Small Battery Research Articles

How to be a good forerunner in carbon neutral trucking

EU countries want to decarbonize their road freight transport quickly. Long-haul electric trucks are a promising technology. There are several competing designs but at present the trade-off is between e-trucks with very large batteries and e-trucks with a smaller battery but combined with motorways electrified via catenary lines. In the latter case a combination of public investment (catenary lines on major motorways) and private investment (electric trucks) is required. As long-haul truck transport is partly international this raises problems of coordination among countries. We study the possible pricing and investment strategy of one forerunner country that faces lagging neighbors. The forerunner can make the use of electric trucks mandatory on its own territory by using very high road charges for diesel trucks. If it has opted for a catenary system, it faces still the choice of how it will price the use of its electric motorways. International diesel trucks, when crossing the border of a forerunner country, must choose between paying high charges and transferring the load into an e-truck. We study the outcome of this international coordination game exploring the non-cooperative outcome varying the relative size of the forerunner in international truck traffic. The same investment coordination is present when one counts on a combination of more dense and cheaper batteries with fast chargers. It is the country with the smallest appetite for decarbonized trucking that will dictate the development in international electric trucking.JEL classification: Q54, Q55, Q58, R42, R48.

Battery Sizing for Mild P2 HEVs Considering the Battery Pack Thermal Limitations

Small capacity and passively cooled battery packs are widely used in mild hybrid electric vehicles (MHEV). In this regard, continuous usage of electric traction could cause thermal runaway of the battery, reducing its life and increasing the risk of fire incidence. Hence, thermal limitations on the battery could be implemented in a supervisory controller to avoid such risks. A vast literature on the topic shows that the problem of battery thermal runaway is solved by applying active cooling or by implementing penalty factors on electric energy utilization for large capacity battery packs. However, they do not address the problem in the case of passive cooled, small capacity battery packs. In this paper, an experimentally validated electro-thermal model of the battery pack is integrated with the hybrid electric vehicle simulator. A supervisory controller using the equivalent consumption minimization strategy with, and without, consideration of thermal limitations are discussed. The results of a simulation of an MHEV with a 0.9 kWh battery pack showed that the thermal limitations of the battery pack caused a 2–3% fuel consumption increase compared to the case without such limitations; however, the limitations led to battery temperatures as high as 180 °C. The same simulation showed that the adoption of a 1.8 kWh battery pack led to a fuel consumption reduction of 8–13% without thermal implications.

Evaluation of a Symptom-Based Algorithm for Managing Battery Ingestions in Children.

While complications from battery ingestion can be severe, especially with the emergence of stronger battery elements, not all ingestions require prompt removal. We aim to evaluate a symptom-focused algorithm for battery ingestion that emphasizes observation over intervention to investigate its safety. Patients were identified through a query of foreign-body ingestion radiographs obtained between 2017 and 2020. A retrospective chart review was then performed of all patients who presented with button battery ingestions to identify compliance with our algorithm, overall outcomes, and complications. In total, 2% of all radiographs (44/2,237) demonstrated button battery ingestions. The median age of patients was 3.8 years (interquartile range, 2.6-5.3). Most batteries were found in the stomach (64%, n = 28), but were also identified in the esophagus (14%, n = 6), small bowel (14%, n = 6), and colon (9%, n = 4). All esophageal batteries were managed with immediate endoscopic retrieval. Ten gastric batteries were not managed per protocol, with seven admitted for observation despite being asymptomatic and repeat abdominal X-rays demonstrating persistent gastric location of the battery. Four patients underwent esophagogastroduodenoscopy; however, in two patients the battery had migrated past the stomach prior to intervention. All small bowel batteries and three of four asymptomatic colon batteries were managed per protocol; one patient had additional imaging that demonstrated battery passage. Adherence to a symptom-focused protocol for conservative management of button battery ingestions beyond the gastroesophageal junction is safe and frequently does not require admission, serial imaging, or intervention.

