Circuit board help

I want I build a triple xpg r5. What board do I need to use if I run the triple in parallel , and what board to use when running in series? I will be using a one battery setup using a aw16340 or a protected 16340. I want as many lumens as possible. What are the voltages I need to figure out,etc? Thanks

tattoosteve99 said:

I want I build a triple xpg r5. What board do I need to use if I run the triple in parallel , and what board to use when running in series? I will be using a one battery setup using a aw16340 or a protected 16340. I want as many lumens as possible. What are the voltages I need to figure out,etc? Thanks

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Hi tattoosteve99,

Current draw of AW16340 is about 2.2A.
So I think that this is just right if you think about building of 1 cell light.

zanzan

A LiCo AW 16340 should be like other LiCo chemistries -- good for up to 2C max discharge rate, or about 1A. A 6x7135 driver is too much for that cell. An AW IMR16340 is good up to 8C discharge, or about 4.4A.

However, if you want to get max lumens from a triple XP-G, you need to deliver 1.5A drive current, which is the max recommended in the XP-G datasheet. For 3 in parallel, that means a 4.5A driver. If you use a 7135-based driver, that means that the cell will have to support a 4.5A discharge rate. That exceeds even the IMR16340. And even if the IMR16340 were discharged within spec, the run time in regulation will be essentially nil. At 4.5A draw, an IMR16340 will stay above 3.5V probably for about 3 min (see here for IMR16340 discharge curves).

For three XP-Gs in series, you need a boost driver that can deliver 1.5A drive and boost ~3.7V up to ~10V-11V load. You are looking at ~15W right off the bat, and that ignores the fact that drivers are not 100% efficient. If we assume 80% driver efficiency, you are looking at about 19W. A single 16340 is roughly 3.7V*0.55Ah = 2Wh. You will get a calculated run time of ~6 min. Of course, this also assumes that such a boost driver exists.

If you really want to drive a triple XP-G at max lumens, you need to re-think your battery configuration.

Thats some good advise. Maybe I will drive it at a lower rate, but still I want a bright light. I already have a kerberos triple and it runs on one battery (IMR16340) perfectly. I'm not looking for a light to be brilliant just bright enough to burn my friends eyes at close range lol. So what could I possibly do to get good brightness with at least decent runtime on 1xbat config? Thanks

The kerberos product looks like a triple XP-G in parallel, powered by a 2.8A 7135 driver. Thus, each XP-G gets about 930mA drive and Vf is probably around 3.3V (based on the datasheet, in real life I bet it's lower than that). I assume that you are powering it with 1x17670 or 1x18650? If you are using an 18650 with say 2500mAh capacity, the kerberos triple XP-G draws about 9W. Based on a capacity calculation, you could run for about 3.7V*2.5Ah/9W, or about an hour. Since Vf is low (I'm assume that it is 3.0V), most likely you'll run in full regulation for basically all of that calculated hour.

If you are satisified with output and run time with your kerberos triple, then use the same driver for this new triple. Check cpf for a multimode 8x7135 driver.