Technical Specs
Table Of Contents
- 1) REVISION HISTORY
- 2) INTRODUCTION
- 3) HARDWARE FEATURES
- 4) SOFTWARE FEATURES
- 5) SOFTWARE OPERATION
- General guidelines.
- The BMS collects a series of data using a set of sensors. The data consist of Current, Voltage of the battery cell and also half Voltage in the middle of the cell. Also Temperature and electrolyte levels are measured. Depending on these measurements the remaining Ah and Kwh are calculated, as well as the battery status. Periodicaly these values and other battery status indications are recorded in files and all together are sent to an external server for further analysis.
- STATE MACHINE
- The BMS can be in one of the 5 following states :
- Charge Active : High level positive Current to the battery resulting in the charge of the battery cell.
- Charge Idle : The battery is at a state of charge but the positive current is low.
- Discharge Active : High level negative current from the battery results in battery discharge.
- Discharge Idle : The battery is at a state of discharge but the current is low intensity.
- Storage : Both the positive and negative current is of negligence level for a long period of time so the battery is at storage state.
- In order to pass to status Charge Idle the battery must be in Charge Active state and the mean current for a given time period must be less than 1A/100Ah.
- In order for battery going to status Discharge-Idle the battery must be at Discharge Active status and no current sample above 1A/100Ah is received for the given time period.
- The battery can fall to Charge Active state when :
- a) The status is Charge Idle and the mean current for at least one minute is at 5A/100Ah
- b) To be in Discharge state and current is greater than 5A/100Ah for at least one minute.
- For the battery status Discharge Active to occur the battery must :
- a) Be at Discharge Idle state and have a mean current for one minute greater than 1A/100Ah.
- b) Be at charge state and have a mean discharge current for one minute greater than 2A/100Ah.
- A new cycle starts every time the BMS goes from Charge state to Discharge state.
- The battery has also the following proper function states :
- Overdischarge False : (Correct function)
- Overdischarge True : The battery cell is allmost empty.
- Level Normal : the electrolyte level is normal.
- Level Fill Soon : The electrolyte level is low.
- Level Fill Now : The electrolyte level is low for a long period of time.
- As well as this the following temperature status are available :
- Temp Normal : Normal Temperature
- Temp Over : High Temperature
- Temp Xtrm : Extremely high temperature.
- Communication
- The BMS communicates with the server in regular time intervals. The communication is performed using HTTPS Protocol and POST method is used. The measurements are transported using JSON form. Using the same methods the user can send commands to the BMS and those can be executed when communication is established.
- Detailed Function
- The BMS receives measurements from its sensors periodicaly. Current and Voltages are measured every 100 msec, electrolyte level every one sec and temperature every 10 sec. After each measurement it refreshes the various counters :
