[T3] Battery voltage with headlamps on ?

Jim Adney jadney at vwtype3.org
Fri May 6 17:25:24 PDT 2022

On 6 May 2022 at 14:58, William Jahn wrote:

> Jim , when I read the VDO voltmeter I have it calibrated to read voltage
> off the battery even though it's not connected to the battery 

There's no way to do that, because the voltage drop between the battery and 
the fuse box will vary depending on the load being served from the fuse box. 
As the load varies, the current dependent voltage drop will also vary.

If you want to indicate battery voltage, you would need to run a small wire 
from the battery to your voltmeter.

Keep in mind also that those dash mounted analog instruments are 
notoriously inaccurate. Even if you change the calibration to be correct at 
one voltage, it's unlikely that it will be accurate anywhere else.  

Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA

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