Browse technical resources about solar mounting systems, tracker technology, structural design, and installation best practices.
HOME / Will Battery Discharge If Stored Cordless Drill - BeTheFuture Solar Foundation & Infrastructure
Manufacturers specify the capacity of a battery at a specified discharge rate. For example, a battery might be rated at 100 when discharged at a rate that will fully discharge the battery in 20 hours (at 5 amperes for this example). If discharged at a faster rate the delivered capacity is less. Peukert's law describes a power relationship between the discharge current (normalized to some base rated current) and delivered capacity (normalized to the rated capacity) over some s.
The rate at which a battery is discharged can also affect its characteristics. When you discharge a battery at a high rate (i.e., a large current is drawn quickly), its effective capacity can decrease. The reasons behind this are multi-factorial and tied to changes in chemical reactions and impacts tied to the battery's internal resistance.
The battery discharge rate is the amount of current that a battery can provide in a given time. It is usually expressed in amperes (A) or milliamperes (mA). The higher the discharge rate, the more power the battery can provide. To calculate the battery discharge rate, you need to know the capacity of the battery and the voltage.
Capacity: Measured in ampere-hours (Ah), capacity indicates the amount of energy stored in the battery. . It's like the fuel tank of a car, showing how much “fuel” is left. Discharge Rate: Expressed as a fraction of the battery's capacity (e.g., 0.5C, 1C, 2C), the discharge rate shows how quickly the battery is being used.
This phenomenon is due to increased internal resistance and inefficiencies that arise under high discharge conditions. Slower Discharge: On the other hand, a slower discharge rate allows the battery to use its capacity more efficiently, extending its runtime and overall effectiveness.
Conversely, batteries operating at low discharge rates tend to exhibit more stable and reliable performance. For example: Lithium-Ion Batteries: These batteries are particularly efficient at lower discharge rates. They maintain a higher proportion of their nominal capacity, which results in longer-lasting power and better overall efficiency.
Rate tolerance: EV battery cells generally tolerate high discharge rates better than high charge rates, maintaining performance with less degradation. However, if unchecked, frequent high discharges can still shorten battery life.
Formula: Lead acid Battery life = (Battery capacity Wh × (85%) × inverter efficiency (90%), if running AC load) ÷ (Output load in watts). I won't go in-depth about the discharging mechanism of a lead-acid battery. Instead, I'm going to share the key points to remember when discharging your lead-acid battery.
50% Depth of Discharge for Lead Acid Battery “Lead acid batteries should be discharged only by 50% to increase its life” – is an oft used phrase. This means that we should cycle them in the 100% to 50% window as shown below in the Typical state of charge window parameter.
The faster you discharge a lead acid battery the less energy you get (C-rating) Recommended discharge rate (C-rating) for lead acid batteries is between 0.2C (5h) to 0.05C (20h). Look at the manufacturer's specs sheet to be sure. Formula to calculate the c-rating: C-rating (hour) = 1 ÷ C
“Lead acid batteries should be discharged only by 50% to increase its life” – is an oft used phrase. This means that we should cycle them in the 100% to 50% window as shown below in the Typical state of charge window parameter. So it follows that the usable capacity of a lead acid battery is only 50% of the rated capacity.
Formula: Lead acid Battery life = (Battery capacity Wh × (85%) × inverter efficiency (90%), if running AC load) ÷ (Output load in watts). Let's suppose, why non of the above methods are 100% accurate? I won't go in-depth about the discharging mechanism of a lead-acid battery.
This means that we should cycle them in the 100% to 50% window as shown below in the Typical state of charge window parameter. So it follows that the usable capacity of a lead acid battery is only 50% of the rated capacity. So if you have a 100Ah battery, you can only use 50Ah. In this blog, I will provide reasons as to why this is so.
Therefore, 50% represents a good balance between capacity and cycle life, also taking into consideration the cost of replacement. So why should we not discharge more than 50% for lead acids? This is because if the DoD is more than 50%, it would reduce the life of the battery. How & Why?
Battery balancing and battery redistribution refer to techniques that improve the available of a with multiple cells (usually in series) and increase each cell's longevity. A battery balancer or battery regulator is an electrical device in a battery pack that performs battery balancing. Balancers are often found in packs for laptop computers, electrical vehicles.
