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  1. #1
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    Question About GeoManGear Recall Batteries

    I was wondering if anyone else is experiencing this. No matter how much charge the new batteries have on them, the battery level LED on the light head always stays red. I have two batteries and they both do it. I've tested them on two different Magicshine lights as well as my Gemini XERA and the behavior is the same. The runtime seems to be normal on the packs (2.5 - 3 hrs on high).

    I've shot an email to GeoMan and they say this is to be expected because of the different cells their battery pack has in them as compared to the Magicshine pack. However I haven't seen anyone reporting this issue so I want to make sure this truly is a common occurrence and not just a problem for me.

    Thanks.

  2. #2
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    Quote Originally Posted by jhymel View Post
    I was wondering if anyone else is experiencing this. No matter how much charge the new batteries have on them, the battery level LED on the light head always stays red. I have two batteries and they both do it. I've tested them on two different Magicshine lights as well as my Gemini XERA and the behavior is the same. The runtime seems to be normal on the packs (2.5 - 3 hrs on high).

    I've shot an email to GeoMan and they say this is to be expected because of the different cells their battery pack has in them as compared to the Magicshine pack. However I haven't seen anyone reporting this issue so I want to make sure this truly is a common occurrence and not just a problem for me.

    Thanks.
    Same here, I think i saw it posted in the recall thread too.

  3. #3
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    Yep...normal.

    I think mine go to blue or orange for a while, but never green. Geomangear stated up front that the lighthead "battery meters" wouldn't read correctly with these batteries.

    Screw the meter, I'll take the higher quality batteries any day.

  4. #4
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    I think the reason for this is that the batteries are only charged up to 8.2v output total. Most Lithium batteries rated for 7.4v are actually charged up to 3.7v per cell or 8.4v. The original batteries, and even current Magicshine batteries are 3.7v 18650 cells. I think Geoman is trying to keep their batteries from being overcharged AND undercharged, thereby extending the life of the battery and eliminating the possibility of fire. Probably a good idea, but I agree it's annoying. It still does this on my brand new MJ-872 light head. I get maybe 2 minutes of green and then it goes to blue.

    I was looking at their testing documents and the batteries used are even stated as being 3.6/7.2v instead of the normal 3.7/7.4v. The light head is measuring the voltage coming from the pack and expects a full charge(green) to be 8.4v which the new battery packs never reach.

    Specs: http://geomangear.com/pdf/OL4.5Data.pdf
    Testing Data: http://geomangear.com/pdf/TT4.5UN_Cert1.pdf
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  5. #5
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    TwoHeads is pretty much spot on. The charge indicator is just reading voltage and changing color based on the voltage level. The trouble with that is that lithium-ion batteries have a very flat discharge curve. That makes the difference in voltage at various levels of discharge very hard to determine. Batteries from different manufacturers have slightly different discharge curves. Blend those two issues together and now you have your non-functional battery level indicator. It was likely not very accurate with the original battery anyway due to production variances.

  6. #6
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    Great, thanks everyone for the information. It's good to know this is the norm. It would be nice to have the level indicator but I'll take the better battery cells over the indicator any day.

  7. #7
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    Hmm, my indicator works fine
    Honestly... ahh I give up

  8. #8
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    magicshine

    I'm having the same issue. Rode to work this morning for the first time with the new battery as I've been using another light for commuting. The red light came on about 50 minutes into my ride, so I powered down from high to medium and it turned green again. Coming home, it stayed on red the whole way no matter what level the light was on, so I kept it on low most of the way. Turned it up to high during the final 10-15 minutes of my commute and it worked the whole way. It kind of freaked me out because I was afraid that I would get stranded in the dark with no light. So I guess the low-battery indicator is essentially useless now. So how are you supposed to know how long it will last on a charge?

  9. #9
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    I tested one of my GMG batteries and a P7 Magicshine ran on the high setting for a little over 3 hours. You have to provide proper cooling for the light if you do this.

  10. #10
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    Quote Originally Posted by TwoHeadsBrewing View Post
    I think the reason for this is that the batteries are only charged up to 8.2v output total. Most Lithium batteries rated for 7.4v are actually charged up to 3.7v per cell or 8.4v. The original batteries, and even current Magicshine batteries are 3.7v 18650 cells.
    How is the charge terminated with the Magicshine charger/old batteries and the Magicshine charger/new Geoman batteries? The way you describe it, it sounds like maybe it is something in the battery pack that cuts off the charge.

    I know Chris at Gemini recommends that the chargers and batteries not be interchanged, but I wonder what is actually compatible between Gemini and Magicshine - how are the charges terminated in each, and is it something in the battery pack or charger, or both? Anyone know enough to say if I can use my Magicshine charger on my Gemini 2-cell battery pack? Or my Gemini charger with the new Geoman pack? I'm asking because I might pay attention to the difference in chargers, but my GF probably will not (she would say I'm geek for being concerned).

  11. #11
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    I've got 1/2 dozen rides on my replacement GMG battery, and the indicator behavior has been consistent, ~1/2 hour green, then the indicator switches from red (~10 sec) to green (~30 sec) for the next hour, then stays red for the rest of the ride. My light head does not have the multicolored power level indicator. The original MJ battery always stayed green until ~15 min before exhaustion for all 50+ rides I had on it.

    Run times are similar. So, you lose the power meter for a better battery case & mounting hardware. I'm OK with that.

  12. #12
    namagomi
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    Indicator was always basically useless, now even more so. Better to track the usage.

  13. #13
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    Quote Originally Posted by xcandrew View Post
    How is the charge terminated with the Magicshine charger/old batteries and the Magicshine charger/new Geoman batteries? The way you describe it, it sounds like maybe it is something in the battery pack that cuts off the charge.

    I know Chris at Gemini recommends that the chargers and batteries not be interchanged, but I wonder what is actually compatible between Gemini and Magicshine - how are the charges terminated in each, and is it something in the battery pack or charger, or both? Anyone know enough to say if I can use my Magicshine charger on my Gemini 2-cell battery pack? Or my Gemini charger with the new Geoman pack? I'm asking because I might pay attention to the difference in chargers, but my GF probably will not (she would say I'm geek for being concerned).
    There is indeed a low voltage cutoff(LVC) chip in the battery. However, there is also one in the light head which is set to a slightly higher voltage. As someone else said, the only way to truly know is to do a runtime test. Each battery should be within 10 minutes of each other given the same light head, but there are differences. I usually run on high with my MJ-872 on the 6.0Ah pack until the red light starts flashing. That comes on around 1:45-2:00 hours, and then I power down to 50% and it lasts another 15 minutes. YMMV.
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  14. #14
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    Quote Originally Posted by highdelll View Post
    Hmm, my indicator works fine
    Yeah, mine too. We must have gotten a bad batch.....

  15. #15
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    Quote Originally Posted by gmcttr View Post
    I tested one of my GMG batteries and a P7 Magicshine ran on the high setting for a little over 3 hours. You have to provide proper cooling for the light if you do this.
    This is the way to go. I think that I'll set mine up in the garage with a fan blowing on the light to see how long it will last on high. Otherwise, I'll always be paranoid riding with the light in darkness.

    Does anyone know if the MS light starts blinking when the charge starts getting really low, or does it just dim and then shut down? My Light & Motion Stella 300 has a nice feature where it will do short flashes every 5 minutes when the battery is starting to get low, and then go to full flash when you've only got a few minutes of charge left.

  16. #16
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    MS lights blink as they are close to discharged as a warning. Rode last night and got about 20 minutes of disco style riding with the intermittent flashing. Made it home.

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