The complete lithium battery pack series is suited for different kinds of applications. :) Download the free printable battery conversion chart here. Click on the icon for your Adblocker in your browser. A new method of sorting retired lithium-ion batteries and estimating the RUL and SOC of the retired lithium-ion batteries is proposed. US Government is pushing for a significant conversion to green energy by 2030. Fast & Free shipping on many items! Mangrove's modular conversion technology can co-locate near the point of lithium extraction, battery recycling or battery manufacturing, creating efficiencies and reduce OPEX and CAPEX across the lithium battery value chain. Best 48V Lithium Golf Cart Battery: Ocell LIFEPO4 Battery; Lithium-Ion Golf Cart Batteries FAQ a, b Chargedischarge profiles of lithiumsulfur (LiS) cells with A lithium-ion polymer (LiPo) battery (also known as Li-poly, lithium-poly, PLiON, and other names) is a rechargeable Li-ion battery with a polymer electrolyte in the liquid electrolyte used in conventional Li-ion batteries. The direct-drive hub motor is designed to deliver more low-end torque and a lower top speed; important for safety on a 3-wheeler. And I dont want to throw my money away. Lithium watch batteries are a little more odd. The characteristics and challenges of estimating batterys remaining useful life (RUL) and state-of-charge (SOC) are critically reviewed, along with a discussion of the strategies to solve these issues. Lithium battery 48 Volt packs come in power starting at 5KWh 100Ah and increase up to 10KWh 200Ah. Dakota Lithium LiFePO4 Battery. To; Mr Peter Kennedy Thank you so much for all the precious informations. Lithium battery 48 Volt packs come in power starting at 5KWh 100Ah and increase up to 10KWh 200Ah. Battery shipping regulations are constantly changing! Lithium-ion batteries have taken over the world. The Institute comprises 33 Full and 13 Associate Members, with 12 Affiliate Members from departments within the University of Cape Town, and 12 Lithium watch batteries are a little more odd. 48v Lithium Battery Pack 105ah Full Conversion Kit. Tesla has bet big on them and built a Gigafactory that is now knocking out Tesla car batteries, as well as Powerwall and Powerpacks for homes and business. 1. This means our partners bring more lithium to market with steeper profit margins and less risks. Lithium-oxygen (Li-O 2) batteries have attracted much attention owing to the high theoretical energy density afforded by the two-electron reduction of O 2 to lithium peroxide (Li 2 O 2).We report an inorganic-electrolyte Li-O 2 cell that cycles at an elevated temperature via highly reversible four-electron redox to form crystalline lithium oxide (Li 2 O). The characteristics and challenges of estimating batterys remaining useful life (RUL) and state-of-charge (SOC) are critically reviewed, along with a discussion of the strategies to solve these issues. Best Value: Ampere Time LiFePO4 Deep Cycle Lithium Battery; 3. Want a printable battery conversion chart? Lithium-ion battery technology, which uses organic liquid electrolytes, is currently the best-performing energy storage method, especially for powering mobile applications and electric vehicles 1. Maintenance Free Power; Low self discharge Less than 1% per month; Faster charging times Can be fully charged in 3-5 hours; Increased battery life An average of 3000 to 4000 charge / discharge cycles; Weight savings over a conventional lead acid battery ( 1/5th the weight of LABs) :) Download the free printable battery conversion chart here. These packs are a kind of environmentally friendly backup power system. Best Budget Option: FlyPower LiFePO4 Lithium Battery; 5. Click on the icon for your Adblocker in your browser. The E-TrikeKit electric tricycle conversion kit with a 48v lithium battery pack is specifically made with increased pulling power for heavier adult tricycles. I am building a camper van now. Two of the more commonly used lithium-ion chemistries--Nickel Manganese Cobalt (NMC) and Lithium Iron Phosphate (LFP)--are considered in detail here. American Battery Solutions has announced its new Energy Storage System division, branded ABS ESS. ABS ESS is unveiling TeraStor, its new lithium-ion battery energy storage platform, specifically for large-scale energy storage projects.Additionally, ABS ESS is releasing StorView, its Energy Management Suite of software and control hardware to optimize The E-TrikeKit electric tricycle conversion kit with a 48v lithium battery pack is specifically made with increased pulling power for heavier adult tricycles. When Lithium battery gets full, does the built-in BMS will shut off further charging from alternator? 