Dual purpose batteries are designed to perform two key functions: starting an engine and providing sustained power for accessories. This contrasts with dedicated starting batteries that provide high bursts of power for starting and deep cycle batteries that provide lower, sustained power for a longer duration.
Understanding Dual Purpose Batteries
Dual purpose batteries, as the name suggests, combine characteristics of both starting and deep cycle batteries. According to a reference, they are specifically designed to:
- Start the Engine: Provide the high current needed to crank and start an engine.
- Power Accessories: Provide continuous power for things like trolling motors or other electrical devices on a boat or RV.
Here's a breakdown of why these capabilities are important:
| Feature | Starting Battery | Deep Cycle Battery | Dual Purpose Battery |
|---|---|---|---|
| Primary Use | Starting engines | Sustained power for accessories | Starting and sustained power |
| Power Output | High burst of power | Lower, sustained power | Medium power for both functions |
| Discharge Cycle | Not designed for deep discharge | Designed for deep discharges | Tolerates moderate discharge cycles |
Benefits of Using Dual Purpose Batteries
- Convenience: Eliminates the need for separate batteries for starting and accessories, saving space and weight.
- Versatility: Suitable for various applications where both starting power and continuous power are needed.
- Cost-Effective: Can be more affordable than purchasing two separate types of batteries.
Example: Marine Applications
The reference specifically highlights the use of dual-purpose marine batteries. In a boating scenario, these batteries:
- Provide the necessary power to start the boat's engine.
- Continuously power the trolling motor, navigation lights, and other onboard electronics.
This makes them a popular choice for boat owners looking for a single battery solution.
Practical Insight
While dual purpose batteries offer versatility, they don't excel at either starting or deep cycling as much as their dedicated counterparts. For very demanding applications where very deep discharges are common, deep cycle batteries may be a better choice, and in very demanding starting scenarios, a dedicated starting battery would be more beneficial. However, for most general use cases, dual purpose batteries offer a good balance between starting power and deep cycling capabilities.