EV Charging in Case of Limited Power Resource

In the case of the widespread adoption of electric vehicles (EV), it is well known that their use and charging could affect the network distribution system, with possible repercussions including line overload and transformer saturation. In consequence, during periods of peak energy demand, the number of EVs that can be simultaneously charged, or their individual power consumption, should be controlled, particularly if the production of energy relies solely on renewable sources. This requires the adoption of adaptive and/or intelligent charging strategies. This paper focuses on public charging stations and proposes methods of attribution of charging priority based on the level of charge required and premiums. The proposed solution is based on model predictive control (MPC), which maintains total current/power within limits (which can change with time) and imparts real-time priority charge scheduling of multiple charging bays. The priority is defined in the diagonal entry of the quadratic form matrix of the cost function. In all simulations, the order of EV charging operation matched the attributed priorities for the cases of ten cars within the available power. If two or more EVs possess similar or equal diagonal entry values, then the car with the smallest battery capacitance starts to charge its battery first. The method is also shown to readily allow participation in Demand Side Response (DSR) schemes by reducing the current temporarily during the charging operation.

Development of a Liquid Immersion-Type Nickel-Metal Hydride Battery Under High-Pressure

A nickel-metal hydride (Ni–MH) prototype battery completely immersed in an aqueous electrolyte solution of KOH under high-pressure was fabricated to examine the effects of high-pressure on the quality of Ni–MH batteries. The small battery cell comprised positive and negative electrode materials, as used in electric vehicles, and an Ag/AgO reference electrode. The electric capacity of the Ni–MH battery was measured at different temperatures and pressures with small currents and charge/discharge voltages of 1.6–1.0 V. High-pressure was found to clearly and effectively enhance the electric capacity of the Ni–MH battery at larger currents. The considerable effect of high-pressure on the Ni–MH battery was elucidated by the change in internal resistance during the charge/discharge cycle life experiment, indicating that the voltage of the positive electrode did not appreciably change under high-pressure compared to that of the negative electrode. Moreover, the use of large currents in rapid charge/discharge cycle tests at high pressures of up to 30 MPa resulted in charge/discharge cycles that were five times faster and a quick recovery of capacity was achieved in the 0.5–2.1 V range.

Influence of Efficiency, Aging and Charging Strategy on the Economic Viability and Dimensioning of Photovoltaic Home Storage Systems

PV in combination with Li-ion storage systems can make a major contribution to the energy transition. However, large-scale application will only take place when the systems are economically viable. The profitability of such a system is not only influenced by the investment costs and economic framework conditions, but also by the technical parameters of the storage systems. The paper presents a methodology for the simulation and sizing of PV home storage systems that takes into account the efficiency of the storage systems (AC, DC standby consumption and peripheral consumption, battery efficiency and inverter efficiency), the aging of the components (cyclic and calendar battery aging and PV degradation), and the intelligence of the charging strategy. The developed methodology can be applied to all regions. In this paper, a sensitivity analysis of the influence of the mentioned technical parameters on the dimensioning and profitability of a PV home storage is performed. The calculation is done for Germany. Especially, battery aging, battery inverter efficiency and a charging strategy to avoid calendar aging have a decisive influence. While optimization of most other technical parameters only leads to a cost reduction of 1–3%, more efficient inverters can save up to 5%. Even higher cost reductions (more than 20%) can only be achieved using batteries that age less, especially batteries that are less sensitive to calendar aging. In individual cases, a small improvement in the efficiency of the storage system can also lead to higher costs. This is for example the case when smaller batteries are combined with a large PV system and the battery is used more due to the higher efficiency. This results in faster ageing and thus earlier replacement of the battery. In addition, the paper includes a detailed literature overview on PV home storage system sizing and simulation.

RANGE EXTENDER ICE MULTI-PARAMETRIC MULTI-OBJECTIVE OPTIMIZATION


 
 
 
 Range Extended Electric Vehicles (REEV) are still one of the suitable concepts for modern sustainable low emission vehicles. REEV is equipped with a small and lightweight unit, comprised usually of an internal combustion engine with an electric generator, and has thus the technical potential to overcome the main limitations of a pure electric vehicle – range anxiety, overall driving range, heating, and air-conditioning demands – using smaller battery: saving money, and raw materials. Even though several REx ICE concepts were designed in past, most of the available studies lack more complex design and optimization approach, not exploiting the advantageous single point operation of these engines. Resulting engine designs are usually rather conservative, not optimized for the best efficiency. This paper presents a multi-parametric and multi-objective optimization approach, that is applied on a REx ICE. Our optimization toolchain combines a parametric GT-Suite ICE simulation model, modeFRONTIER optimization software with various optimization strategies, and a parametric CAD model, that first provides some simulation model inputs, and second also serves for the final designs’ feasibility check.
 The chosen ICE concept is a 90 degrees V-twin engine, four-stroke, spark-ignition, naturally aspirated, port injected, OHV engine. The optimization goal is to find the thermodynamic optima for three different design scenarios of our concept – three different engine displacements – addressing the compactness requirement of a REx ICE. The optimization results show great fuel efficiency potential by applying our optimization methodology, following the general trends in increasing ICE efficiency, and power for a naturally aspirated concept.
 
