How To: Raise voltage by .5v (nearly free)
How To: Raise voltage by .5v (nearly free)
Did this to my wrx / turbo legacy etc. Easy, simple, cheap way to get a little higher voltage.
My evo would barely break 14v with no electrical load, and at WOT it was at 13.5v. With the lights, heater fan, main fans etc. on it ran lower. If your evo runs a little lower than it "should", here is a simple way to bump it up approx a half volt. If your voltage is maintaining 14v or higher, I wouldn't recommend doing this!
You need a diode. Probably one as small as 3 amps would work, but I bought some 6a diodees (1000v but the voltage rating doesn't matter that much).
I got mine here:
You have to install this in line on the wire that lets the regulator in the alternator senses voltage from the battery - so it knows how much voltage to make. This lies to it, and causes it to make another .5 or so volts.
I am now seeing a max of about 14.8 on cold startup with nothing electrical on. Once it warms up it drops down a little from there. WOT maintains 14.0 to 14.1 volts now instead of 13.5ish. Your coils will produce a better spark for one.
Install takes about 3 min. I smashed the leads on the diode a little flatter so they would replace the fuse easier. It might be wise to actually install this in the line, and keep the fuse intact! But I have been running it this way for some time
Do this at your own risk... if you do this wrong, or the diode fails, I believe it is possible the alternator will start generating as much voltage as it possibly can (18+ volts maybe more). Though I can tell you from experiance on other vehicles, I have not had issues doing this, and there are a buttload of subi guys doing this just fine.
Attachted is a pic of it installed. The Stripe must face the alternator. The way it's installed in my pic makes this happen (stripe pointing towards passenger side of vehicle in underhood fuse box - pic was taken in front of the vehicle.. pass to the left, drive side fender to the right)
*Note: it replaces the 7.5a fuse... I moved that fuse up into an unused socket (thats why it's still in the pic... there is nothing there)
My evo would barely break 14v with no electrical load, and at WOT it was at 13.5v. With the lights, heater fan, main fans etc. on it ran lower. If your evo runs a little lower than it "should", here is a simple way to bump it up approx a half volt. If your voltage is maintaining 14v or higher, I wouldn't recommend doing this!
You need a diode. Probably one as small as 3 amps would work, but I bought some 6a diodees (1000v but the voltage rating doesn't matter that much).
I got mine here:
You have to install this in line on the wire that lets the regulator in the alternator senses voltage from the battery - so it knows how much voltage to make. This lies to it, and causes it to make another .5 or so volts.
I am now seeing a max of about 14.8 on cold startup with nothing electrical on. Once it warms up it drops down a little from there. WOT maintains 14.0 to 14.1 volts now instead of 13.5ish. Your coils will produce a better spark for one.
Install takes about 3 min. I smashed the leads on the diode a little flatter so they would replace the fuse easier. It might be wise to actually install this in the line, and keep the fuse intact! But I have been running it this way for some time
Do this at your own risk... if you do this wrong, or the diode fails, I believe it is possible the alternator will start generating as much voltage as it possibly can (18+ volts maybe more). Though I can tell you from experiance on other vehicles, I have not had issues doing this, and there are a buttload of subi guys doing this just fine.
Attachted is a pic of it installed. The Stripe must face the alternator. The way it's installed in my pic makes this happen (stripe pointing towards passenger side of vehicle in underhood fuse box - pic was taken in front of the vehicle.. pass to the left, drive side fender to the right)
*Note: it replaces the 7.5a fuse... I moved that fuse up into an unused socket (thats why it's still in the pic... there is nothing there)
Last edited by GravityKnight; Feb 2, 2015 at 05:40 PM.
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