The There Are No Stupid Questions Thread

I was surprised a few weeks ago to discover they actually exist: Keeppower 18650 3500mAh (protected) - 10A flat top - 18650 - Li-ion - Oplaadbare batterijen | NKON

I’ve got my new XTAR PB2. I’ve noticed this ongoing theme; after using it to charge my phone, it’ll say something like “75” battery life. After unplugging my phone, it’ll jump to 68, or something of the like. I think this is from voltage shenanigans, but why exactly does this happen?

Similarly, when the powerbank gets low (say 30% and lower), when I activate the screen on my phone the powerbank seems to just shut off. The screen LED disappears, it stops charging, etc. After unplugging it and plugging it back in, it begins charging again, with the same situation as before - a lower percentage. I’m guessing this is once again voltage shenanigans; the phone voltage increases under load, it messes with the charging, and things get all funky. What’s going on? Is this bad for the phone/battery?

Lastly, how much efficiency loss should I expect? Let’s say I have 4000 mAh worth of battery in my PBS2, and my phone has a 4000mAh battery. In an ideal world, 1% on the PB would be 1% on the phone, but obviously that’s not the case. Is it closer to 1% on the PB = .75% on the phone?

Protected flat top seem to be more popular 3+ years ago, but are not seen so much these days.

I don’t know if you can really call it a “flat top” since it has a wide, but short button top. They have to connect the strap to the top electrode somehow. If they did not add a cap of some sort the end would not be flat. So they use whatever cap they can. You end up seeing wide and narrow button top and with slightly different heights. It is all a mess with no real standards. :confounded:

It is trying to predict battery life based on calculations of voltage and load. This is very hard to do with accuracy. You can not expect good accuracy for predictions.

This stuff is very specific to the PB2. It has it’s circuitry designed a certain way. You’d need to ask the Xtar people these specific questions.

Hard to say exactly what the efficiency is, but I would not think it’s in the single digits of efficiency, but I really don’t know. Since the PB2 can output 5v from a single 4.2 volt battery it has to have a boost driver of some sort. Boost drivers do produce a loss in efficiency. I’m trying to decipher HKJ’s review and it looks like on battery power alone the efficiency starts at 90% and slowly drops to 85%. This sounds about right to me.

Also, remember that most batteries are rated for capacity by measuring all the way down to like 2.8 volt or less. The PB2 powerbank only puts out 5v from battery only until it’s batteries are down to 3.2 volt. So if you are using two 2000mah batteries you will not get the full 4000mah out of them (assuming they are wired in series, maybe not, but you basically can think of it as 4000mah). How much capacity you actually get will be based on the discharge curve of the particular batteries you are using. Some drop like a rock after 3.2v and some keep going a long time after 3.2v. I would probably use the newest, best high capacity cells I could, like Samsung 35E or equivalent in order to get the most out of the powerbank.

Sorry I can’t answer too exactly, but hopefully it helps a little.

How come some of you guys buy/have the 2 or 3 of the same lights?

You gotta ax yourself, “Would I be happy if my one’n’only got lost, stolen, broken, etc.?”.

If not, you get a spare. Or two. Or three.

In the case of lights with different emitters, because they perform very differently but the owners probably like all the other aspects of those lights.

Other people get them in different colors, metals, etc. which I don’t get but that kind of “collector” mindset is common for lots of hobbies.

:+1: :+1: :+1:
For the ones that really matter

Will I be able to put a stb90 gen 2 in my convoy L6?

Is that the correct name? Search turns up nothing.
I think DB Custom was building a light with similar emitter, but I cant find it.

Transpo. :laughing:

SBT-90.

Why do we park on a driveway and drive on a parkway?

Okay, I was confusing it with CFT-90. That is the hard one to mod and is what DB Custom is using.

SBT-90 can be bought on 20mm star and is 3v so should be simple to put in L6, right?

So I bought a used Sofirn SF11
in the classifieds here. turns out the emitter came off its base, and rattling loose in the reflector.

Where would I find a replacement online: an emitter with base plate, please.

Looks like the previous owner used some phillip screws to secure the base—with a tilt.

Thanks in advance if you choose to reply.

You mean the led came off the metal disc? You can buy replacements if you can solder. Where are you located?

You can buy this for $6.50 plus shipping from MTN E.

You need to know the diameter to order the right one.

Afaict it only comes in CW, dunno if that takes it out of the running. :laughing:

It’s good up to 9A from what I quickly recall from the sheet, so hopefully it wouldn’t cook itself to death.

So… yeah, looks like it should work fine.

Am in Mass.

Don’t want to think of all the possibilities, which LED will the SF11
Take.

It’s a simple matter of desoldering the two leads, and resoldering the new
On once one get the proper LED. The person used two Phillip screws to anchor the Led plate.

The two screws are a bit lopsided. A hack job, I guess….

And the LED became detached….

Would appreciate the part #, if someone is in the know.

TIA.

Mass is Massachusetts, USA? I would order from MTN. The SF11 comes with an XPL stock. You can choose your color, CW, NW, etc… You just need to find the diameter, like 16mm, 22mm, etc…
The screws are probably factory, they are there to keep the MCPCB from rotating.

Yes, Taxachusetts.

Thanks for the info. Screws seem to be from the local hardware. Designed
For countersinking.

Turn of events is forcing me to delve deeper into the realm of flashaholic tinkering
Than I was prepared to do. LOL

But it is a shame to deep six an otherwise working light. :beer:

While its entirely possible , likely even that other life exists out there, it is also equally possible we really are the only ones , so not naive sadly