If you've ever watched your phone battery plummet to single digits at the worst possible moment, you understand why portable chargers have become essential accessories for modern life. Whether you're commuting across Sydney, hiking through the Blue Mountains, or simply getting through a busy day of work and errands, a reliable power bank can be the difference between staying connected and being stranded.
This guide will walk you through everything you need to know about portable chargers, explaining the technical jargon in plain language and helping you understand what actually matters when choosing a power bank.
What Exactly Is a Portable Charger?
A portable charger, also called a power bank, is essentially a battery pack that stores electrical energy so you can charge your devices when you're away from a power outlet. Think of it as a fuel tank for your electronics. You charge the power bank at home, then carry that stored energy with you to top up your phone, tablet, or other USB-powered devices throughout the day.
Inside every power bank are lithium-ion or lithium-polymer battery cells, similar to those in your smartphone but usually with much larger capacity. These cells are managed by internal circuitry that handles charging, discharging, and safety features.
A power bank is simply a portable battery that stores electricity so you can charge devices on the go. The bigger the capacity, the more charges you can get.
Understanding Capacity: What Does mAh Mean?
When shopping for power banks, you'll see capacity measured in milliamp hours, abbreviated as mAh. This number tells you how much electrical charge the battery can store. A higher mAh rating means more stored energy and, theoretically, more charges for your devices.
To put this in perspective, a typical smartphone battery holds between 3,000 and 5,000mAh. So a 10,000mAh power bank might seem like it could charge your phone three times. However, the real world is messier than simple maths suggests.
Why You Never Get the Full Rated Capacity
There's an important catch that manufacturers don't always explain: you'll never get 100% of the advertised capacity delivered to your device. Several factors reduce the usable capacity:
- Voltage conversion losses: Power banks store energy at 3.7V but output at 5V or higher, and this conversion wastes some energy as heat
- Cable resistance: Some energy is lost as it travels through your charging cable
- Device charging circuitry: Your phone's own charging system isn't 100% efficient either
In practice, expect to receive about 60-70% of the advertised capacity. That 10,000mAh power bank will realistically deliver around 6,000-7,000mAh of usable charge. This isn't a scam; it's just physics. Quality brands account for this in their marketing, while budget brands sometimes overstate real-world performance.
- 5,000mAh: One full phone charge, ultra-portable
- 10,000mAh: Two to three phone charges, pocket-friendly
- 20,000mAh: Four to six phone charges, bag-friendly
- 26,800mAh: Maximum airline-approved size, great for laptops
Charging Speed: Not All Power Banks Are Created Equal
Beyond capacity, charging speed is perhaps the most important specification to understand. Nobody wants to wait hours for their phone to charge, especially in urgent situations.
Charging speed is measured in watts (W), which you calculate by multiplying voltage (V) by current (A). A standard USB port delivers about 5W, which charges most smartphones slowly. Fast charging technologies push this much higher.
Common Fast Charging Standards
USB Power Delivery (USB-PD): This is the most universal fast charging standard, supported by iPhones, Samsung phones, Google Pixels, and most laptops with USB-C ports. USB-PD can deliver anywhere from 18W to 100W or more, making it suitable for everything from phones to laptops.
Quick Charge (QC): Developed by Qualcomm, Quick Charge is common in Android devices, particularly those with Qualcomm processors. QC 3.0 delivers up to 18W, while QC 4+ can reach 27W. Most devices with QC support also work with USB-PD.
Proprietary Standards: Some brands like Oppo (SuperVOOC) and OnePlus (Warp Charge) use proprietary fast charging that only works with their specific phones and chargers. Power banks with these technologies are less common.
For maximum compatibility and future-proofing, choose a power bank with USB-C Power Delivery. It works with nearly everything and will remain relevant as more devices adopt USB-C.
Ports and Connectivity
Modern power banks typically offer multiple ports for flexibility. Understanding what each port offers helps you choose the right device.
USB-A ports: The traditional rectangular USB connector. Most power banks include at least one USB-A port for compatibility with older cables and devices. Output is typically 5-12W for standard ports, or up to 18W with Quick Charge support.
USB-C ports: The newer, reversible oval connector. USB-C can handle much higher power levels and often serves double duty as both an input (for charging the power bank) and output (for charging your devices). Look for USB-C ports with Power Delivery support for the fastest charging.
Built-in cables: Some power banks include built-in charging cables, eliminating the need to carry separate cables. These are incredibly convenient for travel but may become outdated if connector standards change.
Size, Weight, and Portability
Here's the fundamental trade-off with power banks: more capacity means more size and weight. A 5,000mAh power bank might slip into your pocket, while a 26,800mAh model feels like carrying a small brick.
Consider how you'll actually use your power bank. If it's too heavy or bulky, you'll leave it at home, defeating the purpose. For daily carry, most people find 10,000-15,000mAh hits the sweet spot between capacity and portability. Save the larger capacities for trips, camping, or situations where weight matters less than runtime.
Safety Features to Look For
Quality power banks include multiple safety features that protect both the battery and your connected devices. While these work invisibly in the background, their presence indicates a properly engineered product.
- Overcharge protection: Stops charging when the battery is full
- Over-discharge protection: Prevents the battery from draining too low
- Short circuit protection: Shuts down if a short circuit is detected
- Temperature protection: Reduces power or shuts off if overheating occurs
- Overcurrent protection: Limits current to safe levels
Reputable brands clearly advertise these features. If a power bank is suspiciously cheap and doesn't mention any safety certifications, consider that a red flag. For more on this topic, see our power bank safety guide.
Choosing Your First Power Bank
With all this information in mind, here's a practical framework for choosing your first portable charger:
- Identify your primary use case. Daily commute? Travel? Emergencies only?
- Calculate your capacity needs. How many full phone charges do you need between outlets?
- Check your devices' charging standards. Do you need USB-PD for an iPhone or laptop?
- Set a realistic budget. Quality power banks start around $30-40 AUD. Spending less often means compromising on safety or longevity.
- Read reviews from Australian sources. Products that perform well overseas may struggle in our heat.
For most Australians, a 10,000mAh power bank with USB-C Power Delivery and at least one USB-A port offers excellent versatility at a reasonable price and weight. This size handles daily charging needs while remaining pocket-friendly enough for everyday carry.
Ready to start comparing options? Head back to our homepage to explore our top-rated power banks and use our comparison tools to find your perfect match.