I had a replacement tailcap shipped to me for my S30R. It worked well initially, but started to develop charging problems recently. I did not even get the light wet so I was rather disappointed. However I was able to fix the problem. I will try my best to describe what I did here, but please if you do this
you do this at your own risk and I accept no responsibility for a damaged light.
How does the tailcap contact function?
The tailcap contains a spring loaded contact. When the light is not on the dock, the spring pushes the contact closed to allow current to flow between the centre terminal (battery negative) and the outside wall of the tailcap, completing the circuit. When the light is placed on the dock, the contact is broken and the charger dock is inserted in series in the circuit with the battery and the light. Some magic in the lights driver allows charging to commence.
Why are there so many problems with the tailcap?
The spring loaded contact is comprised of a small spring (that is connected to battery negative) with a small metal button on the end. This metal button is pressed against the bottom of the tailcap when the light is not docked by the spring. The design has a few problems:
- Water ingress is not very well prevented. Water can easily get past the metal button and will sit inside the bottom of the tailcap until you completely disassemble it. However, assuming your tailcap is in good condition (no loose parts) there is a rubber seal between the moving contact parts and the rest of the tailcap which should prevent water getting further into the light.
- The tailcap button is made of a different metal (probably brass but I am not sure) to the tailcap (aluminium). It may be possible for galvanic corrosion to occur.
- Dust/lint can work its way in between the metal button and the tailcap base causing resistance to increase.
- On my tailcap, the metal was insufficiently clean from the factory causing a higher resistance.
Is there anything I can do to make my light work better?
YES! You need a few things:
- Quality lubricant that will not impair electrical contact or cause corrosion, and is safe on metals, plastic and rubber. I used nyogel.
- 2 screwdrivers or a pair of tweezers to unscrew the retaining ring
- Rags / kitchen paper for cleaning
- Isopropyl alcohol
- Something sharp to scrape away corrosion if required (a small flat blade screwdriver will work just fine)
Step by step this is what I did:
- Start by cleaning your tailcap as best as you possibly can without disassembling it, to avoid getting more dirt into the contacts.
- From now, work over a clean area where you can catch/find small parts as the metal button may get lost / fly out!
- Unscrew the retaining ring (anticlockwise)
- Mind that the small metal button is loose and will fall out - carefully pull out the PCB (which has the battery spring attached to it) - directly upwards. It may feel a bit odd/stuck because there is a magnet in the tailcap and it will attract parts of the PCB towards it as you try to remove it.
- Look for the metal button which may have dropped onto your safe workspace and retrieve it
- You should have the tailcap, a retaining ring, the PCB (with a spring on either side), and a small metal button.
- Clean everything with isopropyl alcohol and dry thoroughly. Pay extra attention to the metal button (including the inner side where the spring touches it) and the area the button pushes into on the bottom of the tailcap.
- Inspect the metal button carefully for any discolouring of the metal. If any is found, clean it up.
- Take your lubricant (again I highly recommend nyogel) and apply to the following areas: the back of the metal button (spring contact), the inner lip of the bottom of the tailcap (other side of the button contact), and around the rubber seal on the PCB (for water resistance). This helps inhibit corrosion and will protect the contacts. It can attract dirt too, so this is a matter of opinion.
- The tricky part: you need to get the PCB back in with the button contact in place. I did this by balancing the button contact on the small spring, then lowering the tailcap on from above. It will try to pull to the side due to the magnet but take your time and it will go back together nicely.
- Screw down the retaining ring just enough to barely apply pressure to the PCB.
- Now, check the metal contact button. Push it in a few times and wipe out any excess nyogel you can see. A toothpick helps!
- Finally tighten down the retaining ring the rest of the way.
- Relube your light and put it back together
I did this procedure a couple of weeks ago, and my light is still working perfectly. If people need pictures, let me know
I don't think this light should ever be immersed in water despite the claim on the packaging. Light rain should be OK if you apply something like nyogel (to help prevent water working its way inside past the metal button).