spooker
Posts: 5
Joined: Thu Jun 11, 2020 4:30 pm

connecting 12V car battery

Sat Oct 10, 2020 5:09 pm

Hi everyone. I am planning to build a car pc with a raspberry pi 4 so I am trying to solve the power problem, ignition, safe shutdown ,etc
I ended up in using this
http://www.uugear.com/doc/Zero2Go_Omini_UserManual.pdf

It has 3 separate channels for power (page 17 on above manual) so I was planning to connect
channel 1:
+12V battery ACC cable to power on ignition
-ground

channel 2:
+12V battery constant power
-ground

Does this sound correct to you cause I am really no expert. I will intercept the cables from the car harness and connect them to the inputs via some kind of plug. Do you see any issues with that?
One other issue I see is that this is rated to 2A but the recommended for rpi4 is 3A although the page explicitly states that it is rpi 4B compatible

pidd
Posts: 1535
Joined: Fri May 29, 2020 8:29 pm
Location: Wirral, UK
Contact: Website

Re: connecting 12V car battery

Sat Oct 10, 2020 9:37 pm

There are thousands of posts on the forum about people using a lower current or cheaper power supplies and having problems with their Pi.

In this case you might be luckier because it is connected directly to the Pi so has no power lead dropping voltage. If you have absolutely nothing else connected it might work.

It is your gamble .... but be aware it is a gamble.

spooker
Posts: 5
Joined: Thu Jun 11, 2020 4:30 pm

Re: connecting 12V car battery

Sat Oct 10, 2020 10:00 pm

I was looking at an alternative power supply from mausberry-circuits
https://mausberry-circuits.myshopify.co ... ply-switch
but this is sold out.
Anyone has an alternative suggestion here?
note that I also want to power an official rpi display and probably one Bluetooth and gps dongle and usb stick.

jim1961
Posts: 52
Joined: Sun Dec 17, 2017 8:31 pm

Re: connecting 12V car battery

Sun Oct 11, 2020 12:54 pm

I use these 12vdc/5vdc "step down" regulators up in my owl boxes to power my RaspPi 3B+ video systems. The 5VDC power supply had too much drop over 15ft of cable so I use a 120VAC/12VDC 2A supply and run the 12VDC up the pole. They've been operating 2 months without issue:

https://www.amazon.com/gp/product/B01ME ... UTF8&psc=1

markost
Posts: 24
Joined: Mon Sep 17, 2018 4:45 am

Re: connecting 12V car battery

Sun Oct 11, 2020 4:28 pm

spooker wrote:
Sat Oct 10, 2020 10:00 pm
Anyone has an alternative suggestion here?

https://www.tindie.com/products/picotou ... w-version/

Spile
Posts: 22
Joined: Wed Jul 22, 2020 5:57 am
Location: Worcestershire

Re: connecting 12V car battery

Mon Oct 12, 2020 6:17 am

I can highly recommend the mp2307 module. Tiny and cost effective...
https://www.ebay.co.uk/itm/MP2307-Mini- ... 2050243664

Gary Stout
Posts: 2
Joined: Sun Jan 05, 2014 7:03 pm

Re: connecting 12V car battery

Mon Oct 12, 2020 10:25 pm

spooker wrote:
Sat Oct 10, 2020 10:00 pm
I was looking at an alternative power supply from mausberry-circuits
https://mausberry-circuits.myshopify.co ... ply-switch
but this is sold out.
Anyone has an alternative suggestion here?
note that I also want to power an official rpi display and probably one Bluetooth and gps dongle and usb stick.
Spooker,
I use these Mausberry circuits and they work great! There is a small script to install and all of the start-up and shutdown is taken care of automatically. The new version of these circuits support usb and usb-c connectors (the old style only had 2 usb connectors). They run super cool. There is basically 3 connections to the vehicle....ground, 12 volts (all-time) and 12 volts switched. If I recall correctly, there is a way to be notified once they are available. I have ordered 2 of the old style and 2 of the new style. I think I may have 2 unused old style that I would make a deal on. The old version supplies 3amps or 15 watts of power.....both styles use the same script and operate the same way.

HTH,
Gary

Kaadk
Posts: 46
Joined: Fri Aug 28, 2020 3:39 pm

Re: connecting 12V car battery

Thu Oct 15, 2020 1:41 pm

spooker wrote:
Sat Oct 10, 2020 5:09 pm
Hi everyone. I am planning to build a car pc with a raspberry pi 4 so I am trying to solve the power problem, ignition, safe shutdown ,etc
I ended up in using this
http://www.uugear.com/doc/Zero2Go_Omini_UserManual.pdf

It has 3 separate channels for power (page 17 on above manual) so I was planning to connect
channel 1:
+12V battery ACC cable to power on ignition
-ground

channel 2:
+12V battery constant power
-ground

Does this sound correct to you cause I am really no expert. I will intercept the cables from the car harness and connect them to the inputs via some kind of plug. Do you see any issues with that?
One other issue I see is that this is rated to 2A but the recommended for rpi4 is 3A although the page explicitly states that it is rpi 4B compatible
I don't think that device does what you want it to. Scanning through the manual you linked, it appears to function as built in auto transfer switch and voltage regulator, so, more like a UPS where you would supply your own battery. Hooking up both Ignition and constant power, doesn't help you with that, it would just be constantly powered. The ignition is purely redunent and unused.

You do have the right idea though that you'd want to leverage constant power in order to perform a safe shutdown when the ignition is turned off. I have some ideas, and experts have even better ideas, of how to accomplish that over in this thread:

viewtopic.php?f=91&t=223155

easterly_gales
Posts: 8
Joined: Tue Nov 10, 2020 10:29 am

Re: connecting 12V car battery

Tue Nov 17, 2020 4:12 am

Make your own (it's what I am doing).
Auto circuits have demands all of their own.

LM338T, read the info, and set it all up.
I don't see why anyone should be charging me loads of dosh when I can get the chip for well under 1 EURO.

LTolledo
Posts: 4553
Joined: Sat Mar 17, 2018 7:29 am
Location: Anime Heartland

Re: connecting 12V car battery

Tue Nov 17, 2020 9:26 am

hmmmm..... LM338T... with a good sized heatsink....
12v to 5.1v....
a good heater unit during the cold winter months..... :mrgreen:
"Don't come to me with 'issues' for I don't know how to deal with those
Come to me with 'problems' and I'll help you find solutions"

Some people be like:
"Help me! Am drowning! But dont you dare touch me nor come near me!"

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