Wireless power bank problem

Hello everyone,

I’ m quite new here so I’m not sure if I’m in the right place to ask this.

So here is the issue :
I just bought from Amazon (the seller is Anker) the 10k wireless power bank for a little more than 2 weeks.And today I just had an issue where 50% of the battery charge just disappeared.
At the time of issue my iPhone 8plus was wirelessly charging without anything plugged in the power bank. 2 white leds disappeared just like that (there was 3 in the beginning) in less than 15 min of charging it.

For your information the power bank was brand new with no liquid damage whatsoever.
I’ve been using a power port atom 20W and an usb-ce to usb-c from Anker as well to charge the power bank.
It didn’t suffer any physical damage as well and apart from putting on the table in the house to charge it, it was placed inside my jacket when I’m outside.

So what do you guys think? Should I worry about this behavior and return it?

Thanks for your time.

It is possible to use another cable / charger.
If not get in contact with the support.
You will get help there.

But may be, when the fellows from over the pond show up, they got other ideas than me! :smile:

Based on your words I’d say this looks most probably a dud unit.

Initiate a warranty process by emailing



  • your proof of purchase like Amazon order
  • serial number, it’s printed usually on the box, and if you have a good microscope and camera it’s also printed on the unit itself. Good luck photo the latter.
  • what you wrote above.

Normally we’d suggest try different cable but in this case it drained from 3 to 2 to empty so I think it’s a failed unit.

If they do though manage to fix, let us know so we can help the next user with same.

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I don’t think the issue is the cable nor the charger because I’m also using them to charge another 26k PB from Anker and I have no issue with it.

I l’ do just that then this afternoon.
However I’m living in France and I’m wondering if it’s the same mail for support?

Havent found a “special phone number for France”.
You may use the normal support-address and contact them via email.

Thanks for your replies again.
I’ll mail the support when I’m free at home.

Good luck and Joyeux Noël ! :smiley:

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I appreciate that. It’s quite hard to enjoy holidays now.

Anyway merry Christmas everyone :christmas_tree:

Hi @TheGamer,
You can definitely reach out to support as this behavior is odd. However, it could be that the battery gauge just needs to be calibrated which occurs automatically after several discharge/charge cycles. You don’t need to drain the battery all way; you can recharge it at any point, ideally before it gets below 20%.
It’s also possible that the power bank became too warm during the charging cycle and shut down as a safety feature. Wireless charging can generate more heat than wired charging.

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I’m using this PB to occasionally charge my phone each day (at most I’m charging 30-50% of my phone which is at most 1500 mA once or twice daily. Sometime I won’t even use the PB) and since buying it I have only fully charged it thrice (I fully charged it 3 days ago and today was the second time I used it to charge). Each time it was not fully discharged as I won’t use the pb when I reach 1 white led.

Well it definitely didn’t reach that point when I took the phone off the PB. And even after waiting 30 minutes there’s only 1 white led on. And I can still charge my phone wirelessly

That last post looks fully normal.

The technology is about 65% efficient. You’d get around 2.5 phone recharge from full. So if you’re doing 30%-50% phone recharge / day you’d expect the full Powerbank to give 6 days.

I’d not use lights on the Powerbank as any indication of how full it is, they are very rough guides e.g. 2 lights doesn’t mean half full, more like it’s neither not quite empty and not full.

As @TechnicallyWell says, the lights will be more accurate if you fully discharge and recharge but personally I’d just fully recharge the Powerbank every night anyway so each day begins full so I’m never looking at the lights anyway.

Where the fault may be is if it was actually half full and your non-empty phone emptied it. That implies may be a fault as roughly a half full Powerbank should do a full phone recharge.

That’s my daily routine for 3 weeks starting from the day I received the PB :smiley:.

I didn’t know about the 65% efficiency and the led not indicating a precise amount. Thank you for enlightening me.


Heres a shameless plug for my review of the Wireless 10k PowerCore.
It has some charging specs which might help you justify the performance you are getting from yours.

Its often hard to tell how “much” you are getting from a PowerCore when using it for odd top ups.
If you are in any doubt and want to know if yours is performing to spec maybe fully charge the PowerCore and charge your phone from flat to see how many full phone charges you get from the fully charged PowerCore.

I wouldn’t agree with @professor in that the lights are a vague indication of its remaining capacity.

And @TechnicallyWell i didnt realise a PowerCore calibrated itself after a few charge cycles. Every days a school day.

I’ll try that this week end.
Should I use a cable so I won’t need to care about wireless efficiency?

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Well to be fair @TheGamer i didnt have much of a drop in efficiency between wired and wireless.
But you could try both and measure the output performance in your scenarios :+1:t2:

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The above review shows it’s not much different in truth, about 5% different so if wireless is preference go for it.

Odd you should ask if you use it, as the wireless 10Ah is considerably higher cost than the non-wireless so assume you bought it explicitly for wireless.

The issue is probably just your lights not a good guide and you should really recharge the Powercore end of each day so accuracy of lights irrelevant.

