Fitbit One battery replacement walk-through with photos

[PureEvil]

Hi everyone,

My beloved Fitbit One (bought it on July 2013) has stopped taking a charge well (I now need to recharge every two days), so I decided to replace the battery to give it some new life.

Note:  Though the Fitbit One tracker has been off the market for a couple of years (so your warranty has likely elapsed), this will definitely void your warranty.  Also, this is not endorsed by Fitbit; I'm just an avid user with some electrical know-how... So keep that in mind before you proceed.

I found the replacement battery on ebay.  You can find one by searching for "fitbit one replacement battery".  The one I got was listed for a Fitbit Charge HR as described as "3.7V 80mAh" for voltage and charge capacity respectively.  It seems to work just fine.

These are the tools used:

1. Clamp - Smaller clamp that I use for hobbies.
2. Bondic - This is a plastic that hardens with a particular light frequency.  It works well for both holding the wires together and insulating wires.
3. Gorilla glue - used to seal the Fitbit One back together after replacing the battery.
4. Utility knife - something with hard blade, used to open the Fitbit One.
5. Soldering iron - this one is a low heat version for hobbies.
6. Solder - Thin and low heat, used for hobbies.
7. Wire clippers - To cut out battery and strip wires.
8. Cotton swab - apply glue (and water) to seal the Fitbit One.
9. Replacement battery.
10. Fitbit One.

Open the Fitbit One - Use the utility knife to pry open the Fitbit One.  I wedged the sharp end of the blade between the plastic and metal and pried the two apart, much like you'd pry a clam or oyster open when you shuck one.

Remove the battery - Once opened, remove the battery.  You can lift the battery; there may be some adhesive to hold it in place, you can still safely lift it and separate it carefully.  Use the wire clippers to cut the wires as close to the battery as possible; this will give you the most remaining wire with which to work.  You'll have significantly more red wire than black wire.

Examine the wires - The convention for wires is red for power and black for ground and with Fitbit this is also the case.  As mentioned before, you'll end up with a longer red wire and a shorter black wire.  Using the wire clippers carefully strip the plastic insulation off each wire so that you may solder them to the replacement battery.  Alternatively, you may solder the black wire directly to the terminal.  I did the former. 

Solder the wires - Solder the wires, one at a time to minimize the possibility of short-circuiting (and thus damaging) the battery.  Cover the soldered connection completely with Bondic; you may apply multiple layers.  This will serve to both hold the wires together and to electrically insulate them (much like you would with electrical tape).  Be sure to use the included light to harden the Bondic material after each application as per their directions.

Install battery - Once you have soldered and insulated the two sets of wires together you may tuck the battery and the wires into the Fitbit One.  This is a good time to make sure the battery works by pressing and holding the button to turn it on.  Keep in mind that the battery may be discharged; if so, you may need to plug in the Fitbit to charge before it turns on.  Here's a picture with the old, removed battery.

Apply glue reseal the Fitbit - Use the cotton swab to apply Gorilla Glue to the inside of the Fitbit unit just below the lip around the entire perimeter.  Gorilla glue requires water to bond, so use the other end of the cotton swab to apply a little bit of water to the metal cover.

Clamp the unit and allow to set - Once glue is applied to the unit, hold the Fitbit firmly together with the use of a clamp.  I also took an opportunity to wipe off any excess glue with a paper towel dampened with some alcohol.  It takes 24 hours for gorilla glue to fully set, so leave it clamped during that time.

The whole process, from beginning to end, took around an hour, but I was taking pictures.

With the new battery the charge lasts for 4-5 days.  This is great improvement over the 2 days before the battery replacement.

I ordered the replacement battery months ago and allowed it to sit before I did the replacement.  I imagine that had I installed it sooner (or perhaps ordered from a different vendor), it would last even longer.

I hope this helps and let me know if you have any questions.

[Williger]

@theguru1974 I wouldn't recommend Gorilla Glue, though do respect others who successfully repaired theirs using it. I use B-7000, it seems to be the same (or very similar) material to what's already on the Ones and can be easily removed the same way you opened the One originally if needed. 

@ekrub fantastic work! and thanks for sharing your experience with the group I love learning when people are able to bring back this wonderful tracker into full functionality! Smooth move on the tinned, it really makes a difference. I like your idea of using the soldering gun to remove the wire insulation, does it expose them cleanly? I carefully strip mine, though if this does it cleanly, it sounds a lot easier than stripping, though do admire your micro stripper and going to get one. I'm using B-7000 glue for mine, it's a flexible glue that holds well and is relatively easy to remove if necessary. Your battery is similar to mine, with different labeling but the same mAh. I'd experimented with @PureEvil's recommendation of using a Charge battery at 80mAh and it lasted for half of the 60mAh's, so perhaps there's another technology at play or something impacting it holding a charge. I'm glad Frank's post is staying up on here, I'd created a detailed thread as did another member proceeding his, and they were both removed by Fitbit. Keep smiling and keep stepping! 

Moderator edit: merged reply

[JEH1]

I love that this is up there! And thanks for posting the link to that battery

mMy dead Fitbit One is here- waiting. I am afraid I am going to have to wait  until I have a day to devote to the project- I am

a lowly biology teacher and have no idea what tinned even means so I am going to order the solder gun, glue, and battery you recommended and give it a try when I finally reach my vacation time in June. Thank you!

