely they will interfere significantly with Wifi communication
The signal being detected is simple – logic HI or logic LO. This means this system could be applied to any number of applications.

14. Electrical Design Elements
The Client and Server nodes use an Atmel ATMega MCU
These boards also contain voltage regulators, crystals, filters, etc.
One PCB design that can be used as either a Client or a Server
Depending on the peripherals attached, the PCB board can be configured for either functionality

16. Power Circuit Functionality
Client Node
Client Node
Server Node
Ultralow dropout voltage regulator used to step down voltage up to 5.5V and output 3.3 V to power the MCU

17. Monitoring Circuit The monitoring circuit is made three parts:
Client Node Monitoring circuit
The monitoring circuit is made three parts:
A battery probe
Creates a conducting path to measure the battery cell’s associated voltage
A voltage regulator
Rated to regulate up to 16 VDC
A CMOS inverter
The voltage from the battery cell is regulated to a 1.8 VDC level to be inverted by the CMOS inverter
1.7 VDC is the threshold between HI and LO

18. MCU Schematic CPU Timekeeping Crystal Antenna And Filter
Antenna Timekeeping Crystal

19. FTDI USB Interface FTDI USB Interface
the connection of the USB interface, through to FTDI board, to the microcontroller's input pins
Connected to the PCB board using through-holes labeled GND, 3.3V, TX in, RX in, TX out and RX out.

20. PCB Board Layout and Layers
Antenna And Filter
JTAG Programming Interface
MCU
FTDI Through-hole Interface
Probe Leads

21. PCB Board Layout and Layers
The inside layers are devoted entirely to VCC and GND.
The outside layers provide the connections between components

22. Wireless Transmission
The Atmel ATMega MCU has a built in Low-Power 2.5 GHz transceiver configured for IEEE
2.45 GHz Harmonic Filter-Balun used between antenna and MCU
From a balanced to unbalanced 50 Ω microstrip
A Swivel SMA antenna used to transmit and receives signals
with 4.1 dBi (isotropic antenna) gain
1.2 voltage standing wave ratio (VSWR)

23. Client Node Power Analysis
Under normal operating conditions
𝑂𝑝𝑒𝑟𝑎𝑡𝑖𝑛𝑔 𝐿𝑖𝑓𝑒𝑡𝑖𝑚𝑒= Days
The lower bound on operating time can be found if 100% operating time
𝑂𝑝𝑒𝑟𝑎𝑡𝑖𝑛𝑔 𝐿𝑖𝑓𝑒𝑡𝑖𝑚𝑒 𝐴𝑙𝑤𝑎𝑦𝑠 𝑂𝑛 = 6.59 Days
𝑂𝑝𝑒𝑟𝑎𝑡𝑖𝑛𝑔 𝐿𝑖𝑓𝑒𝑡𝑖𝑚𝑒 𝐴𝑙𝑤𝑎𝑦𝑠 𝑆𝑙𝑒𝑒𝑝 = Days

24. Embedded Software Overview
Software differentiates the hardware into a Server node and multiple Client nodes.
Client nodes measure the water level on each battery
Server node collects the information and manages the sleep cycles of the clients
Uses the Atmel BitCloud framework to implement IEEE (ZigBee) communication.
Goal of the software is to reliably retrieve the data from each node, while keeping power usage to a minimum.

25. BitCloud Framework
Designed by Atmel, this framework implements important features the microcontroller provides.
ZigBee PRO Certified Communication
Serial Communication (UART)
Timers
GPIO
BitCloud has its own internal task manager that uses cooperative multitasking
User application is run as a task within the BitCloud Stack

26. Network Architecture
The ZigBee network is organized around a single Coordinator, and multiple Routers.
The Server node acts as the ZigBee Coordinator
The Client node acts as a ZigBee Router
Each Client has a unique address that the Server uses to differentiate the Clients.
The Server is always joined to the ZigBee network. The Clients join it only for a short time while sending data.
Clients out of range of the Server, will route their information through nearby nodes.

27. Client Functional Design
Client software is designed to be as simple as possible
On startup or wakeup it attempts to join the ZigBee network.
Once it joins the network, it reads the battery water level, and sends the data to the server node.
The client will wait for a sleep message from the server
Once the sleep message is received, the client will disconnect from the network, and sleep for the specified time

28. Server Functional Design
Server software is designed to manage the clients.
It receives all the logging information from the clients
Forwards the logging information via the UART port to the logging computer.
When all the clients have reported in, the server broadcasts a sleep command to all clients, dictating how long they should sleep.
Will send custom sleep times to nodes that are out of sync.

29. Data Display Module
The Data Display Module is designed to consolidate all the transferred information
It receives all the logging data from the Server via the USB port
It receives this information and stores it in a SQLite database
This information is displayed for the user in a GUI

30. Data Display Module The user has the power to:
Provide the “Name” and “Description” associated with each Client in the network
Choose which serial port to monitor
Track water level trends on a historic level
Check on Client Node status in the network
Monitor Server Node console output

31. Progress Report What Have We Accomplished?
Currently we have a working prototype (right in front of you)
Most of the functionality is completely developed
The design team is testing and polishing niche functionality to bring the entire system to an appropriate acceptance-tested level

32. Future Outlook
The final acceptance tests and bug fixes will likely be finished well under the end-of-semester deadline.
This leaves documentation as the only significant remaining hurdle
A potential Phase 2 prototype has been discussed, with various improvements made in the design, based on experience garnered from the prototype you see in front of you

33. In Conclusion
The Battery Water Level Monitoring System serves to streamline one of the largest hurdles in utilization of lead-acid batteries – maintenance
The three parts of the system divide it into functional groupings, helping to illustrate how each aspect of the design works together to satisfy the requirements proposed
With a working prototype the future looks excellent.

34. QUESTIONS?