There may be a physical issue with your unit as to go down from 3 lights to off shouldn’t really happen as half a recharge should be less than 1 light so 3 should go down to 2 or 2 to 1. Best to know if it’s a battery issue or callibration is do a full empty-full-empty test like Paul did, and confirm you’re getting roughly 6500mAh from it (about 2.5 recharges for your phone).

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@professor @paulstevenewing @Chiquinho
Hello again,

After contacting support, they told me to assess the PB when it’s full and this is the result I had during 3 days :

  • Day 1 : charged for a bit more than an hour my phone for 60% (4 leds on)
  • Day 2 afternoon : charged 60% in 1h17~ (4leds on)
  • Day 2 night : charged 50-55% in 1h10~ (1 led on. After 20-30 min of charging it lost 2 leds and a bit after an hour it lost another led)
  • Today : charged my phone 4% in 6 min and it went off

The support talked about « capacity » and « rated capacity ». To conclude at the end that it’s a normal behavior for my PB to last that long but he didn’t not talk about the PB draining in one session of charging. So I insisted about this point.
There’s another thing I don’t understand : why could I charge 50-60% a day for 6 days each week? Well this lasted until this week where the issue started.

I paid attention to the heat during a session of charging. If the issue is not present then I can feel a moderate amount of heat near the coil (only the mid part of the PB. It’s cold elsewhere).
However when the issue occurred I could feel that it’s hotter near the coil (and not a little bit) and I could also feel it everywhere on the PB if I touch it.

So what do you think?

Thanks again.

Edit : I used another usb-c to usb-c câble (from xiaomi) to completely charge the PB.


  • mAh is a dumb number because it’s actually Wh or.energy is better but we have to find the Voltage out to then multiply and get mWh from mAh X Voltage so crudely we assume the voltages the same and don’t look too accurately comparison.
  • the Powercore loses energy in the cells discharge and the DC-DC conversion , about 94% efficient which relative to everything else is nearly perfect.
  • the transfer loss. This is about 1% loss in a wire and in good wireless setup is 15% loss. This may sound terrible but that’s the nature of this Universe. Photons go in all directions as they don’t hold a charge and it’s only via a coil and proximity it does better. Electrons hold a charge so can be guided by a voltage difference. Wired will always be better than wireless, but wireless is convenient no cable to plug. For a wall socket charger you don’t care or even know but when you think you bought 10000mAh Powercore is becomes more obvious.
  • the phone loses energy in the electronic DC-DC conversion and in the chemical recharge of its battery
  • phones lose energy while on. Slower charging means the phone is on for longer while charged so loses more.
  • these add up to a rough rule of about 65% efficiency is normal, most of it loss is your phone and very little is Anker fault who in a fully working unit is nearly perfect.

So in your case from full Powercore you charged a

Which reviews suggest has about 9 hours battery life.

I’m not exactly sure what you mean by % but I’m assuming you mean the % increase so if I add them all up 60+60+52.5+4= 180% so you got 1.8 phone recharges.

That meant you got 4815mah from 1000mAh so about 50% efficiency.

That’s low.

Look at Paul’s review, he got about 65% efficiency.

So you do have some kind of problem. It could be

  • a failed unit so warranty replacement
  • your phone is being used a lot while being charged, something is draining it battery while it is being recharged.
  • terrible wireless efficiency such as a case is slowing it all down and more energy is just radiating into space and warm a wall , or you, instead.

To help eliminate which try:

  • wired charging, this removes one of the causes, if you get much better performance then focus on causes of wireless inefficiency like no case it’s well positioned etc
  • confirm the phone is not do anything, when it’s not being charged but just on a surface, how much is lost in the above durations such as you mentioned an hour. For example if in 3 hours not used you lost a lot of power then the issue is fully resolved the phone is burning energy away itself and so less gets into its battery. Paul’s excellent review removed this via turning the phone off.

Further education would if you thought 65% was itself low, shouldn’t it be nearer 100% and so you bougbt a bad Anker product, well no actually that your iPhone fault it loses energy itself recharging itself as is the source of heat, check out the more detailed review of a different wired product where USB meters helped eliminate that about 4/5th of last energy was in the phone and Anker is >90% efficient.

I’m here just to clarify on the situation of my PB. That’s why I’m asking for help here.

The percentage does indicate the increase. I’m sorry if i wasn’t accurate (English isn’t my main language).

As for the problem :

  • Failed unit : from your comments and the message from the support, I think I can push aside this case (well maybe not for the leds since they are behaving strangely)
  • I’m not using the phone but I didn’t activate the power saving mode as well. However Bluetooth and wifi are disabled.
  • I do have a phone case every time I charge the phone
  • I will try using a cable instead of wireless (but that’s not the point of buying this PB :frowning:)

Anyway, I’ll do more testing tonight and this week-end when it is fully charged.

Apart from that, why is the last charge (the last 1400mA) releasing way more heat?
And are the leds not working properly anymore?

This is why we here challenge the purpose of a wireless Powerbank and why many reviews feedback is a bigger 20Ah would be better match to the niche.

The history preceding the product release was discussed at length here

If you want compact and efficient go wired, if you want convenience of no wire go wireless. You can’t have both.

You may have a dud unit so keep digging.

I’d suggest if you like the convenience then just plug in the Powercore to recharge more often like each night or every other night and now know is the effective results.