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adamhanlon

Wetpixel Live: Batteries for Underwater Image-Making

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Nearly underwater imaging gear relies on batteries of some form for power. Traditional batteries are being gradually replaced by more powerful Lithium-based versions, but this in itself is not without risk. @Alex_Mustard and @adamhanlon discuss some of the pros and cons of different types of batteries and how we can increase the safety of using and charging Lithium-based ones.
 

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Thanks Adam and Alex, one thing you touched on was loose batteries and one of the concerns with them is shorting them out which produces a lot of heat and a real fire risk. This could happen for example from contacting metallic items in your camera bag.  To get around this make sure all your batteries have protected terminals, your camera batteries probably cam in a plastic little box or had a clip on cap to protect the terminals.  NiMH batteries are also a concern as these can produce massive currents due to low internal resistance and you can get little storage boxes for them that take 4 or 8 batteries - good for organisation and keeping them in sets as well.

I believe a lot of regulations require protection for battery terminals for loose batteries and restrict how many batteries you can carry and in some cases only apply to Li batteries so having NiMH batteries for a strobe doesn't contribute to your quota.  The other tip is to know where on the the battery the W-hr rating is, most Li batteries will have this printed on the battery.

If you are interested in batteries, the battery university website is a great resource.   Not all of it is applicable to carrying camera batteries around , but there is still a lot of useful info there:  https://batteryuniversity.com/articles

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A few years back I had a trip from UK to the Canaries.  On the way out, UK check in insisted I take all batteries out of my hand luggage and put them in my hold bag. On the way back, Spanish check in insisted I take all batteries out of my hold bag and carry them in hand luggage.

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I think there was a lot of confusion about battery carriage in general a few years ago. We can all share anecdotes from that time I'm sure! 

However, it seems to be largely sorted now, as check in staff have got got to grips with the IATA regulations. I find that printing this document out can help: https://www.iata.org/contentassets/6fea26dd84d24b26a7a1fd5788561d6e/passenger-lithium-battery.pdf

I also shamelessly use the "all lithium in my carry on" explanation to justify why my carry on weighs 25kg :)



 

 

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Posted (edited)

As Alex states in the video, I am concerned that one day I may lose or break my focus light ACDC battery charger and be left with a paperweight.

My focus light has a proprietary LI-ION battery pack (14.8V 3400mAh 50.32 Wh) charged with a DC pin from a proprietary ACDC adapter (Out 16.8V 2.8A). I'm making the assumption there a 4 Li-ION cells in the battery pack rated to be charged at 4.20V/cell. Said charger is big and heavy and requires a free wall plug. 

The battery pack says 'Do Not Charge It Other Than With Exclusive Battery Charger'.

I'm interested in the potential of charging this battery pack over USB power delivery. I have a 65W PD USB charger and am interesting in running USB-C to a type-c female to DC jack adapter. These come in all sorts of sizes and voltage classes. For example:

https://www.ebay.co.uk/itm/233853237121?_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20160908105057%26meid%3D8578709eb63e43e1bc14b5c08840fc06%26pid%3D100675%26rk%3D1%26rkt%3D15%26sd%3D233853237121%26itm%3D233853237121%26pmt%3D1%26noa%3D1%26pg%3D2380057&_trksid=p2380057.c100675.m4236&_trkparms=pageci%3A5eaf3b50-db54-11eb-831c-0621da914732|parentrq%3A6818dc9517a0acf3822d1081ffe59aba|iid%3A1

Would it be safe to use a USB PD - 15V DC adaptor for this battery pack? Does using less than specified voltage do any harm to the battery other than charging it at slower rate? Could this in fact be advantageous?

I expect if I were to use a 18V or 20V USB PD - DC adaptor, this will likely exceed the 4.20V/cell and cause damage to the battery pack and cause a hazard. I do not know the extent of overcharge protection on the battery pack and therefore the acceptable risk is zero.

Any expansion or clarity on this solution highlighted at the beginning of the video would be greatly appreciated.

Edited by joncroweucl

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You need to control the voltage applied to a Li-ion battery fairly closely, there is a fairly tight specification for voltage.  Generally they charge at constant current for a period then constant voltage till the current drops to a certain level.  The charger must be able to control these currents and voltages.  You do not want to overcharge a Li-ion cell for safety reasons.

Devices that charge off USB will generally have internal circuitry to take the USB supplied power and adjust the voltage to the required level.  There might be a USB-C based battery charger for such a cell, but it would be a specific Li-ion charger

DO NOT use the device you linked - it just supplies AC power with nothing to control it. 

You can find universal 14.4V Li-ion battery chargers with varying capacity for example this one:  https://www.onlybatteries.com/showitem.asp?ItemID=16853.14&cat1=27&uid=1913

You would need one with about the right capacity to charge your cell, the one I linked would take about 3.5 hours to charge yours.  You could install a DC plug of the right size on the leads of this charger.  I'm not saying go out and buy that item - it's just an example found by googling around that you could buy in the future.

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