Retro Heated Windscreen

[notorious]

Hi Tore,

Good luck and let me know if you will have more questions.

What AGM battery have you got?

>> I've also changed my voltage regulator on the alternator
>> to one with an external adjustment. This also has the
>> temperature/voltage compensation giving a higher voltage
>> at low temperatures. I've adjusted it while measuring
>> on the the battery poles until I got about 14.3- 14.4 V.

Oh this is great stuff! Where you've got it from? Link to manufacturer?

I'm just curious, what was the voltage on the output poles of your alternator and on battery poles before you did this upgrade? If there was big voltage drop between alternator poles and battery poles perhaps it would have been a good sense to find where the voltage drop was?

Tell me more

[ainarssems]

I thought the stock regulator was adjusting voltage automatically depending on temperature between 14-15V

[notorious]

Hi Ainars, the stock regulator adjusts voltage fine, but this happens on alternator poles. For instance, voltage on alternator of my car is 14.2v -- tip top. But on battery poles I have 13.8v -- God knows where the voltage drops on the way to battery. What I want is to have 14.2v on battery poles.

Also, very interested to know if the 'Battery ECU' can be retrofitted from newer cars to D2. I hope those devices provide battery with 14.2-14.5 volts and take into account temperature and age of battery, etc.

[Goran]

Thats useful info Sergey, thanks. Not good news for me, I intended to get a lithium battery but it looks like it is expecting to see 14V+, not sure its going to be happy with 13.8V
http://www.voltphreaks.com/technologydir.php

I'll have to investigate on my car, and see if there is a way to 'bump up' the voltage.
Maybe its one of the corroded distribution points thats causing the extra resistance?
The one near the front driver's wheel usually corrodes or so people say.

[notorious]

Goran, yes distribution point on starboard side in the wheel arch is classic place for corrosion:



But on my car that place is fine -- I have checked it. Voltage drop on my car is elsewhere.

Here is electric scheme:



TV1 is the box in the wheel arch.

But if you look at 'TV2' you will see that whole Terminal 30 is connected to battery, so God knows that draws current from there while engine is running. I'm sure that voltage drop comes from that part of the scheme.

[ainarssems]

T1n goes to switched +12V and is used to supply current to rotor of alternator through the voltage regulator.

[ToreBj]

The modification for the external adjustment was done by a local workshop specialized in starters and alternators. They've been in the business for as long as I can remember and know their stuff. We are are talking about a customized job solved with a simple approach. He used a standard voltage regulator, the ones that have the regulator and brushes as one unit and just popped off the regulator. Then he cut a piece of cable with 3 wires and soldered on the brushholder contacts and at the regulator itself. Then some epoxy was applied to cover the rear of the regulator. Bosch do not make regulators with an adjustment potmeter, but other manufacturers do.
The pictures will speak for themselves so you get the idea. One could of course drop the cable all together, but I liked the idea of adjusting it if I felt like experimenting a litlle bit (which is a tendency of mine) Keeping it higher during the cold season f. ex.
On the last picture you can se that the regulator is just hidden under the crossframe above the headlamp.

My battery is from a scandinavian chain called Biltema. I attached a picture of that as well.

[notorious]

Tore, -- yep, great stuff.

I was thinking about this kit here: http://www.davebarton.com/AdjustableVoltage.html

The same idea basically.


** Question for everyone***

New A6s, A8s and Q7s all come with "Battery Control ECU". Do we know what exactly that thing is doing and designed for? Is is possible to configure it to charge battery with specific voltage? If yes, I want to retrofit it!

[ToreBj]

Originally Posted by notorious

Hi Tore,

I'm just curious, what was the voltage on the output poles of your alternator and on battery poles before you did this upgrade? If there was big voltage drop between alternator poles and battery poles perhaps it would have been a good sense to find where the voltage drop was?

Tell me more

I measured it to about 13.7 V. Adding consumers it would drop below 13.5 V and then you are actually discharging the battery.

[notorious]

Yep, -- similar situation. Mine was about 13.86v or so on battery poles (without extra consumers) and at the same time exactly 14.2v on alternator poles. I think that voltage drop between alternator and battery is caused by everything that hangs on Terminal 30 (see scheme above).