adjustable voltage regulator

[P944GUY]

anyone familiar with this..from a while ago...sorry posted over on for sale by mistake..



From: Michael (Prospeed Motorsports) [michael@prospeedmktggrp.com]
Sent: Thursday, June 28, 2001 1:16 PM
To: 928
Subject: [928] Adjustable Voltage Regulator

Have you noticed, like I did, that the factory Bosch alternators doesn't
seem to put out much voltage? I was curious about this and had a chat with
my local rebuilder. What I learned was the Bosch voltage regulator caps the
maximum alternator voltage at about 13.5 - 13.8 volts and tends to drop as
the alternator gets hot.

The solution I found is an Adjustable Voltage Regulator. This regulator will
allow a maximum voltage output of 14.4 volts. For comparison, this is the
voltage that you will find on most if not all domestic vehicles. With the
Adjustable Voltage Regulator installed on my 1993 968, the results were
brighter lights, no drop in interior fan speed when the second cooling fan
kicked in, tighter bass from the aftermarket stereo, etc. Basically solved
all the issues associated with alternator low voltage were completely
eliminated. I now find the dash volt meter will stay right on the 14 volt
mark with the stereo, lights, A/C and wipers on (Basically everything
possible turned on). A tremendous difference.

The Adjustable Voltage Regulator replaces Porsche part #928 603 142 00 and
will fit:

911(C2/4 & 993) 89 - 98
928 87 - 95
924/944/968 83 - 95

It is a direct bolt-in replacement. A couple of screws and a wire to remove
and plug-in replacement. Easy!

The Adjustable Voltage Regulator retails for $45.95 plus $5 shipping. You
can get additional information and how to order by going to
prospeedmktggrp.com. For the regulator (and info on high output
alternators) click on the "Electrical" button. For ordering information,
click on the "How to Order" button or call, toll free, 866.968.944

Michael G. Wachholz
Prospeed Motorsports
400 Pond Ridge Circle
Wayzata, Minnesota 55391
866.968.2944 toll free
952.475.267 fax

[P944GUY]

and here it is:

BusDepot.com - VW Bus / Camper / Vanagon / EuroVan Specialists

[P944GUY]

IB 373A Bosch Regulator Voltage

[kfanazini]

Thanks for doing all the leg-work for me!
I was just about to start looking into a rebuild, I cant believe you posted this.....THANKS!

The increase in output has no negative side-effects??????

[P944GUY]

I'm still doing research on this, but the NUMBER 1 problem with our cars is that at a minimum your battery cables and some other wiring needs to be upraded before attempting to fool around with the voltage----bad battery cables are only going to cause a fire if you try to put more voltage thru them if not replaced....So firstly, I am planning on uprading my battery harness to a minimum of 1 gauge or 0...Secondly, the cable from the alternator to starter needs to be replaced as well which I will match to the battery harness--with the 2 other wires, one being the voltage regulator exciter wire...So now from what I have read, the stock voltage regulator only puts out about something in the mid 13.0-13.5 volts...and goes lower when it gets hot...so the first link that I posted I think is a straight 14.5 voltage regulator, which our system says a max of 14.4 volts...not sure about that extra .01 of a volt on our system...the secon..the transpo adjustable is supposed to be set at 14.1 volts and adjustable .05..thus getting our needed 14.4 volts...I am gonna do some more research and consult my mechanic today to see what he thinks....but firstly I am gonna do the cables..and will try and see about getting the adjsutable voltage regulator from a source and let you all know...

[kfanazini]

Thanks. Keep me posted. I am in the middle of a head gasket and a bunch of other stuff and thought I would rebuild my alt while I was at it.

[9FF]

Trying to recall my electrical theory but increasing the voltage output of the alternator shouldn't require new cables. You are not increasing the ampage going through the cables and cables are rated for amps. It won't hurt but I don't think it is nessecary.

If you go the route if fitting a higher ampage alternator, say 200 amps, then yes, upgrade the cables also.

