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Old 27-03-2016, 07:50   #1
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Recharge laptops tablets phones on a 12 V battery

I hate to see if this might work and fail. How can you convert a 12V DC circuit to recharge electronics? I guess an option would be an inverter which I have but I am thinking these will be an additional drain transforming from 12V DC to 120V AC then back to the necessary power to recharge the electronics. Any ideas?
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Old 27-03-2016, 08:12   #2
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Re: Recharge laptops tablets phones on a 12 V battery

It's usually economic to get 12v chargers for pretty much anything.

With good heavy duty 12v sockets, it should be nice and reliable, and you aren't going to get conversion losses. I have some very good marine ones that I have used for years for power on motorbikes, with no problems (charging satnav, walkie talkies, laptop, etc).

I now have a range of 12v chargers for my SSB receiver, camera, torch batteries, etc., all picked up cheap on Amazon (I prefer Amazon as you get a lot of customer feedback on specific products which has proven to be reliable), and Ebay.
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Old 27-03-2016, 08:19   #3
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Re: Recharge laptops tablets phones on a 12 V battery

What charging voltage is needed by the electronics? You can buy 12 volt to 5 volt USB chargers for phones and such almost anywhere. They plug into a cigarette lighter outlet. Electronics store, drug store, dollar store and of course, telephone stores.


And, you can buy replacement outlets with 5 volt USB outlets built in.
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Old 27-03-2016, 08:28   #4
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Re: Recharge laptops tablets phones on a 12 V battery

CIG lighter chargers are available for everything these days. They call it a car charger kit. For my laptop and printer in the truck back when I drove I had a 400 watt inverter to charge laptop and run printer when needed. Paid $30 USD . They make DC to DC chargers for laptops however I was willing to accept the power loss in inverting verses the cost of the DC to DC for the laptop.
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Old 27-03-2016, 09:39   #5
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Re: Recharge laptops tablets phones on a 12 V battery

Depending on your laptop (how expensive/important) you might want to find and buy the manufacturer's own "car" adaptor/charger for the laptop, or a good unit from a 3rd party that's known to work with your computer.

If you're handy with electronics, there are many options for stand-alone DC-DC converter modules that can convert 12v boat DC to the required voltage and current required by the laptop.

Most phones and tablets charge from a standard USB port. USB adaptors for use with lighter sockets are common and inexpensive. Blue Sea make a nice dual USB outlet that mounts in a "auto lighter" sized hole.

Besides charging, USB power is also nice for other things like small gooseneck lamps, so I've installed several USB ports in our small boat, driven by an efficient DC-DC stepdown converter.
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Old 27-03-2016, 10:04   #6
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Re: Recharge laptops tablets phones on a 12 V battery

Yes, perfect. I know about but never have used these. Never made the connection (no pun intended). Thanks all.
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Old 27-03-2016, 10:14   #7
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Re: Recharge laptops tablets phones on a 12 V battery

Most laptops need 19v DC to charge. On my laptop that required 9 to 10 amps of current at bulk charge. The issue is the current flow generally exceeds what the typical 12V outlet will pull. Things get hot and melt. I burned up several plugs and outlets, before hard wiring the 12V laptop brick direct to the panel. Life has been good every since.
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Old 27-03-2016, 10:19   #8
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Re: Recharge laptops tablets phones on a 12 V battery

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Originally Posted by captainwireman View Post
I hate to see if this might work and fail. How can you convert a 12V DC circuit to recharge electronics? I guess an option would be an inverter which I have but I am thinking these will be an additional drain transforming from 12V DC to 120V AC then back to the necessary power to recharge the electronics. Any ideas?
A 35 dollar 400 watt inverter works great and there is very little drain. It also has the USB connection.

Your solar basically replaces what is being used during the process.

