testing for a current draw with 2 batteries

[steve meltzer]

I'm pretty certain I have a current draw on my '69E, but to be certain, I want to know if it matters which battery you work from? It doesn't seem like it would, but i wanted to check. thanx. steve

[proporsche]

hi Steve ,no,it does not matter where you check...
Ivan

[steve meltzer]

thanx so much, Ivan. s

[dannobee]

You need to disconnect the other battery if you're going to check for current draw.

[911pcars]

Originally Posted by dannobee

You need to disconnect the other battery if you're going to check for current draw.

IOW, just use one battery source (B) for the parasitic current draw tests. Deactivate by disconnecting the ground cable on the non-test battery (A). Perform the test on the active battery (B).

Connect an ammeter in series with its ground cable (B) to measure parasitic current.

Sherwood

[steve meltzer]

OK, thanx guys, i had no idea, so i'm glad I asked! I've done this test before, but not on a two battery system.

[steve meltzer]

can someone explain the science and reasoning for dc'ing the non-test battery? thanx s

[HarryD]

Originally Posted by steve meltzer

can someone explain the science and reasoning for dc'ing the non-test battery? thanx s

Picture worth 1000 words.

Wiring is like this.

Ground Connection -|--BATTERY 1 (Driver Side) ++++|+++LOADS
Ground Connection -|--BATTERY 2 (Passenger side)+|^

you have 2 separate ground connections. If you only measure at one, you will have current flow at the second as well.

[steve meltzer]

OK, i got it. thanx so much. s