 
 

Development of low-cost inclination sensor based on MEMS accelerometers

Rapid development of Micro Electro Mechanical Systems (MEMS) and the minimization of sensor cost, size and energy consumption in the last two decades leads to an effort to replace traditional sensors with their MEMS alternatives. The power consumption is one of the key problems, due to necessity to provide long term device power supply. Therefore a newly developed device was designed with the accent to low power consumption, to be able to operate with one small internal battery at range several months to years. The main goal was to develop a wireless monitoring system capable of continuous stability monitoring of various building structures. The sensor is designed to measure slow inclination variations or changes and in combination with variant designed for high frequency monitoring should represent complete solution of real time structure health monitoring. The STATOTEST compact measurement system is mainly composed of triaxial MEMS accelerometer as a sensing unit, motherboard containing IOT modules and battery, all placed in single waterproof box. The raw signal measured by MEMS accelerometer is preprocessed inside the unit and the data are sent to the cloud via LoRaWan, NBIoT or satellite. The results can be displayed, managed and exported through the web application. This paper presents current state of sensor development, refer to number of problems, which were solved during the process and deals with estimation of its accuracy characteristics in the laboratory conditions. During the laboratory experiment, small defined changes of inclination were performed and compared with values registered by the inclination sensor. The testing was performed before and after calibration procedures. After eliminating of accelerometers production errors, the accuracy of the unit measurement RMSE is less than 0.002° for the step change of 0.09°, tested in six different orientations of the sens or. One measurement is mean of 1000 measurements and its residual random error for one measurement is 2°x10e-5. Series of laboratory tests proved high short-term device accuracy in stable conditions. It is well known, that MEMS accelerometers strongly depend on the sensor temperature. To perform temperature compensation, we built own climate chamber, which is able to change automatically temperature of the several devices at once in specified ranges. Temperature compensation was then performed by using of polynomial approximation to obtain the field measurement accuracy close to laboratory conditions. This task is challenging because it is necessary to improve the proper material composition between the MEMS and the monitored structure and the device fixing methods.

A versatile wearable sEMG recording system for long-term epileptic seizure monitoring.

Surface electromyography (sEMG) can be used to detect motor epileptic seizures non-invasively. For clinical use, a compact-size, user-friendly, safe and accurate sEMG measurement system can be worn by epileptic patients to detect and characterize a seizure. Such devices must be small, wireless, power-efficient minimally invasive and robust to avoid movement artefacts, friction, and slipping of the electrode, which can compromise data integrity and/or generate false positives or false negatives. This paper presents a highly versatile device that can be worn in different locations on the body to capture sEMG signals in a freely moving user without movement artefact. The system can be safely worn on the body for several hours to capture sEMG from wet Ag/AgCl electrodes, while sEMG data is wirelessly transmitted to a host computer within a range of 20 m. We demonstrate the versatility of our sensor by recording sEMG from five different body locations in a freely moving volunteer. Then, simulated seizure data was captured while the device was placed on the extensor carpi ulnaris. We show that sEMG bursts were successfully recorded to characterize the seizure afterward. The presented sensor prototype is small (5 cm x 3.5 cm x 1 cm), lightweight (46 g), and has an autonomy of 12 hrs from a small 110-mAh battery.

