FYI/DIY - voltage regulator modification for more power

[Hit Man X]

I posted this on Scottie's 745i board years back, may as well post here too:



The fix to bump the charging voltage up to the currently normal 14.5v which is optimum for some of the newer generation of batteries follows.

The regulator senses the voltage between D+ and ground and adjusts the current to the rotor to obtain the nominal voltage. If one could raise the regulator ground slightly above the alternator ground, this would be seen as a higher output voltage.

In normal operation a current flows from the ground terminal of the regulator to the alternator ground and we would need to create a small voltage drop between the regulator ground and the alternator ground. The simplest device to use for this is a diode. A silicone diode has a fairly constant forward voltage drop of 0.5V - 0.8V and inserting this between the two grounds would increase the output voltage.

The unmodified regulator. The flat metal tongue that goes around the screw hole to the left is the regulator ground connection.

A 1N5402 diode (available at Radio Shack) works well and it handles 200V and 3A nominally. Verifying the voltage drop using the multimeter we see that it is around 0.5V with the small current the multimeter uses.

Here you remove the tongue off the regulator, soldered the anode of the diode to the regulator ground and wrapped the cathode around the screw hole. After installing the alternator again you can now see that the voltage across the battery poles, with the engine running, is around 14.5V, which is just what we aimed for in this instance.

[CMG]

Wasn't there a volvo regulator that works to do this!

[Jay535is]

Wasn't there a volvo regulator that works to do this!

Exactly, a Bosch regulator for a Volvo that did the same thing, without soldering.

[heifetz17]

What are the benefits of having 14.5 volts vs. 13.5? Would it make my windows function a little faster?

[CMG]

It might barely make a difference. Usually in old cars if it's not a physical problem with the windows it's because of long sections of wiring and old grounds combined. The 14.5 volts will charge the battery better these cars don't charge well at low speeds in my experience.

[Hit Man X]

No clue on the Volvo regulator.

Why replace a perfectly good reg when you can modify it for $1 or less?

[CMG]

I found some notes i took long ago and i think the volvo reg is vol 041605. Huco 14.6v.

[poopin04]

I found some notes i took long ago and i think the volvo reg is vol 041605. Huco 14.6v.

Bumping an old thread, but needed to sort out some charging issues. The part number for this is Huco 3523710, if anyone needs. Picking one up from FCP Euro now.

[BONDOSPECIAL]

Thanks for the part #! I found one on Ebay for $13 new, free shipping, same brand, Huco made in Germany, picking one up now

[DSpoljaric]

Thanks for the write-up Hit Man!

[friens3]

Bumping an old thread, but needed to sort out some charging issues. The part number for this is Huco 3523710, if anyone needs. Picking one up from FCP Euro now.

will his Huco 14.5v regulator fit the AL129X ?

[Hit Man X]

It was the same for me.

[cfisher535is]

Doesn't it matter that the part number on FCP Euro is coming back as an 80 amp and the AL129X is a 115 amp? Wouldn't you need a 115 amp version?