Surron Light Bee EVO GT: Battery Upgrade for Surron Light Bee Model: VTB7250-9C-QF Capacity: 50Ah Voltage: 72V Quick Charging Time: 1h Max Charging Current: 50A (1C) with the support of VTB fast charger (XT90) Driving Range: 165 km (laboratory result measured at the average speed of 25 km/h) Battery Pack: Grade A 21700 Cells (Samsung 50S, volts difference less than 0.01V after 10,000Ah cycles) Battery Cell Lifespan: Minimum 70% of capacity after 3 years Standard Power: 19.2 kW/ 250A Peak Power: 32kW/250A Peak (550A peak BMS for 10 seconds set to 400A peak for this battery) Voltage Drop: Battery voltage drops 7V at 250A More Effective BMS: A 22-pcs HYG017N10 MOSFET BMS enables 10 seconds of 550A peak discharge while limits heat generation under 18W at 250A discharge. Custom design of BMS maintains great stability under high-current pulse and protects the MOS from the risk of short circuits. BMS Protection: BMS protection system blocks 12 battery damages during charging and discharging. Its real time condition shows both in the App on your devices through bluetooth connection and on color LCD. Waterproof: IP67 rating (battery discharge cells sealed with Epoxy Resin provide a comprehensive water-proof level of outdoor riding)Connectors: Two updated RAS 6808 connectors allow continuous current at 240A and peak current at 480A, replacing the Sur-Ron REB6808 200A connector. Spark Prevention: The battery is designed with a holding-down power button to substitute the breaker (air circuit)/ air switch to avoid arc or spark. VTB Interactive Color LCD: The color display shows real time data such as SOC, Volts, Amps, Power and temp from BMS feedback. Easier for riders to locate problems when the battery shuts down. Accidental touch protection turns on whenever it is over 0A current on the screen surface to avoid unintentional turn-off. Mini Charging Port: The built-in XT90 port is extra thin so charging can happen while the battery sits in the bike, but it allows ultra fast input at 50A continuously. The rubber cap of the port provides full coverage for waterproofing. Specifications Weight: 18.2 kg Dimensions: 154x138x385mm Restrained Heights: The battery fits into the original battery tank, pushing up only 2 cm Tabs Material: Traditional nickel tabs are upgraded to CNC (Copper-Nickel-Chrome), improving the discharging efficiency by restricting its resistance to 0.1mΩ. Further Description About the Charging Port Our goal for choosing a charging port is, firstly, to achieve that accessibility as the original factory battery. Charging can happen without removing the battery from the vehicle for a similar height. We also want a quick recharge, 1 hour fully charged. As for safety, a rubber plug needs to be in place to prevent entry of mud and sand. The plug is required to be under full coverage to avoid the risk of electric shock. Accordingly, XT90 charging port became our go-to option both for its extra thin port and continuous current output at 50A. The only imperfection would be that the official XT90 only provides a male panel-type rubber plug which carries higher security concerns. We aspired to have the perfect port, which drove us to develop a female XT90 plug with rubber cap while bearing a significant cost increase. That’s how we got our ideal charging port. About the Color LCD The color LCD screen is a unique feature but under realistic consideration to address the most common issue riders encounter: sudden power loss without knowing the cause. There could be various roots, high-temperature protection, short-circuit protection, low-temperature protection, or other faults. A shortcut to display riders with fault feedback became our goal. It connects directly with the Battery Management System (BMS), showing State of Charge (SOC) and other relevant data that helps locate the problem. We only made it into a touch screen and whenever it is over 0A current on the screen surface to avoid unintentional turn-off. So it functions in muddy and wet conditions during the race. Quick Charging The charging port supports a maximum of 50A, so it’s essential to have a dedicated charger that can deliver that power. Therefore, we have even custom-made a compact 50A charger that can provide 50A output at 220V (or 25A at 110V). Why 50G and 50S? By comparing several top-tier battery cells in the market, including Samsung 50E, 48X, 50G, 50S, 40T, and Molicel P42A, we came to a conclusion that 50S outperforms others in tests on voltage drop during discharge, heat generation, lifespan, and unit price. P42A might have an advantage in exhibiting lesser heat, but in a continuous discharge scenario, the motor would overheat before the battery does. 50S, in contrast, compensates its heating issue with larger capacity.
