Battery SELF_CHECK - Recognize problems

Stromer offers via the Service menu to check the status messages of the battery. The following parameters are displayed in SELF_CHECK.

If there is something wrong with the battery, you will find corresponding information here.

nok = not OK
n/a = not available

The error image below is somewhat special. The alarm state and health are indicated as OK. However, for 'EBus output', 'Realtime clock' and 'Cell drift' there is a n/a.

The error indicates a communication problem with the CAN bus and manifested itself as follows: no lights, brake lights, horn, no assistance. The sensors, the battery ejector or the USB output functioned as they are supplied with 12 V from the battery.

In this example, the wicket cable and the controller were defective and the battery could not communicate with the OMNI.

Explanation of terms

Alarm state: Summary of the parameters. An external problem, e.g. a short circuit in the cabling or a component, can also be nok call.

Health: SoH (State of Health) / Health status

Batteries are subject to an unpreventable ageing process that reduces their capacity and therefore their performance. The term "State of Health" (SOH) describes this ageing state of a battery in comparison to its nominal or new value and is expressed as a percentage. 

Stromer masks the value. However, you can request it from the dealer by stating the VIN number.

EBus output: CAN bus communication

The battery communicates with the charger and the Stromer via the CAN bus. If there is a problem here, e.g. faulty data or a communication interruption, this is displayed.

Realtime clock

CAN controllers use a real-time clock (RTC) with battery backup, which allows them to maintain the absolute date and time when the device is not powered. The RTC enables the CAN controller to add absolute time stamps to recorded messages.

BMS temp

Battery Management System > Temperature

Cell temp: Cell temperature

If the temperature of the cells deviates from the standard range, a 'nok' or 'n/a' is displayed here

Cell drift: Cell drift

Cell drift in Li-ion batteries is when two or more cells are in a state of energy imbalance. If it is not corrected (by a battery management system), excessive cell drift can lead to overcharging or overdischarging of the cells and in turn result in defective cells or a potential safety risk. In the last 20% (in the U part of the charging process), the BMS balances the cells in order to achieve as even a charge distribution as possible across all cells in the battery pack. If one or more cells weaken here, this balancing cannot be carried out properly and the BMS logs the check as 'not ok'.

> See also PROBLEMS - 'Battery'