Battery cell balancing brings an out-of-balance battery pack back into balance and actively works to keep it balanced. Cell balancing allows for all the energy in a battery pack to be used and reduces the wear and degradation on the battery pack, maximizing battery lifespan. How long does it take to balance cells?
Battery balancing works by redistributing charge among the cells in a battery pack to achieve a uniform state of charge. The process typically involves the following steps: Cell monitoring: The battery management system (BMS) continuously monitors the voltage and sometimes temperature of each cell in the pack.
needs two key things to balance a battery pack correctly: balancing circuitry and balancing algorithms. While a few methods exist to implement balancing circuitry, they all rely on balancing algorithms to know which cells to balance and when. So far, we have been assuming that the BMS knows the SoC and the amount of energy in each series cell.
s linked together. A battery pack is out of balance when any property or state of those cells differs. Imbalanced cells lock away otherwise usable energy and increase battery degradation. Batteries that are out of balance cannot be fully charged or fully discharged, and the imbalance causes cells to wear and degrade at accelerated rates.
A battery balancer is a device or circuit designed to equalize the charge levels across multiple cells in a battery pack. It is a critical component of a battery management system (BMS) that ensures the battery pack's optimal performance, safety, and longevity. A typical battery balancer consists of several key components:
In most cases, balancing is performed continuously during charging cycles. Some advanced systems may also balance during discharge or idle periods. For lithium-ion batteries in consumer electronics, balancing occurs automatically with each charge cycle.
It refers to the rate at which a battery releases its stored energy during use, typically measured in terms of current (amperes) relative to the battery's capacity (C-rate).
It refers to the rate at which a battery releases its stored energy during use, typically measured in terms of current (amperes) relative to the battery's capacity (C-rate). The discharge rate significantly affects a battery's lifespan, efficiency, and suitability for various applications.
3. Charge/Discharge Rate (C) The charge/discharge rate measures the speed at which the lithium battery can be charged or discharged, expressed in “C. Discharge Rate (C) = Discharge Current (A) ÷ Rated Capacity (Ah) High Rate Applications: Suitable for rapid charging and discharging scenarios, like electric vehicles.
Maximum 30-sec Discharge Pulse Current –The maximum current at which the battery can be discharged for pulses of up to 30 seconds. This limit is usually defined by the battery manufacturer in order to prevent excessive discharge rates that would damage the battery or reduce its capacity.
Rated power capacity is the total possible instantaneous discharge capability (in kilowatts or megawatts ) of the BESS, or the maximum rate of discharge that the BESS can achieve, starting from a fully charged state. Storage duration is the amount of time storage can discharge at its power capacity before depleting its energy capacity.
The main technical measures of a Battery Energy Storage System (BESS) include energy capacity, power rating, round-trip efficiency, and many more. Read more...
The maximum amount of energy accumulated in the battery within the analysis period is the Demonstrated Capacity (kWh or MWh of storage exercised). In order to normalize and interpret results, Efficiency can be compared to rated efficiency and Demonstrated Capacity can be divided by rated capacity for a normalized Capacity Ratio.
The answer is that it stands for “depth of discharge. ” But what does that mean? Put simply, it means how much of a battery's actual power can be used out of its total power capacity.
A deep discharge typically means discharging a battery by 80% or more of its total capacity. Can all batteries handle deep discharge? Only specific types, like deep-cycle and lithium-ion batteries, are designed for frequent deep discharges without sustaining damage.
In general, most modern lithium-ion batteries have a depth of discharge ranging from 80% to 100%. Can a Deep Cycle Battery Be Fully Discharged? Let's answer this question for lead-acid and lithium-ion batteries separately. Can You Fully Discharge a Lead-Acid Battery? Never fully discharge a lead-acid deep cycle battery!
The recommended battery DoD varies by the type of battery and manufacturer. Let's cover the average depth of discharge of some common batteries. What Is the Depth of Discharge of a Lead-Acid Battery? The recommended depth of discharge for lead-acid batteries is 50%.
Charging and Discharging Definition: Charging is the process of restoring a battery's energy by reversing the discharge reactions, while discharging is the release of stored energy through chemical reactions. Oxidation Reaction: Oxidation happens at the anode, where the material loses electrons.
Let's talk about the negative effects deep discharge has on batteries, especially lithium-ion, which are the most common type found in smartphones, laptops, and electric vehicles. Loss of Capacity: When a battery is deeply discharged repeatedly, its internal structure undergoes chemical changes that reduce its capacity.
