Some questions about 445 1.6W

[2100]

Hi guys,

First off the noob story. I got the hotlight from a nice bro here. 1.6W LPMed driven at 1.7A, so I suppose it is of above average efficiency. I think I measured tailcap at about 4.2-4.3A or more, the protection circuit of the supposedly "high-drain" LiCo kept kicking in. Unfortunately my DMM died, shouldn't have tried to measure the current of a 55W HID! (initial surge is very high, higher than 10A 12V).

After that I received a single used AW IMR 18500 and all was well after recharging it. Don't have a meter at first so it was probably ok after 5 x 1 min runs, then I noticed that the 445 started to somewhat flicker. It was not the On and Off kinda flicker, but rather a very fast "you know it powers down" kind of flicker. I thought that the power was a concern so i recharged it up again.
My charger is a Ultrafire WF-188, that version which can even charge the big fat D cells.

I was running it after recharging and still noticed that it somewhat flickers, and after that it flickers quite a fair bit. I could hear the driver giving some ticking sounds inside the host. I recharged it some more and ran it....the first 60s it was ok, but after that it flickered a wee bit and potentially got worse.

So today I borrowed a DMM and found the cell to be 3.8V. Sheesh.... I thought I must have damaged the diode or something! But its strange, as all my runs I am very careful not to get it past 90s and after which I will give it at least a 2-3 mins rest, and the host never got really hot as in nowhere near "hot till untouchable".

Again I recharged it and the WF-188 showed green light after like 20s. I tried to re-sit it again a couple of times and it showed RED, ie charging. I know of this trick from my camera Li-ion, the charger often has a personality. I am acutely aware of the dangers of overcharging esp with low resistance LiMn IMRs, so I was like taking voltage readings every 5 mins or so. I know the chemistry is supposed to be safe, but it is unprotected and apparently with the older WF-139s it has the tendency to charge till it hits 4.5V as it cannot sense and POOF....can check out CPF on what it does, basically its like a very very large firecracker if it decides to do more than vent.
Finally it turned GREEN again, nicely topped up to 4.2V exactly. Apparently it stopped when it was 3.8V or so. My other LiCo 18650s (many of them) also have the tendency to stop at 3.9-4V.
Cool, the WF-188 is able to work correctly with AW IMRs.

So tested the 445 again, really stable after the initial 2s or so of warming up flickering.

 

[2100]

So my question is

(1) The driver is njg-18 (boosted). I suppose it is normal for it to be drawing over 4A at the tailcap (ie battery) to do 1.7A at the diode? How much voltage does the diode run on?

(2) The 445 dissipates a heck lot of heat. I'd say its like a pocket rocket in the LED world. I think it lases 1.6W of coherent light, the rest of about a few watts is dissipated as heat? How much watts/joules per sec is disspated as heat?

(3) Which component dissipates the most heat? LD or driver? I think its the LD?
I was told the driver is very stable, caps replaced + heatsinked etc.

The aixiz 445 glass lens is cool.....though its slightly less efficient than say a 405-g2, I could focus it really nicely even at 5m or 15ft, I think this is the advantage of the Aixiz 445 lens vs the 405-g2? BTW I just lit a match at about 15 ft!! Have yet to try balloons.

(4) So the 405-g2 is more efficient, but does not collimate it as well esp for long distance spotting?

(5) How tough are these LD and drivers at 1.7A? I read from the flaminpyro thread that 2.1W is really cool at ~ 2A, but at ~2A the MTBF of the LD might be like 10hrs or so. Still plenty of runtime I suppose, but I am not good with DIY of this nature should I ever need to replace the LD!

 

[DrSid]

The rough rule with this diode is 4.5V/1A=1W of light. So generally 3.5W of heat (at 1W).
These diodes can be pushed harder. Some stop lasing before 2A. Some don't. Some get burned. Some will lase again on lower currents. As for durability, I guess it will be lottery as well. 1.5W was reached by anyone who tried (AFAIK). 2W not so much. Anyway 2W is just about maximum. After that, the power does not increase with current anymore, you just get more heat. Btw. with this soft pushing, the thin wires which connects the chip the the leads melt off .. there is no direct damage to the chip, most of the time .. it can even be fixed.

