Reflow 12v to 6v mcpcb

Sirstinky · 2019-11-18T01:07:31.000Z

I have an xhp70.2 on a 12v mcpcb, 12V mcpcb, but I’d like to reflow it to a 6v board. If I get a 6V mcpcb can I remove the led from the 12v board and move it to the 6v?
Thanks

Cereal_killer · 2019-11-18T01:17:20.000Z

Yes but you do realize it’ll then be a 6v led right? Just making sure that’s what you wanted.

There is no difference in led’s, no such thing as a 6v or 12v XHP70, it’s all based on how the mcpcb pads are configured.

Lights-Out · 2019-11-18T03:01:15.000Z

Does a xhp-70.2 take the same amps driver wise ? I academically purchased 6v one from MTNelectronics for a 2cell light will that blow the led

Cereal_killer · 2019-11-18T03:16:14.000Z

Same amps as what? Not sure what you’re asking… Was the original 12v or 6?

moderator007 · 2019-11-18T03:46:52.000Z

The 6v xhp70.2 should take around 20 amps with good heatsink. The 12v should take around 10 amps with good heatsink.
A copper mcpcb is a must with these numbers. Are you asking if you can run a 6v led with a 12v driver or 6v led and 6v driver.
Can you link or post up a pic of the driver your planning on using.

Sirstinky · 2019-11-18T05:02:19.000Z

moderator007:

The 6v xhp70.2 should take around 20 amps with good heatsink. The 12v should take around 10 amps with good heatsink.
A copper mcpcb is a must with these numbers. Are you asking if you can run a 6v led with a 12v driver or 6v led and 6v driver.
Can you link or post up a pic of the driver your planning on using.

I’m wanting 6v since the led is going to be running off a single li-ion on a boost driver. I planned on getting the mcpcb from Kaidomain, dtp 1.6mm x 20mm. I don’t think it will be taking more than 5A in that setup.

Sirstinky · 2019-11-18T05:04:00.000Z

Cereal_killer:

Yes but you do realize it’ll then be a 6v led right? Just making sure that’s what you wanted.

There is no difference in led’s, no such thing as a 6v or 12v XHP70, it’s all based on how the mcpcb pads are configured.

Yep, I’m wanting the 6v so I can run it off a single li-ion boost driver. 12v would be too much to ask of a single cell.

Sirstinky · 2019-11-18T05:05:38.000Z

Lights-Out:

Does a xhp-70.2 take the same amps driver wise ? I academically purchased 6v one from MTNelectronics for a 2cell light will that blow the led

If it’s 6v configured you can run it off 2 li-ions with no issues.

moderator007 · 2019-11-18T05:56:36.000Z

Sirstinky:

Cereal_killer:

Yes but you do realize it’ll then be a 6v led right? Just making sure that’s what you wanted.

There is no difference in led’s, no such thing as a 6v or 12v XHP70, it’s all based on how the mcpcb pads are configured.

Yep, I’m wanting the 6v so I can run it off a single li-ion boost driver. 12v would be too much to ask of a single cell.

12v is no problem for a single good cell using a boost driver. Its the same as the 6v version except the current is cut in half to the led and voltage is doubled, same watts to the led and the same draw from the battery.

Sirstinky · 2019-11-18T07:24:02.000Z

moderator007:

Sirstinky:

Cereal_killer:

Yes but you do realize it’ll then be a 6v led right? Just making sure that’s what you wanted.

There is no difference in led’s, no such thing as a 6v or 12v XHP70, it’s all based on how the mcpcb pads are configured.

Yep, I’m wanting the 6v so I can run it off a single li-ion boost driver. 12v would be too much to ask of a single cell.

12v is no problem for a single good cell using a boost driver. Its the same as the 6v version except the current is cut in half to the led and voltage is doubled, same watts to the led and the same draw from the battery.

