Niwalker BK-FA02S --WARNING: a direct short waiting to happen in the batt carrier

LED Flashlights – General Info
1

Hello,

I received today my Niwalker BK-FA02s.

I tested it a while ago and this is what happened:

I put in 4 30Q cells and fired it up. The light could hardly shine, regardless of the position of the rotary mode selector.

Perplexed, I removed the tube, took out the batt carrier and notice two cells were warm.

I removed all four cells and nearly got burned by the 2 (-) springs inside the batt carrier which are now collapsed, while the remaining 2 springs were still of normal height, and the real hot springs are now almost half of the height of the original springs. What could possibly caused the short ? I am sure I observed the correct polarity.

What could possibly have happened? Is the carrier of the BK-FA01s of different internal connection in the carrier and it’s the one I received?

Below is the aftermath….

Edit: Jan. 26
Note in the photo below, the 2 original stainless-steel springs that collapsed at the bottom of the carrier were replaced with the newer ‘golden’ springs of the same base diameter.

I decided to have the collapsed springs changed with the ones I bought from Ric of Int’l Outdoor about 3 years ago to use in my K40’s carrier.
After the ‘melted’ springs were changed with the new ‘golden’ springs, I tested to carrier again. I put in a storage-charged 30Q and oh boy, a spark of flame and a puff of smoke erupted, then, as I hurriedly took out the cell, the photo below will show what transpired.

A Direct Short is waiting to happen!! (of which admittedly I failed to notice about the protruding, original solder)




Fast forward to Mar. 20, 2017:

Today I received the supposedly “new, improved” battery-carrier from Niwalker.

In the photo below, while the solder blob that caused the electrical short in the original carrier is now smaller and shorter in the new carrier (right), it is still well within ‘striking distance’ as to rub and tear off the cell’s insulator (as has happened in the original carrier) and create another direct electrical short.

Photo below shows even while the cell is still not properly seated and still at angle inside the carrier (not straight up yet), the cell’s negative casing is still dangerously close to rubbing and tearing its insulator when it hits the ‘smaller’ solder blob of the the new carrier if seated properly. I did not attempt to seat the cell straight up because of two reasons: the solder blob is just microns away, and the springs of the carrier are too stiff for comfort. In fact, I even ground away some of the solder blog to make it shorter.

Well, another result of the ‘too stiff’ springs:
I tried to put in cells in the carrier’s side where there is no solder blob, but when I removed the cells, due to the extreme force exerted by the springs, it forces the cell’s insulator to ‘plow’ into the brass protruding positive ends that it deforms, if not tear, the insulation. Remember, I even use the shortest cells around.

2

I shorted out my TM16GT and one of the springs is now not quite right. I had to pull it out with a pair of needle nose pliers but that was whilst I was supidly doing a current check ages back.

Good luck at finding the problem and you’re lucky the light didnt go bang!

3

You mean you shorted it? My case is different, as explained above.

4

Interesting:
Sounds like what I had happen to a Acebeam a few years back, with a battery carrier issue. They had to redesign it to Properly handle the amperage draw. So, that makes me think you got a carrier that has a problem. Maybe a bad connection or cold solder joint? I don’t have one of those lights, so not sure how the carrier is designed. Have others with this light had this problem before?
It also sounds like what happened to a carrier I made for a OL custom maglite. It melted too, and the cells burned my hand. All because the Amperage draw was too high for my design.

Good luck.

5

I just noticed that the voltage of the BK-FA09 is 11v to 16.8v, while the BK-FA02s/BK-FA01s are 4.9v to 8.4v.

Assuming batt carriers were mixed-up, will it have a bearing in my case?

6

yes. I shorted the light out by accident. the spring pretty much welded itself into a shorter length.

7

my first though is when you put the wrong battery carrier in the light two cells were in series but facing with both plus or minus poles together
like —- instead of+±

8

Yup, that is my thought too. The carriers will almost certainly be wired differently so by putting the carrier in you would have basically shorted it out with the carrier. maybe you can check the carrier connectors on the light to the carrier connectors on the carrier. Might be more obvious that way.