Depth of discharge is simply the opposite of state of charge. When that's the case, state of charge is simply the inverse of depth of discharge. Put another way, if a battery is at 100% state of charge, then its depth of discharge is 0%. The opposite is also true. If a battery is 100% discharged, its state of charge is 0%.
A battery energy storage system (BESS), battery storage power station, battery energy grid storage (BEGS) or battery grid storage is a type of technology that uses a group of in the grid to store. Battery storage is the fastest responding on, and it is used to stabilise those grids, as battery storage can transition fr.
A battery energy storage system (BESS) is an electrochemical device that charges (or collects energy) from the grid or a power plant and then discharges that energy at a later time to provide electricity or other grid services when needed.
Secondary energy storage in a power system is any installation or method, usually subject to independent control, with the help of which it is possible to store energy, generated in the power system, keep it stored and use it in the power system when necessary.
In the quest for a resilient and efficient power grid, Battery Energy Storage Systems (BESS) have emerged as a transformative solution. This technical article explores the diverse applications of BESS within the grid, highlighting the critical technical considerations that enable these systems to enhance overall grid performance and reliability.
The other primary element of a BESS is an energy management system (EMS) to coordinate the control and operation of all components in the system. For a battery energy storage system to be intelligently designed, both power in megawatt (MW) or kilowatt (kW) and energy in megawatt-hour (MWh) or kilowatt-hour (kWh) ratings need to be specified.
The third part which is about Power system considerations for energy storage covers Integration of energy storage systems; Effect of energy storage on transient regimes in the power system; and Optimising regimes for energy storage in a power system.
By placing energy storage systems where they are most needed, grid operators can ensure more efficient voltage regulation, especially in areas with high load density or regions far from traditional generation sources. The Power Conversion System (PCS) within the BESS plays a crucial role in providing voltage support.
Note: Use our solar battery charge time calculatorto find out the battery charge time using solar panels. If the C-rating is mentioned as C/n (any number), in this case, C = 1. (E.g, C/2 = 1/2 = 0.5C). 1. C/2 = 0.5C 2. C/5 = 0.2C 3. C/10 = 0.1C 4. C/20 = 0.05C Generally, you will find the battery c rate on battery label or on the specs sheet of your battery. As you can see, the battery c rating is mentioned as "max. charge current" and "max. discharge current". The below chart shows the conversion of different c-ratings on batteries into charge/discharge time. Converting the C rate of your battery to time will let you know your battery's recommended charge and discharge time. Formula: C-rate in time (hours) = 1 ÷ C-rate Formula: C-rate in time (minutes) = (1 ÷ C-rate) × 60 Converting the C rate of your battery into amps will give you the recommended charge and discharge current (amps). Formula: Battery charge and discharge rate in amps = Battery.
[PDF Version]The faster you discharge a lead acid battery the less energy you get (C-rating) Recommended discharge rate (C-rating) for lead acid batteries is between 0.2C (5h) to 0.05C (20h). Look at the manufacturer's specs sheet to be sure. Formula to calculate the c-rating: C-rating (hour) = 1 ÷ C
The lead-acid battery discharge curve equation is given by the battery capacity (in ah) divided by the number of hours it takes to discharge the battery. For illustration, a 500 Ah battery capacity that theoretically discharges to a cut-off voltage in 20 hours will have a discharge rate of 500 amps / 20 hours = 25 amps.
Last example, a lead acid battery with a C10 (or C/10) rated capacity of 3000 Ah should be charge or discharge in 10 hours with a current charge or discharge of 300 A. C-rate is an important data for a battery because for most of batteries the energy stored or available depends on the speed of the charge or discharge current.
Sealed lead-acid batteries are generally rated with a 20-hour discharge rate. That is the current that the battery can provide in 20 hours discharged to a final voltage of 1.75 volts per second at a temperature of 25 degrees Celsius.
Formula: Lead acid Battery life = (Battery capacity Wh × (85%) × inverter efficiency (90%), if running AC load) ÷ (Output load in watts). Let's suppose, why non of the above methods are 100% accurate? I won't go in-depth about the discharging mechanism of a lead-acid battery.
