> Each of these USB ports may have an always on 12v to 6v transformer inside > which may setup a little always on draw. Anyone know?
Where I work we design and manufacture transformers, mostly for aerospace. I am not an EE but have worked with them regarding transformer efficiency. We do not sell into the consumer or computer market but I have been involved with some related design projects and looked over the incredibly small coils and transformers used in today’s computing devices. Many of the leading “chip” inductor and transformer companies have developed highly engineered and automated products and processes. Almost all are manufactured in Asia. A power transformer almost always has some amount of excitation current or related power waste when idling. Some smarter switchmode power supply circuits may be able to limit the losses at a cost of complexity. I use a SWAG (scientific wild ass guess) of 15% to 30% loss at each conversion (i.e. shore power to computer battery, comp battery to USB = 30%+ loss). In my opinion, using a separate battery or the boat’s own power system would be more efficient than using a computer’s power system for onboard accessories. Having said that, if you have your laptop plugged into your boat’s 12V supply and have the ability to maintain the battery bank (solar, engine etc.) then using the USB power for convenience power may have little penalty. In summer keep an eye on heat buildup around the battery and the power circuitry. Martin Calypso 1971 C&C 43 Seattle [Description: cid:D1BF9853-22F7-47FB-86F2-4115CE0BAF2F] From: CnC-List [mailto:[email protected]] On Behalf Of D Harben via CnC-List Sent: Wednesday, July 16, 2014 6:16 PM To: Dennis C.; [email protected] Subject: Re: Stus-List USB ports and users Hi Each of these USB ports may have an always on 12v to 6v transformer inside which may setup a little always on draw. Anyone know? Has anyone tried a desperate 6 v battery to feed a bunch of bare non transformer ports, like those found on the front of computer desktop boxes? Don .... getting ready for a maiden trip of new to me Viking 34... On Jul 16, 2014, at 9:09 PM, "Dennis C. via CnC-List" <[email protected]<mailto:[email protected]>> wrote: I recently installed a Blue Sea 1016 dual usb port at my navstation for charging our cellphones. (The Admiral has an unlimited data plan and Pandora on her phone. We have a stereo that accepts MP3 aux so we use it a lot.) Anyway, I was wandering through a discount store and saw usb powered fans for cooling laptops. Curious, I googled usb fans. There are a LOT of usb powered fans out there. Look at some of these: http://www.amazon.com/Thermaltake-Mobile-Fan-External-Cooling/dp/B00080G0BK/ref=zg_bs_3015416011_2 http://www.amazon.com/Daffodil-UFN01-Switch-Speed-Adjustable/dp/B002C3IOZG/ref=zg_bs_3015416011_12 There are several muffin style fans for those who want to install a fan in their companionway hatch boards and hook it up to their batteries via a usb port. I found a usb powered refrigerator that cools one can of soda. How about this usb powered aquarium? http://www.smarthome.com/95640/Fascinations-FISHQ1-USB-Desktop-Aquarium/p.aspx Just opening up some options for the list. :) Dennis C. Touche' 35-1 #83 Mandeville, LA _______________________________________________ This List is provided by the C&C Photo Album Email address: [email protected]<mailto:[email protected]> To change your list preferences, including unsubscribing -- go bottom of page at: http://cnc-list.com/mailman/listinfo/cnc-list_cnc-list.com
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