Going to all 12V from 110/120 - Page 1
Forum section: electronics / beginners

author: greygray
author_rank: Newbie
timestamp: April 22, 2015, 06:44:37 am
content: Hello,I live in the USA and am on 110/120 but will be going somewhat nomadic in a motorhome. I will have a few things to convert to low voltage 12V LED lighting, but that leaves me with a Sonicare toothbrush, a TV, and computers, phones, etc, all of which need a "brick" somewhere to convert from th e110/120.Yes, I wil have an inverter that can handle the load of all my devices and plenty of solar to cover it with a bunch of batteries to store the energy.Is it as simple as if the device is listed as a 12V device on the "brick" I can just chop the end off and pop on a cigarette adapter and it will work? What about phones, computers, all this other stuff? I don't want to use an inverter because of the inefficiency.How possible is it to convert as many devices as possible to 12V or whatever the power "brick" says the voltage is?Or am I being too pedantic and the conversion does not lose that much power in the translation in an inverter? It is a pure sine wave inverter so I don't think I will have any problems, but I will have computers, which all have power supplies in them converting from 110/120 to 12V or so. Can I just bypass the Power Supply Unit and feed 12V directly into it? What if the device needs 18V or something other than 12V? What do you do in those cases?Thanks for any info you can share on how to most efficiently live a 12V lifestyle.

author: rob77
author_rank: Super Contributor
timestamp: April 22, 2015, 06:57:14 am
content: for computer - picoPSU ATX power supplies are designed exactly for sch a scenario - to be powered from 12Vfor the 18V stuff - just buy a universal laptop charger with 12V input and adjustable output (usually 16 - 20V)

author: Psi
author_rank: Super Contributor
timestamp: April 22, 2015, 07:06:55 am
content: I've often wondered about running a 19V laptop on 12V but have never been game enough to try it.The laptops internal switchmode psu can easy draw more current to get the same power but the extra current will be an issue if the components are not rated for it. ie, it may work for a while, then bang, diodes release magic smoke.

author: Seekonk
author_rank: Super Contributor
timestamp: April 22, 2015, 01:02:10 pm
content: My camp is 12V and I obtained a lot of defective 12V inverters with a shorted H bridge. I run a lot of entertainment equipment with the inverters 140V DC output. Electronic ballast CFL lamps work fine on DC. That was nice before LED became cheap. Lately I have converted flush mount home LED fixtures to 12V The LED take 40V but work fine with cheapo 2596 boost converters at 35V. They seem to be much more efficient at lower driving levels and don't need to worry about thermal issues with constant voltage.

author: KD0CAC John
author_rank: Frequent Contributor
timestamp: April 22, 2015, 01:19:40 pm
content: You have not given any specific details about your inverter , brand , model ?Most of what is available generally is cheap and problematic and inefficient .Most of the quality gear is through the solar community and mostly around 97% efficient .Here's one site ,http://www.backwoodssolar.com/Then depending , but generally you do not want to use a cigaret lighter for connection to battery , it can not provide much for load .

author: smjcuk
author_rank: Frequent Contributor
timestamp: April 22, 2015, 01:25:27 pm
content: Quote from: Psi on April 22, 2015, 07:06:55 amTried it with a ThinkPad X201 - doesn't detect a charger at all or even attempt to charge.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 22, 2015, 05:05:14 pm
content: Quote from: smjcuk on April 22, 2015, 01:25:27 pmTwo problems: the internal main rail is usually "ideal diode-OR" from the battery, which is usually 14V or so. So you need at least that. Second, they're usually chipped, so you need to repeat whatever data flows down that pesky center pin. Yup, just because everyone uses the same barrel connector (usually..) doesn't mean we're any closer to solving Charger Hell!Tim

author: smjcuk
author_rank: Frequent Contributor
timestamp: April 22, 2015, 05:15:31 pm
content: ThinkPad chargers are straight voltage sources. Not intelligent at all as I could charge it off my bench supply at 19v (which I did when I managed to yank the cable out of the charger (oops!)Battery is rated at 10.8v apparently so it looks like a min voltage requirement as you said. I didn't experiment with it - just needed power.Pretty versatile bits of kit thinkpads - couldn't do that with a macbook (those are stupid chargers)

author: Richard Crowley
author_rank: Super Contributor
timestamp: April 22, 2015, 05:25:08 pm
content: Computers that take >12 are very rarely satisfied with 12~13.6VOTOH, it is not terribly difficult to make (or buy) a purpose-built boost SMPS to convert 12V to 19V. Almost certainly with much higher efficiency than 12VDC to 120VAC type. And of course there are commercial "car cords" for laptop computers.And, as others have mentioned, there are replacement power supply boxes as found inside desktop/tower computers that operate on 12VDC for mobile use as you are proposing.

