Extend Battery Life Time by Optimizing Charge and Discharge Process with Weather Forecast
Battery life time is impacted by several factors, such as charging speed, depth of discharge, loading and exposure to adverse temperature, etc. Like mechanical device that wears out quicker with heavier use, in real solar lighting application, the depth of discharge (DoD) plays the major role that determines the cycle count of the battery. The smaller the discharge (low DoD), the longer the battery will last.
Below is the Modeling of Lithium-Ion Battery Degradation for Cell Life Assessment:
* Source: IEEE Transactions on Smart Grid·June 2016
What we can see from the test is:
Case 1: 75–65% SoC offers longest cycle life but delivers only 90,000 energy units (EU). Utilizes 10% of battery.
Case 2: 75–25% SoC has 3,000 cycles (to 90% capacity) and delivers 150,000 EU. Utilizes 50% of battery.
Case 3: 85–25% SoC has 2,000 cycles. Delivers 120,000 EU. Uses 60% of battery.
Case 4: 100–25% SoC; long runtime with 75% use of battery. Has short life.
In order to extend the life time of battery, we need to optimize its charge and discharge process by maximizing the cycles of low DoD and minimizing the cycles of high DoD. But battery does not know how much power will be enough for coming days, to make sure that the battery will always be working sufficiently as much as possible, the traditional way is to charge it to a certain high level like 90% even 100% at every charge time. This will dramatically reduce the cycle count of battery.
* Traditional charge and discharge process:
SolarFusion, by connecting all solar lights to a central management system through LoRaWAN network which can monitor the energy level of each solar light’s battery and obtain weather forecast everyday, is able to create an optimized charge and discharge schedule for every solar light which will deliver sufficient power without undermining the lighting service.
* Optimized charge and discharge process:
Energy Saving - Deliver Right Brightness at Right Time by Smart Dimming
Same as smart street lighting application, SolarFusion enables the lighting authority to configure multiple working schedules for different solar light groups to deliver an energy-efficient environment-friendly luminous output without compromising the traffic safety. In terms of solar lighting, the smart dimming will not only reduce light pollution but also extend the battery life time due to low DoD at every night.
Maintenance Saving - Automatic Fault Alerts & Maintenance Scheduling
The working status of the lamp, solar panel, battery is constantly being monitored by the solar light controller. The CMS will automatically issue a fault alert if any fault has been detected and reported, and then a maintenance schedule will be created automatically and forwarded to maintainers. There will be no need to send labour intensive patrol to do any on-site inspection, which will save a considerable physical surveillance overheads cost and shorten the service response time.