How 48v Batteries Work

 The "48V" denotes the nominal voltage of the battery. Voltage is a measure of the electrical potential difference between two points. In a 48V battery, the total voltage is achieved by connecting multiple individual cells in series (a set of batteries or electrical components) arranged so that the current passes through each individual cell. Each individual cell in a battery typically has a lower voltage, often around 3.6 to 3.7 volts for lithium-ion cells. To achieve 48 volts, you would connect approximately 13 cells in series (since 13 x 3.7V ≈ 48V). The energy a battery can store is measured in watt-hours (Wh) or kilowatt-hours (kWh). This depends on both the voltage and the capacity of the battery (measured in ampere-hours, Ah). For example, a 48V battery with a capacity of 100Ah would store 4.8 kWh of energy (48V x 100Ah = 4800 Wh or 4.8 kWh).    Individual cells are connected in series (to achieve higher voltage) and in parallel (to increase capacity). A BMS Battery Management System is integrated to monitor and manage the battery's performance, ensuring safety and efficiency. The BMS regulates charging and discharging, balances the cells, and monitors temperature and voltage. The connected cells and BMS are encased in a protective housing to shield them from physical damage and environmental factors. The battery is subjected to charge and discharge cycles to stabilize its performance and identify any potential issues. 

 The most important way to preserve the high voltage Battery is to LEAVE YOUR VEHICLE PLUGGED IN when you are not using it. This is particularly important if you are not planning to drive Model 3 for several weeks.  When left idle and unplugged, your vehicle periodically uses energy from the Battery for system tests and recharging the low voltage battery when necessary.  There is no advantage to waiting until the Battery’s level is low before charging. In fact, the Battery performs best when charged regularly.  If you allow the Battery to discharge to 0%, other components may become damaged or require replacement (for example, the low voltage battery).  The peak charging rate of the Battery may decrease slightly after a large number of DC Fast Charging sessions, such as those at Superchargers. To ensure maximum driving range and Battery safety, the Battery charge rate is decreased when the Battery is too cold, the Battery’s charge is nearly full, and when the Battery conditions change with usage and age. These changes in the condition of the Battery are driven by battery physics and may increase the total Supercharging duration by a few minutes over time.  

Never allow the Battery to fully discharge.

Even when Model 3 is not being driven, its Battery discharges very slowly to power the onboard electronics. The Battery can discharge at a rate of approximately 1% per day, though the discharge rate may vary depending on environmental factors (such as cold weather), vehicle configuration, and your selected settings on the touchscreen. Situations can arise in which you must leave Model 3 unplugged for an extended period of time (for example, at an airport when traveling). In these situations, keep the 1% in mind to ensure that you leave the Battery with a sufficient charge level. For example, over a two week period (14 days), the Battery may discharge by approximately 14%.

Discharging the Battery to 0% may result in damage to vehicle components. To protect against a complete discharge, Model 3 enters a low-power consumption mode when the displayed charge level drops to approximately 0%. In this mode, the Battery stops supporting the onboard electronics and auxiliary low voltage battery. Once this low-power consumption mode is active, immediately plug in Model 3 to prevent a jump start and low voltage battery replacement.

 For better long-term performance, avoid exposing Model 3 to ambient temperatures above 140° F (60° C) or below -22° F (-30° C) for more than 24 hours at a time. 

CAUTION:

1. If the Battery’s charge level falls to 0%, you must plug it in. If you leave it unplugged for an extended period, it may not be possible to charge or use Model 3 without jump starting or replacing the low voltage battery. Leaving Model 3 unplugged for an extended period can also result in permanent Battery damage. If you are unable to charge Model 3 after attempting to jump start the low voltage battery, schedule a service appointment.  
2.  The Battery requires no owner maintenance. Do not remove the coolant filler cap and do not add fluid. If the touchscreen warns you that the fluid level is low,  contact us or Tesla to avoid deadly mistakes.

WARNING:

 The high voltage system must be serviced only by a trained technician. Under no circumstances should you open or tamper with the Battery. Do not disassemble, remove or replace high voltage components, cables or connectors. High voltage cables are typically colored orange for easy identification.