Help! Battery charging slowly

I have the same issue since last Android update. When I charge the FP3 at night the alarm does not work; in the morning I wake up late and the flippin’ screen says ‘Charging xx%’
I have reported it to the Fairphone helpdesk.

I do not want to perform reset to factory default yet but I’m afraid that will be the fastest solution. Unfortunately Android will start bugging me for Updates Available. If only FP would have stuck to strictly pushing security updates only and not this useless update that rendered my FP3 practically useless.

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did that but Helpdesk is taking way too long to fix this


I have just sent a request to support for clarification on battery changing for the FP3+ as follows:
"Since purchase and continuing after latest update 0066 I have dubious charging issues. I would like to point out that, although some decades ago, I used to maintain sea to air missiles in the Royal navy so have some electronic training :slight_smile:

The issue can be broken down as follows.

1. As no battery charger is supplied people have to make their own choices, however I note from the forum that there are the same issues with some who have bought your FP charger and cable.
I have the same problem since a short time. I’m using the original charger and cable. The device and the equipment is approximately 8 months old. I think the problem started with the last Update to 0066. Before that, I had no Chargingproblems."

2. I have kept records lately to try and understand the charging routine.

a) Whatever the battery state 6% or 46% the battery states ‘charging slowly’ Often if I unplug and replug in the cable the notification that the battery is ‘charging slowly’ goes away.
b) Irrespective of notification ‘slowly’ or otherwise the battery charges 1% in just under three minutes, so will take 3 to 5 hours dependent upon initial state. These figures are in Airplane mode with wifi, NFC and Bluetooth off
c) There is never a drop in charge rate at 90% or 96%.

So the questions are
1 Can you tell me the rate of charge expected ‘slowly charging’ and otherwise.
2. Can you tell me how the hardware/software decides at what rate to charge.

I reside off grid use solar panels with a base 12v system. I have an inverter that can supply 230v at 5A so I can use mains chargers.

Generally I use a Belkin 4 USB port 12V to 5.1V (two @ 1.2A and two at 2.4A)

The battery is 3000mAh (not 3040 as advertised)

Over 5 hours this equates, without losses, to some 600mA per hour, well below what I can provide.

Using a mains adapter that provides 5.1 @ 3A is no different.

So although I have no problem waiting 4 to 5 hours I wonder if this is what you expect.

From the following link you will see others with the same and/or similar concerns, there \are other topics too.

Help! Battery charging slowly

Well I hope you can enlighten me/us on what we should expect, and please provide me with details on the hardware and software set up.

Thank you and best wishes."

EDIT 1 The initial reply by email says “We aim to reply within 5 working days”


Brilliant job thank you for taking the time and writing such a detailed message. Highly appreciated. I will point them to the forum and your post specifically as well in addition to my own problems (that are largely the same).


Update on my long post: Help! Battery charging slowly

Today I accidentally allowed the battery to discharge to 2% and the following occurred.

  1. After a second it wen t from ‘charging slowly’ to charging

  2. The rate of charge doubled. Whereas usually it takes just under 3 minutes to charge 1% this time it took exactly 90 seconds,


UPDATE on post 29

I received an email from support with general queries, i.e. no useful words.
There was no response to my query about how the charging states are defined or implemented.

Support wanted to know the Build, Charging mechanism and battery test results both static and when plugged in.

Still I have a human response after 8 days which given the demands of the users and the COVID etc stress is not bad at all. :slight_smile:


Any further updates? Do they recognise this as a software problem that affects many users?

No real answer! The last email said that 4 to 5 hours to charge wasn’t normal and asked me to try a new cable ~ my reply was ~ I bought two new from Fairphone and it’s the same with those cables.

They did not respond at all to my query on how the charging system works. I.e. when is it supposed to change from one to the other and why etc. :frowning:

I noted that when I accidentally let my battery drop to 2% before charging it charged in 2.5Hrs, so I’m going to try letting drop to 2% or thereabouts again to see if I can replicate the 'fast’er charge :slight_smile:


Thank you for update, sb from Fairphone just reacted to a comment I left on their fb page so I directed them to this thread.

The 2% phenomenon you describe sounds encouraging but of course not desirable to have to let your phone drop to such a low battery % to get any consistent, reliable charging level

I might open another case if we don’t hear back in a few more days time

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hi, I have the same problem ones in a while :unamused: my f3 then charges “very slow”. that means it takes a night to charge 20 %. I cannot really use the phone on a daily basis.
this happened to me 3 times for a period of e few days since I got the f3 in november 2019.
Support didnt help much. they were just asking about my charger which works pretty good the rest of the time (charges fast from 20% to 100% in 2 hours).

maybe I have to do reset to factory settings :rage:

does someone have other ideas? please let me know

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The once in a while is a problem as it can’t be emulated, though I have noted that some people just plug from the phone then reinsert it which sometimes does a reset.

‘very slowly’ is well out of order, I only had that once or twice and not recently. It seems maybe the system thinks the battery 90% or more charged. Another issue is extreme cold will stop normal charging.


Li ion can be fast charged from 5°C to 45°C (41 to 113°F). Below 5°C, the charge current should be reduced, and no charging is permitted at freezing temperatures because of the reduced diffusion rates on the anode. During charge, the internal cell resistance causes a slight temperature rise that compensates for some of the cold. The internal resistance of all batteries rises when cold, prolonging charge times noticeably.

