Final answer:
Leaving a solar-powered thunderbolt battery charger connected to deep cycle batteries is safe if the charger has a built-in charge controller with protection features. Without such features, there's a risk of overcharging and damaging the batteries, so the safety truly depends on the specific charger model.
Step-by-step explanation:
The safety of leaving a solar-powered thunderbolt battery charger connected to deep cycle batteries continuously depends on the features of the specific charger in question. If the charger has a built-in charge controller, it is designed to prevent overcharging by regulating the charge to the batteries, making it safe to leave connected at all times (answer a). However, if the charger lacks this feature or is not functioning correctly, it could lead to potential overcharging and damage to the batteries over time, representing a safety risk (answer b).
The best practice is to use a solar charger that has a proper charge controller with features like overcharge protection, over-discharge protection, and temperature compensation. These features ensure the battery's longevity and performance by preventing any damage that could arise from improper charging. Therefore, the most accurate answer would be (c) Safety depends on the specific charger model, as different models come with various features that enhance or compromise safety.
Regarding the option of leaving it connected occasionally (answer d), it may not represent a consistent approach to maintaining battery health. Regular and careful monitoring is crucial if the charge controller capabilities are unknown or limited.