I still think that this is wrong, even in the context you described. I think you might be thinking of Vref but I’m not sure?
I'm sure you're right. It would be great if I knew the exact technical terms that I should be using, but I just have no desire to research and learn them. Even if I did, I would forget them in not time. I think I have provided enough other info for most people to follow what I actually mean. Not making light of your comment, I just have too many higher priority items on my to do list. I do appreciate the record being set straight and thank you for your feed back.
If you know what terminology I should use, please tell me and I will try to correct my above posts.
My light is an original solar storm. One of the “good” ones, but not one of the super-good ones with the toroid. My driver looks to the one in Reply #1, but I’ll have to open it up and check.
So I had some time to take a few measurements tonight after my upgrade to the XM-L2.
At the LED’s, I am drawing 2.20A after 60 seconds of being on. It starts around 2.38 initially and drops to 2.20 within 5-10 seconds. And stays at 2.20. I didn’t hold it there long enough to see at what point it starts to decline, if any. Voltage with two xm-L2 in series was 6.20V.
So here’s the interesting part…not sure if my driver was out of regulation or not, I decided to hook up an adjustable power supply to the light. At 7.4V, it performed like it does on my battery. I bumped it up slowly to 9V. Still exactly the same. No change in output at all. I then bumped it up to 11.1V (to simulate 3S pack) and the light became noticeably brighter. I’d say 10% brighter??? I couldn’t measure the current with how I had everything set-up though. It wasn’t a huge improvement, but it was a noticeable improvement none-the-less. So does this mean that my driver would have been out of regulation, or is something else causing the increased brightness at 3S?
At the time I upgrade the emitters on my SSX2, I also upgraded my Yinding (gemini duo clone) with the exact same emitter’s/bases (from same supplier, same part number) as I wanted to make sure my bar and helmet light had the same tint. With the XM-L2’s in the Yinding, it current to the LED’s were 1.90A. This surprised me as Yinding’s are generally known to output around 1.6-1.7A. So for fun, I attached this light to the power supply as well. And the results were completely opposite. I started at 7.4V and everything looked normal. When I bumped it to 9V, output decreased. When I bumped it to 12V, output decreased even further. Opposite of the SSX2. Any clue what may be going on here?
Sorry if I’ve hijacked this thread a bit. You guys are amazing and I’m learning so much!
I Googled the Yinding and found the following images on MTBR (Link to thread in picture).
I can't get a link to a picture of the switch side of the driver. There is a pic in the OP of the linked thread. It's a buck driver as the buck controller (I'm trying to learn wight :)) is in the bottom left of the above image. I'm clueless as to why it would performed the way you observed neons97. You could pull out the driver and try to see if anything gets too hot feeling when running at normal voltage. If nothing gets hot, then try 9 volts and check for something overheating. That might give a clue as to what is going on.
EDIT: You could also watch for components that normally get warm that don't generate any heat. On high, I would expect some heat generation from the voltage sense resistors, those 2 large diodes above the inductor, and the inductor itself (may not be able to feel it though..
wight,
Sorry, I forgot to post an image of the indicator LED's. They are on the switch side of the driver.
My yinding is an original, but one of the newer, lower quality ones. My driver looks different than this one.
Seems like pictures of your driver is worth a thousand words with so many different variations out here.
I’m doubting that there is anything overheating as the light wasn’t on for more than 60 seconds and I could still hold the lighthead comfortable in my hands. Maybe something in the driver doesn’t like the higher voltage?
I’ll measure the current of my ssx2 at 7.4, 9 and 11.1v hopefully tonight to see how much actual boost I am getting at 11.1v.
I’m not too worried about that particular term in that particular scenario… I really don’t know that your recollection is wrong. No big deal on my side of the fence, Vref is just my best guess as to what you were talking about. [that’s specifically in reference to nomenclature for building CC drivers with stuff like LM1084, which we don’t need to do anymore] If you want to change something in your earlier posts, changing Vdo to Vsense would be correct. I wouldn’t bother though, or I’d use strikethrough text to help preserve the flow of the conversation.
I don’t know exactly. We expect current to fluctuate slightly with input voltage, it’s not flat. As you now realize, your description of the Yinding’s behavior doesn’t get us very far without driver pics.
On the SolarStorm, do you actually have HX-1289 for sure? eg the 321 op-amp is present next to a sense resistor with a value of R010? That’s important.
