Osram Oslon Boost HX

Oh, that’s more current than i anticipated.
But, i take it you mean 10 Amperes (7.5 A for the KW CSLPM1-TG) is the absolute maximum, and probably only a few % more output than on something like 8 Amperes (say 6 A for the KW CSLPM1-TG)?

But you know i like my LEDs running constant current regulated and the electrical path optimized :slight_smile:

I really like FET diy Djozz style driver(nanjg AK 47 one). This is the thread about mentioned driver: comfychair-inspired quick+cheap+lazy single-sided 17DD FET-driver (poor man's nanjg92)

I produced and potted over 200 of them. Only few failed because of mine soldering mistake so I would say after several years that they have almost 0 failure rate!

I would like that Djozze reinvents mentioned nanjg AK 47 FET Djozz driver but this time with some kind of added resistance so we can safely run that little osrams… Pretty Please Djozz ? :slight_smile:

So you want DD with resistance, but not constant current with much less resistance, like the LD25 or the SST-40 Convoy drivers or the LD4 from Led4power.
So you prefer to only have full output with a fully charged cell = for a short while.
That doesn’t make sense to me.

Nothing against brand driver manufacturers. I always liked diy stuff…
So yes! It does make sense if FET with added resistance would pull no more than lets say 5A… Plus it is cheap and effective.

But then you’ll have to always have fully charged cells for maximum output.
That doesn’t make sense to me.

Why?
It has perfect sense for me. You don’t have to have flashlight pressed on turbo all the time :slight_smile:
For example:
Turbo mode 5A, Middle mode 2,5A, low is 1A. You can run it on middle or low mode(saving the battery) and turn turbo for a minute or two when needed.

But even if one wants to run it on turbo only it should not be issue… But FET driver would have to be modded or restricted somehow with added resistance that should not pass 5A.
Since we know that mentioned Osram emitters loose very little on performance and we know how fet driver behaves we could approximately calculate that 4.2-3.3V of battery cell = 5-3.5A current draw on turbo mode which is approximately 30 minutes of turbo mode on 1x18650 Samsung INR 30Q cell by looking HKJ minutes/runtime diagram for Samsung INR30Q cell. Even if it is not in regulation it will still run strongly and one that uses it will not visually notice significant candela/lux intensity change.

I would really like to know how to add and limit resistance on the FET driver. I have very good soldering skills but I can’t do nothing if someone who knows does not show me necessary ingredients of “how to restrict resistance on FET driver”.

The easiest way to reduce current in an FET driver if it is marginally too much is just to reduce the max PWM. This works great for LED’s like the 219C where 100% turbo gives them maybe 25% too much current. Knocking the PWM down to ~75% fixes the issue and works great.

Now if the 100% current is way way too high this might not work of course.

A minute or two is probably what it takes to discharge to 4.0 Volts, and so your current will drop.

It may be better to start with a battery that is already discharged to 3.8 Volts, because that’s where the voltage starts to stay the same for a longer time, just slowly dropping.

But hey, do as you see fit.

I done hundreds of diy FET drivers and some Texas Ace one so I know how they behave. I am looking for permanent solution of restricting FET driver current, and since Djozz mentioned that some kind of resistor can be added to driver circuit I would really like to know what type of resistor and where should I place it in a circuit?

If someone wants to run Osram WF with FET driver just use low current 18650 cell and don’t bypass springs. But however that is not proper and safe solution. Proper solution for FET drivers would be current restriction on FET driver. It should be doable but I don’t know how.

I’m sorry l.i. but although I produced the AK-47 hack back in the days, which was purely an extension of comfychair’s work, I’m not very knowledgable in drivers, not like Texas_Ace or Lexel or DEL or wight.

The idea of putting an extra resistor in this hacked driver is not a really practical one because it would have to be a big one that can handle 5A current.

Maybe if you can guarantee buying a large amount of them, you could ask Simon from Convoy Flashlight to produce a batch of his 5A drivers with high-med-low without memory?

Yes I could. But what should I do with hundreds of AK47C1 drivers(also ordered from Simon) ? :laughing: I would try to place big resistor on driver cause I pot drivers anyway. Can you suggest me proper resistor for this potential current restriction FET driver mod?

The added resistance is going to be in the 0.05 to 0.1 ohm range I think.

These are two resistor mods I did for the 2mm WF. Added resistance was about 0.1ohm. For the 1mm WF it should be a bit less.

I wonder…would it be possible to adjust PWM as battery discharges to maintain something closer to constant current?

I think it’s possible. Some discussion here.

Finally someone with a will for FET solutions :beer:

Is there any way to put some kind of resistor on a top of a driver and where would you put it? I pot drivers so it would be nice if I could merge resistor with a driver for permanent bond :+1:

You would put the resistor anywhere in the main current path. The challenge is the heat dissipation. It will be producing between 2 and 5W depending on what current you choose (5 to 7A), and that is a lot for a small resistor so it will get very hot.

has anywhere got stock of these yet? Also does convoy do a 4040 gasket or are we stuck with reaming out the 3030 ?

EasyB,
Can it fit to 17mm diameter? Can I cut it to fit if needed? I have aluminum and copper plates as potential heat sink for resistor and when I merge everything with potting compound it will look like it is made from one piece and whole driver should act as a heatsink.

But if it generates serious heat at 5A (more than 60 celzius) that could be problem…

The extra heat is not large compared to the total heat from the LED. The risk is that if the resistor you choose is too small or not heat sinked enough it will burn up. You will have to look for resistors that will fit in your lights.