Hello friends! I’m thinking ahead to some builds that i would like to do. Recently i purchased a couple XINTD X3’s and i would like to mod one of them and put in an MT-G2 led and a 20mm driver that will power it using 3x 14500’s. My desired amperage would be around 4amps or so(im not sure how many amps i can get with 14500s?). Im having a hard time finding a driver that fits all of the conditions of this build. Could someone point me to something that might work well?
Thanks for any comments!
At first I thought this quest had little hope. But hey the quest is most the fun anyway. So I went over to the experts charts HKJ. This is what I found
http://lygte-info.dk/review/batteries2012/AW%20IMR%2014500%20600mAh%20(Red)%20UK.html
http://lygte-info.dk/review/batteries2012/Windyfire%20IMR14500%20600mAh%20(Red)%20UK.html
These are the only two batteries in that chart that are up to your needs and for 14500 3 amps is probably max. I did check the whole chart, lots of those size batteries are #$^%.
This driver http://www.mtnelectronics.com/index.php?route=product/product&path=67_115&product_id=473 will probably suit your needs when it comes back in stock.
Thanks for the battery links! That’s very helpful. $3 a piece for the windyfire isn’t too bad…
Ya… It looks like that driver would work. You think 3amps is the max I can get from the 14500s? Would it be better to use two 18650s?
Using 3cells in series is an advantage over 2 in series.
Quick and dirty math:
6.5V x 3A = 19.5W / (4V x 3)= 1.6 A. So let’s say around 1.6 to 2 A that the batteries has to deliver.
Should work, especially if you use some good cells.
Two 18650 will have more power to supply than 3 14500(or even 4) but you should certainly be able to get 4A from the 14500’s if only for a little while as long as they are imr’s but using them in series requires more diligence in keeping the cells matched for either size. The 5A driver with a 20 mm contact board which he also has might do the job as well. Works for 2 or 3 xml’s in series so it should work for a 6V led.
Ok. This is what I’m looking for. This is my first build using multiple cells so I’m not that confident using these components yet.
Another option is a purpose built Zener modded fet driver made by him. It can have LVP and run on 2 x li-ions. 17mm or 20 mm it will supply whatever the cells can deliver.
As stated above, I guess it will be better to go with three 14500 rather than two 18350. Idk though, it seem like I would have much more options if I went with a two cell setup.
Also, I am just learning to build and flash my own drivers. I don’t know if that will help me with this build or not. It would be nice to have more firmware flexibility than the simple three modes offered by some of these drivers.
I think the MtnE buck drivers use the attiny mmu which can’t be reflashed once in place so for that option you’re better off getting one of the other drivers that use the larger attiny mcu’s.
Unbalanced series cells are really only ever a problem when they are sealed up inside a pack and you can't get at the individual cells. If you can remove them it's not an issue. Remove them and charge in parallel. Only the worst cells will become unbalanced over just one discharge cycle, and if they are doing that you should toss them in the recycling bin anyway.
I’ve been studying up on this stuff. My mom got me a box with 30-40 laptop batteries from her work. Some are still sealed in plastic wrap. Idk how old they are though. I just read through the post from another member all about internal resistance and its usefulness in monitoring lion batteries. He documented a way to measure this resistance, but I think my best bet is to buy a charger that does the measuring. Or… I could just pop it into my f6 with dr jones rgbw driver. It has that ability. The usefulness of the measurement would be relative though, as it includes the resistance of the setup.
Considering Dale (DBCstm) and I are pulling 10-11A from a single IMR14500 (Efest & AWT) to drive triple XP-L emitters in Kronos X5 hosts I’d say 3A from three 14500 cells in series would be a breeze. Considering that Dale has also ran MT-G2 and XHP50/70 emitters using just two 18350 cells (also 600mAh cells) at WAY more and 3A to the emitter (more like 7-9A or more IIRC) You should be able to drive your emitter at way more than 3A using 3 14500 cells. Just remember that your runtime will be laughably short but it sure will be fun.
What I'm getting at is that even poorly matched cells will show very little difference after just one single discharge cycle. It's when you have a bunch of cells in series AND without proper monitoring/balancing/protection circuitry built in AND they go through charge after discharge after charge after discharge and the small differences are allowed to accumulate with nothing there to step in and say 'hey man, somethin's wrong here', THEN you will have a problem.
If you break the series cells apart (like, individual cells in a flashlight, where you can unscrew a cap and remove them), and charge them all together in parallel, you've just 'balanced' them just as well if not better than any built-in balancing circuit could do. And they get reset all back to equal every time they are charged, after every single discharge cycle.
I mostly agree with comfy. As long as the cells are decent and decently matched it shouldn’t be a big deal. The more cells that are put in series, the more tolerant (bad!) the equipment may be to a single very poor cell. With 3 cells powering a buck driver I think it might be possible to have a single very bad cell get roasted (bad bad bad!). As comfychair indicated - an intelligent charger which can say “hey man, somethin’s wrong here” will help keep you on top of any bad cells. If one cell ends up getting a significantly different amount of mAh put back into it… that certainly indicates a problem.
Personally I think it would be reasonable advice to avoid using “pulls” in series lights.
Determining IR can also help you figure out what will happen to a cell at high current. Generally speaking I think that most folks will recommend against using high IR cells in high-drain applications. I’m not enough of a guru to make that recommendation myself, especially in light of how A123 M1 cells are high IR but often recommended for high-drain. I think that’s a special case though.
Used pulls and new old stock pulls are also very different things. I'd avoid used pulls for anything at all even if you know they've been treated well. The clock really only starts ticking after they are charged the first time.
This was poorly worded. Let me try again...
Even poorly matched cells are likely to be perfectly fine and safe to use in series because any imbalance is corrected at the next charge cycle when they are removed from their series config and charged in parallel. For a cell to cause problems during just one discharge cycle inside the light, it would have to have very serious issues that would be hard to miss as long as you are doing all the right things when dealing with LiIon batteries.
They might terminate at the same charge voltage but if capacities don’t match well enough then the weakest cell could be driven negative. At the very least you should start with a capacity check on used cells you plan to run in series.
For now. I agree and think it is best that “I” use laptop pulls only in parallel. It’s the safest thing for me til I get more comfortable with series cells.
For this light, my first series cell light, I will buy the 14500 new and will only use them in this light. I have a two bay xtar charger that I will use to charge for now until I do some research and find a good four bay charger with good cell monitoring. A charger like this will also help me determine the condition of the laptop pulls.
So… For a three cell configuration to a 6v MTG2 it looks like I am stuck with the limited supply of buck drivers in this range. If I go with 18350s instead, I will have many choices of drivers with advanced UI, but I will have less run time. This XINTD X3 is set up nicely to take three 14500 so i will keep looking for a good buck driver. I have enquired about the 5amp buck driver from mtn.
Does this sound like I am thinking clearly?