12.8V 100Ah Next Generation Concept Advanced Battery Management System Several Times the Life Cycle of Equivalent Lead Acid Battery We are one breakthrough away from one Ive made one just for you. The number system on the cell (i.e. When Lithium battery gets full, does the built-in BMS will shut off further charging from alternator? To; Mr Peter Kennedy Thank you so much for all the precious informations. 15. Get the best deals on Sony PlayStation 5 Consoles and upgrade your gaming setup with a new gaming console. Get the best deals on Sony PlayStation 5 Consoles and upgrade your gaming setup with a new gaming console. EV and ESS Lithium-Ion Battery Giga Factory Feasibility. Lithium-ion can refer to a wide array of chemistries, however, it ultimately consists of a battery based on charge and discharge reactions from a lithiated metal oxide cathode and a graphite anode. Supply availability and price risks for Lithium, Nickel and the refined salts stem from a potential demand-supply imbalance driven by long lead times Global supply and supply characteristics for battery raw materials [kt LCE/metal eq. Low Self Discharge: ExpertPower LiFePO4 Deep Cycle Lithium Battery; 4. The Institute comprises 33 Full and 13 Associate Members, with 12 Affiliate Members from departments within the University of Cape Town, and 12 The complete lithium battery pack series is suited for different kinds of applications. Lithium batteries are flat, thin batteries that resemble nickels (see image). Multi Billion Dollar Integrated Li Battery Facility Indonesia TRU Group In 2021 is engaged to determine the viability of a multi-billion-dollar lithium ion battery manufacturing plant in Indonesia. 48v Lithium Battery Pack 105ah Full Conversion Kit. The Lithium Market Renewable Energy is Here to Stay. These packs are a kind of environmentally friendly backup power system. Benefits of Lithium Battery Conversion. Ive made one just for you. EV and ESS Lithium-Ion Battery Giga Factory Feasibility. Want a printable battery conversion chart? An area of 3 km could require about 300 charging stations with about 4-5 charging slots.To reach a milestone of meeting the charging requirement of 2,000,000 Electric Cars, around 400,000 nos of Charging stations are required by 2026.Apart from vehicle manufacturers, third party companies are also in the race to announce plans to set up charging infrastructure in the country. According to research from Deutsch Bank, battery consumption worldwide is expected to increase 5x over the next 10 years, placing substantial pressure on the battery supply chain. The number system on the cell (i.e. Catalytic conversion of polysulfides is regarded as a crucial approach to enhancing kinetics and suppressing the shuttle effect in lithiumsulfur (LiS) batteries. Best Budget Option: FlyPower LiFePO4 Lithium Battery; 5. Two of the more commonly used lithium-ion chemistries--Nickel Manganese Cobalt (NMC) and Lithium Iron Phosphate (LFP)--are considered in detail here. Lithium battery 48 Volt packs come in power starting at 5KWh 100Ah and increase up to 10KWh 200Ah. Here's how to disable adblocking on our site. p.a.] According to research from Deutsch Bank, battery consumption worldwide is expected to increase 5x over the next 10 years, placing substantial pressure on the battery supply chain. To; Mr Peter Kennedy Thank you so much for all the precious informations. Goal Zero Yeti 3000X Portable Power Station, 2982Wh Portable Lithium Battery Emergency Power Station, 2000W Portable AC Inverter, Outdoor Portable Generator, Portable Solar Generator for Solar Panels Down the line we plan on doing a van conversion and the Yeti 3000x will be our life support! Catalytic conversion of polysulfides is regarded as a crucial approach to enhancing kinetics and suppressing the shuttle effect in lithiumsulfur (LiS) batteries. There is no universal definition of SOH: State of Charge (SOC, %) The relative available capacity (%) in a battery. 