UAV Assisted Wireless Network

With the increasing demand of social network service, the unmanned aerial vehicle has been used as a base station to assist terrestrial base station to improve wireless network performance. UAV base station provides high efficiency and wider data transmitting range due to the small size and flexibility of UAV. However, UAV wireless network faces few challenges. Energy efficiency is hard to achieve due to small battery capacity. The base station performance is also very important. It can be determined by aircraft’s flying stability, the performance of air to ground communication and the limitation of wireless coverage of UAV. In order to achieve optimal UAV deployment, improving deployment delay, communication coverage and UAV number limitation are important. Trajectory optimizing problems also need to be considered. This article analyzes UAV assisted wireless networks through investigating UAV energy efficiency, UAV aided network performance, optimal deployment methods and flight trajectory. It is shown that energy efficiency can be optimized by applying LoS based channel in UAV trajectory planning. And inequality iteration algorithm proposed by former researchers is used to determine optimal flight trajectory. This method is efficient because of cellular network’s interference-free ability. As for performance, channel selection methods are used to reduce overflow rate and boost data-received size. These methods are analyzed and proved to be effective for improving UAV aided wireless network performance.

Real-Time Power Analysis of Smart Sensors Using Advanced Debugging Methods.

To achieve a good estimate of the power consumption of an embedded system, including its firmware, is a crucial step in the development of systems with a severely constrained power supply. This is especially true for cases where the device is powered by a small battery or through energy harvesting. The state-of-the-art approaches to measure or estimate the power consumption are formal methods, using power debugging tools with the real hardware or simulation based estimations. In the work at hand, a novel method to estimate the power consumption is proposed, it utilizes the sensor-in-the-loop architecture and enhancing it with a power estimation functionality. The proposed method combines the benefits of former methods, allowing for run-time analysis of the power-consumption in a reproducible way using recorded data without the need for power debugging hardware. In the experiments it is shown that, once set up, the proposed method is able to estimate the power consumption with an error of less than 1% compared to a power debugging hardware. Thus, the proposed method provides a reliable and fast way to estimate the systems power consumption.

Easy-Riding Compact Electric Shopping Vehicle

We are developing a small compact electric vehicle for shopping purposes. In this study, we fabricated an experimental vehicle, that uses only six small rechargeable AA batteries (7.2 V, approximately 2 A·h) as an electric power source. The vehicle user can select between two driving positions: standing and sitting. A compact transmission with a 90-W DC motor and a speed controller that uses pulse width modulation control was designed as an actuating system. Running experiments were conducted to observe the performance of the fabricated vehicle on a flat floor in a gymnasium. The fabricated vehicle was able to operate for 52 min at a speed of 2.73 km/h. The getting-on and getting-off processes in the vehicle were repeated many times during shopping. The human leg strain while getting on and off the vehicle was investigated by electromyogram measurement. During the getting-on and getting-off processes in the vehicle, the myoelectric potential of the quadriceps increased in the sitting position but did not increase in the standing position. The experimental results show that a user suffers more strain in the sitting position than in the standing position.

Comparative Analysis of Off-grid Small Hydro-Solar PV-Diesel Hybrid System in South-west, Nigeria

Reliable, efficient, and affordable power supply system is a necessary tool for rapid socio-economic development of any country. Power supply in Nigeria is grossly inadequate and inefficient. This work presented a comparison analysis of Off-Grid Small hydro-Solar Photovoltaic-Diesel Generator hybrid system in three selected locations in South-west, Nigeria. The selected locations are Molete (Oyo state), Abeokuta (Ogun state) and Ede (Osun state). The hydro data for the three locations were collected from their respective River Basin Development Authorities, while the solar data were obtained from National Aeronautics and Space Administration’s global satellite database. The hybrid components consisting of Small hydropower (SHP), Solar Photovoltaic (PV), Battery (BB) and Diesel Generator (DG) were modelled and run using Hybrid Optimization Model for Electric Renewable software with the stream flow, the solar radiation, load and the system components costs as inputs. The work also carried out a comparative analysis based on economic parameters-return on investment and simple payback period different from the conventional use of net present cost, cost of energy(COE) and operating cost. The optimal hybrid combinations for these areas were compared with the usage of autonomous DG. The most optimal hybrid combination for Molete and Ede is PV-BB-SHP System with COEs of $0.347/kWh and $0.161/kWh respectively. The most optimal configuration for Abeokuta is PV-DG-BB-SHP with COE of $0.290/kWh. The results obtained (based on economic and technical considerations) showed that the hybrid system is viable for these areas. The outcome of the research will serve as guide for the government and prospective investors in formulating effective policies towards rapid development of renewable energy technologies in these areas.

