I have been using the ultrafire charger and their 18650 batteries with no problems. I recently purchased two ultrafire RCR123 batteries for use in a different light from battery junction. The batteries do not fit the slots on the charger correctly even though it is advertised to work. I found on the internet that I need some type of a spacer. I called battery junction and they do not have the spacer. Can anyone help me find the spacers or give me a tip on how to make them work in the charger?? Thank you in advance.
I went to the local hardware store and bought two M8 - 1.25 metric coupling nuts and two M8x25 metric socket caps (I used stainless, but also tried anodized first and it works fine / is cheaper) and made a couple "rapid adapters" for about $4.
Here you can see the AW RCR123 battery in the UltraFire WF-139 charger, it's too short to engage the spring loaded contact. Below it is the adapter extended in the storage config, notice the chargers spring loaded contact is engaged just a little, this keeps the adapter in the charger when it's not in use. The chargers negative and positive contacts each have a button tip that fits inside the socket cap and the coupler nut keeping them it in the charger. Below that is an AW RCR123 and the other adapter collapsed. Notice the socket cap sticks through the coupler nut just a bit so it contacts the bottom of the RCR123 battery better. The coupler nut alone seems to contact the plastic coating on the battery and not make a solid connection. This socket cap bolt serves two purposes 1) to extend the adapter for storage and 2) to make positive contact on the negative side of the battery.
Batteries in charging config, adapters collapsed:
Adapters extended in storage config, there is enough retension as described above to keep the adapters inside the charger even when the whole thing is shaken vigorously. I have been able to leave the adapters, extended, in the charger even with it plugged in and the charger doesn't seem to care (althought I can't say this is recommended).
Adapters in various states, note the button top end made via the socket cap protruding through the coupler nut
I'm not sure what the retail adapters cost (I think they're just bearings?), but these stay secured to the charger when not in use so I don't lose them which I like much better.