Fly 6 Repair, Battery Replacement

With regular use, the internal lithium ion battery on the Cycliq Fly6 will eventually expire. Although not designed to be user serviceable, I have twice replaced it and having been asked how I did it, decided to document the repair the second time.

Disclaimer, li-ion batteries are slightly explodey, attempt this at own risk. If your Fly6 is still under warranty speak to Cycliq (who are brilliant). If you try this, your Fly6 definitely won’t be under warranty afterwards.

- Replacement 18650 li-ion battery (unprotected)
- Wire Glue
- Basic tools

Buying reliable li-ion batteries can be a challenge (eBay has many fakes), stick to known brands and recommended sellers. I used Panasonic 3400mAh cells, which have better capacity than the Fly6 originals and good life expectancy. I bought them through Amazon UK, delivered by them to avoid any problems receiving lithium batteries in the post (Royal Mail won’t carry them except as part of a product).

Several places sell the wire glue, but the cheapest I found was The Gift Oasis

This guide is for the Fly6 mk2. Most of the information is probably applicable to the original mk1, with a little improvising.


Access four screws beneath rubber seals to remove back cover.

The front panel has a short ribbon cable to power the LEDs, flip this up and remove the three screws holding main PCB in place.

Remove main PCB carefully, two pairs of cables are soldered directly to the board for the buzzer and crash sensor. Disconnect power cable and undo single screw on left side holding battery in place.

Remove battery and set aside main unit. As it will be like this for a full day, put it somewhere safe where the cables won’t be damaged.

Start removing outer wrap from battery.

Under the black tape, you will find the charge protection circuit mounted along the length of the battery (IC is facing the battery).

The metal bands are spot welded directly to the battery terminals. This has to be removed with care, retaining as much of the metal band as possible. Some of it will remain, the spot weld is stronger than the metal strip.

Secure the protection circuit onto a new 18650 li-ion battery. Double check it’s the right way around, getting this wrong would be bad. Really bad. You have home insurance?

Secret ingredient, wire glue, a few £ via eBay or Amazon. Don’t attempt to solder directly to a li-ion battery unless you know exactly what you’re doing, and have already prepared a cool story to explain the loss of your eyebrows.

Wire glue is much less conductive than solder, use a small amount on both ends and keep the metal surfaces as close as possible. I applied the glue using a toothpick, and then used the same to push the parts together.

Allow to dry for a full day, conductivity changes as it sets even though it appears to dry very quickly. After a full day, reconnect to main unit and attempt to charge. Doing this somewhere with fire protection would be a very good idea. Don’t leave it charging unattended, now is the time to take all those small print precautions about rechargeable products seriously, so that no one has to buy a new house.

In my testing, this stage has been temperamental, half of my attempts have failed and the connection has had to be remade. Wire glue isn’t great, but it’s a lot cheaper than a spot welding machine.

Once you have a battery that is working with the main unit, seal the ends with a few drops of superglue as wire glue is very brittle.

A little extra protection via foam pads (or improvise).

An outer wrap of electrical tape for extra protection. Single layer at most, the fit is quite tight.

Put it all back together. There’s a notch in the piece of plastic that holds the battery down which matches the position of the charge protection IC. However, I’ve found it easier to fit back together with the band positioned to one side.

And of course, dispose of the old battery safely.


I’ve now gone through this process for a third time and took a slightly different approach. I used an 18650 cells with tags spot welded on, as there are now a few reliable sellers doing this themselves.

Using a Samsung cell, I mounted the charge protection IC strip along one side and then folded the spot welded strips over it. These could have been soldered relatively safely, but I thought I’d stick to the wire glue as it’s also easy to remove when the whole process has to be repeated again for the next battery.

So the electrical connections are a simple sandwich. A layer of insulation tape, the charge protection IC, a dab of wire glue, then the battery tags and finally another layer of insulation tape wrapped over the top to hold it all in place. This gave a much more reliable electrical connection than attaching to the ends.

Leave to set overnight and then add an outer wrap of insulation tape before reassembling. This time I also removed the plastic piece that’s meant to hold the battery in place. It’s a lot easier to put back together with that little bit of extra space and it’s not really necessary.