Here’s what I think we don’t know with the HX-1289 with it’s amplified current sensing:
The original set current
Sense voltage
The low Vf you measured for the LED string indicates that you are probably in regulation on 2s. In your testing you were probably in regulation when the output is constant, as I’ve described the HX-1289 appears to be built to have an exceptionally low dropout. When you reached the point where output is going up you have probably reached a dangerous point at the limits of your hardware. The more I think about it the more I think it’s fair to say that the HX-1289 is very possibly not compatible with 3s - and that 3s is potentially harmful. ImA4Wheelr’s 3s conversion was with a fairly different driver! Please test at lower voltages and see where the driver drops out of regulation - it might be at just over 6.2v.
I don’t think ImA4Wheelr was suggesting that overheating was causing what you described. Finding or not finding heat generation at the appropriate points would just be a way of telling whether things were doing what they were supposed to - or not!
I think I found the issue with my measurements last night. The power supply I was using was probably the issue. I don’t think it could supply enough current, so at higher voltage, it was coming closer to a battery pack’s performance.
So tonight, I tested a few things on the SSX2:
Power Supply @ 7.5V: 2.0A
Power Supply @ 9.0V: 2.2A
Power Supply @ 12V: 2.3A
On fully charged packs:
Samsung 5200 2s2p pack (3 years old, about 40 cycles): 2.5A for about 1 minute, dropped quickly to 2.4A for about 15 minutes, then started to drop down to about 2.35A for a long time, at which point, I just shut it down.
The cheap chinese “4400” pack that came with this light: 2.2A, then dropped to steady 2.1A
With regards to the HX1289’s ability to handle 3S and in/out of regulation…I have no clue what signs to look for. But on the power supply, when I brought it down to 6V, the light shut off completely. I don’t have a second DMM, so I wasn’t able to be very exact in adjusting my power supply voltage.
So I think my first order of business is to get a second good battery pack as I run the Samsung pack with my Yinding and this other cheaper pack with the SSX2. It’s worth 0.25-0.3A.
I will then slowly adjust the current sense resistors while keeping an eye on heat. But most of my night rides are in sub 10 degree celcius weather (will be sub-zero for the next 3-4 months), so I don’t usually have to worry about any heat issues when out on the trails. But I have a feeling if I bump up to 3A on the SSX2, I may want to consider turning it down to low/medium when I stop.
When you measured .25 volts on your HX1289A6 driver that is in the X2, were you measuring across the Resistor that is marked R010? Maybe it was 25mV like wight wondered about earlier?
EDIT: More important than monitoring for temperature is to watch for thermal sag using a lux meter. It's super easy to do and a HS-1010 will probably cost less then $15 on ebay. You just put the meter anywhere in front of the light and watch lumen output. If the output starts drooping, but the emitters are still being fed the about the same current, then the heat is not being wicked away from the emitters into the host or the host is saturated.
If current to the emitters drops (and its not due to the voltage source. e.g. low cells), then start feeling the driver for overheating components.
20 Watts is still quite a bit for such a small thermal mass of aluminum, but like you said, decent moving air will help dissipate the heat much better.
Do you think the whine comes from the inductor, could possibly running some CA on the coil help reduce the transformer whine?
I am thinking that a very thin slathering of heat sink compound on the outside of the copper pipe would not only help with thermal transfer but act as a lubricant to help press the pipe in
I'm not sure where the sound comes from. I've done several mods like this and each one that I reflowed a pin or two down to the PCB has whined. One I completely air wired and it doesn't whine. So maybe the MCU itself if whining and then certain driver components resonate with it. You have given me an idea. Sometimes I use a screwdriver as a makeshift stethoscope to pinpoint the source of a noise within a automotive engine or accessory. Next time I need to try the same technique on a driver.
Your idea for the thermal paste is a good one. I will try to keep that one in mind.
I’m enjoying these mods…My wife thinks I’m nuts for playing around with $40 lights, going out to the backyard at night taking pictures, hooking up meters to the lights, etc.
Got an HS1010 on order off ebay for $10.99 (USD) shipped. And some resistors off Fasttech. As-is, by adding thermal paste between emitter base and pills (very little in stock form), and thermal paste between paste and housing, the housing now gets a LOT hotter, and a lot quicker than it ever used to. But I do think that if I bump up current, I will need to draw on your copper thermal path upgrades in this thread.
Man neons97, you are in the thick of it already. You must be a very fast learner. You're way ahead of where I was when I had a similar level of light modding experience. In fact, you sound close to catching up to me. Good on you. We need more modders around here. I hope you stick around after you finish your bike light.