Mine does and I only have a 100 watt panel that charges my two batteries which are in parallel
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Old 27-03-2016, 10:58   #9
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Re: Recharge laptops tablets phones on a 12 V battery

"Most laptops need 19v DC to charge."
And try as I may, I can't ever get an answer as to why that is. Some of the Toshiba's used to use just 12 volts, years ago.
But there's nothing IN a laptop that runs on more than five volts, except of course the battery pack, and that's often only around ~10 volts anyhow.
If anyone has heard "the 19v rationale" from anyone who actually knows it, please do share.
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Old 27-03-2016, 11:18   #10
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Re: Recharge laptops tablets phones on a 12 V battery

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"Most laptops need 19v DC to charge."
And try as I may, I can't ever get an answer as to why that is. Some of the Toshiba's used to use just 12 volts, years ago.
But there's nothing IN a laptop that runs on more than five volts, except of course the battery pack, and that's often only around ~10 volts anyhow.
If anyone has heard "the 19v rationale" from anyone who actually knows it, please do share.
Yes the batteries are what drive the 19V requirement.
Most laptops use Lithium Ion batteries. Lithium needs roughly 4.2V per cell to charge the cell to 100%. 19 V provides a voltage which is suitable for use for charging up to 4 x Lithium Ion cells in series using a buck converter to drop the excess voltage efficiently. The minimum requirement is 16.8v for four cells, but 19v gives a safety factor.



Various combinations of series and parallel cells can be accommodated.
Voltages slightly below 19 V can be used but 19 V is a useful standard voltage that will meet most eventualities.
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Old 27-03-2016, 11:32   #11
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Re: Recharge laptops tablets phones on a 12 V battery

Does anybody know of a good high-power 12VDC connector? The Andersons are a bit of overkill, Perko are barely suitable for running lights (any connector that requires jewelers screwdrivers is hardly marine). On my hotrod roadster I used molded trailer plugs for body-to-chassis connection, and am thinking of using them in my mast.
Suggestions anyone?
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Old 27-03-2016, 13:11   #12
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Re: Recharge laptops tablets phones on a 12 V battery

Sailorchic-
All the laptop LiOn packs that I've seen for the last ten years are either 2p(or 3p) x 3s configuration, never more than 3 cells in series. Which puts them at 3x4.2= 12.6 volts if they are being fully charged, which is generally not recommended for best battery life or performance. Even 16 volts would be excessive and unnecessary.
And I've seen a number of packs that clearly said 10.x volts, with the higher voltage chargers. It really sounds almost like some engineer said "Well, we've always used the SuperWidget5000 voltage converter chips, and those are all 19 volt designs, so let's keep on using them." Sort of like cigarette lighter sockets: The wrong design, perpetuated now only because there's so much of it.


Bill-
Those simple cheap 4-wire trailer wiring plugs are still commonly used, mainly because they're cheap and easy to find. Grease the contacts, and overwrap the connected plugs with some butyl or other waterproof tape, and they'll get you through the year just fine.
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Old 27-03-2016, 14:57   #13
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Re: Recharge laptops tablets phones on a 12 V battery

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Originally Posted by hellosailor View Post
Bill-
Those simple cheap 4-wire trailer wiring plugs are still commonly used, mainly because they're cheap and easy to find. Grease the contacts, and overwrap the connected plugs with some butyl or other waterproof tape, and they'll get you through the year just fine.
I went to cheap molded 4-wire trailer light connectors for our trailerable boat's mast light connector after observing that our trailer's connectors look like hell after 5 years... but still work fine. Plus you can get them anywhere. Yes, greasing and tape helps.

Also, all my mast lights are now LED, so the current is now under 1 amp per circuit.
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Old 28-03-2016, 09:36   #14
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Re: Recharge laptops tablets phones on a 12 V battery

Another reason for higher brick voltages than absolutely necessary is that for a given amount of total power (Volts x Amps) delivered to run/charge the computer, lower current is needed and smaller cheaper cable and lighter duty connectors are necessary. Operative word here is cheaper, but also to some extent lighter.


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Old 28-03-2016, 09:47   #15
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Re: Recharge laptops tablets phones on a 12 V battery

I use a cheap ( under $10) 12v cig to 19v adapter to power either of my laptops, both of which can be power hungry, one of them is a 17" with an i7 CPU. Works fine, but gets a little warm if trying to charge the battery and run the laptop.

As for better DC connectors, I prefer Anderson connectors. Small, excellent contact area, color coded, keyed, easy to assemble and use, and cheap. I bought a bag of 10 pair rated up to 30 amps for under $10 at the Ham Radio Outlet store.
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