Short Review of Sofirn SP33 v2 with XHP50.2

So you’re saying it’s not really a constant current driver?
Hmmm… I suppose i can live with that, unless the difference between 4.2 and 3.0 Volts is noticeably large…

I ordered the SP33 driver too, recently.
But i wonder if that’s the previous XP-L driver or this one…
We’ll see…

Mountain Electronics has 26mm boards for XHP emitters and they will reflow the new LED on the board, if they have the LED you want in stock.

I have not measured the output current. I measured the battery currents and the lumens in turbo mode with a fully charged battery. I also measured Turbo lumens and current at 3.75v. I think it’s safe to say the output current does drop a little bit.

I’ll measure the lower levels on a 3.75v battery to see if they are different as well.

He’s in Finland, so MTN is not a good choice. He can probably go through Kaidomain, etc… much cheaper.

I think Sofirn is limiting turbo power levels when below 3,8V/3,75V for their cell to keep on running happily.

The cutoff is 3.70v.

The regular Turbo still works at 3.71+v

If you get the original driver out please let is know how. So far I’ve tried heat and pulling on it and it has no effect on the glue. The glue does not even soften.

I’m hesitate to try pushing on it from above.

From comments on Aliexpress.

I wasn’t planning on taking out the driver, but i liked the idea of having a spare one, either the XHP50 version or the XP-L version.
It was only €4 + change so i though i’d order one.
I will report on it here though.

Hmmm… That’s a bit early, isn’t it? Why??

Due to the precise nature of the step down voltage points, it’s clear Sofirn chose these in the software. 3.70v and 3.40v. They probably based their decision on what works best.

Bwrf… My DQG 26650 never steps down and has a similar output.
I mean, what’s the fuss when we’re talking about 20+ Watts / 2500 Lumen lights on a fat battery?
Still under 10 Amperes even when only 3 Volts.
Strange decision.

The amp limit Sofirn has chosen to use is 5.8A.

I don’t think anyone has seen this new SP33 driver design so we are all guessing about how it works.

A stupid choice i.m.h.o.

I’ll post pics when i get the driver.
Not sure if it’s the V1.0 or V2.0 version though.

I think there may be another limiting factor.

The springs are the same found in the original SP33. While steel springs are fine at 3A for the XP-L version, they aren’t at 4A, as they start to heat up a lot faster than at 3A, and at 5A, this becomes even worse, resulting in an even high Vdroop.

Dual springs would have helped in this case like in the Q8 and a brass button on the driver.

So Sofirn chose to limit the current not based on the driver design, but on the spring design.

I’ve actually tried that trick with my Haikelite MT01. Trying to run on 1 cell is fine, but the spring gets stupid hot, and the problem becomes worse at lower voltage levels.

Yep, the springs are wide so it’s a long thin wire, made of iron… :person_facepalming:

So is it ok to do spring bypass or too much current?

YES. It’s always much better to do spring bypasses with buck/boost drivers. Power is regulated, so less voltage loss in the springs means more runtime at high brightneses.

In fact, unless you are running 2+ cells, good springs/spring bypasses are needed for optimal power/runtime.

Thanks, wasn’t sure if they were using the low quality springs to limit current.

It is okay to do, but it may not change anything in this particular driver design.

It seems the driver looks at resting battery voltage to determine whether to have Turbo or not. Voltage sag seems to not effect it. Quite strange.

Maybe a bypass will squeeze out a little more Turbo run time? I’m not sure. On other boost drivers, where the current goes up as voltage goes down, I always recommend bypasses. They make a bigger difference there. With this light, I’m not so sure.