So if I get a single cell boost driver from China it will run my 12v led off 3.7v? That would be asking the boost driver to triple the voltage. I’ve run a project with a hyper boosted led and it’s not good for efficiency and run time.

moderator007 · 2019-11-19T04:40:26.000Z

Most if not all these 6v 12v boost drivers are using a High-Efficiency, Fully Integrated, Synchronous, Boost Converter MP3431.
After 100ma output the efficiency is almost identical with either 6v output or 12v output. The difference being around 3 to 7% less for 12v depending on input voltage. Both should be about 90% efficient with a voltage over 3v in with over 100ma output.
Its the same Boost converter used in this driver. [ GXB172 - 50W Single Cell 17mm Boost Driver! ]
I built a couple and changed a few resistor values that allow 12v operation at 3.2 amps usig a xhp35.2 led. The MP3431 is rated at 50 watts but I pushed it a little over 60 watts, its a beast.
Data sheet for MP3431. Efficiency data is about 1/3 down the page.
https://www.mouser.com/datasheet/2/277/MP3431_r1.0-1384411.pdf
.
I’ll add that these drivers from china are probably not built with some of the best components like Loneoceans driver. They may handle more power mods fine and they may not.

Sirstinky · 2019-11-19T05:08:53.000Z

Interesting. I thought as the voltage went up emergency went down. The last Chinese driver I got runs real hot.

Where would I get a driver like that and how much? I’d rather not pay more than $20 for a driver.

ggf31416 · 2019-11-19T13:16:15.000Z

The Sofirn C8G (12V XHP35 HI) goes from 2A to get 780lm to 8A to get 1600lm, losing half of it’s efficiency. Lower LED efficiency at higher current can explain at most 25% of it. I guess cheap drivers are not up to the task.

moderator007 · 2019-11-20T03:28:56.000Z

Sirstinky:

Interesting. I thought as the voltage went up emergency went down. The last Chinese driver I got runs real hot.

Where would I get a driver like that and how much? I’d rather not pay more than $20 for a driver.

The Loneoceans driver has to built yourself.
Judging by their stated numbers this should be based on the MP3431. I can’t be sure, no pic showing it, but the current numbers seem about right with what I tested.
Page Not Found - Aliexpress.com?
This one for 12v operation I can’t be sure about either. From the pic it shows a fb resistor of .050 ohms for 1.1 amp output. The GXB172 in 12v operation uses a .020 fb resistor for about 2.5 amps out to the led. So these numbers seem about right for the MP3431.
There is also boost drivers based of the TPS61088 boost converter that do well, there just not as powerful as the MP3431 based drivers.
Boost
Alot of good info in this thread. Buck and Boost Drivers, Testing, Modding, and Discussion (Pic Heavy)

Sirstinky · 2019-11-20T07:32:36.000Z

Thanks for that info. I don’t think I’m ready to build my own driver yet. I think I’ll stick to the Chinese drivers. I think if I ever did spend a lot of money on a driver I’d get a taskled. Mtn Electronics has been perpetually out of stock on their high current boost drivers.

Lexel · 2019-11-20T08:32:01.000Z

Why do a reflow when you can short out a 12V MCPCB back to 6V?
Only 12V which are shorting out over the thermal pad can’t be converted

but the ones shorting over thermal pad are generally not use able unless you insulate the MCPCB from body using an N-channel MOSFET driver

Sirstinky · 2019-11-20T19:19:48.000Z

Lexel:

Why do a reflow when you can short out a 12V MCPCB back to 6V?
Only 12V which are shorting out over the thermal pad can’t be converted

but the ones shorting over thermal pad are generally not use able unless you insulate the MCPCB from body using an N-channel MOSFET driver

Level, how do I short it out? It is a 12v dtp board, the generic white kind like this Xhp70.2

If I can get away with that then I’ll do it, otherwise I’ll get a 6v board, desolder off the 12v board and solder it on the 6v.

Can I do it without solder paste? I dont have any.

Lexel · 2019-11-20T19:37:13.000Z

this board cant be modified

Sirstinky · 2019-11-20T20:41:28.000Z

Okay no worries. Good to know.