FP1 Battery DIY Replacement (using Samsung battery) - Unsafe instructions

:warning: This post contains instructions that can cause severe harm to you. :warning:
Opening and modifying batteries is very dangerous.

The battery is the most dangerous part of any phone. It has in numerous cases been linked to explosions, wounds and property damage. Just search on the internet and you’ll find them.

Fairphone employees have seen with their own eyes the issues involved in the process of manufacturing batteries. The health and safety of the workers involved is very often in jeopardy.

The combination of a complex technical product, very severe consequences if done badly and the very limited amount of suppliers who produce in a responsible way, led Fairphone to the conclusion it was not able to produce batteries.

In the absence of complete documentation and information, and the possibility to visit the factory where these batteries are made, we are unable to approve or support third party batteries.

Fairphone values learning by opening your devices but we want you all to stay safe.

End of obligatory piece of text that is part of all topics in which people talk about putting unofficial batteries in their Fairphones.

Hi there,

after about three years the battery of my Fairphone FP1 stopped working. It was swollen and had lost a large part of its original capacity, lasting only a couple of hours after charging. Clearly, it was only a matter of time until it would fail completely. Unfortunately, the replacement batteries are out of stock at the moment. So I decided to try using a off-the-shelf Samsung battery I had lying around.

See this page for details and pictures: http://truthbox.ch/batteryfix.html

Best, BadElvis


Could you tell us the model Nr. of your Samsung battery?


Where did you get a FP1 three years ago??? :wink:

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Nice work, BadElvis!

They should all be 3.7V nominal and have enough mAh left (longer battery life), I assume. The risky part is the disassembling of the FP1 battery to make the battery connector fit! Most Samsung batteries I tested do not fit into the tight “corner” of the FP1. His battery reads “Samsung EB494358VU” on the pictures so it’s a Lithium Ion Battery for the Samsung Galaxy Ace.

A nice solution would be to use a “battery frame” (empty frame that fits tightly to the connector) and to just place the battery inside it. I’ve seen pictures of such a frame here on the blog pages.

Note: The news batteries are back in I just read somewhere :smile:

I hope you know what you are doing. I don’t have a clue about batteries but this looks frightingly dangerous to my untrained eye. Other than that: Nice job!

I agree, do not open up a battery without knowing the risks involved. There are plenty. They can explode, burn, or create toxic fumes if the cells inside are punctured. Check related safety datasheets.

You can see a “battery replacing adapter frame” in action here, I assume. This solution is safer. And it does not matter if you attach another smaller battery or a stable power supply as long as you are around 3.7V. (Most batteries start with a higher voltage … but that’s not that important).


As long as you do not short the battery terminals it should be ok. And you also mentioned correctly that the nominal battery voltages must be the same.

Making a battery adapter would be the perfect task for a 3D-printing-enthusiast, but I needed a quick an dirty fix.

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Yes, now that you mentioned it, I realize my mistake…

One would still need the battery controller from the original battery, wouldn’t one? I guess, that’s the most dangerous part of the whole thing, namely extracting that controller.

I don’t think so. It’s mostly a small circuit/IC to keep the battery “safe” while charging/discharging and to control the temperature. It’s more or less the same in every battery. I forgot the name of the chip but I’m sure one will find it online. But if someone knows more, please correct me!

Update: Link, but this is the “better” stuff. There are others.


Hi Stefan

it would indeed be difficult to reuse the existing controller. Instead, I unmounted all the components using a soldering iron. Then I used the bare controller board to connect to the circuits of the phone.

The circuitry in the Samsung battery is not the same though: monitoring the battery temperature does not work. Its always shows about 40 degrees, which is wrong.

I think I don’t understand. So the controller board you connected to the Samsung battery is not the one from the FP1 battery (you did not extract it from the original FP1 battery)?

He uses the FP battery connector part just as a hardware connector.

There is no IC involved anymore. But the “over/undercharging” control IC inside the Samsung that seems to have no temperature control (Normally that’s why the batteries normally have a third pin, if I recall correctly).

I added two more images to the page linked in my initial post. They show that I only used the FP1 battery controller board itself (with all components unmounted). The board is necessary to connect to the spring contacts in the back of the phone.

Thank you for clarifiing! The pictures make it clearer to me now. I wonder, however, how the FP1 battery looks like below the controller board you took out. Could you add another picture? I’d like to know, what to expect below.

Sorry, I recycled the original battery. There was some brown cardboard material under the controller board, if I remember correctly.

Normally there should be a thin layer as big as the control board below it that contains the chip that keeps the battery safe (over/under charging). If someone is interested I can search around for a picture. Do you remember seeing something like that?

1 Like

Hello BadElvis,

Nice idea. I had the same Idea as I had got my FP2 with a second accumulator. I compared the average replacement battery pack price and tripped over a Samsung replacement battery pack (seems to be a widely used one by Samsung, although many replica are sold even on Amazon). It looked nearly the same as the one from my FP2 beside the contacts for + and - were swopped (maybe all four). So I do believe it´s not hard to match up these contacts and use the pack for replacement. But up to now I´m out for original FP parts to support FP.

Anyway good luck with your approach.



Ars Technica has a great feature on the internals of the late Galaxy Note 7 batteries, with many pictures (including comparison of correct batteries and broken Note 7 batteries).