testing amps with probes/ changing modes - question

Hopefully someone here has an answer to this……

I have 2 C8 lights I am testing:


Keygos KE-5

when I put a meter probe on the (-) battery end of the Kai and touch the other probe to the threads , each time I touch and remove the probe from the threads, it will change the mode of the light.

when I do this to the Keygos, it doesn’t change the modes, it will just stay on the high mode.

batteries are exactly the same. Is this unusual? Is there an explanation? Am I missing something, or is this too deep for me?

thanks if anyone knows ….


Not having either light it sounds like the keygos has same mode memory whereas the KD C8 has next mode memory.

Maybe one has forward clicky switch and the other has reverse clicky switch, don’t know for sure.

That doesn't make any difference in this situation, because he doesn't use the switch! He takes off the switch, and connects leads to the battery and body...

OK, how do people get amp reading for the different modes of a driver high, medium, low?

Making a solid connection between the negative post and bare aluminum on the body of the flashlight. Then briefly disconnecting and reconnecting very quickly. The driver doesn’t have enough time to reset; it’s just like using a switch.

Hello. After reading all replies, especially this one, I checked the 2 lights. This post is correct, the Keygos has same mode memory, the KD does not. Now what? How does one check the amp readings for the different modes on the Keygos? I tried it again, connecting and then reconnecting quickly the probe from the light threads. Funny thing, it seemed the readings would differ, but I know the light never made it thru the modes, I would have noticed the STROBE!

not being knowledgeable about these things, I don’t know what I would do with those readings anyway :frowning:

appreciate the replies … learning.


Unless I’m not understanding something, mode memory should have no effect on switching modes using a multimeter and pulling one of the leads off and placing it back very quickly. I have tested almost every light I own in this manner and they all work the same way.

I actually kind of dislike modes because of this functionality and having to run through the modes to get back to high mode (other mode measurements don’t really matter to me, but can be measured if you stop on them and maintain the connection).

If it doesn’t change modes by doing it rapidly, maybe that driver is a slow learner and needs to think about it for a while.

sorry about the quality of the video. Just wanted to show that the modes don’t change - you never see a strobe or S.O.S. mode. Afterwards I tried doing it slower like the other poster mentioned, no difference. Baffling to me.

My original HD2010 with the bogus driver would only test on high or medium from memory. I could only ever get one reading from it. The second one would test on all modes.

Vid is showing private.

I forgot to mention that some do switch slower than others, but if you’ve tried really quick to really slow disconnects… I’m at a loss.

It does work normally when using the switch?

Could the other modes be controlled by PWM?

I had a light I reviewed (think it's my SkyEye F13) that wouldn't change modes with meter probes but would with the tail switch. Actually I got a reading a few times, but it was random. Never figured it out.


Could it be the probes?
Too thin to bump the driver through the modes.

Yeah try it with something else besides the probes .. a third hand would come in handy .Sometimes you need to make sure the battery is pushed and held all the way in the tube ..

I'm assuming you have your meter set correctly to test amperage... right ?

I usually do it with the light face down since I don't need to see the beam just the numbers ..that way I can mash the one probe down hard enough to get good pressure on the spring that's on the driver .. without the meter , you will want to see the beam so put your light face down on a piece of plexi or across a couple of chopsticks ?? and try to get the light to change modes with a piece of wire.

If that doesn't work ..throw the light away ...the modes have run out of the light and are somewhere in your house . Call a lumen exterminator immediately .Modes in your home can be extremely dangerous as they breed quickly and soon you will be infested with mini-modes or multi-modes.

Boaz, you are not only a great preacher, but you’re hilarious!

Last night I actually got it to change a mode but who knows how it happened. I just kept mashing the probe all around the threads. Couldn’t get it to do it again however. I used a wire tonight instead of the probes, same result. By the way, on this light, the spring is in the tailcap. Does that matter? All I know is it works every time very easily on my KD C8, and not on this Keygos. I’d take your advice and throw it away but I think it’s one of my best lights.
I know zero about electronics. Some online flashlight bud taught me that probe trick, I thought it was pretty cool. Who could I impress with it? He was the same one who talked me into buying a DMM, and I learned how to read volts, and amps, hoo-yah! Whatever. Around 35 lights and maybe close to $500 later, and what for? Whoops, #36 on the way in the Tangsfire C8. Maybe I can change modes on that one with the probes!
I have appreciated the helpful people here at BLF, but I have to say I’m a bit surprised no one has an answer to this problem. I mean, shouldn’t it be black and white?
I’m thru with it, it’s not an issue, really. If I was into electronics I would WANT TO KNOW!

… hello operator, could I get the number for the local lumen exterminator please?

Sounds exactly like my experience! Every so often I could get my SkyEye F13 to change modes, but it was only by accident and couldn't be done again on purpose. I have no issue with numerous other lights. It's not you or anything you're doing; it's something with that driver.