A lead-acid battery reads 1.175 specific gravity. Its average full charge specific gravity is 1.260 and has a normal gravity drop of 120 points (or.120) at an 8 hour discharge rate. Solution: Fully charged – 1.260
In this project, we will build an IoT based Battery Monitoring System using ESP8266 where you can monitor the battery charging/discharging status along with Battery Voltage & Percentage. As we know, the battery is the most important component for any device as it powers the entire system. So, it is important to monitor. You will need the following components for the IoT Based Battery Monitoring System Project. You can purchase all the components online from. A lithium-ion battery or Li-ion battery is a type of rechargeable battery. Lithium-ion batteries are commonly used for portable electronics and electric vehicles. In this battery, lithium ions move. In order to Monitor the Battery Data on ThingSpeak Server, you first need to Setup the Thingspeak. To set up the ThingSpeak Server, visit. We will design a system to monitor this battery voltage along with charging and discharging status. For the microcontroller, we use WeMos D1 Mini which has an ESP8266 wifi-enabled.
[PDF Version]In this IoT-based Battery Monitoring System, we will use the NodeMCU ESP8266 board to send the battery status data to the Arduino IoT cloud. The IoT Cloud Dashboard will display the battery voltage along with the battery percentage in both the charging and discharging conditions.
The proposed battery voltage status monitor circuit using 4 LEDs makes use of comparators in the form of opamps from the IC LM324. This IC is much versatile than the other opamp counterparts due to its higher voltage tolerance level and due to the quad opamps in one package.
How to Set up the above explained battery status indicator Circuit. It's pretty simple. Apply the full-charge voltage level across the point indicated "to battery positive" and ground. Now adjust the preset such that the last LED just illuminates at that voltage level. Done! Your circuit is all set now.
This allows users to monitor the battery status remotely from anywhere in the world via their smartphones or computer dashboards. The server displays the battery voltage, load voltage, current, and power, providing a comprehensive overview of the battery's condition in both charging and discharging states.
Battery is the most important component for any device as it powers the whole system. And it is important to monitor the voltage level of the battery as improper charging and discharging of a lithium battery may lead to a big safety issue.
In this IoT-based Battery Monitoring System, we will use Wemos D1 Mini with ESP8266 Chip to send the battery status data to ThingSpeak cloud. The Thingspeak will display the battery voltage along with the battery percentage in both the charging and discharging cases.
For the purposes of this document, the following terms and definitions apply; Power Generating Modules are categorised in EREC G99 as Power Park Modules (PPM) or Synchronous Power Generating Modules (SPGM). Both contain one or more. When you are ready to submit a formal application for connection, we will require information from you to enable us to make a reasonable assessment of the works required to facilitate the. Discussing your plans with us at an early stage can help to provide a better insight to any potential network reinforcement and complexity issues that. If you are not ready to enter into a formal agreement for connection works, or you do not yet have full details of the specific conditions required, you.
Below is a detailed explanation of the primary technical parameters of lithium batteries, along with additional related knowledge, to assist you in better applying and managing energy storage systems.
Learn about the key technical parameters of lithium batteries, including capacity, voltage, discharge rate, and safety, to optimize performance and enhance the reliability of energy storage systems. Lithium batteries play a crucial role in energy storage systems, providing stable and reliable energy for the entire system.
Lithium batteries play a crucial role in energy storage systems, providing stable and reliable energy for the entire system. Understanding the key technical parameters of lithium batteries not only helps us grasp their performance characteristics but also enhances the overall efficiency of energy storage systems.
Specific capacity, energy density, power density, efficiency, and charge/discharge times are determined, with specific C-rates correlating to the inspection time. The test scheme must specify the working voltage window, C-rate, weight, and thickness of electrodes to accurately determine the lifespan of the LIBs. 3.4.2.
Energy density is often a more relevant indicator than capacity in practical applications. Current lithium-ion battery technology achieves energy densities of approximately 100 to 200 Wh/kg. This level is relatively low and poses challenges in various applications, particularly in electric vehicles where both weight and volume are restricted.
LIBs are prominent energy storage devices to meet the growing energy demands of the modern era. They offer high specific capacity, energy density, thermal stability, and long calendar life compared to other types of batteries. LIBs are used in a diverse range of applications, from powering household appliances to supporting electric vehicles.
Battery storage is a technology that enables power system operators and utilities to store energy for later use.