Comparative Analysis of Off-grid Small Hydro-Solar PV-Diesel Hybrid System in South-west, Nigeria

Reliable, efficient, and affordable power supply system is a necessary tool for rapid socio-economic development of any country. Power supply in Nigeria is grossly inadequate and inefficient. This work presented a comparison analysis of Off-Grid Small hydro-Solar Photovoltaic-Diesel Generator hybrid system in three selected locations in South-west, Nigeria. The selected locations are Molete (Oyo state), Abeokuta (Ogun state) and Ede (Osun state). The hydro data for the three locations were collected from their respective River Basin Development Authorities, while the solar data were obtained from National Aeronautics and Space Administration’s global satellite database. The hybrid components consisting of Small hydropower (SHP), Solar Photovoltaic (PV), Battery (BB) and Diesel Generator (DG) were modelled and run using Hybrid Optimization Model for Electric Renewable software with the stream flow, the solar radiation, load and the system components costs as inputs. The work also carried out a comparative analysis based on economic parameters-return on investment and simple payback period different from the conventional use of net present cost, cost of energy(COE) and operating cost. The optimal hybrid combinations for these areas were compared with the usage of autonomous DG. The most optimal hybrid combination for Molete and Ede is PV-BB-SHP System with COEs of $0.347/kWh and $0.161/kWh respectively. The most optimal configuration for Abeokuta is PV-DG-BB-SHP with COE of $0.290/kWh. The results obtained (based on economic and technical considerations) showed that the hybrid system is viable for these areas. The outcome of the research will serve as guide for the government and prospective investors in formulating effective policies towards rapid development of renewable energy technologies in these areas.

Nail Penetration of Small Pouch Cells under Water: Investigation of Hydrofluoric Acid Formation in Dependence of the State of Charge

Accidental damage to electric vehicle batteries can poses an unknown safety risk and, as such, they are placed in a container filled with water. The present study investigates the extent to which a battery stored under water may still react in the case of an event. The focus of this study was to find out if hydrofluoric acid (HF) is formed after nail penetration of small lithium-ion battery cells under water. Three different states of charge (SoC) were examined: 0%, 50%, and 100%, to determine how strongly HF formation depends on this parameter. The test was repeated three times at each SoC level. The highest formation of HF was found at a SoC of 100%. Despite the use of the same cells, the same and mostly automatically procedure, a high variation of fluoride concentration was observed for 100% SoC. The cells with a SoC levels at 0% and 50% showed quite low fluoride concentrations. Overall, it was concluded that the low reactivity of the cells was caused by the surrounding water.

An Aging Study of NCA/Si-Graphite Lithium-Ion Cells for Off-Grid Photovoltaic Systems in Bolivia

Performance and aging of lithium-ion 18650 cylindrical cells containing NCA and Si-graphite composite electrodes are investigated during long-term low current rate (∼0.1C) cycling protocol resembling charge/discharge profile of off-grid photovoltaic battery system. The cells are cycled within 30% and 75% state-of-charge ranges (∆SOC) with low, middle and high cut-off voltages. Electrochemical impedance spectroscopy data of full cylindrical cells exhibit severe aging for cells that have been cycled at higher cut-off voltage of 4.2 V. Symmetric cell impedance from each electrode shows that aging of NCA is dominant over aging of Si-graphite. Using a Newman-based impedance model, the NCA symmetrical cells’ impedance spectra are parameterized to evaluate the aging modes. The resulting parameterization confirms increased particles’ surface film resistance due to possible electrolyte oxidation and tortuosity increase at high cut-off voltages. Cycling the cells with middle and low cut-off voltages causes few significant changes when compared to calendar-aged samples. This opens up the possibility to significantly increase battery lifetime for small photovoltaic battery systems in rural areas of Bolivia.

Heatsinks to Cool Batteries for Unmanned Aerial Vehicles

This study aims to develop several different models of heatsinks, designed to cool a vertical take-off and landing unmanned aerial vehicle (UAV) battery, through topology optimization, aimed at being manufactured through selective laser melting (SLM) technology. A battery’s temperature must be properly managed for a safe and efficient operation. The methodology developed was with the support of software to carry out several simulations which, starting from several scenarios and restrictions imposed by the small space available to accommodate these small batteries in this type of aircraft. The conception resulted in several battery thermal management systems (BTMS) models, with different applications and efficiency degrees. A relevant aspect is the topology optimization being coupled to computational thermal analysis to reduce the mass of the heatsink whilst ensuring a maximum battery temperature threshold. Together with the use of topology optimization, the SLM process was selected to manufacture the heat sinks, under conditions of geometric freedom, using several high thermal conductivity metal alloys, such as, aluminium and copper to obtain the designed models.

