Are you desperate with your power bank?
Portable power bank is a practical solution to charge your phone, tablet, headset and other kind of small electronic devices or gadgets. A power bank is characterized by its nominal capacity, typically expressed in mAh (milli-Ampere-hours). For example 5’000 mAh, 10’000 mAh, 27’000 mAh etc. The nominal output voltage is standardized. Practically every power bank features 5 Vdc output. That is the standard USB-A und USB-C port. Some power banks may offer also higher output voltages, used for fast charging (9 V for phones, 12 V for tablets, 20 V for laptops).
Tired of power banks that do not last?
Okay, most people look for the capacity. The higher the capacity the more energy stored inside the power bank. With a 10’000 mAh power bank you should be able to fully charge your phone 2-3 times before the power bank is completely discharged. However, here we talk about the nominal capacity of a brand new power bank. And here is the point: while some power banks keep their capacity for a few years, majority of them start to degrade early. Very early! I have a power bank with official capacity of 10’000 mAh. I can charge it from a solar panel to the full capacity. But as soon as I use it to charge my phone, the power bank gets empty in seconds. Can I use it for anything? Not really. Quality issue? Well, it looks more like a systematic problem. The power banks last way too short. And, in my view, the trend is getting worse. We are flooded with cheap products of poor quality that do not last, are not properly controlled or tested, generate huge electronic waste and even present a safety risk.
Figures 1a and 1b show two examples of my power banks. One has a cool color and is very compact. The other one has higher capacity and enables also wireless charging. Both are made in China. Both lost vast majority of their capacity after several months.
What moved me to author this article?
It was primarily the bad experience with China made power banks that are absolute crap. Those products are often waste of money and waste of resources as well. As their capacity degrades fast, the energy put into their production likely exceeds the energy they could cumulatively store across their lifetime. Meaning no good for the environment either.
It is basically a planned obsolescence issue – something I really dislike. Planned obsolescence is an expression for intentionally designing products to wear out, break, or become outdated sooner than necessary, often to force consumers to buy replacements. And that is exactly what we witness. Technologically it is perfectly feasible to design and manufacture power banks that last. But it seems that most manufacturers are not interested in manufacturing quality products. Instead, the power banks are treated like consumables. You use them for 1-2 years and then throw them away. Almost like the standard AA or AAA single use batteries.
What can you do against it?
This is the key question. And the answer is relative. Does the poor quality bother you or not? Or do you just buy a new power bank every few months without challenging the status quo?
For me the quality matters. Poor quality electronic products turn to be expensive despite their cheap price as you need to replace them frequently. Besides the price, frequent replacement means that we produce considerable amount of electronic waste. Purchasing of new device costs you some time as well. And most importantly: you simply can’t rely on the device when it degrades so rapidly.
My approach
The bitter experience with multiple power banks lead to my personal decision:
⇒ Purchase product from European manufacturer
⇒ Seek for Europe made product or at least product with final assembly in Europe
⇒ Check for references of the manufacturer
⇒ Purchase price is secondary. Quality will pay off in the end.
⇒ Go for extended warranty and insist on it. Check carefully what the extended warranty covers and what not. If the seller does not offer such option, drop him and look for another one.
Unfortunately, it is not easy to find a good alternative. However, they exist.
I just bought this model:
27’000 mAh Fuel Series 5 Dual USB C / USB A Powerbank Power from the company Xtorm
- Dutch company (NL)
- Product is designed in the Netherlands
- Some models assembled in Europe (but not all)
- High quality and rugged design (according to Microsoft Copilot)
- Suitable for outdoor use/in combination with solar applications
It is early to say if the quality will be better but I stay hopeful. If you want to hear about my experience, leave a comment below and I keep you updated.
Why industrial capacitors last for years under continuous duty while the consumer electronics has such a poor lifetime?
Is the degradation of power banks natural or a consequence of poor quality? I am absolutely convinced that the latter is the true. If you look in other applications, you find battery storage systems that last for years under heavy duty conditions. Let me present you a couple of examples.
