Last Updated on April 17, 2025
The Fenix PD35 Tactical Flashlight is a favorite among outdoor adventurers, emergency responders, and tactical gear enthusiasts due to its compact size, powerful brightness, and user-friendly design. What makes it even more reliable is its dual battery compatibility—you can use either a rechargeable 18650 Li-ion battery or CR123A lithium batteries.
This guide will walk you through everything you need to know about charging the Fenix PD35, battery voltage safety, common troubleshooting tips, and battery-saving features—all while keeping your flashlight in peak condition.
Which Batteries Can You Use with the Fenix PD35?
The Fenix PD35 flashlight supports:
- One 18650 Li-ion rechargeable battery
- Two CR123A non-rechargeable lithium batteries
🔎 Why it matters: The 18650 battery is great for daily use, thanks to its rechargeability and longer lifespan. However, CR123A batteries are cold-resistant, making them suitable for extreme weather conditions where Li-ion batteries might underperform.
How to Charge the Fenix PD35 Flashlight (Step-by-Step)
Unlike flashlights with built-in charging ports, the Fenix PD35 flashlight is charged via the battery itself, which typically includes a micro-USB port.
i) Turn Off the Flashlight
Before charging, always turn off the flashlight. Charging while it’s on can disrupt internal circuits, cause overheating, or shorten battery life.
ii) Connect the USB Cable
Insert a micro-USB cable into the charging port on the 18650 battery (not on the flashlight body). Plug the other end into a USB power source, such as:
- Wall adapter
- Computer USB port
- Portable power bank
iii) Observe the Charging Indicator Light
Most Fenix batteries feature a built-in LED indicator:
- Red Light = Charging in progress
- Green Light = Fully charged
This indicator is a handy feature that eliminates the guesswork and ensures safe, efficient charging.
iv) Unplug When Fully Charged
When the indicator turns green, promptly unplug the charger to prevent overcharging, which could degrade battery performance and lifespan.
✅ Pro Tip: Always use genuine Fenix batteries and accessories for the safest and most reliable charging process.
What Is the Ideal Charging Voltage for a 18650 Li-ion Battery?
Knowing the correct charging voltage is essential for preserving battery health and preventing overheating.
- Standard Charging Voltage: 4.2V
- Safe Voltage Range: Between 4.2V and 4.4V
- Maximum Voltage: Should not exceed 4.4V
Charging with a voltage too high can damage the battery, while too low might not charge it fully. Most Fenix batteries are designed to regulate this automatically.
⚠️ Never use unbranded or off-market chargers—they might overcharge or damage your battery.
What to Do If Your Fenix PD35 Isn’t Charging?
If you find your flashlight isn’t charging, follow this comprehensive troubleshooting checklist:
Step 1: Remove and Inspect the Battery
Open the flashlight and remove the 18650 battery. Check for:
- Physical damage
- Leaking or corrosion
- Swelling or overheating
If the battery is compromised, replace it immediately.
Step 2: Test the USB Cable and Port
Try using a different USB cable or charging adapter. Also, clean the charging port on the battery gently using a dry brush or cotton swab.
Step 3: Check Internal Flashlight Components
If charging still fails, inspect the flashlight’s internal connections:
- Any loose contacts or broken wires?
- Are the springs in the battery compartment bent or damaged?
If you’re not confident opening the flashlight, consult Fenix support or a certified technician.
How Can You Confirm That the Fenix PD35 Is Charging?
Most Fenix rechargeable batteries include a clear LED status indicator, usually located near the micro-USB port:
- Red Light – Charging in progress
- Green Light – Charging complete
If no light appears, it may indicate a problem with the cable, port, or the battery itself.🔋 Battery Life Management: Does the Fenix PD35 Conserve Battery Power?
Yes! The Fenix PD35 comes with an intelligent battery management system that protects the battery and ensures longer runtime.
When the voltage drops below a certain level, the flashlight will:
- Automatically reduce brightness to conserve energy
- Protect the battery from over-draining, which helps prolong its lifespan
- Provide consistent output during the remaining battery life
💡 This feature makes the PD35 perfect for extended use in field operations, camping, or emergency situations.
Does the Fenix PD35 Flashlight Give Low Battery Warnings?
Absolutely. When the battery reaches a critical low level, the flashlight activates its low battery warning system.
Here’s what happens:
- The main LED starts blinking every 5 minutes
- This serves as a signal to recharge or replace the battery soon
- Helps avoid sudden darkness during important tasks
This flashing alert is a valuable feature when you’re in the dark and can’t afford your light going out unexpectedly.
Can You Use CR123A Batteries in the Fenix PD35?
Yes, the Fenix PD35 flashlight is compatible with two CR123A lithium batteries. These are ideal for:
- Cold climates where rechargeable Li-ion batteries lose efficiency
- Backup use when recharging isn’t an option
However, CR123A batteries are not rechargeable, so they’re better suited for short-term or emergency use.
Final Thoughts
The Fenix PD35 Tactical Flashlight is a powerful and dependable tool when maintained properly. Understanding its charging process, ideal voltage requirements, and troubleshooting steps ensures you get the best performance and extended lifespan out of your flashlight.
Whether you’re using it for tactical missions, camping trips, or power outages, knowing how to charge and care for your Fenix PD35 will make all the difference in how well it serves you.