Q8, PMS SEND TO THOSE WITH ISSUES BLF soda can light

Sorry about that. They were supposed to link.
I’ll fix them in a bit.

0.35V basically means that your batteries are dead, too much discharged to be considered safe, even if they do charge up again.

I wonder how that could have happened inside a Q8? When the light is switched on it has a low voltage protection and will shut off with the batteries still at 2.8V. When off, the green indicator light will drain your batteries lower because of the small drain/MCU not powered, the LVP will not work (at least that is what I have understood), but that green led uses so little power that it should drain the batteries in years, not weeks.

Yes, don’t try to charge them. Keep them at a safe place and dispose them properly.

battery at 0,35V ? wow… that is kinda insane low… all individual give those kind of readings ? thats not even half a volt if thats true…. i havent seen anyone post such a low voltage….

I wonder if those batteries are even legit and not some garbage cells…

Really toss these batteries its just dangerous to try them in a light and turn them on, dont charge them either! :person_facepalming:

Unless you used the batteries in some device that ran them way way down, you recieved bad cells. You should contact the company you bought them from and explain that they never worked and you just now bought a multimeter and measured their voltage at 0.35v so they are ruined. See if they will send you replacement cells.

The first thing you should check when buying new batteries is the voltage. They usually get shipped around 3.4-3.8v. Never fully charged due to airline safety rules. If they arrive to you below 2.5v then they are ruined. Once a lithium ion cell goes below 2.5 volts it forms crystals inside which screws up the chemistry. If you put it on a charger it can get dangerously hot and possibly vent or catch fire. So mark those batteries as ruined and don’t use them. It’s not worth the risk.

If you dont have a warranty, usually Banggood has good prices on button top 30Q. I got 4 for $20 shipped a year ago, but at the moment they seem to be $29 shipped.

Illumn.com has them locally for $22 plus shipping.

IMR Batteries has them for locally for $24 plus shipping.

Hopefully you can get them replaced at no cost.

Well, good thing I didn't try to charge them *twice* after it stopped working. :FACEPALM: :FACEPALM:

since u are from usa, buy from illumn or something that sells legit stuff and u be fine.

Oh wait, I see your earlier post where they did work, but now they don’t. I’m guessing they got drained while in the light. This should definitely not happen unless you have a defective driver.

What you need to do is measure the parasitic drain on your light. You do need at least one proper battery to do it so this may have to wait till you get one, but here is the whole procedure.

Basically you can use one cell and hold it on the head like this similar light.

You keep your test leads in their current meter spots which is COM and V Ω mA.

Then set the dial to the green DCA section 200m. Apply the test leads to connect the ground side, but leave the flashlight off. The light should blink twice, then wait about 5 seconds and it will go to sleep mode. Then you can get a reading. Assuming it’s not overloaded, you can switch the dial to the next 20m then 2000μ and then 200μ. Normally this light measures about 30μ when asleep (green switch light off, with green light on about 130μA) which is super low amperage. Since you might have a big drain, we start at the higher 200m setting and work our way down.

It’s pretty rare for these lights to have a big drain, but they do happen from time to time. If both your lights check out fine, you might have had one bad battery which was self discharging. Since they are all in parallel, one bad cell could pull the other three down. This is also pretty rare. 30Q are very high quality cells. Still, something happened and we need to find the source of the problem.

The batteries I have came with the light (bought it used) so I’m not sure I’ll have much luck getting them warrantied.

I’ve got a set on the way from Illumn and I’ll make sure to pop them on the meter, then charge before using.

If these die, I’ll report back, since there’s probably something wrong with the light at that point.

Thanks for all the help.

I have a flat top Samsung 26FM and since I’m holding it in place, thought it would work for the test.
I get –08.7 on the 200m setting on my old light and –05.6 on the new one.

Why risk ruining 4 new cells? It’s pretty easy to measure parasitic drain. Then you know if there’s a problem or not.

I wonder if the person sold it because they knew it had a drain problem? Maybe. If the driver is bad, you can get another for $10. To swap drivers requires soldering 5 wires.

If you can’t solder, well, another option to “fix” it is to just twist the battery tube when your done using the light. This cuts all power. It won’t drain at all. This is the best way to store a light.

I posted the drain I’m seeing on both lights 1 post up.

I think your not waiting the 5 seconds for the reading to change. On my light I initially see 5.2mA (milliamp), but then it drops to 0.11mA.

Just a note, I said the parasitic drain should be about 30μA (microamp). I was going from memory and that is with the green light turned off. With the green light turned on it’s about 130μA (0.13mA).

With the green light on, it starts at –08.7 then drops to –03.6 after the 5 seconds.
Both are over reading for the μA settings.

To make sure I’m doing this right, should I have the black on the inner threads or the outer ring of the driver?

Usually the test probe polarity doesn’t matter for current, but if you see a negative number, just switch the leads around. It should read the same just without the minus sign. Oops, I misunderstood. Pressing against the outer driver ring is best.

So the 8.7mA drops to only 3.6mA after 5 seconds? That’s 30 times too high. Let’s see, with 4 x 3,000mah cells that’s 12,000mah ÷ 3.6mA is 3,333 hours or 138 days for it to go from 4.2v down to about 2.8v or so. Let’s say you were pretty low on power when you last used it, say 3.2v. About 30 days doesn’t seem like enough time to drain it to below 2.5v. Especially since the parasitic drain tends to drop a bit as the voltage drops. Weird, I might be off in my numbers, though. Also, the drain might vary based on what’s causing it. It might have been worse before you checked it over. Stuff like filtering capacitors can short or 7135 chips can leak. Who knows? You’d really have to trace the current leak to find the problem.

Did you check the new light?

It appears to ramp down. It goes from 5.6mA to 118μA after the 5 sec.

I double checked the old one and it doesn’t ramp down any further.

Okay, that’s good. That’s what it’s supposed to be.

So something on that first lights driver is bad. With a decently powerful soldering iron you can swap drivers. Maybe you know someone who solders?

Or else just always twist the battery tube after your done using it.

Here’s the link to the driver if you are interested.

#Aliexpress US $9.52 | BLF Q8 Driver Chip Q8 Circuit Board

Awesome, thanks!

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thank you for your sharing