A lead-acid battery consists of two lead plates separated by a liquid or gel containing sulfuric acid in water. The battery is rechargeable, with charging and discharging chemical reactions. When the battery is being used (discharged), electrons move from the negatively-charged lead plate to the positively-charged plate. The. When the battery is fully charged, the negative plate is lead, the electrolyte is concentrated sulfuric acid, and the positive plate is lead dioxide. If the battery is overcharged, electrolysis of water produces hydrogen gas. Calling sulfuric acid"battery acid" gives an indication of the acid concentration. There are, in fact, several different names for sulfuric acid that typically reflect its usage. 1. Concentration less than.
The battery acid is made of sulfuric acid (H2So4) diluted with purified water to get an overall concentration of around 29-32, a density of 1.25-1.28 kg/L, and a concentration of 4.2 mol/L. The pH value of electrolytes is about 0.8, so we need to take utmost care when handling battery acid. What Is Battery Acid?
Batteries contain acid because it's fundamental to the electrochemical reaction that takes place. Also referred to as battery electrolyte, battery acid is the medium that carries the electrical flow between positive and negative electrodes.
Car battery acid is around 35% sulfuric acid in water. Battery acid is a solution of sulfuric acid (H 2 SO 4) in water that serves as the conductive medium within batteries. It facilitates the exchange of ions between the battery's anode and cathode, allowing for energy storage and discharge.
Battery acid primarily refers to sulfuric acid, with the chemical formula H2SO4. Now, if we break that down, we get two hydrogen atoms, one sulfur atom, and four oxygen atoms working together in harmony to perform a critical role in the battery's operations. Think of it as the fuel that powers the entire battery system. Why Sulfuric Acid?
Battery acid (AKA sulfuric acid) is used in lead-acid batteries to help create and store electrical energy, which powers many devices and vehicles.
These batteries are highly corrosive, and react vigorously with the skin, causing burns and irritation. Battery acids have a high electrical conductivity. Usually, these acids are colorless. However, they can easily pick on impurities. The density of an acid battery is twice that of water.
Specific Steps for Regular MaintenanceRegular Monitoring of Battery Status: Use specialized equipment to measure the battery's voltage, internal resistance, capacity, and temperature. Inspect Cables and Connectors:. Maintain the Thermal Management System:.
Establishing an adequate battery maintenance procedure is essential for ensuring a productive & safe work environment. Charts and maintenance plans are a fantastic approach to ensuring that batteries are properly maintained. Battery maintenance is essential for ensuring their best performance and longevity.
Different types of batteries, such as lead-acid and lithium-ion, require specific maintenance techniques to ensure their longevity and performance. Knowing the type of battery you are working with is essential to guarantee the correct charging and maintenance techniques are employed.
Specific maintenance requirements will vary depending on the type of battery; however, the following are general step-by-step procedure that apply to many different types of batteries, including lead-acid batteries typically used in cars and uninterruptible power supply (UPS) systems. Step-2: Do Not Top Off Before Charging
From visual inspections & cleanliness to evaluating electrolyte levels (if appropriate), charging system tests, and load testing, this complete approach covers essential procedures for maintaining several battery types, including lead-acid & lithium-ion.
It is still important to check their state of charge regularly using a monitoring tool that interacts with the integrated battery management system. Proper charging practices, such as quick charging of the battery after each period of use, will also help maintain their performance.
Construction equipment batteries, including deep cycle batteries, may require additional maintenance due to harsh operating conditions. Ensuring proper maintenance for all batteries used for construction equipment can help prevent costly downtime and keep your equipment running smoothly.
In this article, we will examine a circuit that allows charging Li-ion cells connected in series while also balancing them during the charging process.
The following graph suggests the ideal charging procedure of a standard 3.7 V Li-Ion Cell, rated with 4.2 V as the full charge level. Stage#1: At the initial stage#1 we see that the battery voltage rises from 0.25 V to 4.0 V level in around one hour at 1 amp constant current charging rate. This is indicated by the BLUE line.
If the cells are protected and one cell charges faster than the other it's protection will cut it off and current will not flow the other battery in series. That is the function of battery management circuits. Lithium ion batteries are fully charged at 4.2V, and discharged at about 3 V.
Although Li-Ion batteries are vulnerable devices, these can be charged through simpler circuits if the charging rate does not cause significant warming of the battery., and if the user does not mind a slight delay in the charging period of the cell.
It is possible to charge the cells individually, but limit the current and don't exceed 4.2V, and monitor the battery temperature. Many lithium batteries have built in protection for overdischarge.