15. (or 30 Amps) 1. These battery packs are equipped with aluminum cases for the best safety. Low Self Discharge: ExpertPower LiFePO4 Deep Cycle Lithium Battery; 4. American Battery Solutions has announced its new Energy Storage System division, branded ABS ESS. ABS ESS is unveiling TeraStor, its new lithium-ion battery energy storage platform, specifically for large-scale energy storage projects.Additionally, ABS ESS is releasing StorView, its Energy Management Suite of software and control hardware to optimize Buy Jackery Portable Power Station Explorer 240, 240Wh Backup Lithium Battery, 110V/200W Pure Sine Wave AC Outlet, Solar Generator (Solar Panel Not Included) Maybe just maybe if I did the whole off grid living and conversion van life I would get Goalzero 1000 as well but Im not. Their 12v lithium-ion battery is a great, middle-priced option thats high-quality and reliable. (or 30 Amps) 1. The Lithium Market Renewable Energy is Here to Stay. A measure of a battery (cell or battery pack) to store and deliver electrical energy, compared to its ideal conditions. Goal Zero Yeti 3000X Portable Power Station, 2982Wh Portable Lithium Battery Emergency Power Station, 2000W Portable AC Inverter, Outdoor Portable Generator, Portable Solar Generator for Solar Panels Down the line we plan on doing a van conversion and the Yeti 3000x will be our life support! The Institute comprises 33 Full and 13 Associate Members, with 12 Affiliate Members from departments within the University of Cape Town, and 12 :) Download the free printable battery conversion chart here. Catalytic conversion of polysulfides is regarded as a crucial approach to enhancing kinetics and suppressing the shuttle effect in lithiumsulfur (LiS) batteries. The complete lithium battery pack series is suited for different kinds of applications. Lithium batteries are flat, thin batteries that resemble nickels (see image). Dakota Lithium manufacturers lithium batteries for a wide variety of applications including boats, wheelchairs, and of course: RVs. We have top quality lithium battery shippers and battery shipping kits. This means our partners bring more lithium to market with steeper profit margins and less risks. Read more. Their 12v lithium-ion battery is a great, middle-priced option thats high-quality and reliable. American Battery Solutions has announced its new Energy Storage System division, branded ABS ESS. ABS ESS is unveiling TeraStor, its new lithium-ion battery energy storage platform, specifically for large-scale energy storage projects.Additionally, ABS ESS is releasing StorView, its Energy Management Suite of software and control hardware to optimize 12.8V 100Ah Lithium Deep Cycle Battery CAT.NO: SB2215 A LiFePO4 battery that weighs less than half of its Lead Acid counterpart. 3. An atomic battery, nuclear battery, radioisotope battery or radioisotope generator is a device which uses energy from the decay of a radioactive isotope to generate electricity.Like nuclear reactors, they generate electricity from nuclear energy, but differ in that they do not use a chain reaction.Although commonly called batteries, they are technically not electrochemical and The most common lead-acid golf cart battery is a group-size GC2/GC8 battery. They have 10-year factory warranties and can be paralleled. The chemistry of the battery packs consists of Lithium Iron Phosphate (LiFePO4) which is the safest li-ion battery. Many items ship next day! Manufactured with automotive-grade battery cells, it offers excellent cycle life expectancy even under high and varied loads. Low Self Discharge: ExpertPower LiFePO4 Deep Cycle Lithium Battery; 4. Electrochemical performance of cells with different sulfur mass loading. 1. EV and ESS Lithium-Ion Battery Giga Factory Feasibility. A new method of sorting retired lithium-ion batteries and estimating the RUL and SOC of the retired lithium-ion batteries is proposed. Battery shipping regulations are constantly changing! Simply remove the Lead-Acid Batteries and replace them with the 48v Lithium Battery Pack 105ah. An atomic battery, nuclear battery, radioisotope battery or radioisotope generator is a device which uses energy from the decay of a radioactive isotope to generate electricity.Like nuclear reactors, they generate electricity from nuclear energy, but differ in that they do not use a chain reaction.Although commonly called batteries, they are technically not electrochemical and Lithium-ion battery technology, which uses organic liquid electrolytes, is currently the best-performing energy storage method, especially for powering mobile applications and electric vehicles 1. It relies on a It relies on a But battery tech is cutting-edge. Find a variety of UN Certified Battery Packaging - Hazmat Boxes - at Labelmaster. These battery packs are equipped with aluminum cases for the best safety. a, b Chargedischarge profiles of lithiumsulfur (LiS) cells with The most common lead-acid golf cart battery is a group-size GC2/GC8 battery. Battery shipping regulations are constantly changing! many other manufacturers are working on their own supply chains of lithium-ion batteries.. There is no universal definition of SOH: State of Charge (SOC, %) The relative available capacity (%) in a battery. 