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All Journal Jurnal Asiimetrik: Jurnal Ilmiah Rekayasa Dan Inovasi
Herlina
Universitas Sriwijaya
Civil Engineering, Building, Construction & Architecture Computer Science & IT Electrical & Electronics Engineering Industrial & Manufacturing Engineering

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Performance Analysis of Time Capacity and Coulomb Methods for SoC Estimation in VRLA Batteries Herlina; M. Rafli Leo; Sri Agustina; Wirawan Adi Pradana
Jurnal Asiimetrik: Jurnal Ilmiah Rekayasa Dan Inovasi Volume 7 Number 2 (2025)
Publisher : Fakultas Teknik Universitas Pancasila

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.35814/asiimetrik.v7i2.8774

Abstract

The climate crisis and limited energy availability in remote areas encourage the use of VRLA battery-based off-grid solar energy systems, where accurate state-of-charge (SoC) evaluation is essential for system efficiency. At middle SoC ranges, the VRLA voltage curve's flatness makes voltage-based methods less effective. This research investigates the efficacy of two practical methods, Time Capacity and Coulomb Counting, in estimating the SoC of 12V 10Ah VRLA batteries at varying discharge rates (C20 to C1) using a system that incorporates Arduino Uno and ACS712 sensors. The experimental findings show that Time Capacity is the best strategy, with an inaccuracy of 0-12%. Due to sensor error and temperature sensitivity, Coulomb Counting's error is 30-38.4%. Heatmap imaging proved Time Capacity's stability across all C-rates, making it suitable for remote monitoring. These findings lay the groundwork for reliable and cost-effective renewable energy systems and encourage further research on hybrid algorithms and environmental optimisation.
Thermal Safety and Efficiency of a 24 Volt DC Motor Used as a Prime Mover for a Single-Phase Generator Sri Agustina; M. Aldi Ramadhan; Herlina; Wirawan Adipradana
Jurnal Asiimetrik: Jurnal Ilmiah Rekayasa Dan Inovasi Volume 8 Number 1 (2026)
Publisher : Fakultas Teknik Universitas Pancasila

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.35814/asiimetrik.v8i1.9537

Abstract

Brushed DC motors are often used as low-cost prime movers in small generator sets. However, users rarely evaluate thermal safety together with efficiency when the set operates under repeated electrical loads. This study investigates a 24 V, 750 W brushed DC motor mechanically coupled to a 220 V, 50 Hz single-phase synchronous generator and a lamp-based resistive load bank. Three generator load levels were tested (1000 W, 1400 W, and 2600 W). Each test ran for 10 minutes to represent a short-time duty that is practical for repeated laboratory trials and long enough to reveal a clear temperature trend while maintaining safe operation. The DC terminal voltage (V), input current (A), and motor surface temperature (°C) were recorded every 2 minutes. Input power, temperature rise, estimated loss power, output power, and apparent efficiency were then computed at the 10-minute mark. The results show a monotonic temperature rise with load: after 10 minutes, the motor surface temperature reached about 36.0°C (1000 W), 39.3°C (1400 W), and 41.5°C (2600 W), corresponding to a 9–15 K rise above ambient. The apparent efficiency remained high at 94.3–96.3%. These findings support a simple and replicable approach to discussing the thermal safety and efficiency of small motor–generator sets in laboratory practice.
Preliminary Study on Wind Turbines for Power on Floating Net Cages Herlina; Sri Agustina; Sariman; M. Akbar Pratama; M. Ichsan Azhary
Jurnal Asiimetrik: Jurnal Ilmiah Rekayasa Dan Inovasi Volume 6 Nomor 2 Tahun 2024
Publisher : Fakultas Teknik Universitas Pancasila

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.35814/asiimetrik.v6i2.6869

Abstract

Focus of this primary study is to investigate how efficient horizontal-axis wind turbines (HAWT) and vertical-axis wind turbines (VAWT) are in preserving floating net cages. The expansion of the aquaculture sector, which is increasingly dependent on advanced technologies like monitoring and data processing systems in open waters, need a reliable energy source. The investigation was carried out by manipulating wind speed, battery charging duration, and electrical load for both types of wind turbines in simulated field circumstances. Based on the test results, HAWT outperforms VAWT in generating a greater battery voltage and achieving a more consistent charging period at the same wind speed. The smallest voltage rise in HAWT is 2.2 m/s with a 5-minute 0% charging time and the maximum is 1.2 m/s with a 15-minute 38.1% charging time. While the VAWT demonstrates better stability under specific load conditions, the HAWT can generate substantial power throughout a wide range of wind speeds. This renders HAWT more appropriate for utilization in dynamic maritime applications, such as floating net cages.
Co-Authors M. Akbar Pratama M. Aldi Ramadhan M. Ichsan Azhary M. Rafli Leo Sariman Sri Agustina Wirawan Adi Pradana Wirawan Adipradana