The charging also different than the lead-acid batteries. The 3.9v Lithium-ion batteries need 4.2 v of charging voltage and 1A charging current. The charging time is about 2-3 hours. if the optimized charging is not done, the battery will be damaged or reduces the battery capacity.
You can also view the Lithium battery Charger PCB, how it will look after fabrication using the Photo View button in EasyEDA: After completing the design of this Lithium battery Charger PCB, you can order the PCB through JLCPCB.com. To order the PCB from JLCPCB, you need Gerber File.
To troubleshoot and diagnose the battery not charging problem on your laptop follow the below steps in order:Check Power Supply connections & Battery. Run Windows Battery Troubleshooter.
If your battery isn't fully charging, the first thing you can try is the Battery troubleshooter in Windows 10. Complete the wizard then restart your device to see if the problem is resolved. Most laptop computers include their own factory diagnostics utilities, too. It is recommended you also use those to test your battery.
To see if Windows can fix the battery not charging problem, you can run the power troubleshooter. 1. In the search type "troubleshoot settings " and then click to open them from the search results. 2. In the 'Troubleshoot' window, select Additional troubleshooters. 3. Scroll down and click on Power.
Battery not charging to full If you experience the problem which is The battery doesn't be charged when power level is above 95% with AC adapter connected. This is a normal condition for battery protection, not a problem for either the battery itself or the charging function. When the battery is charged to 100%, it will stop being charged.
To troubleshoot and diagnose the battery not charging problem on your laptop follow the below steps in order: Check Power Supply connections & Battery. Check Power Cable & Battery Connection. Disconnect External Devices. Diagnose Battery Health. Run Windows Battery Troubleshooter. Uninstall & Reinstall Battery Device Driver. Update Chipset Drivers.
Because one cannot run on battery power alone. It's a good idea to keep up with Windows updates so your system can continue to run smoothly and your data stays secure. On occasion, however, an update can cause a conflict that breaks something. After installing a previous Windows update, for example, my laptop's battery stopped charging.
Plug in your laptop. Power on your laptop. Click the battery icon in the system tray and you should see that your laptop is plugged in and charging. By reinstalling my Lenovo laptop's battery drivers and disconnecting its battery and then reconnecting it, I got my laptop's battery back to charging when it's plugged in.
Cycle life can be negatively impacted when batteries from different manufacturers are charged in the same manner. Even the same types of batteries, such as Li-lon and NiMH, may require separate charging considerations. Inspection of the manufacturer's data sheet revealed that some types of NiMH batteries can take a. Insufficient run time is caused by undercharging the battery, which can happen by misapplying technology. For example, charging of a 4.2. By ensuring proper Li-Ion and NiCd battery charging, your result is improved time-to-market, reduced development costs, and a finely tuned battery and charger system. Avoiding all of these overarching concerns. The "one stop shop" approach to custom battery packsand chargers is extremely beneficial to the person purchasing the batteries and chargers. If the battery pack and charger are ordered.
[PDF Version]The blue wire W1 must be connected to the opposite end of the battery pack as the black wire at the top of the battery pack. When batteries are connected in parallel, only use one charger. Do not connect a charger to each battery, unless you break the electrical connection between the batteries.
To charge the battery, set the charger to the appropriate settings as indicated in the user manual. Turn on the charger and monitor for any unusual signs such as overheating or fumes. The charging time will vary based on the battery size and charger type.
Do not mix and match different battery voltages in the same battery pack. In this example the battery pack voltage is 12 volts which is exactly the same as each of the individual 12-volt batteries. The capacity of the battery pack is the sum of the capacities of the individual batteries.
Batteries connected in series strings can also be recharged by a single charger having the same nominal charging voltage output as the nominal battery pack voltage. In Figure 8, a single 24-volt charger is connected to a 24-volt battery pack. In Figure 9 we see a pair of 12-volt batteries connected in parallel.
How to use a battery charger and the battery type should be determined first—lead-acid, lithium-ion, or any other—as each requires a different charger. To ensure a smooth connection, match the charger and battery voltage and amperage specifications.
When batteries are connected in parallel, only use one charger. Do not connect a charger to each battery, unless you break the electrical connection between the batteries. The reason is that the chargers will very likely complete one or more their charging subroutines (charge modes or stages) at different times.