Is It Safe To Leave A Phone Connected Or Is It Overcharging?

Is it safe to leave a power bank charging overnight

With our busy lives, it’s surely not possible to keep watch over your phone every time you want to charge it with a power bank. At some point, you’ll leave the phone connected to a power bank even after it’s full. Some people have asked in the comments whether a phone battery can ‘boil over’ due to a power bank charging too long. We decided it was time to investigate whether or not it’s safe to leave a phone connected once it’s fully charged.

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Battery Degradation

The reason why some people may be concerned about leaving their battery connected to a power bank is because of batteries. Yes, batteries, our favorite topic. To bring you up to speed, phones use lithium batteries which are partly made of an electrolyte solution. We previously broke it down on this blog post about lithium-ion batteries, but in short when your battery’s electrodes are plugged into a circuit, it forces the electrolyte to start transforming. The solution slowly begins changing forcing electrons to move through the circuit, and when plugged into a device, creates a charge. However, electrolytes are extremely combustible and also sensitive to temperature. The myth that batteries can ‘boil over’ is therefore derived from the battery getting too hot when no more charge can be stored. This has also led to other concerns like “is it safe to leave a phone charger plugged in?” and “is it safe to leave a phone charging overnight?”. However, the idea of a battery ‘boiling over’ isn’t correct for one reason – overcharge protection.

small power banks charges iPad outside on the pavement

Overcharge Protection

That idea of a battery significantly degrading due to overcharging was viable years back. This however doesn’t apply to the modern devices and power banks, at least if you use the right one.

Quality power banks feature overcharge protection. This is a form of technology that protects your phone battery from overcharging when connected to a power bank. It involves putting in place a power circuit that detects the upper limit of the terminal voltage. When the circuit realizes that your battery has reached its limit, voltage is cut off. This means that your power bank will not continue charging a full battery, averting the concern whether your phone is safe when connected to a power bank.

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So What Degrades A Battery?

Though leaving a phone connected to a power bank or charging overnight doesn’t do any mentionable damage to your phone, there are other factors that can contribute to your battery having a short life span.

Charge Cycles: Every battery has a lifetime, and it is majorly affected by the charge cycles. A normal phone battery can have at least 500 charge cycles without significantly degrading. This is about 1 and a half years of use, which is more than the duration some of us use our phones. This degrading occurs because of the chemical reactions that typically occur as you charge your battery.

Temperatures: Temperatures on both ends of the spectrum normally affect the performance of a battery. Very low temperatures increase the internal resistance within a battery and lower the capacity. Extremely high temperatures on the other side can subject lithium-ion batteries to short-circuiting. These can be temperatures from the environment, or even heat from pass through charging.

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Wrap Up

It is safe to leave a phone connected to a power bank. However, you also need to take a few precautions, and especially when choosing your power bank. Some of the cheap power banks in the market can miss features like over-current protection, overcharge protection, short circuit protection, over discharge protection, or high-temperature protection. By getting a quality product, you won’t have to watch your phone as it approaches 100%, or even worry whether it’s safe to leave a phone charging for too long.

Have you ever worried about leaving a phone connected to a power bank?

32 Replies to “Is It Safe To Leave A Phone Connected Or Is It Overcharging?

  1. The blog you published here is very informative. Power banks are popular for charging smartphones and mobile tablet devices. A power bank is a portable device that can supply power from its built-in batteries through a USB port. They usually recharge with USB power supply.

  2. Hmmm, but after the phone internal battery reaches 100% and the power bank stops supplying power what happens when the phone gradually depletes the power of it’s internal battery?

    I use a phone as a security camera in a location with no utility power. My phone’s internal battery is 2460 mAh and I connected a 15000 mAh power bank thinking that would give me days of power. Instead once my phone’s internal battery reached 100% for the first time the power bank goes to sleep and will never supply power again. The phone battery then goes flat a day or so later.

    Is this likely to be the case with all power banks?

    At the moment I need to drive back to the warehouse and press the power bank’s button to wake it up again. Alternatively if I were to disconnect and reconnect the power bank cable it would also wake up. That makes me wonder if an app could be written for the phone to trick the power supply into waking up when the internal battery is depleted to a certain percentage.

    1. Hi Omo!

      Thanks for getting in touch. Unfortunately in this situation, the Power Bank will enter a state of sleep and turn off any output after fully charging your device. After your device’s power drops, it will not automatically wake up and continue charging; as far as we are aware, all power banks on the market are in the same situation! You must press or plug the cable in to charge again.

      If you end up writing that app, please let us know!

      1. Hello

        Thank you for the detailed answer and ver informative blog.

        My questions is what happens if my powerbank have all the above mentioned protection features and it does not sleep at 100% charging of device?

        My powerbank does not sleep when my phone reaches 100% charging.
        But my powerbank has all the overcharging and other features you mentioned above

  3. No never leave your phone laptop plugged in all time because it will damage your battery and not good for your device as well.

  4. I think the power bank is a good device and there is no danger if the powerbank is low voltage just like 10000 but if you are using more than that, that can be dangerous, And one thing you need not to put the power bank for the whole night as the power bank is a portable device so you can take it with you, where you want to go.

  5. Power banks are now must product. Actually I travel a lot so I keep 2 power banks in my bag and they help me a lot in my travelling. Everyone who travels should keep good quality power bank with them.

  6. nice article, it is very informative for me. recently i bought a best power bank charger for phone. I found it amazing. my question is that, can my power bank is affected if i over charged it. kindly guide me. thanks

  7. Hallo RavPower,

    Can you please suggest me which Power Bank is good for Travelling ? I am world Traveller and I read blog and i need it like “Overcharge Protection”. It will be really helpful if you suggest me best Power bank for Travelling.

    Thank you in Advance,

  8. I think the power bank is a good device, is no danger in use.. But everyone know thats the best.. Just read a bit articles like this one… 😛

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