3. The units of SOH are percent points with 100% = the batterys conditions match the batterys specifications). But battery tech is cutting-edge. Revitalize the life of your existing golf cart with a high-performance Lithium Ion golf cart battery conversion upgrade! Manufactured with automotive-grade battery cells, it offers excellent cycle life expectancy even under high and varied loads. Replace your lead-acid batteries with Lithium-Ion and enjoy a Quicker Charge Time, Longer Range, Longer Life Span, No Maintenance and a 5-Year Warranty! Goal Zero Yeti 3000X Portable Power Station, 2982Wh Portable Lithium Battery Emergency Power Station, 2000W Portable AC Inverter, Outdoor Portable Generator, Portable Solar Generator for Solar Panels Down the line we plan on doing a van conversion and the Yeti 3000x will be our life support! Lead Acid batteries have short ranges, only last 2-4 years, require weekly messy watering, can Many items ship next day! Revitalize the life of your existing golf cart with a high-performance Lithium Ion golf cart battery conversion upgrade! And I dont want to throw my money away. The chemistry of the battery packs consists of Lithium Iron Phosphate (LiFePO4) which is the safest li-ion battery. p.a.] Dakota Lithium LiFePO4 Battery. Find the lowest prices at eBay.com. The chemistry of the battery packs consists of Lithium Iron Phosphate (LiFePO4) which is the safest li-ion battery. Best 48V Lithium Golf Cart Battery: Ocell LIFEPO4 Battery; Lithium-Ion Golf Cart Batteries FAQ There is no universal definition of SOH: State of Charge (SOC, %) The relative available capacity (%) in a battery. 12.8V 100Ah Next Generation Concept Advanced Battery Management System Several Times the Life Cycle of Equivalent Lead Acid Battery I am building a camper van now. 3. They have 10-year factory warranties and can be paralleled. According to research from Deutsch Bank, battery consumption worldwide is expected to increase 5x over the next 10 years, placing substantial pressure on the battery supply chain. Lithium batteries are flat, thin batteries that resemble nickels (see image). p.a.] US Government is pushing for a significant conversion to green energy by 2030. A new method of sorting retired lithium-ion batteries and estimating the RUL and SOC of the retired lithium-ion batteries is proposed. The Renogy Smart Lithium Iron Phosphate Battery with Bluetooth is designed for the drop-in replacement of deep-cycle lead-acid batteries with its standard BCI group size. A measure of a battery (cell or battery pack) to store and deliver electrical energy, compared to its ideal conditions. The lithium iron phosphate battery (LiFePO 4 battery) or LFP battery (lithium ferrophosphate) is a type of lithium-ion battery using lithium iron phosphate (LiFePO 4) as the cathode material, and a graphitic carbon electrode with a metallic backing as the anode.The energy density of an LFP battery is lower than that of other common lithium ion battery types such as Nickel Two of the more commonly used lithium-ion chemistries--Nickel Manganese Cobalt (NMC) and Lithium Iron Phosphate (LFP)--are considered in detail here. Supply availability and price risks for Lithium, Nickel and the refined salts stem from a potential demand-supply imbalance driven by long lead times Global supply and supply characteristics for battery raw materials [kt LCE/metal eq. The Lithium Market Renewable Energy is Here to Stay. Benefits of Lithium Battery Conversion. The organizations note that these hazards are increasing as more lithium-ion batteries get discarded and improperly placed in curbside residential waste or recycling collection containers and bags. An atomic battery, nuclear battery, radioisotope battery or radioisotope generator is a device which uses energy from the decay of a radioactive isotope to generate electricity.Like nuclear reactors, they generate electricity from nuclear energy, but differ in that they do not use a chain reaction.Although commonly called batteries, they are technically not electrochemical and Tesla has bet big on them and built a Gigafactory that is now knocking out Tesla car batteries, as well as Powerwall and Powerpacks for homes and business. The E-TrikeKit electric tricycle conversion kit with a 48v lithium battery pack is specifically made with increased pulling power for heavier adult tricycles. This means our partners bring more lithium to market with steeper profit margins and less risks. This set includes 1 x 48V Golf Cart Lithium Battery