sega dude
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Using a mirco USB car charger with the Raspberry Pi

Sun Jun 30, 2013 7:52 pm

I got a dual screen portable DVD player for a long 9 hour trip I will be going on soon. The second screen uses normal composite video inputs to connect to the screen. Since the Raspberry Pi has a composite video port, I will use this to connect the Pi to the second screen. In order to power the Pi, I want use a micro USB car charger that has an output of 4.4v ~ 5.4V MAX 700Ma. The milliamps shouldn't be a problem, but I'm worried about the voltage. I'm scared to try it because I don't want to fry my Raspberry Pi. Is it safe to use this adaptor on the Raspberry Pi? It's an original 256MB Model B if that makes a difference.

klricks
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Re: Using a mirco USB car charger with the Raspberry Pi

Sun Jun 30, 2013 9:48 pm

The voltage specified will not burn your RPi however if the voltage drops below 4.75V then you run the risk of corrupting your SD card.
Get a volt meter and measure voltage when the RPi is connected and running.
Test with both engine running and engine off.
Unless specified otherwise my response is based on the latest and fully updated Raspbian Buster w/ Desktop OS.

sega dude
Posts: 31
Joined: Fri Mar 23, 2012 1:08 am

Re: Using a mirco USB car charger with the Raspberry Pi

Wed Jul 03, 2013 11:39 pm

I plugged it in with the engine off, but it didn't power the Pi at all. It didn't do anything. I tried with the key in both "ACC" and "ON" positions, but none of them worked.

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solar3000
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Re: Using a mirco USB car charger with the Raspberry Pi

Wed Jul 03, 2013 11:46 pm

The other problem is voltage dips from:
* when the engine cooling fan spins up
* when you turn on the air conditioner
* when you stomp on the gas at the entrance ramp
* when you turn on your headlights

But give it a try and let us know. Other people have had their pis working in their cars.

What would be better is if you had a battery and voltage regulator specifically for the pi. But that requires knowledge of electronic circuitry such as how to build voltage regulators.
Antikythera

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solar3000
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Re: Using a mirco USB car charger with the Raspberry Pi

Wed Jul 03, 2013 11:50 pm

One other thing is that those tiny car adapters usually have no heat sink. Use one of them to charge your phone for a bunch of months then take it apart. You'll see that the regulator chip has no heat sink of any type and that its enclosed in a tiny space with no air vents. You will also notice that the circuit board is either browned or blackened and the regulator chip is browned or blackened up.
They're usually poorly made.
I wouldn't trust them for your 9 hour rides.
Antikythera

sega dude
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Joined: Fri Mar 23, 2012 1:08 am

Re: Using a mirco USB car charger with the Raspberry Pi

Thu Jul 04, 2013 12:08 am

I tried this other adaptor I have and it worked.

pjc123
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Re: Using a mirco USB car charger with the Raspberry Pi

Thu Jul 04, 2013 10:42 am

sega dude wrote:I tried this other adaptor I have and it worked.
I have the AC version of the Griffin power supply that I use to power one of my pis, but based on Amazon reviews at the time, I had selected the following for cigarette lighter power for the pi (Mediabridge PEC-USBX2-12V):

http://www.mediabridgeproducts.com/stor ... 91p357.htm
My Raspberry Pi Project Page:
https://www.flaminghellmet.com/launch/

geekinthesticks
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Re: Using a mirco USB car charger with the Raspberry Pi

Thu Jul 04, 2013 10:56 am

The other approach which requires a bit of DIY wiring is to use a UBEC (google eBay). This converts the car's 12v to 5v and does some regulation. You can wire it to one of the plugs that fits into your car's cigarette adaptor and then put a micro usb adaptor on the other end. I have got one in my car that works OK for me.

xander143
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Re: Using a mirco USB car charger with the Raspberry Pi

Wed Jul 31, 2013 7:25 am

I suggest the Vority Dual USB Car Charger , I assure it's really worth it my mom gave it to me when I was on having my lon and it was assuring it really save me a lot.e me a lot. I've checked the car charger my mom gave to me http://www.amazon.com/Dual-USB-Charger- ... B00CD0JBZK and it was really true the car charger have positive feedback.

