Fraz Labs Mechanical Flashlights (formerly QTC Non-Battery Crush)

[ecmp]

I have not seen any Fraz light direct drive tests that could help answer that question.

Hoping there would be numbers or more information to help determine those.

As a rule of thumb for direct drive:

I would avoid using a battery with a higher Amperage max drain rate, than the max Amperage the LED is rated for

for example, I would suggest 3A batteries, paired w LEDs that can handle no less than 3A.

I would avoid using a 10A battery on direct drive, with an LED rated for less than 10A

Thank you!

 

[jon_slider]

How many Amperes is the battery rated for?

good question, I trust thermal guy will confirm...
and thanks for helping me understand the goal of your questions better now

fwiw, A typical protected 18350 has a 3A discharge rate, which would match an LH351d max 3A

Unprotected batteries tend to be the ones with higher than 3A discharge rate, though there are also unprotected 3A

It is also a good idea to use protected batteries in the Fraz, since they do not have LVP built into the light.

 

[ecmp]

A typical protected 18350 has a 3A discharge rate, which would match an LH351d max 3A

Thank you! Didn't know this.

Was inquiring along the lines of 18650 cells and assuming 18350 to 26650 would have more or less the same range of ampere ratings.

For 18650, the lowest found is 4A. The more common ampere ratings for protected 18650 would be around 8A to 10A. Fraz seems to use the same LED for 18350 and 18650.

 

[jon_slider]

Fraz seems to use the same LED for 18350 and 18650.

but with QTC.. not direct drive

if you put a 15A 18650 in a Fraz w a 3A LED such as LH351D, you should be able to fry the LED on direct drive..

 

[ecmp]

It is also a good idea to use protected batteries in the Fraz, since they do not have LVP built into the light.

Thank you!

For unprotected batteries, what is the worst that can happen? Would going below the minimum battery voltage only ruin the battery or will it result to catastrophic battery failure?

 

[jon_slider]

will it result to catastrophic battery failure?

the danger of overdischarge comes during recharging. Overdischarge can happen if you fall asleep with the flashlight On. In normal use you would see that the light was becoming very dim, so you would stop using the depleted battery.

If the overdischarge was far below 2.5V, especially if the battery sits for a long period (weeks), in an overdischarged state, it may overheat during recharging and Vent With Fire.. the fumes are very corrosive, do not inhale

it is prudent to charge under supervision so you can notice is the battery gets hot. It is not a good idea to recharge overnight, while sleeping. It is prudent not to recharge overdischarged batteries.

 

[ecmp]

If the overdischarge was far below 2.5V, especially if the battery sits for a long period (weeks), in an overdischarged state, it may overheat during recharging and Vent With Fire.. the fumes are very corrosive, do not inhale

Thank you!

Suppose the minimum forward voltage of a LED is 3V and the capacity of the battery is currently at 3V as well.

Can a LED draw beyond it's minimum forward voltage? ie., Would leaving the flashlight in the 'on' position overnight allow the LED to drain the battery beyond 2.5V?

 

[jon_slider]

Suppose the minimum forward voltage of a LED is 3V and the capacity of the battery is currently at 3V as well.

Can a LED draw beyond it's minimum forward voltage?

I believe the answer for the Fraz circuit is No.
I believe the LED would turn off when the battery goes below 3V.

looking at the excellent data you collected in this post, the only LED with a forward voltage lower than 2.5V is the Red SST-20. For the LH351d your list shows a minimum forward voltage of 2.7V.

My guess is that the Fraz can not draw a battery below 2.7V, when using the LH351d.

I like where this is going. Thanks to your data collection and questions, it appears the Fraz with an LH351d would be unable to overdischarge a LiIon, so it does not actually need to rely on a Protected battery, to prevent overdischarge.

The only LED on your list that poses a risk of possible overdischarge is the Red SST-20, whose minimum forward voltage is 1.8V.

Thanks for sharing your inquiries. Im learning a lot, with you, about the Fraz (I dont have my own).

disclaim: I have not tested to confirm these assumptions about the discharge limit imposed by the forward voltage of the LED in a Fraz. Im not an expert, seek confirmation.

trust but verify ;-)

 

[kerneldrop]

2.5V from my mulitmeter lights up the 351d with a soft glow. Certainly not usable light. But moonlight folks would go nuts over it.

The LED doesn't draw volts... the battery pushes volts to the driver and the LED/driver draws current.
If it didn't work like that then the LED or whatever using the battery would die every time we used it because it would get flooded with current it couldn't handle.