Regarding my copper mod. I can be a bit trigger happy when it comes to stuffing copper in a light. It may have been adequate to just upgrade to Notigons/Sinkpads and thermal paste. My instincts told me that there was more than just the aluminum stars causing the thermal sag. That was based on how the sag was not immediate and how it continued to increase throughout the test run. It would be cool when you get your lux meter, if you would check for thermal sag and report back. If you end up showing I over killed, that is fine. I rather know the truth.
So sorry to bother you again on this. Do you know if your reading was actually 25mV (.025 volts)? Now that we know for sure you have the same driver in Post 1, .25 volts doesn't make sense.
I made a mistake in my decimal place. It is .025. I’m learning accuracy of my measurements and documenting them is extremely important in these forums. No estimates and remembering in my head.
You guys are pretty scientific about all of this.
I also ordered a few parts to upgrade my old Gemini Titan with a ssc p7. The driver was putting out 2.5a on my good battery pack. So I figured a switch to an xm-l2 would be a nice upgrade. With the big reflector, I put in one f the xm-l’s I took out of the ssx2. It is spotty but not too much of a halo. Would make a great helmet light for one of my riding buddies. And good amount of mass so going 3a hopefully won’t be problematic with a single emitter.
I’m just not sure if I should go panasonic 18650 through hunk lee or go lipo.
I’m comfortable with lipo but I got rid of all my rc gear afew years back. And I know I’m not the type to settle in on a $30 hobby charger when my old Chargers were high end units with dual 400w charging channels. :). So I fear this may get expensive. With the 18650, u would just keep using quality Gemini/gloworm wall wart chargers.
What PSU do you have? Ignore my previous comments about the driver’s ability to handle 3s, that was based mostly on the bad data. Based on the new data you’re just seeing normal behavior for a QX9920 I think. I now see no problem.
If it suddenly cut off without dimming I’d assume that it’s the MCU’s LVP stopping the output rather than limitations of the buck circuit. I could be wrong though.
ImA4Wheelr and I aren’t just asking about the sense voltage for curiosity, you should check that again. With such a low sense voltage I think precision adjustments (eg precision low-value resistors) may get expensive. Instead I’d look at the link I provided in post #26. If you follow that thread you’ll end up over here (#106) where Pavithra_uk explains how to calculate the gain on your op-amp. Adjusting the gain may be the easy and cheap way to change your set current.
In fact, I just glanced at the pics in reply #1 here and I see the 153 and 202 resistors (15000ohm and 2000ohm). Looks like the gain is set exactly the way Pavithra_uk described for the SRK over there. Reducing the gain as described in some of those posts will push your sense voltage even lower, giving a higher set current with the same sense resistor (R010). You can pickup a large 0805 component assortment (I assume that the 153 and 202 resistors are 2mm long, right? That’s 0805.) from Sure Electronics for <$9, I’d recommend that.
So basically, I can either adjust the gain on the OP Amp or adjust mod the sense resistor. But the easier of the two to mod is the OP Amp gain due to its larger size, and the higher resistance requiring a less precise resistor.
I think I”ll have something in this pack that will get me going from 2.5A to 3.0A.
Just picked up a pair of lipo’s off HobbyKing for $18 ea. (2s2p, 4000mah, 5C discharge, built-in PCB with 2.85V LVC (too low in my opinion) and a 4.2V charge cut-off. They’re meant to be put into RC transmitters. Technically you can charge these with a standard wall-wart LiIon charger without a fancy Lipo hobby charger with the built-in PCB. But I got a cheap Hobby King hobby charger on order as well.
With their 5C constant discharge, and lipo chemistry, I should be in the optimal voltage a lot longer than my existing packs (even my best 3-year old Samsung 5200 pack). My rides now are all morning rides at 6am, so it’s light out by 7:30am so 90 minute runtimes on a 2.5A (emitter) draw should be no problem. Especially since the lipo has built-in LVC. And the batteries are only 133g…far lighter than 2s2p 18650 at around 200g. I also ordered some really nice 24ga silicone wire from HobbyKing (I used their 12-14ga all the time in RC) and will re-wire my lights with this higher quality silicone wire.
Will be riding and won’t be opening up these lights again till my resistors arrive from FastTech (around 3-4 weeks). Will post results and beam shots probably in early December.
Get yourself a 3V LVA/C. I have an ebay PCB with a 3V/cell cutoff and max 15A continuous current bench tested and voltmeter to get a general info(https://www.fasttech.com/p/1222902). Good luck with LiPo, I run it and like it Great thread anyway, still a lot of stuff here to learn from
GJ
Great thread anyway, still a lot of stuff here to learn from