Hello,
I’d like to know if I can use my pc charger (that I always left at work) whith my Fairphone 4 in order to avoid to take mine each time I go to my office.
Here the specifications :
65W
Input 100-240VAC 50/60Hz 1.7A Max
Output 5.0V/9.0V/12.0/15.0V=3.0A, 20.0V=3.25A
Total 65.0W Max
Thanks.
Welcome to the forum!
I assume your charger has a USC-C connector. Given that and the specifications above there should be no harm in trying. Depending on compatibility issues there is a chance that it won’t charge but at least it should not break anything and the odds are good that it does what it is supposed to.
There is of course a USB-C connector.
Thank you for your response.
Hi and hello 
The voltage range and current are common for PD chargers and the Fairphone uses QC
[Power Dilivery or Quick Charge]
They are different protocols which communicate the charging rate required by the device, depending upon it’s state of charge, but most modern chargers handle both protocols.
I the Fairphone gets no response from the charger it will just use the lowest voltage and but as, according to your ‘specs’ still provides 3A it should charge fairly rapidly. (rapidly may not happen)
The only concern is that if there no control the phone may take a bit too much when it is already nearly fully charged, you can only tell by looking at the rate of charge which isn’t easy. (This refers to the fact that a fully charged battery left plugged in will be topped up keeping the battery at an increased stressful level)
Ensure you keep an eye on the phone as it reaches 90% 95% and see if it says it is charging slowly, that means it is communicating and there should be no concern that it overcharges.
Saying that, there are many recommendations, including by Fairphone that battery ‘life’ can be extended by not fully charging the battery. Some people use 80% as a max so they either root the phone to install a control app or, as I do, keep my eye on the phone.
On the note of battery ‘longevity’ it is also touted not to let the battery go too low, especially in cold climes. Although I have no routine I rarely let the battery drop below 10% nor charge it above 90%, with commonly an even smaller range.
All the best.
EDIT: Emphasised text added following criticism
That’s an impressive explication !
To resume, according to you, I can use the charger as long as I keep an eye on the telephone to avoid overcharging ?
There should be no overcharging, because the charging controller is in the phone and takes only as much as energy, as it wants.
What’s the exact type of the charger?
The technical details pretty much sound like this one that I got for my work notebook, too, and that has successfully charged my wife’s phone already (my FP2 has the wrong connector):
https://www.dell.com/en-uk/shop/dell-65-watt-usb-c-ac-adapter-uk/apd/450-alji/
I have some Dell USB-C chargers available at work as well, but never thought of testing this so far, will do so next chance I get.
There is no risk in using certified chargers. If the combination of charger and cable(!) works, it will be fine. And for laptop chargers that should work because the FP4’s quick charge protocol is compatible to the PD protocoll which is used for laptops.
Anyway fast charging leads to a higher battery temperature especially in summer which reduces their lifetime. And uncertified chargers or cables from unknown sources may induce a risk.
My daughter used her XPS 13 charger for the FP3 too
Thank you everybody.
Thats the nice thing about USB-C, it’s always plug and play.
I’m also often using a 65W lenovo Laptop charger.
Your FP will choose what’s needed.
Just note that not all phones and laptop support both PD and QC and if the charger and device don’t communicate they revert to the old fashion 5V 0.5A, which is slow.
In fact, many phones support PD 3.0 but not QC 3.0, or vice-versa.
PD 3.0 vs QC 3.0 - What's the Difference? - Nerd Techy
There’s very little chance of damage to the device but a clear possibilty it won’t get a fast charge.
Assuming with “overcharging” you mean a level of more than your preferred 90% or so, as you won’t ever reach 101% and charging will simply stop at 100% and not blow your device.
Yes, that was the main idea for superseding the µUSB standard.
But is it lack of communication or fear of damaging something,
these days still many look curious when seeing a mobile connected to a notebook psu.
But yes, there were and probably still are cable types and chargers out there not being certified causing severe damage.
We are talking about the FP4 here. This phone supports USB PD as well because that is part of the QC 4.0 specification, hence it should do fast charging with both phone (QC) and laptop (PD) chargers.
For the FP3 you are right, fast charging is not guaranteed with that phone.
Overcharging in this situation is where a charger isn’t communicting well with the device and keeps charging it.
Contrary to comon sense a battery can be overcharge and it will be possible to get 110% of the designed AmpHours.
Trickle charging can do this and the only thing stopping it is a reliable communication between the battery and the charger and reasonbly accurate monitoring of the battery by the phone and the batteries intrenal safety features.
None of the auto safety measures are fail safe so it is always wise to unplug the device from the charger when it had reached a user desired level 100% or 90%
100% doesn’t equate to a full battery just to the maximum the software has set. For ‘longevity’ of the battery it would make senes to have the 100% readout for the user to be only, maybe, 90% of the real maximum capacity of the battery.
It is the phone, not the charger, which prevents overcharging. The charger and phone negotiate a maximum current, after which the phone may draw that current, or less.
The phone will simply draw progressively less current if it’s close to 100%. The charger can’t “push” more current through the phone.
What could happen with a faulty charger is that it goes outside its voltage range if little current is drawn. But that would simply cause the charge controller in the phone to heat up or shut down, as that controller limits the voltage to the battery in any case.
I would hope that is the case, as designed, that the charger can respond to the phone as designed and the phone, with it’s design, and the battery with it’s safety measure all work in harmony. Probably fine 99.9% of the time when using a recommended charger, otherwise it can be comforting to keep an eye on the charge level and the heat of the phone.
I have no recommended chargers. I use 12V to 5V USB A, 12V to QC 18W QC USB A and 12V to PD 60W USB C. It’s taken a while to get comfortable with my charging methods, some 19 months.
But I did buy a couple of ‘official’ fairphone cables
Some correction is in order here.
USB power supplies actually don’t controll the charging of the battery at all.
All they do, is provide a negotiated voltage up to a given current. By default, that’s 5V at 900mA (=0.9A) for USB 3, or 5V at 500mA for USB 2.
USB PD (which stands for Power Delivery, not Power Direct) can be used to negotiate up to 20V at 5A. This only happens, when a USB PD negotiation is successful, so this cannot harm devices that don’t support USB PD. In that case, it falls back to 5V.
The voltage is supplied by the power supply, but how much current (ampere) is actually used is determined by the device. The ampere ratings of the power supply don’t determine how much current flows, but what’s the maximum amount of current, that can be drawn safely.
Overcharge protection, same as the charge process in general is completely managed by the phone and has nothing at all to do with the charger.
Otherwise, phones would blow up each time you connect them on a dumb charcher which just supplies 5V and leave them there over night.
To prove the point, I’ve got a non-USB power supply here, that supplys 5V with 11A at maximum. That’s about 12 times as much maximum current as USB 3 normally supplys. I cut up a USB cable and connected it only to the 5V output. So here we got a supply, that can supply crazy amounts of current at regular USB voltage, but with no USB PD negotiation.
When I connected it to my phone, it totally worked, and charged my phone. At 0.9A. The reason is, that, since there was no USB PD negotiation, the phone didn’t know the capabilities of the power supply and thus fell back to only using as much current as it knew would be safe: USB 3 standard 5V@0.9A.
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