 

[jon_slider]

the battery pushes volts to the driver

The Fraz does not actually have a driver... it only has a QTC variable resistor, like Peak Eiger.

With no driver, if the battery voltage goes below the LED voltage, I thought the LED would turn off. Is that not correct?

I dont actually have a Fraz, nor a Peak Eiger, so I cant test first hand.

 

[kerneldrop]

The Fraz does not actually have a driver... it only has a QTC variable resistor, like Peak Eiger.

With no driver, if the battery voltage goes below the LED voltage, I thought the LED would turn off. Is that not correct?

I was just generalizing…the battery pushes volts to driver or LED Positive when there's not a driver.

Correct, in direct drive or any drive when the input voltage falls below the minimum the diode won't send signal to the other diode.

I hooked a Samsung 351 direct to a 1.5v battery and no light. Hooked it to 2.5v and got moonlight. The 351 diode needs somewhere close to 2.5v to send power to the other diode.

 

[thermal guy]

2.5V from my mulitmeter lights up the 351d with a soft glow. Certainly not usable light. But moonlight folks would go nuts over it.

The LED doesn't draw volts... the battery pushes volts to the driver and the LED/driver draws current.
If it didn't work like that then the LED or whatever using the battery would die every time we used it because it would get flooded with current it couldn't handle.

Yep mine will run off a 123 that's way below 3 volts.

 

[jon_slider]

CR123 Voltage Range

1.5V to 3.3V

I hooked a Samsung 351 direct to a 1.5v battery and no light

thank you for sharing your test results 🍺

2.5V from my mulitmeter lights up the 351d with a soft glow. Certainly not usable light.

Since Fraz lights do not have a driver, they can not use a CR123 when its voltage goes below the forward voltage of the LED.

To use CR123 effectively, requires a driver, such as in the HDS Rotary.

 

[geisto]

I checked the current draw on direct drive on my QT-SS 18650. Using an old Panasonic NCR18650PF, my meter showed 3.6-3.7A. This is not factoring resistance from the tailspring since I needed to take the bezel off the body.

I didn't take the engine off the bezel yet but by the ho-hum green tint on low power, it's probably a Samsung LH351D 4K. No biggie since it's easy to swap LEDs on the new design. The Carclo optic looks the same as the previous model and a Cree XM-L or XP-L should improve the beam pattern a little.

I've used and abused the old Qzark QTC light for 8yrs...thousands of hours of total runtime till the XM-L insta-poofed on me. Thing about the Qzark was it chewed through a QTC piece in about a month of two of use, in which the brightness control gets erratic. Not so with the new lights, I would say the QTC or similar material would last a year before needing a change. Thing is, it's so easy to change it now, I wouldn't have mind if it needed to changed often.

 

[ecmp]

Thank you for sharing @geisto! Congratulations on snagging a QTSS!

I checked the current draw on direct drive on my QT-SS 18650. Using an old Panasonic NCR18650PF, my meter showed 3.6-3.7A.

What is the max ampere rating of the battery?

 

[geisto]

Thank you for sharing @geisto! Congratulations on snagging a QTSS!



What is the max ampere rating of the battery?

NCR18650PF max discharge is 10A.

 

[kerneldrop]

I'd be curious what the amperage is after 30 mins or so of continuous use. The amperage will increase as the LED and battery gets hotter.

If that QTC material doesn't last a year then they need to look at what is tearing it up and make some changes.

 

[KITROBASKIN]

The piston design is said to only apply compression to the QTC, not shearing. Well used QTC in my experience is less springy, more flat. Not flaky. Curiously it is quite pleasant to begin predawn workdays with the Lumenite II because when twisting it for activation, the amount of light starts out low then increases undetected. This gives the night adapted eyes a gentle wake up.

There is plenty of discussion on older threads regarding the nature of QTC material.

I can't help getting protective about speckacuda and fraz spending a lot of time answering wide ranging questions when they could be making more flashlights instead. So grateful to you forum members for responding to ecmp (who is certainly entitled to ask whatever will advance the discussion, don't you think?)

 

[kerneldrop]

The piston design is said to only apply compression to the QTC, not shearing. Well used QTC in my experience is less springy, more flat. Not flaky.

Yea this the first time I've heard of QTC failing.
Failing in a couple months or even a year seems a rarity because there should only be compression, not rotational forces. So I dunno how it could fail.

 

[jon_slider]

the brightness control gets erratic...
I would say the QTC or similar material would last a year before needing a change.

thanks for the details..
at what use frequency...about 3 times a day or what ballpark?

does the material get compressed and loses low modes and just wants to produce high modes?

is replacement QTC readily available?