The There Are No Stupid Questions Thread

Quick look at the 4x18a shows that uses the xhp 70.2. This is a 6 / 12 volt LED. The sbt 90.2 is a 3 volt LED. So in order to run it you need to install a 3 volt driver plus the work involved in mounting and centering the LED.

The stock driver must be a Boost design. It’s not a common driver layout due to the large battery contact ring. You’d need a driver similar to the Q8 (which happens to be a DD FET driver and should work well with that led). Most likely you’d loose the built in charging.

As a rule
man’s a fool.
When it’s hot
he wants it cool.
When it’s cool
he wants it hot.
Always wants it
what it’s not.

I would accept that as an axiom.

Jasonww- thank you so much for this info. I appreciate the guidance towards an appropriate driver as well. Are you saying that the 4x18a must be a boost design, and that’s not common? Or are you saying that a boost design is needed for the sbt90? I’m assuming you said that the 4x18a is a boost design considering the 6/12 volt led … thanks !

It’s dendroaxonic when it’s hot, and axodendritic when it’s cold.

I miss aXXo.

I can see the battery configuration in the 4x18a is 3v. The LED that it’s using requires either 6 or 12 volts. The only way to get to higher voltages to use a boost driver. Boost drivers tend to be more complicated so they cost more and they’re not as common. They’ve only really started to hit the scene in the last year or two. Also note that Max output for the 4x18a is 5 amp. That’s also very realistic for a boost driver to do.

The SBT90.2 is a 3 volt led. A decent FET driver should push it to over 20 amps.

You would probably need to talk to someone like Lexel about having a driver made to fit the 4x18a. He may have an existing design that can be modified to fit or else he may need to design a new one from scratch. He’s not going to do that unless you can sell enough to make it worth his while, though. Not completely from scratch, he already has the electronics worked out, its just a matter of getting a pcb with the correct size and shape.

A potential complication could be if the switch is soldered onto the driver. If the switch is separate and it’s connected to the driver with wires then it shouldn’t be any problem. Do you have a 4x18A or have seen the driver?

Thank you for taking the time explain these things,

I do not have the 4x18a, I’m just searching for something that’d be a good fit (both thermally and size-wise - personal preference) to house the sbt90. I was also considering the convoy L21a host, but after receiving my ft03s and seeing how fast it heats up, I’m thinking a larger multi cell light would be a better fit, for my needs.

I have not seen the driver in the 4x18a either…

The info about the switch makes me Leary on trying the mod, unless I can find more info about how it is connected first. Although to be honest I was hoping for a mod that was a little less involved since it is my first one (meaning something that is a little more “setup” for a sbt90, like maybe has a 3 volt fet driver in it already and I can just swap led, ream reflector/insulate, and maybe bass the sprinngs).

I have gotten some advise from some others about using L21a host for sbt90 and doesn’t sound too bad, actually sounds a little easier then say using the 4x18a light and having to switch drivers and switches. Maybe I can find a larger host out there that’ll work.

If the mind is the devils playground .Does that explain the swing set and monkey bars ?

What exactly is “evening”?

Let me expand on it: here in Brazil we have no concept of evening as native English speakers do. We only have terms for afternoon (tarde) and night (noite), and even during the sunset we still consider the time of day to be afternoon. On English study we are taught to say “good evening” when greeting people in the early hours of the night, such as between 7 and 11 PM when the sun has already set and there are no traces of its light in the sky (“good night” is taught strictly a farewell, not a greeting). Depending on the time of year and whether DST is in effect, some of us more or less jokingly say for example “sete da tarde” (seven in the afternoon) when the sun is still up in the sky during the summer, at a time that (at least for us) is pretty late and in any other time of year it’d be nighttime.

I’m guessing this has to do with latitude differences, as sunrise and sunset are universally shorter for us than for Europeans or US and Canada folks. The time between the sun touching the horizon and ambient light being too dim to do anything with ranges from 3 to 30 minutes; for the majority of our population it lasts between 15 and 20 minutes.

(On the other hand we have a time of day that has no easy English equivalent - madrugada, the set of hours between midnight and dawn. I’ve heard of this period in English being referred to as “late hours” or “witching hours”, but it’s most often purely considered night.)

Here we call that zero-dark-thirty.

Yep, that one too, or its twin “o’dark-thirty”.

Sadly that doesn’t answer the main question.

Wellp, “eve” (“evening”) was always considered “the night before”, presumably when people were still up and about.

“Christmas Eve”, “New Year’s Eve”, “All Hallow’s Eve” (Hallowe’en), etc., are well-known examples.

Midnight was when the day would change (ie, no longer Christmas Eve but Christmas Day), so that limits the “eve” part to before midnight, but when still dark.

Why only the nighttime before, and not include the afternoon or the whole day before? ’Cause it’d be called “Day Before Christmas”, then.

Just tell me when it is beer-thirty.

Funny you mention it, as I just knocked off some Warsteiner. My treat for today…

I’m about to grab a brew myself. Cheers.


Would someone suggest a 12V car charger that is pro-rated for a 10A draw? :+1:


I have not heard the expression All Hallows’ Eve in many moons . I was beginning to think it faded into obscurity .

Oh, no. I’m keeping it alive, even if I have to do it all by myself.