200A Alternator Upgrade: Porsche Alternator 928 944 968 HIGH AMP 200 AMP | eBay

[kfanazini]

Originally Posted by 9FF

Trying to recall my electrical theory but increasing the voltage output of the alternator shouldn't require new cables. You are not increasing the ampage going through the cables and cables are rated for amps. It won't hurt but I don't think it is nessecary.

If you go the route if fitting a higher ampage alternator, say 200 amps, then yes, upgrade the cables also.

200A Alternator Upgrade: Porsche Alternator 928 944 968 HIGH AMP 200 AMP | eBay

Even better...

[AA_Ezra]

I have a post some weres on her. I did get an adjustable voltage regulator " transpo or transpro" was the brand and i ordered 2.. But i did also upgrade all my wireing.
Alt to starter was like 10guage.. then from the starter to battery was like what? 10 guage again i think.. and the gound was some weird wire strap.

Anyways i upgraded the wire from alt to starter and starter to battery to 4 Guage, battery ground i used 2 4 guage cables to the same original ground post but i made sure it was nice and clean and used di-lectric grease on all the connections to prevent wear. Havent had a batter drain charge problem since.

Oh and i think i set my voltage regulator at some 14.1-14.3. im not sure its been a while. all i know is it made the car run smoother... and my radio wouldent shut off lol.

[HondaDustR]

Originally Posted by 9FF

Trying to recall my electrical theory but increasing the voltage output of the alternator shouldn't require new cables. You are not increasing the ampage going through the cables and cables are rated for amps. It won't hurt but I don't think it is nessecary.

Not sure which electrical theory we're talking about, but increasing the volts does increase the amps for stuff like PM DC motors, lights, heating elements, etc. V=I*R, right?

Regulated devices like the DME and car audio draw a certain amount of watts internally, which runs at some regulated voltage (like 5V for the DME). The regulator can accept a relatively wide range of input voltages while maintaining a constant output voltage regardless of load, up to the maximum power rating of the regulator. If input voltage goes up, input current should go down since power=V*I. Efficiency does go down for most simple linear regulators as input voltage increases over regulated output voltage, but the additional current draw is usually negligible. Often only the max output power decreases.

The problem becomes, esp in the case of high draw devices marginally wired like car audio, the resistance of the thinner wires under high current flow can cause the input voltage to drop below the dropout voltage of the internal power regulators, which is the minimum input voltage required to maintain the output voltage at the regulated level required by the internal circuitry, which then will affect the performance of the device. Additionally, even above dropout, if the input voltage sags, the input current must increase to continue to supply the power demands of the device after the regulator, which can exacerbate the previous decribed issue and cause the the regulator to dropout.

So wire gage is important for best performance. I doubt you will set anything on fire by increasing the voltage to 14.4V. It will increase the losses (heat) in the wires supplying linear loads in addition to increasing their performance, and should improve performance of regulated devices with inferior wiring by increasing the voltage available. Sometimes it would be cheaper and easier, while still being within the temperature specs of the wiring to run more voltage versus upgrading every bit of wire to reduce voltage drop. Very marginal, unreliable devices like the early headlight switch will definitely suffer due to higher voltage, though. That's where it would be wise to upgrade the wiring and use relays in that case. A case where either more voltage or better wire would help is the primary supply wires to the fuse pannel, but both upgrading the wire and increasing the voltage will definitely improve overal performance for all devices, esp the radiator fans and their affect on the rest of the fused devices.

Still, overspec'd wire will help for critical/high performance devices like the DME, souped up headlights, subwoofer amps, etc. and also to prevent the audio, fans, and headlights from overloading the main supply wires and affecting more sensitive low power devices like the DME and the dash gages.

If I'm incorrect about any theory, speak up. I'm actually in mechanical engineering but still find alot of electrical stuff very useful. I've designed and built a couple power supplies, so I've seen this before.

[kfanazini]

So......good idea or bad idea to replace voltage regulator with the 14.4 volt?