As title say. Im thinking of using 4 batteries. So it needs to function nicely in the 3,7-6V range.
1 emitter on copper. Most likely XP-G2.
The driver needs to be suitable for nimh as well as alkaline. But I dont expect it to be able to run on high when using alkalines.
Im quite flexible on circuit board size. Output, Im flexible, but I would not mind to see 2,5A or higher.
I would prefer if it did not have any PWM whine, more than 1 mode and maximum 3 modes. But im open for suggestions.
I am not interested in using the 3-18V from IO. PWM noise and size (26mm) is a deal breaker. Output is too high too. 23mm board or smaller. Smaller is better.
How would nanjg 105C work with 4 Eneloops?? As far as I know it works, but it would just have to turn the extra voltage into heat, so it would be just as good to just run it with 3 batteries. Someone correct me if im wrong though.
Im thinking specifically on the Qlite. Officially its only rated for 2.8V-4.5V.
With alkalines I could use 3+1 dummy. But again. 4AA batteries would be the goal…
Some info for other modders:
I have just measured output on the 1-mode 3-18V driver that came with XM-L U2 drop-in from KD. 1,5A with 4 Eneloop XX batteries. I could use that, but I would like to get more options with higher output.
Ill probably share my findings with that driver in another thread…
I have also tested the LD-29 from FT since I had it laying around. But as expected. It thinks im running it with two li-ions with low voltage. So battery protection/ dimming feature kicks in.
I’m using 4 “Duraloops” with a 105c and a XML. It’s worked well for me. I draws the full 2.8 amps at the tail. I also have the board mounted directly to the bottom of the rather large heatsink.
I can only comment on the 105C. I use 4 Enelopps with them all the time and I prefer 4 over 3. I know about excess voltage and heat, but really, when you want to push 3-4 amps I think the excess voltage is not an issue since the batteries will sag. From the results I have seen, the 105C@ 3-4 amps works better with four NiMHS than it does with 3 NiMHs. Output is closer to expected. Especially since I usually add a couple more chips and am closer to 4 amps than 3 amps.
i was told the 105C couldn’t take more then 5V so thats why i never tried it, i think since then the recommendation is max 6V, but voltage sag really kills the output so i can imagine 4 in series working far better.
Thanks Justin… That have been my thoughts too…
Im just thinking that when you run it on say, low, you will barely have any voltage sag at all. So with freshly charged batteries the driver would get up towards 5,6V (1,4*4). That is way above the rated 4,5V. And the LED would only need around 3V. But I as others have mentioned, I believe those drivers should take 6V max. And with a very low current I would assume it would be no issue. Except quite low efficiency.
But do you (or others) have experience with it? Basically, reliability when used for a longer amount of time on low or medium with freshly charged batteries.
LD-29 is a nice driver, 85% to even 87% efficiency all across the input range on High mode.
Now the LD-29 behaves like this: at 6.55V it start to dim down entering into a medium mode which dims down. This is measured gradually with a power supply. The low voltage warning lasts from 5.85V to 5.5V, so we have some dead area there.
Then will again enter in low voltage warning at 3.35V. At 3.60V outputs about 2.77A, at 3.50V outputs 2.5A and at 3.40V outputs 2.1A. Otherwise it pretty much outputs 2.79 -2.77A on the other voltage ranges that I have not mentioned.
The 105C is really getting very hot and it has under 70% efficiency at over 4.2V. But there are worse drivers out there like this one, which is basically disaster on Medium and Low modes.
Notice these Atmel Attiny13A SSU are only rated to +85C Max temperature, also the 7135 do not like more than +75C
Maybe not much help, but it's good for orientation.
I might end up doing a test setup out in the open some time with 4xAA and a 12+ AMC 7135…
I could use IR gun to check temperature on the boards. Could always add heatsinking onto the driver…
105C will be fine on 4x AA NiMH. They have been shown to stand up to much higher voltage than that. Higher input voltage means less efficiency, but the sag from pushing 3A will mean the heat is distributed to the cells a little bit as well.
When not using a Li-Ion, I prefer 4xAA when driving a heavy load like an XM-L or XP-G2. 3xAA is not going to push the current for very long, unless it’s direct drive with a really good current path.
They can stand even at 6V, but for example on 6V and 1A input after 1 minute the driver gets to about 70Celsius and starts dropping the current lower and lower and has nothing to do with the LED which has stayed at 30C max. Initially for 10 seconds it's got nothing, tested on a power supply, with batteries may be different as the voltage will sag.
When the current is low power consumption is low and the chips don’t heat up at all. The mcu only uses a small amount of power so it should be fine up to 6V. If your worried about it you can replace one of the 7135 chips with an ld2981 5V regulator from Mouser. It looks just like a 7135 and with a bit of modding will work just fine to protect the components. It was an idea for series LEDs with series liion.
