Hybrid Cars: Dashcams & Batteries

Hybrid cars that use high-voltage electric traction motors as well as an internal combustion engine still use a 12 volt system for most vehicle components, and they are generally supplied with a 12 volt lead-acid 'auxiliary' battery. Typically this is a low capacity (45-60 Ah) 'cranking' battery, even though it is not required to crank an engine. Some owners, for example those who use accessories such as dashcams while parked, wonder whether it is feasible to replace this cranking battery with a deep-cycle battery. Among current technologies, LiFePO4 (LFP) chemistry provides the best combination of safety and deep-cycle performance for use in cars. But LFP batteries need an appropriate charging profile for safety and optimal performance. This site explores whether it is feasible to use LFP batteries in hybrid vehicles.

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Front and Rear Dashcam Installation in a Rav4 Hybrid

Summary: This article: (1) describes how to install a dual dashcam taking the Viofo A129 plus duo into a Toyota rav4 hybrid as an example; (2) recommends against long use of dashcam parking mode from the small auxiliary battery usually installed in a hybrid car; (3) gives some limitations of power banks to run a dashcam; (4) describes a better way to achieve automatic activation of parking mode in a Viofo dashcam; (5) considers power use of the dashcam in relation to available battery capacity; and (6) concludes that for use of a dashcam in parking mode beyond a few days, there is no practical alternative to installation of a deep-cycle vehicle battery of suitable capacity.

Reference & Link: Birch RG (2021) Front and Rear Dashcam Installation in a Rav4 Hybrid. https://scithings.id.au/Dashcam.pdf

Is It Feasible to Use an LFP Auxiliary Battery in a Hybrid Car for Improved Deep-Cycle Performance?

Summary: The use of a LiFePO4 (LFP) 12v battery is only worth considering by a few hybrid car owners: those who drive in mild climates, use power-consuming accessories such as dashcams while parked, and are willing to ensure that battery state of charge remains high enough for safe recharge currents. The capability might be improved by interposing an LFP-optimised charger and return power diode in the 12v circuit, but this would be expensive, and a job for a professional automotive electrician. For most current hybrid car owners, feasibility requires some help from the manufacturer, in the absence of which it is best to stay with the OEM (lead-acid) auxiliary battery. Those who drive at ambient temperatures beyond the 0-40℃ range, and/or do not want deep-cycle ability from a 12v battery, should certainly stay with lead acid.

Reference & Link: Birch RG (2021) Is It Feasible to Use an LFP Auxiliary Battery in a Hybrid Car for Improved Deep-Cycle Performance? https://scithings.id.au/LFP.pdf

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