A-BMS – Active Battery Management System for cycle applications
This system is intended to support high capacity 48V stationary batteries installed in diesel-battery or RE hybrid power systems, performing continuous hard non-stop cycles that supply off-the-grid telecom or other critical loads.
Batteries may be any lead-acid type or Lithium LiFePO4, and capacity in the range of 500 – 2400 AH.
Battery support includes:
- Active control of the SOC of the individual cells
- Protection against cell sulphation
- Protection against cell over-charge and over-discharge
- Protection against cell over-heat and thermal run-out
- Optional control of the diesel generator
- Battery life extension beyond the typical service life limits stated by the manufacturer for the actual operating conditions (DOD and temperature).
- Actual results from our customer’s reference installations have shown 7-12 years of service life and over 4X the cycle limit of the manufacturer.
- At least 10% reduction in the fuel consumption and the daily operation time of the diesel generator
- Elimination of On-site battery preventing maintenance
- Remarkable increase of watering intervals for flooded batteries
- Early detection upcoming faults to individual battery cells.
- Accurate remote view of battery SOH
- Capability for remote full battery test (including discharge test)
- Detected faulty battery cells (or cell blocks), may be individually replaced. It won’t be necessary to replace the entire battery
Functional description (concept)
The operation of the system is based to the Dynamic Battery Management Concept:
Cells are maintained properly balanced.
Cells are operated in slight PSOC for charging efficiency.
Individual cells are cleaned from sulphation periodically, gently, with no loss of plate active material.
SOC control is implemented by exchanging periodically calculated amounts of charge among individual cells.
Battery cell SOC and overall condition is determined by long term analysis of cell voltage, current, internal resistance and temperature, during the sequence of the charge-discharge cycle segments, using specially developed sophisticated algorithms.
Battery is protected against cell over-discharge, by a hardware signal to start the diesel generator or to disconnect the loads. Similar protection against cell overcharge is provided by a second hardware signal to turn-off the diesel generator or the battery charger. Alternative, the BMS may control directly the diesel generator operation through the optional diesel controller module.
Detailed battery status and battery management equipment activity reports are sent over the IoT to the central server for further processing and distribution.
Our Remote Monitoring and Control Platform running on our central meeting point server is a seamless extension of the software running on the Active Battery Management Equipment. It performs the following tasks:
- Collects the status reports from the individual BMS’s are stores them to the Battery data Database
- Analyzes battery data and detects faulty cells and strings. On any such detection, it issues appropriate alarms for early cell replacement
- Analyzes further the ageing course of the batteries and generates end-of-life and replacement forecasts
- Checks the BMS operational integrity for equipment faults and updates automatically the firmware to the latest version
- Provides the link between batteries and battery owners
- Battery owners and battery owner organization employees join the Remote Monitoring and Control Platform, as users belonging to the specific battery owner and according to a manageable matrix of rights, using commercial web-clients and access the Battery Management Interface
The Battery Management Interface is a seamless extension of the Remote Monitoring and Control Platform for the user side.
It is a very flexible and user friendly tool, accessible by the stuff of the Battery owner organization, through web-clients, from PC’s, tablets and Smart-phones. It provides to the users the following functionalities:
- Organization-site-level overview of real-time battery status (including BMS equipment status), also with geographic visualization
- Site-level real-time battery parameter and BMS activity analytic presentation extending down to cell level.
- Manual control of all the BMS equipment features, in order to perform special tests and cell treatments manually (for qualifying users only, according to their rights levels)
- Site-level history data presentation for batteries, down to cell level and for BMS activity
- Real-time alarms
- Alarm history
- Quick data trend analysis for all battery parameters, down to cell level, extending to the entire battery life
- Battery replacement history
- System Configuration settings control (BMS equipment setup, threshold settings, system preferences etc.)
- User management (user creation, user data editing, user rights level control)
Physical description of the solution
The product is a distributed system consisting of a central control unit and for every string one string current measurement module and twelve cell modules.
The string current measurement module is inserted between the string and the positive or the negative bus.
The cell modules are mounted on the cells. Each cell module serves two adjacent cells. It includes for each cell high accuracy measurement circuits for the detection of its electrical and thermal conditions (for SOC evaluation) and also a high efficiency 2-way converter (charger/discharger) to perform, whenever necessary, charge exchange as scheduled by the central unit.
The central unit collects and processes the data from all the cell modules and the current measurement unit(s). It determines the SOC of the cells, detects the weak and the strong ones, plans according to the Dynamic Battery Management Concept, the required cell SOC variations for proper cell balancing, charge efficiency control and cell desulphation maintenance and schedules the amount of charge to be exchanged and between which cells.
It connects over the internet to the central server and provides the remote monitoring and control to the battery owners.
Special peripheral interface adapter units may be connected to the central unit, to extend the remote monitoring and control to other pieces of equipment (rectifiers, air conditioners, PV chargers, diesel generators etc.) installed at the same site with the batteries.
The cell modules and the current measurement unit(s) are connected to the central unit through an optically isolated modified RS485 bus, physically implemented by daisy-chaining all the modules with the supplied wiring.