Protected vs un, change in size?

I am going to try to fit two 18650's inside a stinger xt to run a wa1274 bulb. I figured using 18650's was a good idea based on capacity, however, I am not sure they will fit.

I would like AW's protected cells for obvious reasons, however, are they longer than the standard unprotected ones?

Also, will either of these choices fit and if they don't, what would an alternate battery choice be?

is it this stinger?
"The three cell, 3.6 Volt, sub-C nickel-cadmium battery"

D-Dog, I'm not sure of the sizing for your light, since I don't have it...but there is a slight increase in length because the PTC board is on the bottom of the cell. See the pictures I took of a disassembled protected Li-Ion.

The Protection circuit board on AW's p18650 cells takes up 2 mm, making them 67 mm long . They are a shade over 18 mm diameter because of the metal strip (makes them 18.2 mm max).

Thanks for the replies

With that being said, I think I will have to go with the unprotected, as even 4 mm will make a difference where I am already very pressed for space. The 2200's lighthound sells have a button top, right?

D-Dog said:

I think I will have to go with the unprotected, as even 4 mm will make a difference where I am already very pressed for space. The 2200's lighthound sells have a button top, right?

Click to expand...

I just tried to look, but their site is acting up for me at the moment. If they aren't button-top, a small neodymium magnet is a possible solution, although you need to be careful it cannot short against the side of the tube.

The 1274 pulls ~2.9A, which is ~1.3C for a 2200mAh cell, so you should get a good enough indication when your unprotected cells are running low. As soon as the light starts to dim – IMMEDIATELY – switch the light off, as the cells will now need recharging.

Take a note of resting voltage before you recharge, to get an idea of where they got to. Take the voltage reading 15-30 mins after switching off. If you get a resting voltage of >3.0V, you are safe, but >3.5V is much better. If in doubt, you can recharge the cells at any time, as this is better for them.

You will need a good charger that terminates properly at 4.2V. Some chargers do not terminate properly, or continue to trickle-charge after the light has gone green. With unprotected cells you have no protection circuit to rely on for preventing over-charging, so please be careful.

Alright, would you trust the ultrafire wf-139 (I think...it's the "fast charger")

The WF-139 is not recommended for unprotected cells. If you decide to use it for them, you should do the following:

1. Determine whether or not you have a good one, with a the light going green at no more than 4.2 volts. This means taking a slight risk with the first charge. Pull the cells IMMEDIATELY the light goes green, leave them to stand for ~15 minutes, then test their voltage. If it is 4.20V, the charger is a good one.

2. If the voltage is too high, do not use it for these cells.

3. If it is OK, you need to understand that this charger can continue to trickle-charge after the light goes green, even if the light does go green at 4.2V. That means an unprotected cell, if left on the charger, can continue to take more and more charge until eventually it blows up like a toxic firework. You MUST supervise EVERY charge, and NEVER leave the charger unattended.

4. This can be a PITA, and I am sorry for all the 'shouting' caps in the previous para, but it is important – we don't want to read about your house burning down. You just have to be super-aware and responsible with unprotected cells.

5. You may however decide to get a better charger, such as the Pila IBC - it is twice as expensive, but a much better unit.

Hello D-Dog.

AW:s 18650 is 67,40mmX18,35mm


Anders

First off, thanks for confirming the size as even 67 mm will be too long. I am talking about a leeway of about 1 mm with UNprotected cells...

As for the charger, I will just have to be careful. I have two nano chargers for my Jil Intelli and I haven't had problems with either so far, although I always charge attended and pull them out when they are done... although there was one time when I forgot about the cell overnight and luckily I woke up the next morning with the house intact. I tested the voltage and it was right around 4.21 which I deemed was fine. I know that you can't compare the 18650's with a little 300mah cell, however, I must be sure to be much more careful. Thanks for the heads up though, better safe than sorry

I would not recommend using unprotected cells just so you can get a fit to light. There are a number of issues that have been posted in many threads, in addition to what has been posted here.

I agree that the Ultrafire is not the charger to use for an unprotected cell.

I agree and if I had a job, source of income, or even was out of school, I would probably better choose a host, however I am not in this position... so I kinda have to work with what I have and little more. I know unprotected batteries are not safe and that they are unpredictable, especially draining them over 1C. However, don't even unprotected cells need thermal protection to be sold? If not, well... I'll just have to be safe (stand over them and pull them out right away, maybe even before the light turns green if I can get the timming down based on the voltage). Over $50 for a good charger is kinda out of the question right now , even if it is a lot safer...