Alexa Mini and D-tap Problems

Discussion in 'MōVI M15' started by Yuki Noguchi, May 14, 2017.

  1. Yuki Noguchi

    Yuki Noguchi New Member

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    Hey guys,

    On Movi M15, I m having a bit of powering problem with Alexa Mini.
    I have V Mount battery Velcro to the Mini Body and D-tap out to the camera. The camera sometimes dies when I push record button. Or sometimes dies out of nowhere. I learned that all the D-taps are 50Wh on IDX batteries and Mini takes more than that especially when it goes to Slow Mo Mode ex. 200fps.
    I m using WCU4 for that set up too. Not sure if motor is pulling extra wattage, but I m curious if anyone is having the same issue and what could be the solution to the problem. It happens every once a while, but sometimes there is nothing but keep trying to roll camera.
    LMK if you have same problems as mine, and if you know the answer to the solution. Thanks.
     
  2. Graham Futerfas

    Graham Futerfas Active Member

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    Which model IDX battery are you using? Can you try a different battery than the IDX?

    I should clarify there's a difference between 50Wh and 50W, and if your battery is only 50Wh (I don't think they make one that small), then it's not enough. If it has a 50W limited port, it should be OK, especially if it's not regulating the voltage to 12V.

    I use an IDX PV-212 V-mount battery plate that has a D-Tap on it rated at 50 watts. This is the same one sold in the Freefly Alexa Mini V-mount battery adapter kit, and it works very well, even with the WCU-4.

    I use 95Wh batteries from Global Media Pro, which I like because they're the thinnest ones I've seen, and they're much less expensive.
     
  3. Yuki Noguchi

    Yuki Noguchi New Member

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    My bad. I use CUE D75. I meant 50W D-tap.
    I did try on PV212 or other IDX plate. Most of time it works. Even when it dies if I keep trying it it will work at some point, but very annoying to see all the crew watching us keep rebooting camera... Not fun.

    Here is the response from IDX.

    "Please be advised that D-Tap on battery’s max draw is 50W and a load of Alexa Mini is approx. 59W. Alexa Mini exceeds the limit of D-Tap’s specification unfortunately. Also, if you set the camera on high frame rate, the load of the camera is higher than 65W, which cann’t be handled by D-Tap."

    And Alan from Media Blackout recommended this, and I tried but still fails.

    "Alternatively, the only thing that limits the P-Tap output from an IDX P-Tap is the glass fuse rating. All you have to do is replace the 6A fuse with a 10A fuse. There is no downside to doing this. The ratings they give are because they assume that you will be powering a camera with the internal output, and they don't want you to pull a large amount simultaneously; that would cause the battery's internal fuse to trip, which would cause the camera to lose power. You can prioritize one of the P-Taps to be used for your camera, and keep the other capped at 6A."

    So, I m wondering if other people are having the same issues. When I m using Mini on M15 with this set up, it dies probably 10 times a day. I love the P-tap solution. It is fast and compact.

    I haven't looked into other batteries, so I should look into them if they have higher D-tap capacity.
     
  4. Graham Futerfas

    Graham Futerfas Active Member

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    When I was looking at v-mount batteries for my kit, I was told the Cue 75 can't really supply enough power to do the Mini or the Epic, so I started looking at 90Wh batteries. Over 100Wh is not convenient for airline travel.

    You'd need a Cue 95, or maybe look at the options from Global Media Pro, which like I said, are quite a bit thinner than the IDX's, which is nice given the limited amount of room on the gimbal. Check out the Global Media Pro Li-95S. I have 7 of them, and they've been really good for the last 18 months, and a bit cheaper. I have an IDX charger, though.
     
  5. Alan Rencher

    Alan Rencher Member

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    If you are not burning out the glass fuse in the battery plate, then the power failure is most likely caused by tripping the battery's internal resettable fuse. Double-check your battery's max discharge current rating; you may need to use a battery that can handle a higher current draw.
     
  6. Wolf Schiebel

    Wolf Schiebel Active Member

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    I managed to overload a 75Wh BEBOB battery going 200 fps on the Mini. Went to 98Wh instead and never any problems. The rating of Ptap is in my opinion too low for a safe operation of the Mini. I built an adapter using the LEMO plug and soldered it direct to the V-Mount plate.
     
  7. Alan Rencher

    Alan Rencher Member

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    P-Tap connectors can actually handle a higher output current than one of those small 2-pin Lemo connectors (10A as opposed to 7A). IDX plates are wired with 18 AWG wire to the P-Taps, so they are able to handle current flow.

    As I told Yuki, "Alternatively, the only thing that limits the P-Tap output from an IDX P-Tap is the glass fuse rating. All you have to do is replace the 6A fuse with a 10A fuse. There is no downside to doing this. The ratings they give are because they assume that you will be powering a camera with the internal output, and they don't want you to pull a large amount simultaneously; that would cause the battery's internal fuse to trip, which would cause the camera to lose power. You can prioritize one of the P-Taps to be used for your camera, and keep the other capped at 6A."
     

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