author: AG6QR
author_rank: Frequent Contributor
timestamp: April 22, 2015, 05:46:25 pm
content: Look up "Anderson Power Poles" for 12V outlets and power distribution. They are capable of much higher currents, with much lower resistive loss, than cigarette lighter plugs. And they're smaller. I'd recommend getting a crimp tool, plus a boatload of Anderson Power Poles, and putting them on most of your 12V devices. I have a camping trailer, and have installed power pole outlets in the walls.One possibly problematic device on your list is the Sonicare Toothbrush. If it's like mine, it charges via inductive coupling -- basically a transformer where the primary is in the base and the secondary is in the toothbrush. I haven't tried running mine on a "modified sine wave" inverter, but I can imagine it may not be happy with a all the higher frequency harmonics. It may want a pure sine wave form. It definitely won't run directly from DC. But maybe you could hack into one, open it up, and figure out a way to trickle charge the internal battery directly from 12VDC? Or switch to a different type of toothbrush entirely.

author: Richard Crowley
author_rank: Super Contributor
timestamp: April 22, 2015, 06:00:23 pm
content: Yes, Anderson Power connectors are standardized for 12VDC connections across amateur radio groups certainly in the US and maybe internationally. Recommended.Those inductively-coupled toothbrushes (and other appliances) tend use high-frequency (audio or ultrasonic) magnetic coupling. I would think it rather simple to hack a 12VDC powered substitute for the HFAC oscillator in the charger base.

author: greygray
author_rank: Newbie
timestamp: April 23, 2015, 04:59:22 am
content: Quote from: smjcuk on April 22, 2015, 01:25:27 pmI don't know which brand of inverter I will get. It is all going in my motorhome. I will have 4 250 watt panels, all going into the proper regulators, inverters, and multiple batteries, though I may not use flooded lead acid and go with Li Ion or similar. I have not made those decisions yet, but it will all be high end solar gear. I estimate the entire system, once I install it, will put me back 5 grand.So yes, I am certain I can plug right into the inverter that will actually be wired to whatever 110v outlets are in the motorhome, somewhere around a 3000-4000 pure sine wave inverter. I need to be able to hit certain peak voltages for a second when you first turn them on.I'm still learning about all this stuff, mostly, I want to go as 12V as possible, but something, that may be more trouble that it is worth than to take the 20% efficiency hit by using an inverter to go from 110 to 12.

author: greygray
author_rank: Newbie
timestamp: April 23, 2015, 05:04:01 am
content: Quote from: AG6QR on April 22, 2015, 05:46:25 pmReally? They make a PSU for a computer that has a cigarette lighter on one end not the standard US 110 style plug? I have never heard nor seen these, I will have to search them out.

author: greygray
author_rank: Newbie
timestamp: April 23, 2015, 05:05:49 am
content: Quote from: Richard Crowley on April 22, 2015, 06:00:23 pmLuckily, the Sonicare I have is the only USB chargeable one they offer, though I hate the design of the brush and how they programmed the modes so every time you toggle it on and off it goes into a different cleaning mode instead of turning off, which sprays stuff all over the mirror. I would have pure sine wave too. I will take a look at Anderson Power Poles. Thanks!

author: mtdoc
author_rank: Super Contributor
timestamp: April 23, 2015, 06:12:12 am
content: Quote from: greygray on April 23, 2015, 04:59:22 amLots of things to consider for your system. My advice FWIW:Define you loads - both 24 hr total kWh and peak watts. This will define your PV, battery bank, charge controller and inverter choices.Don't try to go all 12V. A good inverter will give > 90% efficiency. You'll lose much in appliance and lighting choices as well as wiring losses by trying to go all 12V. If you have a 12V battery bank (feasible if you keep your system reasonably small), you can still run some things directly at 12V.Rules of thumb:Total PV nominal watts should be at least 1/2 of your 24 hr kWh loads ( eg 1000 watt PV for 2 kWh 24hr load).Battery bank sized (Lead acid chemistry) to 25 % depth of discharge with 24 hr load (giving 2 days to 50% DOD with no sun or genset run time).For the example above this means about 600 AH (20 hr rate) 12 V battery bank. This conveniently also works out so that PV can provide the needed 5-10% charge rate.Size inverter large enough to meet peak load.My recomendation for system this size: Midnite Solar Classic 150 charge controller andone of these Outback inverters.For knowledgable, experienced advicethe NAWS forumis excellent.

author: Ice-Tea
author_rank: Super Contributor
timestamp: April 23, 2015, 06:37:43 am
content: Quote from: Psi on April 22, 2015, 07:06:55 amDone that with a number of lappies. Tends to work fine except for charging, which simply doesn't work. I also made sure that I didn't plug it in when the engine was cranked