Lithium Battery Safety

Besides performance, safety plays an important role for lithium batteries. In our view, five influencing factors need to be considered in order to ensure that safe really means safe:

Battery management system (BMS) with redundant safety features: unlike lead-based batteries, lithium batteries always need a BMS to perform balancing and safety functions. If electronic components of the BMS fail it can itself become a safety problem for the battery. That's why there is hardware backup for all safety-relevant components in Torqeedo batteries. Incidentally, this is also stipulated in the automotive industry, in aerospace and for medical technology.

Safe, individual cell packaging: Torqeedo only uses individually welded cells or modules which are equipped with multiple safety mechanisms. Other forms of packaging such as foil-sealed cells ("coffee bags") offer a lower standard of safety as they afford less effective protection against internal short circuiting within the cells. (An exception here are cells with ceramic separators, which also provide safe packaging, but these are extremely expensive and very seldom used.)

Clean, precision production processes on the part of the cell manufacturers. Torqeedo only uses cells sourced from reputable manufacturers in Japan and the USA.

Waterproof to IP67: water in lithium batteries can lead to various problems such as corrosion of the BMS hardware or the creation of electrolytic gas. Lithium batteries on board a boat should therefore be waterproof.

Safe battery chemical engineering, e.g. LiFePo (lithium iron phosphate) or LiNMC (lithium nickel manganese cobalt oxide). These are now widely used.