My first attempt resulted in attaching the four 7135 ’’s really well , but when removing the positive lead to attach a thicker cable the the d1 diode detached itself at one end, I pushed it down and resoldered it. Max current draw at switch approx 2.4 amps.
Second attempt, I used too much solder on the tabs of the 7135’s on the outside of the board so the driver board wouldn’t sit down far enough when installing it. Tried removing the excess solder, applied too much heat and one of the 7135’s detached itself. So I scrapped that one.
Third attempt, all went well in soldering on the four additional 7135’s.
So 12 in total now, max current draw at switch = 2.14 amps!!! Less than I started with! |(
Maybe you could share some pictures of your work so we can see if we see something. Its kinda hard to diagnose a problem like this without some details.
Which battery? How is the measured stock qlite current(should be 2.8A)?
Have you used big leads for your amperemeter?
I usually bend the legs from the 7135 90° downwards than I apply some soldering flux to all 7135 and make a small blob of solder on all the 7135(the ones on board and the ones to be stacked). After tinning all legs I remove bigger solderblobs with a desoldering pump.
Now I simply lay the 7135 on top of another one and clamp it together with a crocodile clip.
Now i apply a bit flux again on all legs.
Just touch the bottom legs and wait a bit to melt the solder and pull the solder to the upper leg…
Last step is inspecting it with a magnifier to be sure I have soldered all legs properly.
The biggest mistakes I made when I started this is that I skipped all the preparation and didn’t use flux to make it faster but the result was that it took a lot longer.
The current draw was 2.4 amps with the stock driver, which is lower than expected.
Reasonable quality multimeter with average leads, I expected the measured current to be a little lower as a result but not this low.
Werner, I used your suggested method, I watched a video made by Richard at Mountain Electronics and a few other’s.
I was using one of those headband magnifiers and inspected the soldered joints a few times after cleaning away the flux residue.
emarkd, I’ll have another look and maybe post a photo.
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I must admit that the bending of the legs didn’t look perfect when you examine them closely with a magnifier, I held them with pliers when bending but the legs appear to fracture slightly at the 7135 body, when soldering I tried to fill it all with solder to account for this.
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One thing that I have just realised, I’ve been soldering the 3 legs first on all of the 7135’s and then soldering the tabs at the rear. One or two of the tracks at the Base of the pins look a little suspect as if they’ve been under a little strain. I’m sure it’ll be adisable to solder the tabs at the rear first. :8)
After looking again at a method on here I’ll try again, I’m not going to bend the legs and just solder the outer legs and the tab at the back.
You should also make short and thick leads for measuring current. Some just stuff a thick cable in the DMM, I just bought a pair of bananaplugs in the right size and soldered a short thick wire in it AWG12 or so…
You also can measure and while measuring short the two multimeter leads and have a look on the brightness level, often with stockleads you see a real jump in brightness. That would indicate that you measure to low.
The ncrb is not able to give you more than maybe 4.5A or so and also the current decreases fast with depleting, that combined with the leads won’t make you happy to measure tailcapcurrent.
But stacking just 4 additional on a 2.8A sounds absolutely doable with this setup.
Thanks, I made sure it was fully charged just to make sure.
Another attempt in attaching the 7135’s.
It’s not good for your blood pressure when you get a solder bridge that proves difficult, not to mention struggling to hold the tiny spring in place whilst soldering it back on. In the end I just put up with the heat and held it in place with my finger.
The cheap multimeter leads resulted in the current reading 0.5 amp less than what is with some short thick cables.
I’m now reading 3.36 amps , which is still disappointing. You would think it would be nearer 4 amps, I also braided the spring.
I wonder if I’ve fried one of the chips when removing a solder bridge? :_(
From my own experience w/ soldering and attempts to mod 7135 based driver board I’m guessing you may have several base (original) 7135s w/ open or bridged solder joints. One clear indication is the lower drive amps. The original board had 8 x 7135 so ~ 2.8A. If you removed or bridged two chip connections the result is 2.1A.
In the case of the Qlite board you attempted to add 4 chips to one side, meaning that 4 chips have not been touched. If that is the case then you at a minimum have 4 good chips = 1.4A. The double chip side adds 0.7A per stack meaning you have one working stack (0.7 + 1.4) and 3 stacks w/ open or bridged tabs on the base chips.
Werner’s solder advice is spot-on in my book. I use a very old Hexacon re-work iron w/ a very tiny tip. As Werner suggests, tinning and using flux makes solid solder joints very quick. A small tip set on HIGH will produce a joint with only a quick touch.
When attempting to bridge the tabs you need to avoid applying heat for more than a second or two otherwise you can fry the chips (I’ve done it plenty of time). I like Werner’s suggestion to use a clip to secure the chips. In addition you can use micro clips / heatsinks to keep the chip temperatures down. What I do is make an attempt, failing I move to another joint on a different chip then go back to the first joint, giving the chips plenty of time to cool.
Consider all this practice and let the frustration slide. Don’t expect to be good or comfortable until the small muscles in your hands get to know the job. Then you’ll be able to relax a bit and not fight yourself. Some people bend the pins to shorten the bridges while others say don’t since you might damage the internal connections in the chip. I’ve done both. Do whatever pleases you and helps you get the job done, you can always do it differently the next time. Solder behaves differently at different temps. Play with that and watch the results but don’t fret over them. Or scream and flatten the stupid thing with a hammer but make sure you have a spare first.
Rufusbduck, I’m going to have another go this afternoon. I did scream a few times yesterday, I remember year’s ago when I was doing something I took a large chunk out of the bench (particle board) with a hammer! haha - I’m normally quite patient.
I’ll have another practice first and I’ll definitely avoid putting too much heat into them.
Hi I have to say your totaly wrong about that. I have JAX Z1 modded with a SBT 70 a FET Driver and with ncr18650b It pull 8.90amp.(with my imr26650 I got 9.90 its a keeppower 5200mah black)
