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Thread: DIY flash external battery pack using common 5V USB or 12V power banks?

  1. #1
    Enlightened
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    Dec 2013
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    Europe
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    Default DIY flash external battery pack using common 5V USB or 12V power banks?

    Since some OEM camera flash manufacturers (e.g. GODOX 850) started using Li-Ion packs for their strobes (±12V 2000mAh pack gives a lot faster recycle times than even a best set of 4xAAs unless you are still using high discharge current NiCd AAs, and still has over 4x the capacity over best high-C NiCds), I have been toying with the idea of making a DIY power pack for my strobes, preferably one that could be semi-permanently attached to the strobe with good velcro and recharged easily. Long ago, for the old potato-masher Metz strobes, I did make some DIY external packs just to increase the capacity using dummy battery connected to high capacity NiMH notebook cells (obviously not a great idea since my cells were not individually charged), however, this time I was thinking about using a good quality Li-Ion 5V USB powerbank or 12V Li-Ion power bank because of the ease of use and safety features.

    However, I wonder if it's a completely stupid idea or not. Most of the banks are limited to 2.1Ah output at 5V, I guess that could be too slow to charge the flash quickly enough, or not? A 5V power bank would necessitate using dummy battery, and would not be of much benefit (apart from easier charging with any USB 5V power source) over just using Eneloops inside the flash. Another concern would be the load sensing circuitry in the power bank (would it act just like a battery, or would it shut off in-between flash pops?)

    So that got me wondering if I could utilise the external power port on the flash, designed for 8xAA external packs from Canon and OEMs. Unfortunately, I have no access to one and no idea if the external pack just puts 9.6-12V into the flash using a different path from the internal 4xAAs (which are still needed for the other circuitry) or if it has internal DC-DC circuitry to feed 300V directly to the flash capacitator. If it's the former, it would be easy to make a holder for 3 Li-Ion cells and get a good charger for them, although I would much prefer a self-contained solution like the 12V Li-Ion powerbanks, if only for the benefit of self-containment, easier charging and better enclosure than any DIY one I could probably manage. I can always get an OEM flash specific battery pack, but as these are usually upwards of 300$...

    Therefore, I want to ask if anybody tried it, or at least has got some more experience with the matter, or what your thoughts on that are.

    Thanks!

  2. #2
    Flashaholic* Echo63's Avatar
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    Apr 2004
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    Perth - West Australia
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    Default Re: DIY flash external battery pack using common 5V USB or 12V power banks?

    i have been led to believe the 8xAA power packs you are talking about feed 300V straight to the flash capacitor (via a diode system, so you don't zap yourself touching the pins in the flash)

    you could try the GODOX power packs, PB820 or PB960 - they are $180ish and have two ports (one cable though) and can run two flashes together.
    they are also a Lithium Ion battery, rather than the frustrating to swap/carry/charge AA cells in the manufacturers packs.
    http://www.amazon.com/Godox-Flash-Po.../dp/B00HX8DDBU

    I have been considering getting a pair of Ving850 and a AD360 so i don't have to worry about AA cells any more
    flashlight collector by day
    flashlight user by night

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