eBike Battery Systems – Safety In The Design

Lithium-ion batteries are complex, finely tuned systems with a high energy content. Their contents can, in principle, be flammable in certain conditions. When shopping for an eBike, its important that the model you choose is made by a reputable eBike component manufacturer who is ensuring the battery and drive units are made to the highest standards. One of the highest rated and most trusted eBike components are supplied by Bosch eBike Systems.

Bosch eBike Systems goes above and beyond the strict legal requirements, with certain tests, and pays special attention to battery safety throughout the entire value chain. For peace of mind, the entire Bosch eBike system is certified to UL 2849, which is a standard covering the electrical system of eBikes powered by a lithium-based, rechargeable battery. UL 2849 has strict requirements for electrical shock, mechanical and fire hazards. Additionally, the high-quality lithium-ion batteries have a Battery Management System (BMS) that detects significant potential sources of error and effectively protects cells against overheating.

How Bosch technology makes batteries safer

Bosch eBike Systems continuously optimizes its products and processes to ensure the quality of its components. The same applies to battery production. Lithium-ion batteries are complex, finely tuned systems with a high energy content, whose ingredients can, in principle, be flammable in certain circumstances. Bosch sets new benchmarks in battery safety with a combination of various technological safety mechanisms, additional tests, and a high degree of manufacturing automation.

  1. Safety is a Top Priority For Bosch eBike Systems

Bosch eBike Systems takes the topic of battery safety into account at every point in the value chain. In addition to the legally required tests, Bosch eBike Systems demands further tests at the cell level, both from the cell suppliers and from its own manufacturing department. The result of this voluntary “more” testing: Batteries produced by Bosch eBike Systems not only meet the legal requirements, but in some cases even exceed them.

For peace of mind, the entire Bosch eBike System is certified to UL 2849, which is a standard covering the electrical system of eBikes powered by a lithium-based, rechargeable battery. UL 2849 has strict requirements for electrical shock, mechanical and fire hazards. Additionally, the high-quality lithium-ion batteries have a Battery Management System (BMS) that detects significant potential sources of error and effectively protects cells against overheating.

  1. Safety Mechanisms for All eBike Batteries Provide Additional Protection

From the very beginning, Bosch eBike Systems has advanced and continuously improved the safety of its batteries with technical innovations and comprehensive tests. All eBike batteries from Bosch eBike Systems therefore meet safety standards that have been tested over many years and are constantly being expanded:

Mechanical separation of the battery cells

The individual cells of an eBike battery from Bosch eBike Systems are encased in flame-retardant plastic (mechanical separation). In an emergency, for example in the rare case of a short circuit within the cell, this encapsulation ensures that an affected cell provides the best possible protection for the other cells.

Electrical separation of the battery cells

In addition to the mechanical separation, the battery cells of the Bosch eBike batteries are also electrically separated from each other. An integrated fuse ensures an electrical interruption in the

event of an increased current flow of a cell. As a result, the other cells of the battery are protected and the possible spread of heat is contained.

  1. Protected in wind & weather: minimizing the risk of water ingress

Two other important safety precautions are the reduction of the risk that can arise from the entry of water and the protection of the eBike batteries against adverse weather conditions. For example, Bosch eBike PowerTube batteries have seals with multiple sealing lips at the front and rear ends. In PowerPack batteries, the battery housing is sealed all around. These precautions protect the battery from water ingress when installed. Thus, the eBike can be ridden without hesitation even in wet conditions.

  1. The smart system: New standards. More safety.

In 2021, Bosch eBike Systems presented its new system generation: The smart system in which all components (drive unit, battery, display, control unit and eBike Flow app) are networked with each other. In smart system batteries, the existing high protection mechanisms are supplemented by additional safeguards, including further automation and thermal separation:

Increased degree of automation in the production of batteries

Bosch eBike Systems has increased the level of automation in the production of batteries for the smart system: Starting with the assembly of the cell holders with the cells, through the connection of the individual cell blocks, to the sealing of the entire eBike battery, the process steps now take place fully automatically. The risk from potential assembly errors can thus be reduced and leads to even more safety in use.

Holistic safety: mechanical, electrical and thermal separation

In addition to the mechanical and electrical separation, there is also thermal separation in all PowerTube batteries (smart system and previous generation) as well as in all smart system batteries through fully encased cells. Thermal separation is an important mechanism to reduce the risk of overheating in the battery and a possible thermal chain reaction. In the event of gas development in the battery, it enables a controlled process: The gas can escape in a controlled manner via a predetermined breaking point.

  1. A residual risk remains despite higher safety precautions

Despite the higher safety standards that Bosch eBike Systems applies to its batteries, it can happen that a battery is damaged. Risks can be further reduced by handling the battery with care.

All important information about handling Bosch eBike Systems batteries can be found in the Bosch Battery Guide. And at Cite Cycle.

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