What blew my 5W/BB750/Pila?

[wptski]

My McLux 5W BB750 V3U using Pila 168S just quit during use, not after changing a battery, meaning I didn't short it out. I'm also using a McE2S with a value of 1.7 ohm, rather low but it draws less than half the current of what the resitors are rated at. A single CR123A won't lite the LED and assembled with two batteries, I get 5.9V at the positive side of the LED. A couple of times I got 7.5V but powering OFF/ON, I'd get 5.9V again! Problem there??

I was wondering with the stock SF tailcap spring it's hard to keep it depressed in high and it flickers back/forth between low/high.

Most electronic devices, etc. will draw a higher start up current. I'm wondering if this current pulsing caused by the stiff spring coupled with the use of Pila's which some claim to stress a BB750 to the limits could have blown my BadBoy? /ubbthreads/images/graemlins/mad.gif

I know that fellow CPF'rs are using Pila 168S with BadBoys! Are we asking for trouble?

 

[hotbeam]

Have you tried a freshly charged 168S? If that doesn't work, it is likely to be the BB750 itself.

I had my BB750 die on my after several months of use also. The problem was the BB750. It is being pretty highly stressed running at 750mA and if the potting was not perfect, heat from the components will cook the driver.

At the risk of sounding stoopid, is the McE2S essentailly a resistor in the tailcap and somehow you can get 2 levels of current drive? That is, normal (no resistance) and 1.7R? If it is, take it out and do not use it with the BB750. The BB750 is a constant current driver. If you limit the power going to the BB750 with the 1.7R in line, you are forcing the BB750 to work much harder to try to output 750mA. That may have *blown* the BB750. Sounds plausible?

 

[wptski]

[ QUOTE ]
hotbeam said:
Have you tried a freshly charged 168S? If that doesn't work, it is likely to be the BB750 itself.

I had my BB750 die on my after several months of use also. The problem was the BB750. It is being pretty highly stressed running at 750mA and if the potting was not perfect, heat from the components will cook the driver.

At the risk of sounding stoopid, is the McE2S essentailly a resistor in the tailcap and somehow you can get 2 levels of current drive? That is, normal (no resistance) and 1.7R? If it is, take it out and do not use it with the BB750. The BB750 is a constant current driver. If you limit the power going to the BB750 with the 1.7R in line, you are forcing the BB750 to work much harder to try to output 750mA. That may have *blown* the BB750. Sounds plausible?

[/ QUOTE ]
It doesn't work with the stock switch, SureFires don't work, another 168S doesn't work and the head on another power pack/switch either! The LED is dead.

Current draw through the switch resistors is less than 1/3 of the total current without them. The switch is in series with the battery, dropping voltage.

While deciding what resistance I wanted, I left it ON for an hour with a 2.1 ohm resistor if I remember correctly and the head barely got warm! I measured 375 lux in low at one meter compared to 1160 lux in high. This makes it sound like the BB750 isn't working to hard at all.

I used a Fluke 189 in Fast min/max function to read current surge at power up on my KL4/E2e. Actually SureFires had a higher peak of .47A compared to .29A with the Pila 168S. Normal draw from the SF was 1.0A and the Pila was 1.5A.

 

[wptski]

bump

 

[tvodrd]

wtpski,

I've reread your post abt 3 times. It seems to me that if you are getting 5.9-7.5V at the LS It should emit some level of photons! It is puzzling because if the LS died, I would think it would go open circuit, and open circuit is death for a BadBoy! I would try 6V (series a pair of 123's) to the LS. If it doesn't light, it's a pretty good candidate for the problem.

Larry

 

[wptski]

[ QUOTE ]
tvodrd said:
wtpski,

I've reread your post abt 3 times. It seems to me that if you are getting 5.9-7.5V at the LS It should emit some level of photons! It is puzzling because if the LS died, I would think it would go open circuit, and open circuit is death for a BadBoy! I would try 6V (series a pair of 123's) to the LS. If it doesn't light, it's a pretty good candidate for the problem.

Larry

[/ QUOTE ]
Larry:

Well, too late to test anything now! The CPF'r that I got it from requested it back for a refund. A very gracious offer on his part.

Well, it's either the LED or the converter that's bad. I've seen another post where they mentioned to put 3V across the LED, what's putting 6V going to tell us? Where did the 7.5V come from?

I found a thread, actually I posted in it too, where there users were powering 5W BB917/BB1000 with Pila 168S. If I was pushing a BB to hard, what are they doing?

I started this post to really find out if using Pila 168S was/is a problem or it and the combination of using the McE2S also for some reason.

 

[tvodrd]

Bill,

I got the 7.5V from your original post and it sounded like you measured it at the LS terminals. I suggested trying 6V as 3V usually won't light a 5W. 3V lights 1W and LSIII's fine. With a 5W, anything up to the LS's Vf is fine for a BadBoy. I am assuming you used a single 168S.

Larry

 

[wptski]

[ QUOTE ]
tvodrd said:
Bill,

I got the 7.5V from your original post and it sounded like you measured it at the LS terminals. I suggested trying 6V as 3V usually won't light a 5W. 3V lights 1W and LSIII's fine. With a 5W, anything up to the LS's Vf is fine for a BadBoy. I am assuming you used a single 168S.

Larry

[/ QUOTE ]
Larry:

Okay, I meant, how did I read 7.5V and other times I'd get 5.9V? Using a single 123 was suggested by the builder of the head and I didn't know that it wouldn't lite a 5W!! Interesting because it's been mentioned to several people and they didn't catch the mistake.

Yes, I used a single Pila 168S to power the BB.

