For many, the convenience of having a Car Fridge is undeniable, especially on long journeys. The idea of keeping drinks cool or food fresh using your vehicle’s power seems straightforward. However, if you’re an electric vehicle (EV) owner, particularly of a BMW i3, powering a car fridge directly from the 12-volt outlet might lead to unexpected issues. Unlike traditional gasoline cars, EVs like the i3 have a 12-volt battery system that operates quite differently, and understanding these differences is crucial before plugging in accessories like car fridges.
The critical distinction lies in the purpose and capacity of the 12-volt battery in an EV compared to a conventional internal combustion engine (ICE) vehicle. In ICE cars, the 12-volt battery is a robust component designed to provide the substantial power needed to crank the engine. These batteries typically boast capacities of 70-90 amp-hours (Ah). Conversely, in EVs like the BMW i3, the 12-volt battery serves a more limited role. As BMW’s General Vehicle Electronics document explains:
In contrast to a vehicle with a combustion engine, the requirements of the 12 V battery in the I01 with regard to an engine start are different. In the I01 the job of the 12 V battery is only to ensure the powering up of the high-voltage system.
This means the i3’s 12-volt battery is primarily there to boot up the car’s computer systems and activate the high-voltage system. It’s akin to the small coin battery in older computers that initiates the startup process. Once the high-voltage system is active, a DC/DC converter takes over to charge the 12-volt battery and power the vehicle’s low-voltage electronics. Consequently, the 12-volt battery in an i3 is significantly smaller, with only a 20 Ah capacity. This reduced capacity is sufficient for its intended purpose but becomes a limiting factor when you consider powering external accessories.
Connecting a car fridge, even a small one, to the i3’s 12-volt outlet can place a considerable strain on this delicate system. Car fridges, designed to keep contents cool, draw continuous power. While this might be manageable in an ICE vehicle with a large 12-volt battery, in an i3, it can quickly deplete the smaller battery. Drawing excessive power from the 12-volt system can potentially lead to a “bricked” i3, a situation far more easily triggered in EVs than in traditional cars. This occurs because draining the 12-volt battery too much can prevent the car’s computer from booting up, effectively rendering the vehicle unusable until the 12-volt system is properly addressed.
Therefore, a much safer and more reliable approach for powering a car fridge in your EV is to utilize a separate, independent power source. Instead of relying on the car’s 12-volt system, consider using a portable power station or a dedicated battery. For instance, a 55 Ah AGM battery, like the Optima Yellow Top 8014-045-FFP, could provide ample power for a car fridge for several hours without risking your EV’s critical systems. These external power sources can be recharged separately, often at the same time you charge your EV, minimizing inconvenience. This method ensures your car fridge operates reliably without jeopardizing the functionality of your electric vehicle. Embracing this alternative power strategy provides peace of mind and ensures your car journeys remain trouble-free while enjoying the convenience of a car fridge.
