This product is linked to a 3rd party affiliate, BatteryHookup. USED HEADWAY 38120 HP 3.2V 8AH LIFEPO4 BATTERY SCREWS INCLUDED WHICH MAKES CONNECTING THESE TOGETHER SUPER EASY. WE ALSO HAVE THE BUSBARS AND HOLDER LISTED HERE FOR VERY CHEAP PRICES.   HERE ARE HEADWAY 38120HP LIFEPO4 3.2V 8AH CELLS. CAME OUT OF ENGINEERING SAMPLES OR USED AS BACKUP STARTING FOR GENERATORS SO THEY ARE TESTING AROUND FULL CAPACITY. THESE ARE BIG CELLS WITH A CRAZY AMOUNT OF POWER. EACH CELL IS RATED AT 200A DISCHARGE AND CAN BE CHARGED AT 80A. WE LITERALLY STARTED A CAR WITH 4 OF THESE IN SERIES. PLEASE BE CAREFUL WITH THESE AND DO YOUR RESEARCH. THIS IS A MASSIVE AMOUNT OF POWER. WE TESTED THOUSANDS OF THESE AND YOU CAN EXPECT AN AVERAGE OF AROUND 90-100% CAPACITY AT AN INDUSTRY STANDARD 0.2C DISCHARGE RATE (1.6A) SO YOU ARE GETTING CELLS THAT ARE PRICED HALF THE COST OF NEW ONES THAT HAVE A TON OF LIFE LEFT IN THEM. LIFEPO4 ARE THE BEST OPTION FOR 12V BATTERIES BECAUSE 4 IN SERIES IS EQUIVALENT VOLTAGE TO A LEAD ACID BATTERY. WHICH MEANS RV, EV, COMPETITION AUDIO LOOK NO FURTHER. MOST OF YOU WILL MAKE CUSTOM BARS FOR THESE, AND SOME WILL USE THICK GAUGE WIRE OR WELDING. JUST KEEP IN MIND HOW MUCH POWER THESE THINGS ARE CAPABLE OF AND USE THE PROPER THICKNESS TO CARRY THAT POWER FOR WHATEVER YOUR APPLICATION WILL BE PULLING FROM THESE. THESE ARE 40 TIMES MORE POWERFUL THAN MOST 18650 BATTERIES. CHECK OUT THE SPECS BELOW, THESE ARE REAL SPECS.   chemical composition LiFePO4 Nominal Capacity 8Ah Charging voltage 3.65V Nominal Voltage 3.2V Cut-off Discharge Voltage 2.0V Charging Method CC/CV Maximum Discharge Current(continuable) 200A Maximum Charge Current(continuable) 80A Cycle Life 1500cycles 1C 100%DOD 2000cycles 1C 80%DOD Work temperature Charge -10℃ to 45℃ Discharge -20℃ to 65℃ Energy Density 83 Wh/Kg Initial Internal Impedance <4mΩ Dimension(mm) Diameter 38mm Length 120mm(152 with screw) Weight(g) 360