A problem that has emerged in the forums is battery failure when using recuperation. The Stromer battery seems to have a localized issue with the relatively high currents that occur during steeper and longer downhill rides with a high recuperation level. Although the recuperation current is limited to 15 A, it exceeds the maximum permissible charging current of a single cell.
Example: The BQ983 battery (cell configuration 13S6P) uses Sanyo NCR 18650 GA cells. This cell has a nominal charging current of 1.675 A. With a regeneration current of 15 A, 2.5 A are „pushed“ into the cell per cell strand (15 A / 6). This is thus 50 % above the recommended charging current.
The problem is further exacerbated by cold temperatures or an older battery. What exactly goes wrong with the batteries is unknown to me – but presumably it's the BMS. Since this is proprietary to Stromer HTE (TD Hitech Energy) and. SMP (Simplo) was manufactured and programmed, it cannot be bought individually. The company upVolt In Basel, BMS does not repair them, but replaces them with units from the recycling loop. The company Buenzlibatteries also advertises the repair of BMS on its website.
Stromer does not repair batteries, but replaces them with new ones.
See also AKKU - 'Repair / Refitting (Refit / Refurbishing) / Occasions'. Also included is a Table with providers which reprocess power batteries.
To conserve the battery, it is recommended to use recuperation levels 4 and 5 sparingly or not at all on long descents. This problem is also mitigated when an additional battery (extender) is used. Depending on the configuration, 10 or more cell strings are then in parallel, which reduces the recuperation current to below the nominal recommended charging current of the respective cells.
See also PIMP mySTROMER - 'Battery - Extender'