It appears you are referring to the **398L series**, which most commonly refers to the **398L series of silver oxide button cell batteries** (often cross-referenced with SR726W or SR59). These are critical electronic components used to power precision low-voltage devices. Below is a detailed breakdown of the electronic specifications and applications for this part. --- ## 1. Technical Specifications (398L / SR726W) The 398L is a high-drain silver oxide battery. Unlike the 399 (low drain), the 398L is designed to handle sudden pulses of power (like backlights or alarms). | Property | Specification | | :--- | :--- | | **Chemistry** | Silver Oxide ($Ag_2O$) | | **Nominal Voltage** | 1.55 Volts | | **Capacity** | ~28 mAh to 33 mAh | | **Diameter** | 7.9 mm | | **Height** | 2.6 mm | | **IEC Designation** | SR726W | | **Discharge Profile** | Flat (maintains constant voltage until exhaustion) | --- ## 2. Key Electronic Features ### A. High Drain vs. Low Drain The "L" or "W" designation typically signifies that the cell is optimized for **high-drain** applications. This means the internal resistance is lower, allowing the battery to provide a quick burst of energy without a significant voltage drop. ### B. Voltage Stability Silver oxide cells like the 398L provide a very stable 1.55V throughout their life cycle. This is critical for quartz timing circuits where voltage fluctuations could lead to timekeeping inaccuracies. ### C. Leak Resistance Modern 398L parts are manufactured with sophisticated sealing techniques to prevent potassium hydroxide leakage, which could otherwise corrode delicate PCB traces in small electronics. --- ## 3. Common Equivalents & Cross-Reference If you are looking for this part, it is often marketed under different manufacturer codes: * **Energizer/Eveready:** 398 * **Duracell:** D398 * **Maxell/Sony/Panasonic:** SR726W * **Varta:** V398 * **Renata:** 398 --- ## 4. Primary Applications Because of its small form factor and reliability, the 398L is found in: 1. **Analog-Digital Watches:** Specifically those with alarms or LED backlights. 2. **Medical Devices:** Small digital thermometers and glucose meters. 3. **Precision Instruments:** Digital calipers and micrometers. 4. **Key Fobs:** Small remote entry systems for older vehicle models. ---