Electronics, Lighting, & Gadgets - In Depth Gemini Titan battery testing

Hey all, this might be a breach of etiquette. If it is, please let me know. I did a long post reviewing the Gemini Titan here (http://beamreview.com/?p=44).

I'll summarize what I found. Basically, it's a nice light. Solidly built and easy to switch from mode to mode. I consistently saw run times very close to the advertised 4 hours on high Gemini claims (3hr 47 and 3hrs 58 minutes on high and total runtimes over 4 hrs).

One thing I noted was the time between the LED switching from Orange to Red was very brief (under a minute). Other than that, the light was very impressive.

I won't go everything here, hope the summary helps.

I noticed the same on my Titan. The warning indicator does change rather fast from orange to red when running in the Hi mode. Also if I am near the end of the battery capacity, I can turn off the unit while it is still green but comes back as yellow or red after turning it back on.

Other than that, it's been a month of useage on my Titan and everything is still fine. I still can get close to 4 hrs of runtime. I have pretty much retired my MS900 and put that on my backup MTB bike.

I'm glad my data is consistent with yours. Actually, your post inspired me to go all out on the battery testing. I plan on doing another test in another 90 days just to see how well the light and battery hold up.

In the meantime, i'm planning on getting a spectrometer to get accurate "brightness" measurements. I'm also thinking of putting together a side-by-side time-lapse video of a magicshine using the MS battery and a DIY NIMH battery holder I built.

I think lots of folks wonder how good NIMH batteries in the 2200-2900mah range are for the MS. I think a video would help.

I'm also seeing about 4 hrs of run time on mine on high. Haven't had any issues so far either.

Great write-up!

I wonder what the life of the light would be on low mode and on strobe mode.

I'm also seeing about 4 hrs of run time on mine on high. Haven't had any issues so far either.

Great write-up!

I wonder what the life of the light would be on low mode and on strobe mode.

I can do a run without collecting voltage and current data just to get times. I'll work on that and update the review. The voltage and current data take a long time to graph (i took samples every two seconds using photos of the DVMs)

I was also thinking of seeing how long the MS900 runs on the gemini battery.

The voltage and current data take a long time to graph (i took samples every two seconds using photos of the DVMs) I was also thinking of seeing how long the MS900 runs on the gemini battery. I'll look forward to your tests. I recorded volatage and current about every 6 minutes and the "averaged" the values across the life of the tests.

Both my Dinotte batteries as well as the MS units from China and Geoman all supplied 27-30 watt/hours of power. The light heads used in my tests were using 2.7, 5.5 and 11 watts with respect to low medium and high setting. This produced about 2:40 runtime on high.

But what I don't know for sure is this: If I can "see" or count 30 watt hours of usage in testing a battery to low-voltage circuit cut off - does this mean the battery is rated at "30 watt/hours?" Or am I seeing the ~80% usage of a battery that could be rated at 36-37 watt hours.

I'm using the simple formula of: average current x average voltage x (minutes/60) = watt hour to express battery power in wH. I don't know if this "right" or not - but it seems to make sense.



MS lighthead running at 1.5A average