pjc123
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Re: Using a mirco USB car charger with the Raspberry Pi

Wed Jul 31, 2013 4:15 pm

xander143 wrote:I suggest the Vority Dual USB Car Charger , I assure it's really worth it my mom gave it to me when I was on having my lon and it was assuring it really save me a lot.e me a lot. I've checked the car charger my mom gave to me http://www.amazon.com/Dual-USB-Charger- ... B00CD0JBZK and it was really true the car charger have positive feedback.
$25.99.....Wow, that is crazy expensive. There are plenty of good dual port 3.1 Amp chargers available from $8 to $10.

I have this one dedicated to my pi ($9.99):
http://www.amazon.com/Mediabridge-Outpu ... B007TV88F2

And this one for my Nexus 4 ($7.99. Didn't test this one with the pi):
http://www.amazon.com/PowerGen-Dual-3-1 ... 49&sr=1-10
My Raspberry Pi Project Page:
https://www.flaminghellmet.com/launch/

wredlich
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Joined: Mon Sep 02, 2013 2:41 pm

Re: Using a mirco USB car charger with the Raspberry Pi

Mon Sep 02, 2013 2:42 pm

I'm a total newbie. Planning a specific use for RPi in the car. I bought this for it:
http://www.amazon.com/gp/product/B007JP ... UTF8&psc=1

Anyone have any comments?

Kevery Zenlly
Posts: 2
Joined: Thu Sep 01, 2016 3:49 am

Re: Using a mirco USB car charger with the Raspberry Pi

Fri Dec 02, 2016 8:52 am

I am using ESEEKGO car charger, which is charge fast. Now there is the newest 3-port car charger what you can try. I prepare to get it on amazon. https://www.amazon.com/Charger-ESEEKGO- ... %3AESeekGo
Last edited by Kevery Zenlly on Sat Dec 03, 2016 3:20 am, edited 1 time in total.

peterlite
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Re: Using a mirco USB car charger with the Raspberry Pi

Fri Dec 02, 2016 9:44 am

Things on Amazon and Ebay are extremely variable in quality. The photograph of the product is sometimes different to the description. The reviews are almost useless. Read some independent product reviews before purchase.

The USB standard for charging devices is slack compared to the accurate voltage required by the Pi. Read up on the battery supplies for Pi. A good one has accurate voltage regulation on the Pi side and will keep the Pi going when something in the car drops the supply voltage.

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HawaiianPi
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Location: Aloha, Oregon USA

Re: Using a mirco USB car charger with the Raspberry Pi

Fri Dec 02, 2016 10:22 am

peterlite wrote:The USB standard for charging devices is slack compared to the accurate voltage required by the Pi...
This is very true, unfortunately. Phone/tablet charging is far less voltage sensitive than powering a computer. I have tested 5V/2.4A chargers that dropped down to 4.5V at only 1A load. 4.5V will still charge your phone fine, but it won't run a Pi.

That's not to say they are all bad. I own a few different phone chargers with good regulation that work great on the Pi. In fact, my Pi3 has been running off of a RAVPower RP-PC002W charger for several months now. It's rated 5V/2.4A but actually outputs 5.3V and will still be above 5.2V at 2A load. 5.3V is a little high as the max recommended is 5.25, but the micro USB cable connecting power to the Pi will drop the voltage a bit, so it should be fine (also, it's less than a 1% difference).

I also have a few chargers from Ventev that maintain good 5V regulation under load (I have both home/AC and car/DC chargers from Ventev).

The problem with using a phone/tablet charger is, you often don't know until you try.

Another component that's just as important as the power supply is the Micro USB cable connecting the power. Many are quite poor at delivering power due to thin wires and high internal resistance. I did a post a while back on some of the best cables I have used: viewtopic.php?f=63&t=165393
My mind is like a browser. 27 tabs are open, 9 aren't responding,
lots of pop-ups...and where is that annoying music coming from?

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