NiWalker Vostro Black BK-FA09S

Although it’s a matter of definition, I do think all these cells you mentioned are considered high drain cells in the flashaholic community; meaning 10+A. I also believe that battery configuration, i.e. 4P, 4S, 2S2P etc, is initially not relevant to current draw (=power requirement) from the cells. Let me give you example:

For simplicity’s sake V = 4.2V (no sag), and we draw 1A from four cells.

4P: P = 4 cells x 4.2V x 1A = 16.8W
4S: P = 16.8V x 1A = 16.8W

Different driver types as a result of battery configuration leads to different efficiency and different losses, but the initial power requirement remains the same.

High drain cells or not is a matter of definition. But I believe that battery configuration makes a difference because it’s a 12v emitter, you don’t have to boost the voltage to match the emitter requirements when they are in series. If you use 4P or 2S2P you would have to boost the voltage creating a bigger current draw from the cells.

I read this regularly, and I disagree. let me give another example. So 1 XHP-35 emitter (12V), and there’s let’s say 1A going through the led. Meaning the led consumes P = 12V x 1A = 12W (simplified numbers)

For simplicity’s sake I take battery voltage = 4V
Battery configuration 4P (= driver input voltage = 4V):

Total current draw = 12W/4V = 3A.
Current draw per cell = 3A/4cells = 0.75A

Battery configuration 2S2P (= driver input voltage = 8V):

Total current draw = 12W/8V = 1.5A
Current draw per cell = 1.5A/2cells = 0.75A

So you see, current draw per battery remains the same. As mentioned before, variables will determine the total actual power requirement, but the initial power requirement remains the same, independent of battery configuration.

Edit:

Yes, with 2S2P and 4P you need to boost the voltage to the desired 12V for the emitter. But boosting the voltage does not mean more power, thus more current per cell (current is related to power) is required.

Aren’t we only talking about driving a single xhp35 hi for this particular light. If we were talking about something like the TM28, which also takes 4x 18650, yet is driving 4x xhp35 hi, high drains become very relevant to the topic of powering the light. With the BK-FA09s the cells are give 1/4 the amount of LED’s. Granted it’s an overdriven LED but still, regardless of series/parallel the single LED is not going to require 4x high drains to get it’s amps, although it won’t hurt to use high drains either.

A TM28 in either 4s or 4p will require high drains if hitting its max output, BK-FA09s will not. However, I think the BK-FA09s may get a little boost in output if using high drains because less possibility of some resistance. At least I think that’s the case. I’m still rather fresh with all this stuff.

I think you’re absolutely right; old school 18650B should do the job. And also agree that modern 10A cells can only make the light perform a bit better, as in less voltage sag so a bit less current meaning less heat and a bit more runtime etc.

It’s always nice to learn something new :slight_smile: , thank you for clearing this up :beer:

On lights that use a boost or buck converter the voltage drop under load decrease the total power availiable, so high drain cells gain some Wh over low drain cells

Lets say the LED and driver need 30W on turbo

A 18650GA cell gets like 0.15V less drop over a protected low drain cell like 18650B
So 0.15Vx(14Ah)+3.6Vx0.4Ah=3.54Wh more energy
So 7 minutes more runtime

I just got my BK-FA09s this morning. I tested it for lumens against the K70 and got 2565 lumens for K70 and 2520 for FA09s. The reflector dimensions appear the same between the two. The K70 head is wider though to accommodate the extensive thermal fins. The FA09s is a wee bit less cumbersome. The FA09s has much more neutral tint, maybe 5,000k, and much nicer in that specific regard imo. In initial testing, I wouldn’t shy away from BK-FA09s if I was considering a K70, especially if I like neutral tint.

2520 lumens… Niwalker keeps on impressing me… And the price… Just nice :wink:

Would be even better if we could get a discount code for it from somewhere.

I had bought a K70 several months before with a coupon,at a very good price,but this door is closed now for ever.Unfortunately.

Now 159.95$ at hkequipment, i remember it being less than that (wasn’t it something like 129 ?) last time i checked :cry:

Yes, introductory was less. When I saw it, I think $134.99 and used a 1x 15% ebay code for 114.7 from HKE. A week or two later it was $159.9 any and everyplace. I got lucky. So far though, it looks like a nice NW alternative to the K70 which is $179. typical.

I know that Martin has a deal for the BK-FA09S,but I have both a K70 and a TN42,so I pass this one.

Yep me too, but IF it was a E-switch light, I would of snagged one up! :+1:

Are you still digging the BK-FA09 ?

Recieved mine yesterdy :expressionless:

Wow, this is a real lightsaber compared with my Olight SR91 :+1:

I must say that I recently picked up this hobby after a few years and the only thrower I can compare with is this Olight sr91 :wink:

First impressions, nice light and the magnetic power ring does the job nice.

Light came with a little humidity inside the reflector? So after drying no signs inside the lens when power up.

Battery carrier is the most fragile part I believe, put some Efest IMR 3500 mAh inside and this is damned a tight fit :rage:

Had even to tighten the screws that holds the battery carrier together.

Wonder how long this carrier hold together, also you must be very cautious when removing the battery’s you don’t dammage the top of the battery!

Springs in the carrier are very thick and stiff.

Overall very, very impressed by the performance of this light!

got mine too and totally agree on all points!

i think i change the springs to thinner ones

due to the 4S i am not afraid of high Amps

+1. The holder is a battery vice. I saw on another forum a pic where someone’s carrier simply busted apart when they were trying to get the cell into it. It’s not what’s mean by tight tolerances. :frowning:

Does this light step down? If so, how long can/does it run before having to do so? And can you tell when it does?