 

[tylerdurden]

The more I read this, the more I think there must be a short to ground somewhere. If the converter is well-potted, it will probably just have to be junked, and it's already blown the emitter. Was it the downboys or the badboys that had the exposed copper along the edge of the PCB that could cause this ground short? When I build a head, I always coat the converter's edge in nail polish to guard against this defect, even though I believe the problem was fixed some time ago.

 

[wptski]

[ QUOTE ]
tylerdurden said:
The more I read this, the more I think there must be a short to ground somewhere. If the converter is well-potted, it will probably just have to be junked, and it's already blown the emitter. Was it the downboys or the badboys that had the exposed copper along the edge of the PCB that could cause this ground short? When I build a head, I always coat the converter's edge in nail polish to guard against this defect, even though I believe the problem was fixed some time ago.

[/ QUOTE ]
It was the DB with that problem.

I had to increase the solder ball to work with the three Pila 168S that I have. All three were different or required bigger balls! /ubbthreads/images/graemlins/grin.gif

Looking close, I noticed that the board wasn't against the shoulder of the Ecan at one side only but it looks like a gob of AA was keeping it from sitting. It wasn't much of a gap, maybe 1/32" and the battery was still making contact. Lets say that I'm wrong and the battery forced the board up, what could that cause? A short?

 

[tylerdurden]

Possibly. Maybe one of the components on the board was pushed up into the ground wire. If the board was well-potted, though, I think this is unlikely.

 

[wptski]

[ QUOTE ]
tylerdurden said:
Possibly. Maybe one of the components on the board was pushed up into the ground wire. If the board was well-potted, though, I think this is unlikely.

[/ QUOTE ]
I put a battery up against it and pushed but couldn't move it all!

FrenchyLED has a 5W BB750 and ROTHrndir has a 5W BB917. Both use Pila 168S. I wish they would comment on this problem! /ubbthreads/images/graemlins/wink2.gif

 

[Hoghead]

I'm not Frenchy or Roth, but I've been keeping an eye on this thread.

I have a PR/BB750/X4T/E2D that I'm using Pila 168s in. I haven't had any problems with it.
I have a L1/PR-T/2x123/BB750/X3T that uses 123 cells and I haven't had any problems with it either.

Please let us know what happened when you get it figured out.

 

[kakster]

I have run a 5 watt Luxeon with a BB750 and Pila 168s with no problems. I think you hit the nail on the head when you said the BB was working harder with the resistor/2 stage tailcap. The BB will always try to boost the voltage to the required level.

I wonder how the L2 works?

 

[wptski]

[ QUOTE ]
Hoghead said:
I'm not Frenchy or Roth, but I've been keeping an eye on this thread.

I have a PR/BB750/X4T/E2D that I'm using Pila 168s in. I haven't had any problems with it.
I have a L1/PR-T/2x123/BB750/X3T that uses 123 cells and I haven't had any problems with it either.

Please let us know what happened when you get it figured out.

[/ QUOTE ]
I asked the CPF'r that I got it from/returned to let me know what they find, if anything!

Did you by any chance ever check how much current you are drawing from youe Pila with your BB750? I think that I mentioned above that mine was drawing 1.9A.

I have my own theory, just looking for others. /ubbthreads/images/graemlins/grin.gif

 

[MegaMe]

well im thinking with the resistor tail cap you have a lower voltage into the badboy, which means to stay at the right output current it draws more input current, which means the voltage drop accross the tail cap increases, and so the bad boy compensates by increasing input current more and so on...
so you get an operating point of a low voltage into the bad boy with the high output voltage and current , which means very high input currents. And i think the badboy can only regulate up to 1.5 amps of input current??? i dont know what happens when you try to exceed this by a lot, but with the resistor tail cap its trying to exceed this by so much its not that surprising if something goes wrong imho.

 

[Hoghead]

wptski,
I haven't measured the current, sorry I can't be more help!

kakster,
The L2 has two boards, one for low and another for high.

 

[wptski]

[ QUOTE ]
MegaMe said:
well im thinking with the resistor tail cap you have a lower voltage into the badboy, which means to stay at the right output current it draws more input current, which means the voltage drop accross the tail cap increases, and so the bad boy compensates by increasing input current more and so on...
so you get an operating point of a low voltage into the bad boy with the high output voltage and current , which means very high input currents. And i think the badboy can only regulate up to 1.5 amps of input current??? i dont know what happens when you try to exceed this by a lot, but with the resistor tail cap its trying to exceed this by so much its not that surprising if something goes wrong imho.

[/ QUOTE ]
The current draw from the battery through the resistors was only .5A. When I was deciding which resistor I wanted, I had slightly higher value of 2.1 ohm connected. I left it on for an hour and the PR hardly got warm at all. Now this wasn't the exact value that I ended up with! I logged the lux with a Fluke 189 and LM631. Too bad I didn't log the current!

Thanks for your input. /ubbthreads/images/graemlins/grin.gif

 

[wptski]

[ QUOTE ]
kakster said:
I have run a 5 watt Luxeon with a BB750 and Pila 168s with no problems. I think you hit the nail on the head when you said the BB was working harder with the resistor/2 stage tailcap. The BB will always try to boost the voltage to the required level.

I wonder how the L2 works?

[/ QUOTE ]

By the current draw(.5A), it's not working harder and no heat either! I'm not sure that the flickering caused by the stronger spring didn't cause it to blow. A pure guess on my part.

 

[MegaMe]

oh ok i should of actually done some calculations rather than guessing and being way off /ubbthreads/images/graemlins/smile.gif
but anyway that has to mean that the output current is something like 200ma? i dont know how a badboy thats supposed to run at 750ma likes that....???