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Slow charging (7W) google pixel (4a). Which USB A-C cable to use?

Discussion in 'Android Devices' started by germandowski, Feb 3, 2021.

  1. germandowski

    germandowski Newbie
    Thread Starter

    Hi everyone.

    I bought a power bank which has an output power (USB-A - USB-C) of 12 and 18W for my pixel 4a.
    If I understand correctly, with the Pixel the only way to have fast charging is through: USB C-C cable and "power delivery".
    I would therefore exclude the possibility of using 18W but the problem is that I cannot go beyond 7W (5V, 1.4A) whatever cable (USB A-C) I use and this causes a really slow charging of the phone.

    Is there a specific cable that allows me to go beyond 7W?
    (not 18W ok, but a few W more ...)

    NB: this slow charging also happens with all the chargers I have at home using the USB A - C cables I have, so it is not a defect of the power bank but a "problem" of the phone
     



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  2. codesplice

    codesplice Elite Recognized Moderator
    Moderator

    You will not get "Rapid Charging" using a USB A-to-C cable, regardless of the power source. Pixel phones adhere to the USB Power Delivery spec and do not support any other fast charging protocol. A Pixel will not draw more than 7W from a USB A port.

    I'd instead look for a power bank which supports USB-C PD so that you can charge your phone at full speed. I've got one that goes up to 45W and works beautifully for charging my Pixelbook at 45W and my Pixel phones at 18W (the max supported by the phones).
     
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  3. germandowski

    germandowski Newbie
    Thread Starter

    Thanks a lot for the answer.
    Actually the power bank I bought has the USB-PD port but I'm afraid that the battery, always recharging it with "fast charge", will be damaged, let's say, before its time.
    Whoever connects the phone to the original Google charger will always have the phone subjected to fast charging?
    No one has ever questioned whether recharging the battery in this way leads to ruining it ahead of time?
    Since the goal is to carry only one cable (and not a cable for slow charging and one for fast charging) at this point the only solution I can think of is to slow down the fast charging of the USB-PD cable maybe making it arrive precisely on 10 / 12W in order to be less harmful to the battery.
    Is there any way to do this?
     
  4. codesplice

    codesplice Elite Recognized Moderator
    Moderator

    Charging a battery faster does generate more heat, which (over time) will shorten the battery's useful life. So there's kind of a trade-off between the convenience of rapid charging versus the battery's health.

    There is unfortunately no way to decrease the charge rate of PD; that's controlled entirely by the phone's charging circuitry. It will typically charge at full speed to a certain level (~90% or so) and then charge more slowly the rest of the way.

    So you're kind of stuck at capping the rate at 7W with A-to-C or 18W with C-to-C, there isn't really an in-between.

    One way you can help protect your battery's health even while charging rapidly is to stop charging before the battery gets full. I use the Accubattery app to get a notification when the battery reaches 80%, at which I unplug the charging cable. I only charge the phone fully if I expect to be away from a charger for a long time.
     
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  5. Hadron

    Hadron Smoke me a kipper...
    VIP Member

    In which case you can control the charging speed via your choice of cable.
    Correct. Unless they've introduced it since my Pixel 2 stopped getting updates in November, Google do not allow you to choose the charging speed or restrict fast charging via the phone's Settings (some phones do, e.g. at least some Sony models, but not all).
    Many people have questioned it. But most of the industry doesn't care, and the blogs/reviews have all swallowed the "faster is better" groupthink.
    Subjectively and unscientifically my Pixel 2's battery has degraded a bit faster than the HTC One that preceded it. Not catastrophically, it's not died after 1-2 years, but at 3.25 years old the battery degradation (about 72% capacity) is more like the previous phone was at around 4 years.

    Do note though that one person's observation is merely an anecdote, and not evidence of a consistent systematic effect.
    No. Charging speed is controlled by the phone, and the phone has no such control available to the user. And any PD-compatible charger will be able to deliver more power than that.
    I doubt you'll be able to find a dodgy cable that can only deliver 10W, as (a) I expect that if the phone decides the cable isn't up to spec it will charge a lot lower than that, and (b) if it doesn't it's likely to be a fire hazard ;).
     
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  6. germandowski

    germandowski Newbie
    Thread Starter

    If instead of a pixel phone I would have taken another, would this thing I read have been true? Could I have been able to go from 1.4A to 2.4A by switching cables?
    "Proper USB-C to USB-A adapter or cable works like USB-A port. The 56 kohm resistor says that it is legacy USB power. Then, it uses battery charging spec to figure out how much power the charger produces, up to 2.4A. "
    If I can express an opinion, putting fast charging without the possibility of choosing a slower one on a 3kA battery I don't know what a good idea that was.
     
  7. germandowski

    germandowski Newbie
    Thread Starter

    thanks to you too for answering me!
    So as Codesplice said I'm screwed, I can only choose between 7W and 18W
     
  8. Hadron

    Hadron Smoke me a kipper...
    VIP Member

    Marketing.

    These days a phone is slated if it doesn't support fast charging, so there is no choice about that. Even "only" supporting 18W charging is likely to result in it being criticised in reviews for being "slow" or "lagging behind the competition". But they get no criticism for not providing the option to turn it off. And Google aren't renowned for providing lots of options in their software, they are very much a "we know best" company, so it's not hugely surprising that they don't provide this. But bear in mind that many other manufacturers also do not provide such an option - what Google have done is the norm in the industry these days, not the exception.

    I admit that when I see headlines saying that phone X supports 45W or 60W charging (or even higher) my response is "I'm not buying that". But that type of thing gets approving writeups from the blogs, so don't be surprised if it becomes more common.
     
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  9. codesplice

    codesplice Elite Recognized Moderator
    Moderator

    Other phones might support proprietary fast charging protocols (like Qualcomm's QuickCharge) so they can pull more power from a USB-A port, but those protocols are still designed to prioritize charging at the fastest speed available. I don't know of any phone which would allow you to arbitrarily throttle the charging rate.
     
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  10. germandowski

    germandowski Newbie
    Thread Starter

    I understand ... luckily I didn't spend a fortune buying the power bank looking for super performance so I'll always end up using it at 7W. I'm sorry that Google has managed the recharge like this ...
    Thank you so much for the help you have given me !!
     
  11. Hadron

    Hadron Smoke me a kipper...
    VIP Member

    Some Samsung phones have (or used to have) and option to disable fast charging.
    Recent Sonys have an option to set a limit to how high it charges (so if you prefer to only charge to 80% or 90% you can set that), and also have features that claim to spot regular charging habits and adjust charging to match (e.g. plug in overnight and it will delay charging so that it only completes shortly before you normally get up).
     
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  12. codesplice

    codesplice Elite Recognized Moderator
    Moderator

    Now that you mention it, Pixel 4 and newer Pixels have an "adaptive charging" option which kind of does that. I wish it was more flexible and could enforce a charging rate on demand, but, ya know, Google.
     
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  13. Hadron

    Hadron Smoke me a kipper...
    VIP Member

    I'll confess that for my next phone I'm tempted to just dig out one of my old chargers for the bedroom with an A-to-C cable and just opt out of fast charging. I can see the utility if I need a quick top-up (but I can just plug it into my laptop if I want that), but as the default charging mode it doesn't fit my usage.
     
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