Battery Drain

SON240sx Automotive
1

Hia people

I have a parasitic battery drain - I’ve looked around on the net & forums looking for typical resistance (ohm) values for nissan 240sx at the battery terminals (with battery unplugged obviously). I am losing 0.5 volts overnight. Alternator is good - quest putting out 14.1-14.4 volts constant, battery was replaced under warranty 2 days ago and still same issue. FSM doesn’t have what I am looking for.

It’s a 95 base model. When car is OFF (no accessories, no engine running, etc.) I am getting around 0.8 kOhms between positive & ground battery terminals so that tells me there’s a decent size short somewhere. I realize other factors such as constant power drains - remote starters, etc. can affect it so I am looking for someone with an electrically reliable working 240 to compare the resistance values.

Could anyone who has left their car for a week & still started it without removing the terminals please chime in :slight_smile:

Thanks guys

2

wait till night…spray engine bay with spray bottle look for sparks…this is probably a bad idea but i would do it lol

3

how much amperage draw are you getting?
If it’s less than 10amps, you can measure it with your multimeter.

unplug the negetive cable, and run a 10amp fuse inline from the post to the cable.

if it blows the fuse, its a high draw(don’t hook up multimeter).

if its doesn’t blow the fuse, then you can hook up the multimeter instead, and it will give a reading. (amperage reading)

that will give you an idea where to look for amperage draw, whether its a large eclectronic, or just a small problem.

4

btw you do this with the key off

5

310 mAh drain so roughly 12v x 0.31 amps = 3.72 watts per hour drain… I’ll trace it by disconnecting fuses & measuring drain to see when it disappears. For now negative clamp off until I drive :wink:

Thanks guys

6

^ That’s how a shop would start a basic diagnosis, connect the test light between the battery and the terminal, key off for 1-5 min then start pulling fuses.

7

Even if you don’t have a test light, just pull fuses in the dark until you see one arc across the terminals, then you know there’s a draw.

8

Solved. Thanks guys. Tested using ammeter & pulled all accessory fuses - no change. Pulled 7.5 alt fuse and found the issue at the charge alternator connector I replaced a while ago (since old one had torn off). I used the connector from nissan quest which I wired up wrong causing the parasitic drain.

Correct wiring:

s14 alt charge connector quest alt charge connector
white w/red stripe ----- yellow w/stripe
yellow ----- blue

(CREDITS: this picture helped: http://i36.photobucket.com/albums/e25/vancouverbc_2008/alttt.jpg
from this thread http://forums.nicoclub.com/zerothread?id=253113)

Now the battery drain at ignition off is 0.01 amps so about 0.12 watts (30 times less) for memory wire for audio, clock, etc.