Modifying a Nanjg 110 boost driver for higher output

I got two of these Nanjg 110 boost circuits from Intl-Outdoor. Out of the package they’re pretty hot, delivering 1.1+ amps from 2AA. They draw over 2 amps from 2AA NiMH (which were ~2.15V under that load). I want to try and mod it for higher output and possibly better efficiency. Correct me if I’m wrong: I can swap out R1 for a lower value, or simply remove it altogether if I wanted to boost output? R1 and R2 are located at about 9 o’clock in the picture.

Howdy, Slim!

I’m interested in the features of this one too.

Still “twice shy” about pulling too many triggers, though…

On the picture, isn’t R2 void? If the solder pads for R2 = the corresponding pads for R1, then leaving R1 alone & adding a Resistor at R2 should divide R in Parallel. If you can rob a wee Potentiometer from somewhere, use that & you’ll be the first to know! (I’ve done testing in situ by just leaving off the reflector; but I assume you guys already know all that.)

OTOH, tracing the ends of R3 makes me doubt any of that! Does R3 just act as a jumper to connect R2? (I’m guessing that means you could add even more R, which seems weird to me…)

Can you tell what chip they’re using at IC1? I’d love to look at the datasheet.

Thanks for taking the time!!!


Can this driver be run with a 14500? If so, could you measure current with a Li-Ion? Do you have any LifePO4 cells to measure current from? I'd like to compare this to my F20 driver.


So far all of the drivers like this that I have seen(and I check every site I visit for them) max out with either 2AA or 1 lithium primary at best.

The IC seems to be PAM2803 which is a 3W boost driver.

Thanks Microa.

The Nanjg-110 is compatible with 2 AA or 1 CR123a/1 LiFePO4. Whether or not 1 LiFePO4 will require boost depends on the forward voltage of the LED. 1 LiFePO4 works great for a Nichia 219 because they have a higher Vf than most Crees.

I modded one of these drivers with R1=R2=220 milliohm for 110 mohm effective. It measured it drawing >2 amps from 2xNiMH with a crap meter. I have a feeling that input current over 2A is a little much for the little inductor and efficiency is probably hellish, but I haven’t measured output current. It looks like R3 may be in series with R1 and R2, but I’m not positive. I wish I could find a tiny trimpot locally; maybe I’ll order one from eBay for future endeavors.

You can download the data sheet from here
What is the size of the inductor. A 2.2uH 5.8 x 5.2 x 4.5mm inductor can handle 2.3A Idc Max. However, I feel that you had pushed over the IC’s limit.

Look to your scrap bin! Old MODEMs, old power supplies, old telephones mostly all had trimpots here and there. Same in spades for an old “tube” TV (meaning picture tube, not pre-solid-state, although if you still have one…) or monitor.

I’ve heard rumors of trimpots in cellphones, but haven’t accumulated many of those.

IIRC, one of these drivers actually comes with a trimmer, and IIRC it wasn’t useful for normal batteries… The pot was to adjust Vf, which always seemed strange… It would make a good parts donor.

Use it up, wear it out. Make it Do or Do Without!

I got two of these today but the stock resistor seems to be a 0.1ohm…?
So I am confused about your mod, was this another Version before?

will this driver work with a 4.2v battery ? i want to boost the current on a uv led.

No, it stops boosting above 3.6V (this is datasheet value; actually it happens ever earlier, at about 3.3V)

ic ,thanks.

2AA/AAA or 1 CR123 :wink:

incase anyone’s interested here’s a direct datasheet so you dont have to try to read the chineese / chinglish.

Is any of this accurate?

I’ve reviewed the datasheet and I’m reasonably confident that you two are misunderstanding it. Help me understand what makes you think these things?

I wouldn't think there's a need to use a boost driver for a UV LED/4.2V cell combination, unless the Vf is at or above 4V.

Of course, I've not worked with UV lights. Can someone enlighten me?

from a small test i did i couldnt drive a chinese “xpg” uv led more than .9amps direct drive.

If it’s the green base XP looking one you will definitely need a boost driver from a single Li-ion to reach full drive current. They’re not bad emitters (actual output is very good) but they have a very high vF.

yeap its the green one

I’ve got 6 of them I’ve tested but have only built two light’s so far. I put one in an old Fenix 2AA light (boost driver) and it ran great at the 1.5A current. I put the other in a Supfire A6 with a 105c, it would only do ~.7A off a 18650 so I zener modded the driver and run it from 2x CR123 at nearly 2A.