 

[2100]

Thanks for the good info. Guess the limiting factor is the LD wires.

Guess for my build it needs to dissipate 6W. Can I say if I use a cool gel pack chilled to 5 deg C and wrap it around the head, it can safely do 3 mins of run time?
Right now I am keeping it 1 min ON and 3 mins OFF.

 

[rhd]

Ok, so there's a difference between "stable" and "efficient"

This driver may be (and probably is in my opinion) fairly "stable", but it is NOT efficient by any long stretch of the imagination. I believe this has been fairly well documented in the NJG thread and elsewhere, but this driver takes a BUCKET LOAD of current from the battery in order to produce boosted current of even 1A.

So regarding your question:
"I suppose it is normal for it to be drawing over 4A at the tailcap (ie battery) to do 1.7A at the diode?"

No, it's not normal in general (ie, for most laser drivers), but it IS normal for the NJG-18. In my opinion, this is still an awesome driver, I'm not knocking it. But you do need to be aware of the fact that it sucks a lot of current from your batteries.

However, one of the side effects, is that this energy has to go somewhere. Less efficient drivers mean more heat to dissipate (that's the only place those efficiency losses CAN go).

I'm not sure if that helps address your concern - but long store short, this driver does produce a lot of heat. I've noticed 1W NJG builds heat up a lot faster than 1.8W linear driver builds, in situations where both drivers are heatsinked to the host, or main heatsink properly.

 

[DTR]

I like to keep my NJG's under 1.4A for a few reasons. As already stated it is a terribly inefficient boost driver. I usually see around 2.6A current draw @ 1.4A and it climbs dramatically after that. To produce 1.6W-1.7W even with a G-1 you have to be going over that and with an Aixiz probably around 1700mA. I measured around 4.5A current draw at 1.75A on this driver. This is a ton of current. A lot of batteries can't handle it especially protected ones and even if you find one that does you still are stressing some of the weaker points in the host like the clicky or springs witch can burn up or melt. On the flip side I have found the driver to be very reliable when keeping it set below 1.4A.

 

[2100]

For the one that I have, it seems that there is a soft-start, ie after clicky operation to ON it gets delayed for about 0.5-1 second before it lases. If I remember correctly the high current only starts flowing accordingly after 0.5-1 sec. So at least there is no arcing which eats into the contact points.

The spring / terminals / clicky metal all seem to be reasonably happy and no hotspots there. The hotspot is more of the LD.

So I guess more AW IMRs for me then....i can get about 10 mins of combined runtime before it flickers a bit. Pretty ok as I am not too picky about that, heck I think i'll get another 445 before they ramp up the scanning checks on normal airmail (already 1 box got detained via EMS). I'm from South East Asia region btw.

Thanks for all the info.

 

[DrSid]

Well delayed start may protect it when turning on .. but arcing is more of a problem when contacts under current are separated .. ie mostly when turning off.

 

[2100]

Actually if the clicky is of a decent quality, 4A should be ok. I suppose at much higher voltages any visible "arc" esp during seperation from what DrSid said would create more problems. (eg 36V 4A vs 3.7V 4A, same contact area). Those XM-L lights operate at 2.5-3A all the time for much longer periods even for the lower-end brands, and SST-50 more and you'd need IMR if you want max performance. It'd take quite a while before the contact points get eaten away. But I think I read about daguin's clicky overheating recently in B/S/T.

Anyway I cleaned all contacts twice with Caig Deoxit G5 gold contact cleaner....its from my Hifi hobby (it works pretty good, cleaned a lot of cranky headphones and scratchy sounding volume pots). Most of the threads are very dirty even for the higher-end LED flashlights, even though the huge surface area rarely presents any problem.

edit : I slowly released the clicky (so that the power cuts before it sounds off the CLICK) and held my ears right next to the host, don't hear any electrical arc or "piaks".