[Optisolis/E17A/E21A] Jetbeam Jet-µ

So far I recorded 74lm (79,11lm at start) for 1hour 3minutes uncooled for the Jeteria (JetE21A)

- Clemence

……to further your point even more, I used to think my Eagtac MX25L3C Nichia had much better tint, until Clemence drop shipped the first Group Buy of sw45 9080 Nichia leds via Texas Ace, before his Bali store opened.
Those jewels make my D25aaa and Eagtac Nichia 6 led thrower look mucous yellow-green in side-by-side comparisons.
Indications are Eagtac looked for above the ANSI BBL stock for more lumen output, since according to Clemence, above or below was formerly the typical manner in which Nichia offered their sw bins.

I just found this thread & happy I did. I love this little AAA light, & have one in my pocket all the time.
Looking forward to this one…… :+1:

Still testing the runtime for the third time. There’s something weird going on here.
The JetE21A output vary between 74lm - 79lm between lights. This is OK because I measured the current output vary from 230mA to 245mA, and each LED’s output also slightly different. In theory and observations, hotter LED will have lower forward voltage, correct? This usually results in longer regulated runtime albeit reduced brightness. This apply to either boos or buck driver. But in JetE21A the case it’s the other way around: uncooled (much hotter body temp) results in LESS reduced output over time and LONGER runtime! This is weird
Can someone help me explain this?

- Clemence

I don’t know what could cause it but I experienced something similar with a Lumintop Tool AAA. Output was higher and more consistent without cooling. Runtime was longer just like in your case. After I turned a fan on, the output dropped following a slight increase in output. Maybe it does have something to do with the Vf being higher with lower temperature.

One possible cause could be the Eneloop drains more at hotter temp. The tube temperature was 40 °C. Anyway, this is an unexpected benefit in hot wheather. But expect reduced runtime in colder temperature. Did you use Eneloop in your test?

- Clemence

Yes, it was the normal white Eneloop.

Hmmm looks like better NiMh chemistry in hotter temp is the case. For the Jetsolis the voltage could be too high for the boost driver that better battery chemical reaction is not enough to boost the runtime.

- Clemence

Maybe test it with a bench PSU.

Yup, that’s what I thought too.

- Clemence

Standardized testing of batteries is done at 20°C to 25°C, but most batteries (including NiMH and Li-Ion) actually work a bit better at higher temperatures. At temperatures of around 40°C to 45°C (or even up to 60°C) the voltage level is higher and you get slightly more capacity and a decent amount more energy out of the cell. This info is unfortunately not in the Eneloop datasheets, but I found a graph which was on the eneloop.info website back in the day.

Some datasheets of Li-Ion batteries (e.g. the UR14500P datasheet) have such a graph included.

While higher temperatures are good for getting the maximum out of the cell, they are also detrimental to the life of the battery, but that is of course a different topic.

Thanks Noir, that confirmed my suspicion. It’s good to learn new things. I will use the cooled runtime for base reference then.

- Clemence

I have seen the same thing testing batteries at higher currents. The warmer the battery the better it will perform.
If you run a capacity test on the same cell twice and don’t give the cell a rest after the first test after charging the cell, It’s warm from the test and charge. It will tend to have better performance on the second test with usually less voltage sag and higher current. I have noticed it most with the smaller cell sizes.

In all type of cells, being based on a specific chemistry, benefit from higher temperatures in terms on internal resistance along with capacity because of the faster ion movement permitted by higher temps. Although in terms of current provided, it obviously has its limit because of electrical conductivity dropping with temperature.

So don’t push it say above 40-45C, except for high discharge cells, for good cycle life obviously.

This can be used in a certain way to actually be beneficial though:

When discharging in cold weather, internal resistance is increased. However, heat dissipation is increased. So, as you discharge the cell in colder weather, performance actually gets better :slight_smile:

OK, the prototyping is final. Below are the runtimes for Jetusolis and JetuE21A compared to stock XPE2. All measured in cooled 25° condition to avoid fluctuation in battery capacity as encountered earlier,
I will post the beamshot with alternate optics later.

- Clemence

Those look good to me. Very reasonable compromise in output for the significant improvement in CRI.

Since the 5000K Optisolis uses a 420nm diode, compared to the more conventional 440nm diode in the warmer Optisolis variants, with a consequently higher forward voltage, I’m guessing the warmer versions will consequently run a little bit longer at the same current.

UPDATE181218: Some pics and measurements

- Clemence

When will they be available to order?

Looks nice :+1:

Do you have any 5° TIRs, by any chance?

I’m getting it today

Only up to 10°. At very close range this 10° with its rectangular tight spill already creates some artifacts, the 5° will be worse I guess. The narrow spill is very useful in cases such as mouth or nostril inspection where you don’t want too much glare to the patient. I myself prefer the 20°. The stock optic has bad yellow tint shift ring around the hot spot.

- Clemence