So adding resistors to bring up the current (I measured Vdo of 0.25, so very close to your 0.24) really isn’t going to achieve what I want to achieve without going to 3S.
I have to solve my voltage issue first, before increasing current. And by increasing my voltage, my current will come back up to stock of around 2.5A, which should make my light look as bright as before, and maybe slightly brighter with the XM-L2’s…and won’t require increasing current to get it back to a “satisfactory” level.
This may be a good opportunity for me to go to a 3S lipo pack. I also have a cheap chinese liion 2s2p pack that I only use as a backup to my backup. I could turn this into a 3S pack just to see if it improves my current situation.
So adding resistors to bring up the current (I measured Vdo of 0.25, so very close to your 0.24) really isn’t going to achieve what I want to achieve without going to 3S.
I have to solve my voltage issue first, before increasing current. And by increasing my voltage, my current will come back up to stock of around 2.5A, which should make my light look as bright as before, and maybe slightly brighter with the XM-L2’s…and won’t require increasing current to get it back to a “satisfactory” level.
This may be a good opportunity for me to go to a 3S lipo pack. I also have a cheap chinese liion 2s2p pack that I only use as a backup to my backup. I could turn this into a 3S pack just to see if it improves my current situation.
Before I forget again to say this. Please don't take anything I write here as gospel. I'm really a novice when it comes to electronics (and maybe everything else flashlight). I know enough to be dangerous and sometimes get lucky.
With that said, you may want to try a resister mod. There could be something, I'm not aware of in this matter. Thank you for reporting your Vdo measurement. That is dead on with the your stock set up of 2.5 amps and 2 R200 resistors (.25/.1). I measured 2.08 amps stock on my light but that could be due to the DMM consuming current (maybe?) or variation in performance of our drivers. used the data point of 3.1 amps and an additional R33 to get my estimate of .24 Vdo.
I hope you don't mind if I add your measurement to the OP with a reference to you as the source. That is good information, that measurement you took.
I like your idea about just going 3S though. 2S just doesn't seem like enough voltage for even the stock light, at least not for long regulated runs.
If you driver does not look identical to mine and if you have the time, would you please post pictures of the 2 sides of it?
EDIT: I'm sure you have thought of this, but just in case. The voltage indicator lights on the back of your light may no longer give accurate info after you switch to 3S.
err, is Vdo the correct notation for that? I would have assumed that it stood for Drop Out Voltage, not Voltage Drop. The voltage you are discussing is actually called the Sense Voltage, I guess Vsense or Vsns might be an appropriate notation. Glance at a random datasheet such as the one for the ST LED2001 or the Maxim MAX16820 if you aren’t familiar with the sense voltage term.
Also, I’m pretty sure that you guys have your measurements/figures quite wrong. There should be no way you see a 0.24v voltage across that R010, that would be 24amps! (check an Ohms Law calculator - the resistance of an R010 is 0.010 ohms). It’s more likely that you see 0.024v across that resistor indicating 2.4A.
On the subject of a resistor mod not doing much to a light that’s out of regulation… I think you had it right in the first place ImA4Wheelr. While doing a resistor mod might increase current slightly IMO it’s just as undesirable as doing a DD mod. With the driver out of regulation as pack voltage falls, so will output current. My advice is to skip that and go straight for a higher input voltage so that the driver can get back in regulation.
Finally - can you point out the indicator LEDs? I don’t see them.
I need to get caught up on that thread and maybe post some constructive criticism. I think it would be good to make it more clear that DD lights will get significantly dimmer as the battery discharges. For a point of reference, a DD light I recently built pulls around half the current once the battery is >3/4 discharged.
^ Nothing wrong with a resistor mod if you want to change the current fed to the emitters. I think wight meant my suggestion that you might still want to just try a resistance mod in case it works. I agree it will likely not work. I just wanted it clear that I am no authority in these matters.
wight wrote:
err, is Vdo the correct notation for that? I would have assumed that it stood for Drop Out Voltage, not Voltage Drop.. . .
Also, I’m pretty sure that you guys have your measurements/figures quite wrong. There should be no way you see a 0.24v voltage across that R010, that would be 24amps! (check an Ohms Law calculator – the resistance of an R010 is 0.010 ohms). It’s more likely that you see 0.024v across that resistor indicating 2.4A. . . .
Probably not. I think I may have unconsciously made the abbreviation up a long time ago. Way before joining BLF, I use to mod LED lighting into my vehicles. I generally made drivers using voltage regulators like the LM1084. They can be used to make a CC driver. The term for the voltage used to control current is Dropout Voltage. Of course, the LM317/338/350/1084's have significantly higher dropout voltage (something like 1.5 volts) than this driver, but the concept is the same. Enough current is pushed over the voltage sense resistor to get the targeted voltage drop. I guess I must have just made up the term Vdo. Sorry for the confusion guys.
.25 sounds right. The 2 R200's equals .1ohms of resistance.
It appears that two different drivers are in this thread. I see now that the driver in the OP is not the same as the driver in your reply #1.
The driver in reply #1 is HX-1289 (the PCB’s are labeled A6 and B5, eg rev 6 and 5 respectively of the two part driver). It features a single 0.01 ohm sense resistor and an op-amp to interface it with the QX9920 buck controller.
The driver in the OP is HG0802. It skips the op-amp and therefore requires a 0.1 ohm sense resistor array. It’s also using a very different inductor, maybe it has some other big differences as well.
I assume that the HX-1289 is from a legit Solarstorm light. The difference in sense resistors is a big deal because the clone will drop 0.3v at 3A while the HX-1289 drops only 0.03v! That should make a big difference in where the driver falls out of regulation as well wasting nearly a 1 whole watt less.
EDIT:
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?
beam shots? Looks like bright sunlight to me. I want to ride behind you. Amazing job.
I’m a visual type, pics make sense, technical details not so much.
I had a mtb night ride planned for tonight but my buddy got ill.
I’d spent 3 hours last night trying to mount a flashlight to my helmet. All dressed up and nowhere to go. Sipping a Ballast Point Sculpin to ease the pain.
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.
GJ