Need help with Surefire 9P and rechargeables

So heres an odd situation I cant quite figure out. I have a Surefire 9P with both the factory bulb as well as an LED bulb that I use. With either bulb the unit works flawlessly when using 3 CR123 batteries. About 2 years ago I purchased 4 17500's to use as I wasnt too keen on the replacement costs of the CR123's.

Now 2 years ago this combination worked flawlessly as well. If I were to hand the light to someone without telling them they would probably not even know I had swapped the bulb and that I was using rechargeable batteries.

I havent used the light in roughly a year, fast forward to now and it doesnt work. Either bulb will work when using CR123's, neither bulb will work when using the 17500's. I have charged them and all read 4+ volts on a meter. Even more strange, if I tap the bulb end of the light the light will flash for a moment. That would lead me to think it was a short somewhere but the light works fine with CR123's.

So where should I start in getting a 9P to work with 17500's?

I have the same doubt. What would the best LED option for a 9P and 2x17500?

Specop_007 said:

.... I have charged them and all read 4+ volts on a meter. Even more strange, if I tap the bulb end of the light the light will flash for a moment. That would lead me to think it was a short somewhere but the light works fine with CR123's.

Click to expand...

Theres nothing wrong with the light, if it works fine with known good primaries.

Are you certain your charger is working OK?
17500 cells should not drop below 4.10 Volts right off the charger. If you are charging them up to ~4.2V, they should hold steady over 4.10V for several weeks.

The way you describe it, makes me think the 17500 cells are bad or your charger is not charging them sufficiently.

Charges as follows..

4.25
4.25
4.26
4.28

Thats right off the charger for the 17500's.

Bulb is a Cree 3W LED. When it did work a year ago it was a great combo.

4,28v??!?!?

Man, the limit charge is UP to 4,20v! Your batts is close to explode!

I'd lay 2 17500s out on a table, and lay 3 CR123s next to them -- is one stack longer than the other? Could a spring in the light have acquired a "set" that keeps it from making contact?

Specop_007 said:

Charges as follows..

4.25
4.25
4.26
4.28

Thats right off the charger for the 17500's.

Bulb is a Cree 3W LED. When it did work a year ago it was a great combo.

Click to expand...

Yikes, thats .10V too high. But still, I don't think it explains your condition.

Make sure the tailcep end is clean and not gunk'd up with grease and lube. I use isopropyl alcohol to periodically clean the tailcap end. Remove the bezel and clean the large spring contact and the corresponding end of the body tube with alcohol.

Try connecting -B to the body tube with a paper clip. Does it work or is it dead with the paperclip?

having a case of CRUSHED tailcap spring due to battery column length i would say to check this next