What fire suppression strategy should be used for fires involving high voltage battery packs in hybrid vehicles?

For fires involving high voltage battery packs in hybrid vehicles, utilizing a water supply and applying copious amounts of water is the most effective fire suppression strategy. This approach is essential because high voltage batteries can be quite dangerous and are prone to thermal runaway, which is a rapid increase in temperature that can lead to explosions or reignition if not managed properly.

Water serves multiple purposes in this scenario. It helps cool the battery to prevent the risk of thermal runaway from escalating and also helps to extinguish flames. It's important to ensure that the water is applied in significant quantities because hybrid battery fires can have deep-seated heat sources which require sustained cooling to manage effectively.

Other methods, such as using foam extinguishers or dry chemical extinguishers, may not provide the necessary cooling effect on the battery pack due to their limited ability to absorb and dissipate heat in this context. Smothering the fire with a blanket might help in some situations, but it would not adequately address the unique concerns associated with a high voltage battery fire and is generally not sufficient for an active fire involving these batteries. Thus, establishing a reliable water supply and using large amounts of water is firmly established as the best practice in these incidents, making it the correct choice for this question.