9

I’m sure I inserted the cells in its correct polarity, and though the manual says the batt carrier can be inserted either way, this carrier can only be inserted in one way only as there is a clicky switch on one end of the carrier and it goes to the end near of the tailcap with a rubber clicky cover.

10

Sounds like you’ve got the wrong carrier if you can only put it in one way round as the website clearly states “Battery holder can be loaded into searchlight either way”

EDIT… .this website: Thrower | Markus Speckmeier IT-Consulting Blog

Gute Sache: Beide Vostro-Modelle haben nun einen Clicky am Lampenende, der zum Ein- und Ausschalten und damit auch zur Unterbrechung der Stromversorgung gedacht ist. Damit lassen sich die Lampen “hart” ausschalten und es gibt keinen Kriechstrom mehr.

Good thing: Both Vostro models now have a clicky at the end of the lamp, which is intended to switch on and off and thus also to interrupt the power supply. This makes the lamps “hard” off and there is no leakage current

11

Battery carriers suck.

But good luck solving the issue.

12

if the battery carrier can rotate in the light, it provides 2 poles to the light,
good thing is you have not fried the light with 4s voltage

My thought is one battery was in wrong direction, so you get an effective voltage of 2s
inserting the battery carrier to the light and closing the circuit over a FET or converter
now current starts to flow through all 4 batteries, but one is in different dierection

the outcome is that one cell will work against the other 3 cells as it doesnt like to be reverse charged

but as you said the carrier can be separated by the switch in the tailcap you arenot having a 4s carrier
instead you have a 2s-2s carrier
positive light - switch- negative light 16.8V
positive light 2+2- switch 2+2 negative light 8.4V
you end up with 16.8V and most likely burn the driver down turning on the light
positive light +- switch -+ negative light 8.4V but wont allow an effective current flow, and all current will heat up one cell
while a high reverse current will flow through the ++ cells heating em up

13

(borrowed images)
Heres the BK-FA02s carrier… is this what yours looks like? It looks like a 2P-2S arrangement for 8.4V. Not sure what would happen if you connected your light to a 16.8V (4S) carrier. But thats 2x the voltage. I would think most definitely that would have a significant bearing. Flashlight circuits have some degree of safety factor built into them to accommodate for production variations… but double the max Vin would be pretty unlikely.

14

If your carrier is the old type one , without the switch means that can be put in , disregard witch side going in (double sided) !

BUT... in a review done here , on BLF, I do not remmember by who , has been noticed that inside the body that hold the carrier is a spring that COULD short the center (+) of the carrier with the heads of the screws (-) . I've noticed that on mine , so , using a long nose plier I insulated the spring up to the first turn with silicone insulation (was a 18 size or so...). Maybe is your case , I'm just saying...

Good luck !

15

Yes, the carrier that arrived with the light looks like that.

16

Warning: A direct short waiting to happen in the battery-carrier of this light…see the op.

17

the same thing happened to me in the original model. i thought i put the batteries in wrong. when the light wouldn’t come on i opened it up and the batteries fell out because the springs shrunk. i put in protected button tops because flattops wouldn’t fit any more. used the light a few minutes and it was fine but the next time i turned it on it wouldn’t work. i inspected the battery carrier and found a trace on the battery carrier’s circuit board melted. i believed it was caused by the wide anode on the flat top making contact with the trace. of course i didn’t figure that out until i paid $30 for the repair

18

I will be contacting Niwalker about this, for IMO, this design is not only faulty, but extremely dangerous. :person_facepalming:

19

In the meantime, I wonder what safe remedy can be done to the battery carrier? (Please read the op)

I hope some of our more experienced members here have a thing or two on this matter.

Thanks in advance.

20

You reminded me BTU shocker modding days.