Pack that is made to fit EZGO TXT and works with both 6 x 8 Volt and 4 x 12 Volt Precedent configurations. The units of SOH are percent points with 100% = the batterys conditions match the batterys specifications). We are one breakthrough away from one The characteristics and challenges of estimating batterys remaining useful life (RUL) and state-of-charge (SOC) are critically reviewed, along with a discussion of the strategies to solve these issues. These battery packs are equipped with aluminum cases for the best safety. Revitalize the life of your existing golf cart with a high-performance Lithium Ion golf cart battery conversion upgrade! Dakota Lithium manufacturers lithium batteries for a wide variety of applications including boats, wheelchairs, and of course: RVs. Lithium-ion batteries have taken over the world. Supply availability and price risks for Lithium, Nickel and the refined salts stem from a potential demand-supply imbalance driven by long lead times Global supply and supply characteristics for battery raw materials [kt LCE/metal eq. The lithium iron phosphate battery (LiFePO 4 battery) or LFP battery (lithium ferrophosphate) is a type of lithium-ion battery using lithium iron phosphate (LiFePO 4) as the cathode material, and a graphitic carbon electrode with a metallic backing as the anode.The energy density of an LFP battery is lower than that of other common lithium ion battery types such as Nickel I am thinking about using Battle Born Lithium Battery 100-200 Ah and BB1260 Sterling BB1260-12 Volt, 60 Amps Battery Charger. The organizations note that these hazards are increasing as more lithium-ion batteries get discarded and improperly placed in curbside residential waste or recycling collection containers and bags. A lithium-ion polymer (LiPo) battery (also known as Li-poly, lithium-poly, PLiON, and other names) is a rechargeable Li-ion battery with a polymer electrolyte in the liquid electrolyte used in conventional Li-ion batteries. Many items ship next day! Dakota Lithium manufacturers lithium batteries for a wide variety of applications including boats, wheelchairs, and of course: RVs. Best 48V Lithium Golf Cart Battery: Ocell LIFEPO4 Battery; Lithium-Ion Golf Cart Batteries FAQ The units of SOH are percent points with 100% = the batterys conditions match the batterys specifications). a, b Chargedischarge profiles of lithiumsulfur (LiS) cells with Find the lowest prices at eBay.com. Benefits of Lithium Battery Conversion. Multi Billion Dollar Integrated Li Battery Facility Indonesia TRU Group In 2021 is engaged to determine the viability of a multi-billion-dollar lithium ion battery manufacturing plant in Indonesia. many other manufacturers are working on their own supply chains of lithium-ion batteries.. US Government is pushing for a significant conversion to green energy by 2030. Simply remove the Lead-Acid Batteries and replace them with the 48v Lithium Battery Pack 105ah. Buy Jackery Portable Power Station Explorer 240, 240Wh Backup Lithium Battery, 110V/200W Pure Sine Wave AC Outlet, Solar Generator (Solar Panel Not Included) Maybe just maybe if I did the whole off grid living and conversion van life I would get Goalzero 1000 as well but Im not. I am thinking about using Battle Born Lithium Battery 100-200 Ah and BB1260 Sterling BB1260-12 Volt, 60 Amps Battery Charger. The direct-drive hub motor is designed to deliver more low-end torque and a lower top speed; important for safety on a 3-wheeler. A drop down menu will appear. This set includes 1 x 48V Golf Cart Lithium Battery Pack that is made to fit EZGO TXT and works with both 6 x 8 Volt and 4 x 12 Volt Precedent configurations. Replace your lead-acid batteries with Lithium-Ion and enjoy a Quicker Charge Time, Longer Range, Longer Life Span, No Maintenance and a 5-Year Warranty! Click on the icon for your Adblocker in your browser. Tesla has bet big on them and built a Gigafactory that is now knocking out Tesla car batteries, as well as Powerwall and Powerpacks for homes and business. Buy Jackery Portable Power Station Explorer 240, 240Wh Backup Lithium Battery, 110V/200W Pure Sine Wave AC Outlet, Solar Generator (Solar Panel Not Included) Maybe just maybe if I did the whole off grid living and conversion van life I would get Goalzero 1000 as well but Im not. An area of 3 km could require about 300 charging stations with about 4-5 charging slots.To reach a milestone of meeting the charging requirement of 2,000,000 Electric Cars, around 400,000 nos of Charging stations are required by 2026.Apart from vehicle manufacturers, third party companies are also in the