;-) changing a DC voltage to an other DC voltage involves going to AC... It just gets done at a high frequency and the transformers are a lot smaller than at 60 Hz. There is some form of inductance and AC involved in all of the DC voltage changers.
It is true that generating 60 Hz semi sine-wave is rather inefficient, lot of internal losses. The DC to DC converters are working with 'ugly' waveforms at MHz frequency so they can be quite quite efficient, approaching 97% at optimal load. Leslie. Phoenix, C&C 32. -------------------------------------------- On Wed, 2/19/14, Stevan Plavsa <stevanpla...@gmail.com> wrote: Subject: Re: Stus-List Wiring an inverter To: "cnc-list@cnc-list.com" <cnc-list@cnc-list.com> Date: Wednesday, February 19, 2014, 9:51 AM As an aside, charging tablets and phones doesn't necessarily require an inverter. One could go with something like this:http://ca.binnacle.com/p8953/BLUE-SEA-1016-DUAL-USB-CHARGER-2-SOCKET-5V-2.1AMP/product_info.html Phones and tablets are DC, why convert and convert again? I'm looking into DC power supplies for the laptop as well. So far we haven't need AC but I do have a portable inverter on board just in case. I charge my tablet and phone off of the car stereo I installed at the nav station (it has a USB port). I'm considering that Blue Sea unit just as a nice to have but the project list is long with higher priorities. SteveSuhana, C&C 32Toronto On Wed, Feb 19, 2014 at 12:11 PM, Della Barba, Joe <joe.della.ba...@ssa.gov> wrote: I used to have rolls of 2/0 gauge wire for hooking up batteries and inverters. We did a lot of 1500 watt units and a few 2500 and 3000 watt versions. I would suggest most boats carry two of them. 1000 watt units are cheap enough now at Worst Marine for heavy loads like shop vacs and other tools. Then get a second small inverter, say about 100-150 watts, for device charging needs. Large inverters are not efficient when powering tiny loads. Joe Della Barba Coquina C&C 35 MK -----Original Message----- From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of Rick Brass Sent: Tuesday, February 18, 2014 11:15 PM To: cnc-list@cnc-list.com Subject: Re: Stus-List Wiring an inverter My Admiral's hair dryer is 1875 watts on high power setting, so it would draw over 15 amps AC, and 170 amps DC to power the inverter. That needs like size 0 battery cables from the battery to the inverter? I just looked at the things I customarily run with my inverter. PC charger = 1.5 amps. Cell phone charger = .5 amps. Tablet charger = .3 amps. Portable AC fans (one of them is in the back room waiting to go back to the boat) = .5 amps each. The total current draw can add up pretty quickly. And as I said in an earlier post, providing 8 amps of AC would exhaust my 4 battery 460 AH house bank in less than 2 1/2 hours. My point is: figure out what you want to power with it and then chose your inverter and battery bank size accordingly. Rick Brass -----Original Message----- From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of Della Barba, Joe Sent: Tuesday, February 18, 2014 3:33 PM To: cnc-list@cnc-list.com Subject: Re: Stus-List Wiring an inverter When I used to be in that business we divided the AC panel into "inverter" and "non-inverter" sections to keep things like water heaters and battery chargers from running from the inverter. And no - you can't use a battery charger and an inverter to make a perpetual motion machine. Prime reason for inverter purchases back in the day used to be for hair dryers and blenders. Everyone wanted battery powered air conditioning, but few boats have the room for enough batteries to support it. Joe Della Barba Coquina C&C 35 MK I _______________________________________________ This List is provided by the C&C Photo Album http://www.cncphotoalbum.com CnC-List@cnc-list.com _______________________________________________ This List is provided by the C&C Photo Album http://www.cncphotoalbum.com CnC-List@cnc-list.com _______________________________________________ This List is provided by the C&C Photo Album http://www.cncphotoalbum.com CnC-List@cnc-list.com -----Inline Attachment Follows----- _______________________________________________ This List is provided by the C&C Photo Album http://www.cncphotoalbum.com CnC-List@cnc-list.com _______________________________________________ This List is provided by the C&C Photo Album http://www.cncphotoalbum.com CnC-List@cnc-list.com