1. E-mobility
Can you imagine buying a new electric car with purchase price in the range EUR 50’000 – 80’000 where the battery capacity drops significantly after 2-3 years of use? The rumors would spread and nobody would buy such a car. The degradation of electric car batteries is slower than many people think. The rate is about 2-3% degradation after the first year, around 10% after 5 years and in the range of 15-25% after 10 years. In other words, most EVs still have approx. 80% of battery capacity after being in operation for 10 years [1]. The figures cover a mix of high-power fast charging and slow charging. Using slow charging only, the degradation is even less!
[2] summarizes the results of a 5-year study data following:
- 1 year: 98% remaining capacity
- 3 years: 92% remaining capacity
- 5 years: 85% remaining capacity
There are also electric buses or battery powered trains. These vehicles represent significant investment and their batteries shall last 10+ years.
2. PV systems with battery storage
Photovoltaic systems are often combined with battery storage, especially in household applications. Such batteries are charged and discharged on daily base. When you purchase a systems consisting of photovoltaic panels and battery storage, the cost of the battery is about 60-70% of the total cost. That is very high portion and the user certainly expects long lifetime. My parents have a PV plant on the roof combined with a battery storage. Phase 1 was installed at the end of 2020 (more details in [4]). After more than 5 years, the diagnostic system of the battery estimates its actual capacity as 98% of original value. That is absolutely marginal degradation.
3. Variable frequency drives
Finally I make the bridge to the key subject of our blog: Variable frequency drives (VFD). Majority of modern VFDs are voltage source inverters with capacitor based dc link. Do they degrade similar like the consumer power banks? Of course not! Medium voltage VFDs have a design lieftime of 20 years or more. The capacitors are inspected in regular intervals, typically every 2 years, and the actual capacitance is measured [5]. If no major degradation is noticed, the capacitor is kept. Shall the capacity be significantly reduced, the affected capacitors may be replaced. The expected lifetime of the DC capacitors, when operated within the design conditions, would be at least 8 – 12 years.
Same thing as for the VFDs applies to other power electronic converters, such as STATCOMs or static frequency converters (SFC).
In drive systems, power capacitors are not just in the DC bus of the VFD. You can find them also in various filters (inverter output filter, harmonic filter of an LCI etc).
Summary
Battery storage systems can last for many years without any significant degradation, i.e. without losing large portion of its initial capacity. An electric car would have still about 80% of original battery capacity after 10 years of use. Larger vehicles, such as electric buses or battery powered trains, feature similar figures. Medium voltage VFDs have capacitors in DC link that typically last 10 years or more. Power capacitors inside harmonic filters or reactive power compensation units may last well over a decade.
The fact that many portable power banks degrade so fast is not a technological issue. It is a direct consequence of poor quality and/or a planned obsolescence as possible business plan (intentionally weak design causing rapid degradation).
Your consumer behaviour may help to change this. Preferring quality over price benefits quality manufacturers over dirty players. Exact same applies when selecting a VFD manufacturer. Use your finances wisely. Don’t waste your money on crap. And don’t create unnecessary electronic waste.
Sources
[1] How long do electric car batteries last? GEOTAB.com, available online, https://www.geotab.com/blog/ev-battery-health/
[2] The truth about EV battery degradation: 5-year study data, https://coloredcar.com/the-truth-about-ev-battery-degradation-5-year-study-data.html
[3] J. Betancourt, C. Zhao, M. Tuo, Comparative analysis of EV battery degradation: Real-world data vs. lab simulations, IEEE Texas Power and Energy Conference (TPEC), 2025
[4] My experience with renewable energy, MB Drive Services, October 2022, available online, https://mb-drive-services.com/my-experience-with-renewable-energy/
[5] Operation of medium voltage drives: A service cost of ownership, MB Drive Services, September 2025, available online, https://mb-drive-services.com/mvdrives-service-cost-of-ownership/
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