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

[William J]

 In the Bentley electrical system page 25 6.9 they have some test of how to 
check for voltage drops if the gen light staying on. Also page 20 there's a 
chart . nominal data Max current (amps) 30, mean regulating voltage (volts) 
14 , Nominal output speed (rpm) 2000. then test data which I won't type out 
here. Point being the gen cut-in speed rpm is 1450. 2.3 times the engine rpm 
. Here it states you are connecting the voltmeter from the reg B+ 
disconnected to ground so this basically rules out any voltage drops also 
they state since gen rpm is 2.3 times engine speed @ 850 engine RPM results 
in gen rpm of 1950 . I assume 850 rpm is for a standard trans they do not 
mention FI or carbs . So @ 2000 rpm engine speed no load voltage test 
connected as above Reg B+ voltage should  read 13.5 -14.5 .

 This may or may not be of any help to me or anyone or not.

William
----- Original Message ----- 
From: "Jim Adney" <jadney at vwtype3.org>
To: <type3 at vwtype3.org>
Sent: Sunday, July 01, 2018 11:48 AM
Subject: Re: [T3] Question on my 73 T-3 Square back . Charging system.


> On 1 Jul 2018 at 13:46, Bobnotch wrote:
>
>> William, it wouldn't surprise me if it's low, as the headlights draw a 
>> lot of amps from a limited source.
>
> Headlamps draw 4 to 4.5 A EACH, so it's significant, but the charging
> system should be up to that task. The generator is rated at 30 A, and the 
> FI
> and ignition probably draw around 5 A, or less.
>
> As more and more loads are turned on, the IR drop across the main wire
> from the regulator to the fuse box will grow. That will lower the voltage 
> seen
> at the fuse box, even if everything is working properly. Note that it only 
> takes
> a resistance of 0.1 Ohm, including connectors and fuses, to cause a 
> voltage
> drop of 1.3 V when 13 A (8 A + 5 A) is being drawn thru that wire.
>
> I'm not sure how much current is actually drawn by the ignition or the FI.
> When I bench test the Delta Mark 10 capacitive discharge ignitions, they
> draw around 3 A.
>
> I should measure the draw of a standard ignition and the FI sometime. It
> would not be hard for me to do.
>
> -- 
> *******************************
> Jim Adney, jadney at vwtype3.org
> Madison, Wisconsin, USA
> *******************************
>
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