Possible work on the battery
The following work can be done on the batteries of the BO-/BQ series:
- Replace individual defective cells: NO
- BMS Repair
BO: ?
BQ: 3-screw batteries (HTE): Yes | 4-screw batteries (SMP): No - BMS Replacement:
BO: Yes
BQ: Yes - Reset SoH and charge cycle counter:
BO: not necessary
BQ: For 3-screw batteries: Yes | 4-screw: charge cycle counter only - Reset safety position (blocked battery, e.g., due to a short circuit in the electrical system): BO & BQ possible (also by myStromer AG) see BATTERY ,Battery Reset'
- Replacement charging socket:
BQ: Yes – see PROBLEM → BATTERY → ,Battery charging port socket defective'
Repair
Repair must be distinguished from replacement. In a replacement, all cells in the battery are exchanged for new ones. The term repair includes the replacement of individual defective cells, the repair of the BMS, or the housing – e.g., the Rosenberger charging socket.
Stromer repariert keine Akkus. Geht der Akku aufgrund eines Problems in der Stromer-Elektrik in die Sicherheitsstellung, kann Stromer den Akku jedoch zurücksetzen. Siehe here.
Refitting (Refit / Refurbishing)
Stromer batteries are not cheap. Relevant companies have recognized a market here and offer the reconditioning of Stromer batteries with new cells. Physically, this is not a problem – it is only important to ensure that high-quality lithium-ion cells are used and not inferior products.
The crux of the cell replacement is the BMS. To achieve full range after cell replacement, the SoH (State of Health) and the charge cycle counter must be reset to factory settings for batteries in the BQ series. If this is not done, only the old capacity and thus range can be used, despite new cells. Batteries in the BO series are not affected by this. However, if a higher battery capacity than the original is installed, the capacity indicator will be incorrect unless the SoH is reset.
Restriction: Der BQ814- und BQ983-Akku wird für Stromer von zwei Firmen – HTE (TD Hightech Energie) and SMP (Simplo Technology Co. Ltd.) – hergestellt. Ein Reset beider Werte – und damit sinnvolle Neubestückung – ist nur beim Modell von HTE, dem Modell mit drei Schrauben, möglich.
Refurbisher/refurbisher provider (table)
I am aware of providers who offer cell replacement for Stromer batteries in a Table (CH / DE / NL / BE) compiled.
Stand August 2026 sind mir vier Firmen (grün hinterlegt) bekannt, die den Ladezyklenzähler und den SoH-Wert auf Werkseinstellungen zurücksetzen können. Drei sind in der Schweiz, eine in Belgien. Die folgende Tabelle listet die mir bekannten Dienstleistungen der Anbieter auf:
Summary
Many forum posts indicate that a refurbished battery does not function as desired. The new range is not achieved again. The reason for this is an unreset SoH and charge cycle counter.
The technician must either have the software to reset the Stromer BMS via the CAN bus (SoH = 100 % / charge cycles = 0), or know how to do it on the BMS board (reset jumper).
Bis zum Juli 2026 bot nur eine handvoll Refurbisher die Möglichkeit an den SoH (State of Health) und den Ladezyklenzähler bei Akkus des Herstellers HTE (3 Schrauben) zurückzusetzen. Die Firma Bünzli Batteries bietet neu seit Juli 2026 den Reset auch bei den Simplo-Akkus (4-Schrauben) an.
See also: BATTERY → ,Battery reset: SoH & charge cycle counter'
BO series and older BQ batteries: Bei den 36-V-Akkus (BO-Serie) und den älteren der BQ-Serie (48 V, blau, gelb, violett, grün, vor Baujahr 2016) gibt es Hinweise, dass ein SoH-Reset nicht nötig ist, sofern die Nennkapazität beim Zellentausch eingebaut wird. Wird die Nennkapazität erhöht (z. B. ein BQ819 wird zum BQ983), stimmt die Ladezustandsanzeige ohne SoH-Reset nicht, die volle Neukapazität ist aber verfügbar.
Attention: There are battery reconditioners that declare the necessity of the SoH reset as unnecessary on their website or advertise full range after cell replacement. Both are only correct under the reservation of the previous paragraph.
Tip: Have the reconditioner confirm that the new capacity has been reached or that a reset of SoH and the charge cycle counter can be performed.
Occasions
On the myStromer website Under „Used Sales,“ are there bikes, and sometimes batteries, at reduced prices? Used batteries can also be found on various classified ad portals (Ricardo.ch, eBay, Kleinanzeigen.de...).