how to check for a short

The quintessential people and stuff mover.
goatski
Posts: 66
Joined: Fri Nov 02, 2001 12:01 am

how to check for a short

Post by goatski »

I think I have a short in my system, because when Igo to my car inthe morning the battery is dead, which leads me to belive its being drained overnight.

so what is the best way to check for a short without any special tools. also what are your best ways for finding the source of the short. and lastly would disconnecting the positive cable overnight be enough to allow my battery to stay charged?

thanks for da help, mucho appreciation
germansupplyscott
Posts: 887
Joined: Fri Jul 20, 2001 12:01 am

how to check for a short

Post by germansupplyscott »

disconnect the negative cable overnight to save your battery.

here is how to check, simple way:

remove the cable from the battery with everything turned off, keys out etc. if you have a spark, even a little one, then you have a load on the battery. there should be no load unless you have a clock (which may be enough to make a VERY SMALL spark when the cable is removed). load with everything off = short.

here is how to check, more complex way:

again, test is done with keys out, all electrical stuff off. you need an ammeter and a circuit diagram.

connect the ammeter between the positive cable and the battery. look for current draw. if you have draw, then you have a short.

to find the short, have someone remove fuses from the panel, one at a time. once the current draw is at zero, you have found the curcuit that has the short. look at the diagram and it will tell you where to find the short.

hope that helps.

scott lyons
goatski
Posts: 66
Joined: Fri Nov 02, 2001 12:01 am

how to check for a short

Post by goatski »

thanks scott

just to make sure though, in the cimple way, when you say to disconnect the cable, you mean the negative right? or positive.

also how does disconnecting the negative cable save my battery from draining? (im not doubting you, i'm just curious as to how that works : ))
germansupplyscott
Posts: 887
Joined: Fri Jul 20, 2001 12:01 am

how to check for a short

Post by germansupplyscott »

goatski,

i just re-read my post, and you're not being dense or anything for not getting it. it was poorly written.

what you are looking for is a spark just when the cable is taken off the terminal. either negative or positive will do, but it is common practice to always remove the negative cable to disable the battery. assuming that you have no electrical accessories that consume power when the keys are out i.e. clock, alarm system, etc. then when the van is switched OFF there should be zero current running through the battery. if, with the van switched off, you remove the battery cable and see or hear a little (even tiny) zap, then you have current passing through the battery with the ignition switch off. this must be a short, since we know you have no accessories pulling power from the battery.

if you have the zap, you can try the fuse pulling technique till it stops, and that will isolate the problem circuit. you still need the circuit diagram.

hope that works better.
goatski
Posts: 66
Joined: Fri Nov 02, 2001 12:01 am

how to check for a short

Post by goatski »

ok that worked a little better

so I was working on it today, cleaning the terminals and replacing the cables, at no time did I have any sparks, so I guess I dont have any shorts.

thanks for the help scott
Post Reply