In car PC - 12 to 9 V drop when S M

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Forum Name: General Discussion
Forum Discription: General Mobile Electronics Questions and Answers
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=15153
Printed Date: May 10, 2025 at 2:11 AM

Topic: In car PC - 12 to 9 V drop when S M

Posted By: conivty
Subject: In car PC - 12 to 9 V drop when S M
Date Posted: June 19, 2003 at 10:51 AM

This is my first post, so hello to everybody.

I have an in car PC that could already be running when the starter motor is fired. The PC is intolerent of the drop to 9 V & reboots.

Does anyone have any suggestions on how to have a secondary battery put in that would not be subect to this drop, &leaving me with a PC unaffected by the starter motor.

Altenatively are there any other solutions I could use that would avoid having a secondary battery (This would be highly desirable)

KR,

Adam:)

Replies:

Posted By: bberman1
Date Posted: June 19, 2003 at 3:44 PM

I personally don’t know of a way to stop the voltage drop without adding a 2nd battery. But here is some info on installing the 2nd battery
https://www.eatel.net/~amptech/elecdisc/battiso.htm
https://www.walleyeguys.com/gnbhook.html
https://www.wrybread.com/WryRoad/gadgets/battery.htm

Posted By: djfearny2
Date Posted: June 19, 2003 at 5:04 PM

why does your car drop to 9 volts when starting you have to check the current battery and altinator a 3-4 volt drop is big in the car world. and i bet your engine take a while to crank.

but test your current system before taking steps.

-------------
Jon
Installer/Help Technician
---coral springs florida---
mecp certification is not always needed. I have it and it has not helped me out at all. my experience out shines it.

Posted By: MielGibson
Date Posted: June 19, 2003 at 5:46 PM

There are dedicated DC-DC switched-mode power supplies for this setup.
They work from 9 to 18 volts, so the PC won't reboot when cranking.
You can find them here:

Keypower

Opus Solutions

If you can get the Opus power supply, go for it. It's microprocessor controlled. For example:
It shuts down (delay presetable)/turns on the PC automatically. It has a voltage sensor so it won't drain your battery when engine is not runnig.

Anyway, just make sure the power supply you get can handle the power demands (wattage) of your PC.

If you want to know more, visit the MP3Car forums -I'm a member there- and go to the power supplies section.

MP3Car

Cheers!!