Many battery users are unaware that consumer-grade lithium-ion batteries cannot be charged below 0°C (32°F). Although the pack appears to be charging normally, plating of metallic lithium can occur on the anode during a sub-freezing charge. This is permanent and cannot be removed with cycling. Batteries with lithium plating are more vulnerable to failure if exposed to vibration or other stressful conditions. Advanced chargers (Cadex) prevent charging Li-ion below freezing.

Advancements are being made to charge Li-ion below freezing temperatures. Charging is indeed possible with most lithium-ion cells but only at very low currents. According to research papers, the allowable charge rate at –30°C (–22°F) is 0.02C. At this low current, the charge time would stretch to over 50 hours, a time that is deemed impractical. There are, however, specialty Li-ions that can charge down to –10°C (14°F) at a reduced rate.

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Hi, I use to charge my FP3 with a Aukey QC 3.0 supported wall charger, 1h or a little more and my FP3 is ready-to-use. I suggest you to check if your wall charger supports QC 3.0, maybe that’s the reason why it shows “charging slowly” and it tooks 3h or more … :slight_smile:


Hi and thanks. I will have to look into the QC 3.0 issue as I’m running from a 12v system that produces plenty of 5.1v

It may be the case that whereas the QC system not only controls the over charging but without it the phone is at a loss…

The strange this is when I first got the phone it did a 3hr charge and then slow when nearly charged with old cables. Once I bought the FP cables it was similar but now slowing down at 90% etc.

I had read somewhere that proper USBC cables that control the charge have a chip in the cable plug housing.

So thanks for the prod as I can see there are a few things I can look into. Luckily the relatively slow charge is not the most serious issue I have with the phone it was, I hoped, the easiest to resolve :slight_smile:

The question seems to be how the phone demands the current flow and FP have not replied to my question on how the dynamic power unit in the phone works so I can’t make any adjustements to the power supply and I am reluctant to buy an AC power unit and have to convert 12v to 23v back to 5v etc ~ as that requires more gear and more power. So I will stick with what I have until I can learn more.

Thank you again for your input, it’s very thought provoking for me

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Further to the above post, so as not to extend it.

Here is a link to Lion battery charging.
How to Charge a Li-Ion Battery Correctly and Safely.

Basically the voltage at the battery is not the issue it is the power unit that regulates the input from the charger be that reduced from 12v DC or 230V ac. The voltage at the battery is likely to be no more than 4.5V (4.4V is standard max )

With some AC chargers (QC 3) they are able to supply up to 20V to the phones power unit, which in turn can convert this to 4.2V with as much as 4A current ~ the maximum out put being 18W.

So you can see why, if you have a QC3 mains charger you would need a good cable to carry 4A at the lower voltage, hence the idea of carrying less current at a higher voltage and then the phones power unit can convert to to the 4A input.

A 3000mAH battery should not be charged at more than 3A that’s 100% in 1 hour, for longevity of the battery it should be a) a little slower and b) only charged to 90% maybe 96% if you want to push it. So charging the FP battery in 1.5 hours would be a quick charge, anything less implies one of the following, a) power source cannot produce 15W, b) the cable or it’s connectors cannot cope with the current if the power supply is low voltage and high current, or c) the phones power unit is playing up due to either hardware or software issues.

So to go over the charging issue again:

Further to get the 3A from a standard 5.1V USB requires a cable that can handle 3A producing a max charge of 15W and would in ideal case take 2 hours to charge, with a poor quality cable this will not work out well.

With 20V from a QC3 unit it only requires the cable to transfer 0.75A to get 15W and in theory would charge a 3000mAh battery in 1 hour.

So as long as the phone power unit is working well the slow charging is down to the cables capacity and the power supplied to it which should be in the range of 20V to 3.6V with power of 18W.

Well I think that is clear enough. I’m writing this on the hoof with no real layout of ideas o I hope this provides some use.

I will edit this over the coming hours/days to make it more succinct

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Then, you should know that batteries aren’t build to be charge at 100% every time so they took more to go from 90 to 100 instead of going from 50 to 90. Many suggests keeping it from 20% to 80%, honestly I charge my FP3 from 15 to 20/30 and unplug it from 90 to 95. This is the way to keep your battery nice and happy through the years. I can say to you that I feel this usage improvement in screen time. Al last, cable isn’ t the keypoint during a charging phase, but you must have a right and proper wall charger, plus and very suggested that supports QC3.0. Aukey is a wellknown brand and it costs only 11€. I looked to FP official wall charger but it costs 29€ + 15€ of delivery, and it is not a fair component XD.


I bought my USB charger and cable with the Fairphone and the charging worked correctly, switching to fast charging after a minute or two. Although due to lockdown the charger has not moved from the living room and hardly been used it stopped charging fast just before Christmas. Cannot be damaged!!! Don’t know what to do…

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Please, try to toggle plane mode few times, and charge in plane mode, just to see if it have an effect.

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Saw the post about airplane mode - was it you? Thanks but I’ve just been toggling and no change. It’s also awkward I can’t see the charging speed unless the phone screen goes to sleep - do you know how to check it when using the phone :slight_smile:

Did you tried to then charge in plane mode only ? Sorry, I have no other advice, It was just maybe chance in my case.
You can read my own experience here: [solved] Stuck in "very slow" charging mode


I find if I unplug the phone, cable and charger and move to a different plug then it sometimes works. This morning I have done this five times to plugs that worked in the past and on the fifth time it worked. Frustrating! But thanks for your reply.