Just piggy backed two 7135s that I removed from another board.
Unfortunately so far what I get is 2A ==> probably overheated and destroyed the 2 added and 2 original 7135s.
How sensitive are these 7135s? I’ve soldered lots of things, this was a bit of a pain to do but still would not say that they can’t handle little heat
Is it common to blow them up when soldering or are they heat resistant?
Any recommended method to piggyback them?
Bent the legs.
Glue them first, then solder them?
Thanks.
2.7A now, still, nowhere near 3.5A…
3.99V (open), 26650 protected.
Does it really drop so much even with a 26650?
What could be the loss due to DMM?
On the other driver I took the chips from I measured perfect 2.1A with 6*7135.
I haven’t destroyed any with heat, and I’ve really abused some while soldering.
I suggest checking the connections with a magnifying glass.
I bend the legs while they’re clamped onto the spot they’ll be soldered. Super gluing them there might be handy, but watch out for fumes when super glue gets hot. Even a tiny amount is NASTY.
Check the connections. You can also lay in small guage wire along side as jumpers. Are you using thick leads on your DMM? A small dab of glue is helpfull to spot them in place. They are pretty tough but can be smoked if you try. >)
Jackcy, I wish I had an answer to you question. I have tried several times to add chips and have failed miserably every time. Give me a welder and I'm fine. Give me a soldering iron and look out. Mr Rufusbduck here is one off them champion solderer's. I suppose practice and more practice while asking questions and doing the homework and not doing the same wrong thing everytime will pay off eventually. Good luck.
I’ve bent the legs while holding it with my fingers.
Then trying to solder it in when it’s not fixed at least a little, not good.
So I superglued it a little, yes I’ve noticed once when the glue burned once, bleh, have to be more careful with it.
It evaporates quickly.
I’m charging the battery fresh and we will see. Otherwise I can hook it up to 3.3-3.4V/28A and see what it can deliver.
Maybe the protection sucks on those batteries, I’m really surprised the output drops on all the lights since the XM-L Vf is like 3-3.4V or something, seems quite a bit above even when the battery drops voltage under load.
A person can actually “piggyback” 380s on 350s, theoretically correct. Yeah, I took a pair of dikes (he,he) and 90ed them before Supergluing them to the host 7135 chip, and then with a mounted adjustable clip and magnifier glass tree stand, attempted soldering but gave up…
Dikes? 90ed? talking alien language to me I just hold the board with pliers that have a rubber band over the grip so they hold. Put on a cotton rag to solder on. No glass no nothing. Adjustable soldering iron, used a super thin tip but that sucked hard, even when I set it to 330°C the tip would still not heat up well and lose heat quickly. Just use a normal thin tip nothing super long and super thin, 295°C, melts just fine and quickly.
Measured all connections they are ok. 0.12A low (4.08%, ~5%) 0.82A medium (27,89%, ~30%) 2.94A high (100%) Fresh TF 26650 with protection. I suppose in a flashlight it should put 3.5A? And the leads are just normal leads from the DMM.
In a flashlight measured at a tailcap, not even 2.8A, 2.76A or something. The connections do add resistance and it drops down.
BTW you don' need to connect the small middle one, because the big one is the same as the small middle one.
Anybody can share their amperage measurements before and after adding 7135s?
Do note what did you use to measure it and where did you measure.
To me it seems some may just say 4.2A wow, when in fact there might be much less amps going through when measured and might only state the amps based on how many 7135 chips they use.
I want real measurements
Beamshots before and after, lux, etc. are a great bonus.
DMM leads are a huge factor when measuring current. I’ve heard this over and over and when I switched to awg12 stranded with alligator clips and banana plugs the current jumped from around 1.7A all the way up to spec 2.8A. Your soldering looks very nice except for the loose strands on the led- wire which can cause problems if they touch pads nearby(center ground pin on same chip or Vin on next chip over). They don’t look like they’re touching but should be trimmed anyway. MRsDNF assumes incorrectly that because I mod these drivers with reckless abandon that my skill matches my imagination. I wish.
My amp measurements are always very close to the 7135's in the driver, using 12 gauge leads on the DMM. I don't use any glue for piggybacking, just hold in place with tweezers pressing gently on the top - I tried other methods of adhesives and always was a mess. Be sure to get flux on the base 7135 pins and the pins of the one going on top. I always solder all 3 pins and the back - even if duplicate for electrical ground, helps in heat dissipation as well - 7135's do generate heat and use the board to dissipate the heat, so it says in the specs on the chips. I work with the driver in a table top vise, adjustable head, so tilt it back a little - really helps to see and easier to hold the 7135 in place and you got gravity helping the solder.