Hello @Williger ,

I thing I downloaded your detailed instructions. I can’t believe they got pulled down!

The  One is definitely worth rescuing.

Moderator edit: merged reply

[ekrub]

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@Williger wrote:

I like your idea of using the soldering gun to remove the wire insulation, does it expose them cleanly?

While I would usually use a wire stripper (preferably an automatic wire stripper), the wires are so tiny and so short (especially the black one) I was worried about damaging the wires or pulling off too much insulations while stripping. After googling several approaches to wire stripping, I stumbled on the idea of using the soldering iron to melt off the insulation. Since the amount of insulation to remove is tiny, the soldering iron approach worked extremely well for this job. I put the wire down on a safe surface, pinched the insulation to the surface with the hot soldering iron, pulled the wire out, and then removed melted insulation from the wire and soldering iron with a towel. I was actually surprised how well it worked and how easy it was to do. 🙂

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@Williger wrote:

I'm using B-7000 glue for mine, it's a flexible glue that holds well and is relatively easy to remove if necessary.

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Yeah. I wish I had heard this earlier. Even before doing the battery replacement, I was worried the Gorilla Glue might not melt if/when I need to replace the battery again in the future. After googling for alternative glues and the melting temperature of Gorilla Glue, I ended up just going with the Gorilla Glue, using a toothpick to apply as little as possible. If I were to do it again, I would use the B-7000 glue as you suggest.

[JEH1]

Hello @Williger Thanks!

I had not heard of B7000.

[PureEvil]

I had not heard of B7000.  I'll use it next time.

[Williger]

@PureEvil B-7000 was what I'd suggested in my original (ambiguously disappeared) walkthrough, it's really wonderful for Fitbits, and the Engrish on the packaging endlessly amusing! I'd even waterproofed an old Charge-HR with this incredible adhesive. You'll see when you start using it, that it's close to if not the same as the original. 👍

@JEH1 excellent 

 If you do have a copy, please DM it to me, I'll post it up on Williger dot com or somewhere, as regretting not backing it up when I'd posted, though never anticipated unexplained censorship. Just be patient and careful and you'll be fine and ask questions along the way as there are plenty of people here who've successfully upgraded! B7000 is really wonderful for Fitbits. You can use it to help a Surge band that's falling off, to fix the battery connector that often breaks on the Charge and ChargeHR, and most particularly the One as a small bead of this stuff will make a great seal and can be removed by rubbing or with 99% isopropyl if you end up using more than intended. The 99% isopropyl I should've mentioned here too, it's very useful on the circuit board itself as it evaporates quickly. The only other tools jumping out at me to suggest at the moment are a guitar pick for prying, helping hands, and a head magnifier like the kind watchmakers use. If you need links for any of these, let me know.

PS. the world needs good biology teachers, nothing lowly about educating! 

Moderator edit: merged reply

[TNLarry]

I have repaired batteries in 3 Fitbit Ones so far using your technique.  I have also encountered 2 duds where a battery replacement won't bring the Fitbit back to life.  For both duds they would not light up in the charger before the battery was replaced.  That may be an indication that something other than the battery is wrong.

[JEH1]

Thanks for posting this. Those were someone else's famous instructions - and I need the. Can you put the reference here or report them?
Did you but a special craft welder gun?Where did you get your battery?
I was trying to order last year- never received the battery so now I am re-tackling the project.

Thanks- I have NOT abandoned my attempt to revive my One!

[Williger]

@JEH1 this is his technique, I've never heard of anyone doing it as he does. Are you referring to my One resurrection walkthrough? I'd written the first how-do battery install for the One here five years ago and some Fitbit moderator removed it without notification. Then, three years ago someone else created a similar walkthrough, and again, Fitbit moderators removed it (IDK if they gave that member the courtesy of notice, I know they didn't when they disappeared mine). I'm not writing another one, at least here as it was **ahem** rude to delete my words, so I'll put them on my blog or you can ask questions. Or, use this dude's method. I like how he's organized his steps but it's definitely not a method I'd recommend. My technique is easier and gives a better result. I've tried Frank's method twice since he posted this and both are still sitting in a pile of "why the heck did I try this", LOL 

[ZNuts]

Thanks for the walkthrough.  I finally got the courage to give this a try this past weekend.  The tiny wires were quite a challenge for my old eyes but I got it done.  I put it in the charger before putting the glue in to see if it works and ..... well, it powers on in the charger but no dice once I get it out even after charging overnight which was the same symptom before the battery replacement.  Yes, I tried the 15 sec reset a few times.

I wonder if I got a old battery from ebay, maybe I should test the battery with a multimeter before doing all the soldering work.  Any suggestions?

ETA: I removed the new battery and measured its voltage.. nada... so I got a bad one from ebay.  I ordered another one from another vendor.

[pjmurray114]

I am a geek, that's why I love my fitbit one, but this wasn't that hard. I had difficulty sodering it but that was more an eye site issue. 

[ekrub]

For the record, literally two years after replacing the battery with the one I purchased off Amazon, I am still getting 13 days between charges!