Longitudinal auditory pathophysiology following mild blast-induced trauma.

Blast-induced hearing difficulties affect thousands of veterans and civilians. The long-term impact of even a mild blast exposure on the central auditory system is hypothesized to contribute to lasting behavioral complaints associated with mild blast traumatic brain injury (bTBI). Although recovery from mild blast has been studied separately over brief or long time windows, few, if any, studies have investigated recovery longitudinally over short-term and longer-term (months) time windows. Specifically, many peripheral measures of auditory function either recover or exhibit subclinical deficits, masking deficits in processing complex, real-world stimuli that may recover differently. Thus, examining the acute time course and pattern of neurophysiological impairment using appropriate stimuli is critical to better understanding and intervening in bTBI-induced auditory system impairments. Here, we compared auditory brainstem response, middle-latency auditory-evoked potentials, and envelope following responses. Stimuli were clicks, tone pips, amplitude-modulated tones in quiet and in noise, and speech-like stimuli (iterated rippled noise pitch contours) in adult male rats subjected to mild blast and sham exposure over the course of 2 mo. We found that blast animals demonstrated drastic threshold increases and auditory transmission deficits immediately after blast exposure, followed by substantial recovery during the window of 7-14 days postblast, although with some deficits remaining even after 2 mo. Challenging conditions and speech-like stimuli can better elucidate mild bTBI-induced auditory deficit during this period. Our results suggest multiphasic recovery and therefore potentially different time windows for treatment, and deficits can be best observed using a small battery of sound stimuli.NEW & NOTEWORTHY Few studies on blast-induced hearing deficits go beyond simple sounds and sparsely track postexposure. Therefore, the recovery arc for potential therapies and real-world listening is poorly understood. Evidence suggested multiple recovery phases over 2 mo postexposure. Hearing thresholds largely recovered within 14 days and partially explained recovery. However, midlatency responses, responses to amplitude modulation in noise, and speech-like pitch sweeps exhibited extended changes, implying persistent central auditory deficits and the importance of subclinical threshold shifts.

A survey of leakage reduction techniques in CMOS digital circuits for nanoscale regime

ABSTRACT The battery-driven portable systems are the lifeline of the modern era. Very large-scale integration (VLSI) designers are continuously working to enhance the performance of the portable systems. The small size, fast response and high battery back-up are the prime factors for the portable systems. Scaling down of the metal oxide semiconductor field effect transistor (MOSFET) dimensions is mandatory to design the low size systems. The power supply and the threshold voltage must be scaled-down with each new technology node in order to maintain the performance of the devices. The scaling down of the threshold voltage of the device produces leakage current. The amount of the leakage current is large at integration level and harms the characteristics of the systems. Therefore, leakage current mitigation is needed especially at lower technology nodes to boost the battery back-up of the portable systems. Number of leakage reduction techniques are available at different abstraction levels. In this review paper, a systematic flow of the low power VLSI field is explored with the target of the different existing circuit level leakage reduction techniques. NAND3 gate is designed and simulated at 16 nm technology node by using the different existing leakage reduction techniques for the comparison purpose.

Run-of-the-River Hydro-PV Battery Hybrid System as an Energy Supplier for Local Loads

Hybrid hydro energy systems are usually analysed with pumped hydro storage systems, which can facilitate energy accumulation from other sources. Despite the lack of water storage, run-of-the-river hydropower plants are also attractive for hybrid systems owing to their low investment cost, short construction time, and small environmental impact. In this study, a hybrid system that contains run-of-the-river small hydro power plants (SHPs), PV systems, and batteries to serve local loads is examined. Low-power and low-head schemes that use variable-speed operation are considered. The novelty of this study is the proposal of a dedicated steady-state model of the run-of-the-river hydropower plant that is suitable for energy production analysis under different hydrological conditions. The presented calculations based on a real SHP of 150 kW capacity have shown that a simplified method can result in a 43% overestimation of the produced energy. Moreover, a one-year analysis of a hybrid system operation using real river flow data showed that the flow averaging period has a significant influence on the energy balance results. The system energy deficiency and surplus can be underestimated by approximately 25% by increasing the averaging time from day to month.