DC outlet for USB charging

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Old 11-12-13, 07:45 PM
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DC outlet for USB charging

Hello All,

This is my first post on this site.

I have a question and I hope I don't come across as being stupid.

Background
I have a DC system 12V (5Amp max)solar system. It has a 10W panel, and I am using a LFP battery for storage. I am using a suitable LFP charge controller which has a 5A max output also. So i think I have matched the battery, charge controller and solar module as required.

I want to use this small solar system to charge a iphone or tablet device using a USB 5VDC wall socket.

My question(s) is/are..

Do I use a simple 12VDC to 5VDC stepdown cable/unit like the image attached?

When I plug in the device to the USB socket what is stopping the device from overcharging in relation to the current draw?

i.e. does the device only "draw" the current it needs (@5V) or do i have to protect it from the controller if it is "pushing" 5A max (@5V) to it? My understanding is that the iphone and tablets like 2A for charging?

Any advice is much appreciated. I don't want to blow up my devices.
 
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Old 11-12-13, 08:59 PM
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Welcome to the forums!

using a USB 5VDC wall socket.
What is this device? Make, model and link would all be helpful.
 
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Old 11-12-13, 09:28 PM
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You are not coming across as stupid and have a valid point.

I'm an electronics tech but not an authority on Apple products. Technically, you should be able to connect your devices to a 5vdc 5amp source and they should charge normally as they have built in smart chargers.

However, I stopped over at the Apple forum and there was a 23 page thread running on this very subject. I've read it's ok to use a higher powered charger and I've read it hurts and reduces the life of the battery.

I would err on the side of caution and use a 2A maximum converter.

The thread..... in case you'd like to check it out.
discussions/apple/thread/2580579
 
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Old 11-12-13, 09:42 PM
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Old 11-12-13, 09:54 PM
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OK, thanks. I just wanted to be sure that you were looking at something that was USB only, not a combination fed by 120V AC, like a Leviton USB charger/tamper-resistant receptacle.
 
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Old 11-12-13, 10:32 PM
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ok, Thanks PJMAx.

just to confirm...

From my charge controller that is rated at 5A max and 12V output, i need to connect this to a converter that steps it down to 2A max and 5V.

Is this 2A max 12V->5V a common cable or connector?
 
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Old 11-13-13, 12:46 AM
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Correct Nashkat1,

Its not a combination. I am avoiding those with 110/220V AC combined. I just want low voltage DC system.

Thanks
 
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Old 11-13-13, 08:49 AM
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I am avoiding those with 110/220V AC combined.
I would too, if I ever saw one. The ones like the one I linked to combine a 120V AC receptacle with some 5.0V DC USB ports - but I think you knew that.
 
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