[T3] Question on my 73 T-3 Square back . Charging system.

[William J]

 I recall when I wired in the volt meter early 90's it didn't seem to read 
proper it read low so I added a relay to power up the gauges , I have oil 
press and temp and the volt meter and a tach. If I recall I wired the relay 
coil + to the fuse box ,- to dash . on another fuse both hot key on only I 
ran relay #30 and  the other side of that relay contact to power the gauges 
and it seemed to help some . Thinking was I didn't know what the gauges 
actual draw was combined which as far as I know is minimal I never really 
placed an amp meter to check it.

 Trouble is if I run a wire right off battery + to the gauge it will read 
all the time and may or not be a significant draw on the battery when the 
cars sits for days .

 Not long ago I checked voltage at the battery terminals engine running idle 
and 2500 RPM and got the same readings at  the fuse box on the fuses I have 
the relay and gauges connected to , on other fuses that have a load  while 
running voltage was lower because of voltage drop. Some fuses are hot all 
the time , right now I cannot recall which.

 The car sits most times for days before I drive it and because of a few 
past bad battery experiences I had my charger set to 2amp on a timer for 2 
hours at night then I stopped months ago . I didn't feel the need even 
though most trips are short stop and go traffic simply because when I go to 
start it it always cranks over fast and to be honest it seems that even 
short stop and go drives when I'm moving the cars generator seems to charge 
the battery much better than the charger does , meaning either way when I 
check engine off battery voltage it's always at 12.5 volts or a bit above . 
The last interstate battery did have a higher at rest voltage 13.7 volts yet 
it leaked because of the top case cover was not sealed at the neg terminal. 
That extra volt was reflected at the voltmeter on the dash . When I called 
interstate asking why this battery was only 12.5 I was told that was what it 
should be yet before that I was told it should be above 13.5 also by 
interstate it even states this on their ALL so helpfull web site.


 I imagine most people driving these cars don't have a voltmeter . I never 
used to I just knew there was an issue if the gen light was on or flickering 
then did a trouble shoot.

William
----- Original Message ----- 
From: "Jim Adney" <jadney at vwtype3.org>
To: <type3 at vwtype3.org>
Sent: Sunday, July 01, 2018 8:59 AM
Subject: Re: [T3] Question on my 73 T-3 Square back . Charging system.


> There's a good chance that what you're seeing is perfectly normal. It's 
> likely
> that you have your voltmeter wired to the fuse box, so you're seeing the 
> IR
> voltage drop between the voltage regulator and the fuse box.
>
> Since the voltage regulator is only able to control the voltage at the 
> battery,
> you should consider running a dedicated sensing wire from the battery +
> terminal to the + terminal of your voltmeter (and remove the wire from the
> voltmeter to the fuse box.) This will give you a better picture of how 
> your
> charging system is working.
>
> Keep in mind that voltages taken at idle or with the engine off may tell 
> you
> something about the battery, but they say nothing about the charging
> system, since the charging system isn't working then.
>
> On 30 Jun 2018 at 23:27, William J wrote:
>
>>  Tonight was the first time since 2006 I drove at night . With the head 
>> lights and tail on even at 2500 RPM the VDO voltage gauge was just at 
>> about 12.5 volts at least that's what it looked like since these gauges 
>> are not equal spaced marks and at idle it was below 12 volts. Now without 
>> the lights on at idle it's a bit above 12 volts and at 2500 RPM above 14 
>> volts.
>>
>>  I only ask because it's been so long I forgot what it used to read. I 
>> did adjust it because it read low a while back and on VDO volt meters 
>> they provide an adjustment screw so I set it to match what my DVOM reads 
>> and it was steady and the same at all RPM's as the DVOM. As soon as I 
>> turned off the lights when I parked the car the volt meter came back to 
>> 14 volts. The interstate battery is less than a year old never went dead 
>> and reads 12.5 to 12.6 volts after the surface voltage drains off.
>>
>>  Does this sound normal ? The gen light never came on yet it does work .
>
> -- 
> *******************************
> Jim Adney, jadney at vwtype3.org
> Madison, Wisconsin, USA
> *******************************
>
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