1. pjtwyman's Avatar
    I have purchased a Samsung S21 FE 5G (SM-G990E) and am having difficulties with getting it to fast charge. The S21 FE has Android 12, OneUi 4.1.

    I did some comparison tests with my other devices (Redmi Note 5, TabS8 5G)

    Using a Samsung 25W Super fast Charger and USB C/C (that I received when I bought the Tab S8) I got the following:

    S21 FE - from 50% to 96% - 38 minutes

    Tab S8 - 50% to 95% - 45 minutes

    Using a Samsung Adaptive Fast charger (9V,1.67A or 5V,2.0A) and a ordinary microUSB cable with my Redmi I got from 50% to 92% in 38 minutes.

    Using the same Adaptive charger and a USBA/C Comsol cable with the S21 FE (Fast Charge setting DISABLED) I got from 50% to 87% in 45 mins.

    These results suggest that the S21 FE fast charging is a dud. Fast charging seems to work fine with the Tab S8 which has a battery nearly twice the size of the S21 FE (8000mAh vs 4500). But with the S21 Fe/ Samsung Super Fast Charger against the Redmi (4000mAh) and the S21 FE (with the Adaptive charger/ non-Samsung USB A/C cable) it is pretty poor. I would have expected it to be much faster.
    I have not yet resorted to a factory reset.

    I would appreciate advice on this problem. The phone has not been mishandled or exposed or excessive heat.

    12-07-2022 07:08 AM
  2. VidJunky's Avatar
    Well Yes and No. You're charging from the slow down point to the end, which is the longest part of the charging process.

    Let's backup a little. Samsung says stuff like, get to 50% in 15-20 minutes, and they do for the most part. From some percentage, single digits or low double digits, their fast charging devices get to 50% very quickly. It's the last 50% where things slow down. I don't have a good analogy for this right off the top of my head but essentially it slows down to protect the battery as pushing all that wattage into the battery creates heat and resistance and can be harmful to the battery cells, so they reduce the charging speed to protect the battery. The device may still read that it is fast charging even at these higher percentages but what it is really saying is you're connected to a fast charging device and doesn't really indicate that the device is currently fast charging.

    There are a lot of videos on the S22 Ultra and charging because it released as being able to accept a 45 watt charger. While excepting a high wattage charger it still charges in the same amount of time as the 25 watt charger. What it does faster is get from some low percentage to 50% really fast and then slows down to preserve battery health. Just looking at the times you listed I would imagine this to be the same scenario your looking at because if your device gets to 50% in 15-20 minutes then 45 minutes to reach a full charge is accurate to the roughly 1 hour of charging time needed for a full charge.

    There are a lot of charging and discharging videos on YouTube for many of the popular devices, of which the S21 FE is one. You might want to do a little more research and compare what you find to what you have and see if things measure up vs. other similar devices. You could also post this in S21 forums, where other users can chime in on their charging times and experiences.
    J Dubbs likes this.
    12-07-2022 08:44 AM
  3. pjtwyman's Avatar
    Thanks for your comments.

    My main concern was that the S21 FE was slow compared with the Tab S8 considering the respective size of their batteries and that in both cases I used the same charger/cable combination.

    Your comment on the 45w charging was interesting. I have seen stuff on You Tube to this effect and it confirms my own experience with a Comsol 45w charger.

    VidJunky likes this.
    12-09-2022 07:39 PM
  4. mustang7757's Avatar
    [Moved this to the s21 forums]
    12-09-2022 10:03 PM

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