I'll measure amps several ways:
1 - driver w/leads direct to a test emitter, mounted on a metal bracket - use alligator clip on the +spring w/small rare earth magnet disc to battery, then DMM leads across the - battery to the ground ring on the driver, alligator clip or direct
2- on the assembled pill first, same setup as above with alligator clips
3- on the assembled light, standard tailcap method
Definitely you should do #1 after soldering 7135's to verify before assembly of the pill. I've freely mixed 350's and 380's - haven't had any issues there.
I’m going to update my PSU so I will have to do some 2.5mm^2 gold plated banana leads for all sorts of purposes. Good tip for sure. My older DMM leads suck, the newer ones probably are not that much better then. Compared to what wires go to the LED, the DMM leads must be heavenly, I’ll e changing those later as well with the base and emitter.
Ah, if you mean those strands sitting on the chips around the LED- that is dust :bigsmile:
The damn curtains even make the air show dust in it when I light up the flashlight high in the night. Not a dust free environment with white lab suits haha.
I presolder the wires, add flux to both connections with a special pen (it has in it reservoir and small brush tip). The hardest thing is to add the solder, mine is 1mm ~= 1/25 inch and it’s still a bit too thick.
Well on the second driver I took the chips from I do get exactly 2.1-2.11A for 6*7135 so it is surprising to me that with 10*7135 suddenly I get only 2.9A max or so. It’s been hard to get to the 2.8A (always 2.6-2.7A, only very fresh was close to 2.8A) with 8*7135s as well though before I lowered it to 2.1A, either battery protection or measuring leads.
TF 26650 ~4200mAh, 15mOhm, at 4.2V ==> 2.9A outside flashlight, tailcap measurement was 2.7A.
I’ll have to dig out some appropriate resistors (1 ohm) to try and load the batteries at 4A and see what I get out of them and what the DMM will measure.
I’ve been using medium sized alligator clips for holding the extra chip on before soldering it with great success. No need for glue and alignment with the bottom chip isn’t a problem. I bend then legs all at once using the side of my tweezers and they all come out straight.
As for soldering the the legs i usually try to touch the iron on both top and bottom legs at the same time then slip the tip slightly up and i get i nice connection that way.
Although it did take alot of trial and error before i finely got this down.
Also I had at least 6 drivers that flickered after adding chips until i got it right.
Keep trying eventually you will get it.
Boy this is a good one. The battery sounds ok but I never used one of those for testing. Maybe carefully buzz out all your 7135 pin connections, be sure no cross-overs, but you probably did this already... Sounds like you don't have anything else to check against, ie: other available drivers, or other known high amp regulated flashlights to check your DMM measurements with. I'm running out of ideas.
Could be the 7135's. I bend the pins with a fine, bent needlenose to do all 3 at once, holding the 7135 in my hand - seems to work perfect every time. Also, I don't pre-tin the pins - the solder would just get in the way when mounting piggyback style. So, I put solder on the iron and try to touch both bottom and top pin, like devdvr describes. With the flux on the pins, so much easier, made all the difference. Oh, and don't hold the iron too long on the pins, brush it - had the bottom 7135 loosen up on my and slide away a couple of times - real pain... Also, I use a small flat tip iron, not pointed.
I use basically the same method as tom and devdr. I solder two more 350ma amc7135’s on a 105c driver two days ago and measured with a Mastech MS8229. I got 3.5 amps. I added a 380ma amc7135 last night to another 105c and got 3.17 amps.
Both where measured from the tail of the light on high. Used a Panasonic 3100mah freshly charged. Battery used, DMM and leads will make a lot of difference. The cheap harbor freight meters where giving me about 2.9 amps at the tail with the 10 amc7135’s driver if I remember correctly.
I just hold the board with pliers that have a rubber band over the grip so they hold. Put on a cotton rag to solder on. No glass no nothing. Adjustable soldering iron, used a super thin tip but that sucked hard, even when I set it to 330°C the tip would still not heat up well and lose heat quickly. Just use a normal thin tip nothing super long and super thin, 295°C, melts just fine and quickly.
