Dive Rite HP50 missing lumens

[ScubaSamScubaStevesFather]

I can’t find any documentation stating what lumens are for the medium and low settings for the hp50. It says 3500 for high.

Furthermore, the tech spec is ambiguous…does the hp50 maintain a constant brightness, or does it gradually lose its luminosity as the battery level drops?

 

[runsongas]

it is regulated so the brightness doesn't drop as badly as some other cheaper lights, but the maximum brightness is closer to 2500 lumen after efficiency losses

 

[lowwall]

It's regulated. Meaning it will maintain a constant brightness for a period of time and then step down to a lower level. The step down point is determined by either the battery being unable to provide sufficient current to maintain the full brightness or if it detects the charge level is low enough that it is programmed to step down so you'll have at least some light for a greater amount of time, whichever comes first.

LED lumen output is roughly proportional to current. The spec sheet says it will last twice as long on the medium setting, so about half as bright or 1750 lumens (if the 3500 number is legit). Low is 20x as long as high, so around 175 lumens. These are approximations, but give you an idea.

Here's the luminous flux v current graph from the spec sheet for the LED in the light if you want to try to get a closer approximation:

https://assets.cree-led.com/a/ds/x/XLamp-XHP50.2.pdf

Edit - to be complete, I should note that brightness will also be stepped down if the bulb starts to overheat. This can happen fairly quickly for lights used in air, but is obviously much less of a problem in underwater usage.

 

[Whitrzac]

The LX20+ and HP50 lights are a constant output until the light flashes indicating low battery and automatically steps down to conserve remaining power.

The EX35 provides full output for approximately 1 hour and then slowly tapers for the next 5 hours. At that point, the light will flash indicating low battery and step down to power conservation mode similar to the LX20+ and HP50.

The BX2 is a direct drive light like the CX2 and will slowly taper for the duration of the runtime.

 

[ScubaSamScubaStevesFather]

thanks so much everyone! About to buy-once-cry-once and order me an hp50 instead of the lx20+
Hope this info helps others