# Idea for a cheap 12 voltage regulator perhaps...

• 09-10-2003, 11:12 PM
Idea for a cheap 12 voltage regulator perhaps...
I'm driving along in my car and I have an idea for a 12v regulator that I thought I would try putting by you guys. Maybe someone can poke holes in the idea, who knows.

Anyway, the ideas is as follows:

Pick up a 12v dry cell battery that is large enough to run an epia system for say 10 or 15 minutes. You also need one of those low dropout 12v regulators that needs an input of around 13.5+volts and a diode that would handle the current.

Put the diode inline with your car power then the 12v low dropout regulator and then finally the battery. You could probably throw a cap after the small battery, then run to your DC-DC power supply.

My thought is if the voltage should fluctuate below what the regulator could handle it cuts out but the 12v battery supplies the juice for the short period of time. Otherwise the battery will be charged at a constant 12v and everything else would be happy.

Anyway, can anybody poke some holes in this idea?
• 09-11-2003, 01:28 AM
frodobaggins
you wouldn't be able to charge the second battery, you can't charge a 12v battery with 12 volts...

need 13+ to do it effectively
• 09-11-2003, 02:55 AM
Would it matter if the battery didn't quite charge to 12volts? Let's say it only charges to 10.5volts it still should be enough for a DC-DC power supply without cutting out. That is assuming the use of all laptop parts that don't require 12 volts. I'm just trying to figure out a way to easily get a steady voltage that the DC-DC power supply will work with.
• 09-11-2003, 09:47 AM
mp3hombre
Quote:

Originally Posted by adamis
I'm driving along in my car and I have an idea for a 12v regulator that I thought I would try putting by you guys. Maybe someone can poke holes in the idea, who knows.

Anyway, the ideas is as follows:

Pick up a 12v dry cell battery that is large enough to run an epia system for say 10 or 15 minutes. You also need one of those low dropout 12v regulators that needs an input of around 13.5+volts and a diode that would handle the current.

Put the diode inline with your car power then the 12v low dropout regulator and then finally the battery. You could probably throw a cap after the small battery, then run to your DC-DC power supply...

I would try it this way:
Diode-->cap-->small battery-->regulator.
• 09-11-2003, 10:18 AM
Ricky327
Would it matter if the battery didn't quite charge to 12volts? Let's say it only charges to 10.5volts it still should be enough for a DC-DC power supply without cutting out.

Mine cut out at around 10.5V. Remeber your DVD or HDD might pause slighly causing your PC to crash.

Best thing is to run everything you have on your PC, maximum CPU usage and see what happen when you go below 12V.

You dont really need a CAP
• 09-11-2003, 07:31 PM
nzKAOSnz
most cars when running, the alternator is putting out over 12v. mine sitting
at about 13.5 (i think)

for that idea, i saw a circut somewhere, that is made for having two batteries.
uses the aux battery untill voltage on main battery goes over a threshold, then
switches to the main battery, and charges the aux battery