Question for you electrical gurus
Question for you electrical gurus May be a dumb question but....
If I remove the negative battery cable from the battery and I connect a test light to the neg cable, I can touch the neg post and the test light lights up for a few seconds. I can remove the test light from the post and wait a few minutes and repeat and the light comes on again. I also checked it with a voltmeter and can watch the volts slowly climb back up to around 12 volts. Is this normal? The only reason I noticed this was I was chasing an issue with B1S1 not always showing to be working. Just curious if I need to investigate this any deeper.
If I remove the negative battery cable from the battery and I connect a test light to the neg cable, I can touch the neg post and the test light lights up for a few seconds. I can remove the test light from the post and wait a few minutes and repeat and the light comes on again. I also checked it with a voltmeter and can watch the volts slowly climb back up to around 12 volts. Is this normal? The only reason I noticed this was I was chasing an issue with B1S1 not always showing to be working. Just curious if I need to investigate this any deeper.
On The Tree
Joined: Nov 2015
Posts: 132
Likes: 17
I'll give this a stab, no guru here...
In the old days, before computers in cars, when everything was off (no parasitic drain) the above described test light would not illuminate. In that scenario, the test light is introducing a resistance in series to the power for the entire vehicle. My guess is that the additional resistance, which makes for a lower voltage, causes the parasitic devices to go off line bc the battery is not usable...
How does that sound?
In the old days, before computers in cars, when everything was off (no parasitic drain) the above described test light would not illuminate. In that scenario, the test light is introducing a resistance in series to the power for the entire vehicle. My guess is that the additional resistance, which makes for a lower voltage, causes the parasitic devices to go off line bc the battery is not usable...
How does that sound?
PC is right, that's an old way of checking for parasitic draws, it can start out pretty bright then dim after modules go to sleep. With the voltmeter you are completing the circuit so it will show the voltage that is left over basically.
I know you weren't checking this but to check for a draw with a voltmeter you would select amps, normally have to change the position of the lead.
Side bar- don't connect the leads to the battery pos and neg with the leads in the amp spots, it will blow a fuse inside the meter. This is dependent on the meter is question also
I know you weren't checking this but to check for a draw with a voltmeter you would select amps, normally have to change the position of the lead.
Side bar- don't connect the leads to the battery pos and neg with the leads in the amp spots, it will blow a fuse inside the meter. This is dependent on the meter is question also
