What if I direct Drived xpg2 (S2 bin) with a KingKong 26650

Flashlight Modding and DIY Parts
1

I have no problems direct driving with an 18650, but what about 26650?
I don’t know how much voltage sag a kingkong 26650 will have.

Can anyone that has done this before estimate how many amps will be drawn with DD KingKong 26650 on xpg2-S2

thanks for the help!

2

Many. Only use direct copper bond mcpcb. Solder that to the heaksing. If it does not solder to your heatsink I think you may as well forget it. I haven't tried it though. Just that I did make it work with a IMR battery and the brass heatsink soldered to the mcpcb.

3

Use HKJ's reviews. KK has a lot of voltage sag. http://www.lygte-info.dk/info/indexBatteriesAndChargers%20UK.html

4

That is great news! lol!
I went to his review: 4000mah kk

However, there is a chart that mentions “protection”? Not sure what that means.
Is this the graph that measures voltage sag? It is the only graph that has no time in the x axis.
Why are the lines perfectly straight? I would guess voltage sag as a curve of something, but idk. Clarification please?

Thank you so much for your help!!

5

Links to HKJ's website only work when using the "Advanced Post Editor" (look at "Input format" under the box you type your post in). I think you were linking to this review: King Kong ICR26650 4000mAh (Gold)

These cells have no protection, the "Protection test" chart simply illustrates the lack of a protection circuit. I think you are misunderstanding the graphs in general, "Ah" and "Wh" are not measures of time. Even the charts with time on the x-axis are useful to you. Take a look at the link at the bottom of the review, "How is the test done and how to read the charts". Hopefully that will help get you up to speed!

When I say "voltage sag" I am referring to the amount voltage falls below "resting voltage" while the cell is under load. I typically refer to the first chart, but the others are also useful.

In order to have a firm grasp on what's happening in a DD setup (including how much voltage sag you'll have and how much current you'll push) you'll probably also want to look at high current XP-G2 on copper tests done by Match and djozz here on the forum:

Match demonstrates the difference between the XP-G2 on direct-copper and standard aluminum stars in that thread with his graph "Cree XP-G2 Aluminum vs Copper Sinkpad". That's an important thing to understand.
6

haha, I was wondering why linking to that page was not working. thanks for the advice!
What I am worried about is using the battery freshly charged for the first 30 seconds.
I saw those links before, they are definitely useful (if battery had 0 voltage sag, max current would be around 5.5A)
I was planning to use that chart AFTER I found out what voltage sag the KK26650 had under different loads. But I don’t know how to read the charts posted on lygte-info

Could any of those charts be converted to something like:
Load1: 5A
Voltage1: 3.9V

Load2: 3A
Voltage: 4.0V

Load3: 1A
Voltage: 4.15V
?

In short, I just want to know if I DD my dedomed xpg2 with the KK26650, would it die instantly or not. I am hoping that it would sag from 4.2v to 4.0v (4.5A) If I DD the emitter.

Thank you for your help wight
If Led c

7

I don't think that what you want is available. Your only option is to pull both charts up side by side and just puzzle it out.

First of all, let's switch to graphs of KK's newer, stronger cells. That way you get worst case scenario. Start by looking at where all the curves start on HKJ's graph. As you can see, a 5A load will almost-instantly take the cell down to 4.0v. 4v in djozz's chart is still over 5A, but HKJ shows 7A gets the cell close to 3.9v (again basically instantly). When you compare 3.9v with djozz's chart... you see that 3.9v will not even give you 7A. So from doing that you quickly establish where to concentrate your cross-referencing efforts.

I haven't done it, but I understand that the XP-G2 will not poof instantly (at turn on) until pretty high currents. I have seen reports of poofing them with sustained operation at 8A or less though.

8

Alrighty! sounds good. My batteries come tmorrow so i can test them!
I guess i can DD an xml2 first to see if it blows up.

I am really paranoid about this is because I instantly blew up a xmlt6 before. I had 5 18650’s in parallel and I tried to DD it. ,
I will post my results after I finish testing it.

9

What star / MCPCB do you have your XP-G2 mounted on? This is critical information.

10

Noctigon, 2000git lapped copper cap. Used tiny bit of arctic silver 5 in the middle, and an extremely tiny trace of thermal plaster on the edges to make it stick.