BMW 3 Owners & Service Manuals

BMW 3: Cooling system

To increase the service life of the high-voltage battery unit and obtain the greatest possible power, it is operated in a defined temperature range. The high-voltage battery unit is essentially operational at an ambient temperature of -40 ºF to 131 ºF (-40 ºC to +55 ºC ) (actual cell temperature). In terms of temperature behavior the high-voltage battery unit is a slow-action system, i.e. it takes several hours until the cells assume the ambient temperature. Therefore having the battery spend a short period of time in an extremely hot or cold environment does not mean that the cells will already have assumed this temperature.

However, the optimal range of the temperature with regard to service life and performance is more limited. It is between +77 ºF and +104 ºF (+25 ºC and +40 ºC). Here, we are referring to the cell temperature, and not the outside temperature. If the cell temperature is continuously significantly above this range with simultaneously high performance, this has a negative effect on the service life of the battery cells. To counteract this effect, as well as ensure maximum performance at all outside temperatures, the high-voltage battery unit of the G20 PHEV has a regulated cooling system.

If the temperature of the battery cells is significantly below the optimal operating temperature of +77 ºF (+25 ºC), their performance would be temporarily restricted and the efficiency of the energy conversion would not be optimal. This is an unavoidable chemical effect of lithium-ion batteries.

If a vehicle is parked for an extended period (e.g. a few days) at a very low ambient temperature, the battery cells also take on this low ambient temperature. In this situation it is possible the full electrical driving power is not available at the start of the journey.

In this case the combustion engine assumes the drive of the vehicle. Pure electric driving (ELECTRIC driving mode) is no longer possible or cannot be activated.

This is also displayed to the customer as a CC message: "Electric driving temporarily restricted. You can continue to drive. Full electrical drive power will be available again after the high-voltage battery has warmed up/cooled down".

Heating to warm up the battery cells is not available for the SP41 High-voltage battery.



G20 PHEV, system overview of climate control - Installation locations Combined expansion and shutoff valve at the evaporator Combined expansion and shutoff valve at the high-voltage battery u


The cooling system has 2 operating conditions, which result from its function: Cooling OFF Cooling ON Cooling OFF operating condition The "Cooling OFF" operating condition is active when the cell

 Charging the High-voltage Battery Unit


 High-voltage power management

The power management for the high-voltage vehicle electrical system includes two subfunctions: one for driving and one for charging mode. In driving mode, the energy flows from the high-voltage battery unit to the high-voltage consumers and the energy flows during energy recovery to the high-volt

 Points of interest

General information Points of Interest are destinations that can be helpful while driving. Points of Interest such as restaurants, hotels, gas stations, or charging stations, can be added as destinations. Even when the navigation data is current, information regarding particular Points of Interest

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