race to announce plans to set up charging infrastructure in the country. The number system on the cell (i.e. 12.8V 100Ah Lithium Deep Cycle Battery CAT.NO: SB2215 A LiFePO4 battery that weighs less than half of its Lead Acid counterpart. Best Budget Option: FlyPower LiFePO4 Lithium Battery; 5. Lead Acid batteries have short ranges, only last 2-4 years, require weekly messy watering, can An area of 3 km could require about 300 charging stations with about 4-5 charging slots.To reach a milestone of meeting the charging requirement of 2,000,000 Electric Cars, around 400,000 nos of Charging stations are required by 2026.Apart from vehicle manufacturers, third party companies are also in the race to announce plans to set up charging infrastructure in the country. Find a variety of UN Certified Battery Packaging - Hazmat Boxes - at Labelmaster. A drop down menu will appear. Manufactured with automotive-grade battery cells, it offers excellent cycle life expectancy even under high and varied loads. The organizations note that these hazards are increasing as more lithium-ion batteries get discarded and improperly placed in curbside residential waste or recycling collection containers and bags. Their 12v lithium-ion battery is a great, middle-priced option thats high-quality and reliable. 48v Lithium Battery Pack 105ah Full Conversion Kit. Lithium-ion can refer to a wide array of chemistries, however, it ultimately consists of a battery based on charge and discharge reactions from a lithiated metal oxide cathode and a graphite anode. We are one breakthrough away from one It relies on a Simply remove the Lead-Acid Batteries and replace them with the 48v Lithium Battery Pack 105ah. The lithium iron phosphate battery (LiFePO 4 battery) or LFP battery (lithium ferrophosphate) is a type of lithium-ion battery using lithium iron phosphate (LiFePO 4) as the cathode material, and a graphitic carbon electrode with a metallic backing as the anode.The energy density of an LFP battery is lower than that of other common lithium ion battery types such as Nickel A drop down menu will appear. Best Overall: Enduro Power LiFePO4 Lithium Battery; 2. Lithium-oxygen (Li-O 2) batteries have attracted much attention owing to the high theoretical energy density afforded by the two-electron reduction of O 2 to lithium peroxide (Li 2 O 2).We report an inorganic-electrolyte Li-O 2 cell that cycles at an elevated temperature via highly reversible four-electron redox to form crystalline lithium oxide (Li 2 O). But battery tech is cutting-edge. Want a printable battery conversion chart? The most common lead-acid golf cart battery is a group-size GC2/GC8 battery. Here's how to disable adblocking on our site. These packs are a kind of environmentally friendly backup power system. I am thinking about using Battle Born Lithium Battery 100-200 Ah and BB1260 Sterling BB1260-12 Volt, 60 Amps Battery Charger. Read more. We have top quality lithium battery shippers and battery shipping kits. Lithium watch batteries are a little more odd. Best Value: Ampere Time LiFePO4 Deep Cycle Lithium Battery; 3. Fast & Free shipping on many items! 12.8V 100Ah Lithium Deep Cycle Battery CAT.NO: SB2215 A LiFePO4 battery that weighs less than half of its Lead Acid counterpart. A measure of a battery (cell or battery pack) to store and deliver electrical energy, compared to its ideal conditions. Replace your lead-acid batteries with Lithium-Ion and enjoy a Quicker Charge Time, Longer Range, Longer Life Span, No Maintenance and a 5-Year Warranty! Mangrove's modular conversion technology can co-locate near the point of lithium extraction, battery recycling or battery manufacturing, creating efficiencies and reduce OPEX and CAPEX across the lithium battery value chain. I am building a camper van now. This set includes 1 x 48V Golf Cart Lithium Battery Pack that is made to fit EZGO TXT and works with both 6 x 8 Volt and 4 x 12 Volt Precedent configurations. Lithium-ion battery technology, which uses organic liquid electrolytes, is currently the best-performing energy storage method, especially for powering mobile applications and electric vehicles 1. Mangrove's modular conversion technology can co-locate near the point of lithium extraction, battery recycling or battery manufacturing, creating efficiencies and reduce OPEX and CAPEX across the lithium battery value chain. We have top quality lithium battery shippers and battery shipping kits. The Renogy Smart Lithium Iron Phosphate Battery with Bluetooth is designed for the drop-in replacement of deep-cycle lead-acid batteries with its standard BCI group size.