How can you trace down something in the car drawing power from the battery?

[kravamagaguy]

OK thanks again to everyone for there help on my major last car issue.

This one is when the car sits and is not driven for more then 2 or 3 days the car is dead and will not start. The altenator is good.

The battery shows 11.3 volts sitting, but when you go to turn it over on the acc post. it goes to 9.1 volts. Then if you try and turn it over it goes down to 5 volts.

I do have a big stereo in it, and an aftermarket alarm system.

Any help on this would be appreciated.


Thanks again.

 

[samickguy15]

Get a ammeter that clamps around wires. I believe Sears sells them. It could be a bad connection at the battery also. If you notice alot of corrossion build up in a short period of time I would suspect that. Otherwise I would buy the ammeter and start tracing.

 

[Distortion 5.0]

You can also use a meter with probes to check each fuse to see if any of the circuts are drawing power with the key off.

Tech's call it a "parasitic drain" .

Good Luck, wires are no fun.


EDIT:

If it only reads 11v after a good drive, you might have another problem.
A good battery should hold up to a 14.4V surface charge w/ 0.0 load.
Maybe take it to the zone and have it checked before you go chasing wires...

 

[kravamagaguy]

Ok.

Yes i had the ZONE check it out, they said it was bad. But the car has been doing this for years. I'm thinking its the stereo or alarm maybe?

 

[jrichker]

Typically it is something draining the battery. Small things like glove box or courtesy lights are often the culprits. If you have an aftermarket stereo or alarm system, it is also suspect.

The ideal method is to disconnect the positive terminal on the battery, and connect a Digital Multimeter (DVM) between the positive terminal on the battery and the positive cable. Set the DVM on a low current scale of 2-5 amps if it doesn't auto range. Watch the current draw, and then start pulling out fuses. When you see a sudden drop in the current, that circuit is the likely culprit. Note that the computer, radio & clock will draw less than 1/10 amp to keep the settings alive.

 

[Jack's95gt]

I had the same type of problem. I pulled all the fuses and it still went dead after a few days. I bought a battery charger and used it every couple of days. The battery went bad from all the discharging. After a new battery, I bought a battery cut off switch that attached to the battery post and I cut off the battery after every ride. I found the problem by accident went I pulled the engine. The positive battery cable rubbed against the K member and created a short. I would have never found this. It was completely hidden.

 

[Mustang5L5]

Are your connections good??

 

[HISSIN50]

A bad battery can act like this. It just gets worse over time till it's a total PITA. In this case, there is no excessive accessory draw or anything - it's simply the battery.

 

[pastfast125]

Mine kept draining all the time, found out it was just because my connections that clamp on the terminals were worn out and not clamping tight enough. Check those out, like 4$ to replace.

 

[kravamagaguy]

Here you go.

Yes Connections are good.

Replaced the postive cable. Need to replace the negative cable.- Even though it does not look bad. Has brand new altenator- and also have a brand new high current alt. in the box waiting to go on- I think it's 160 amp-3g, with all the proper wiring etc. from rjm injection.

Has brand new battery, as well.

And for everyone that wants a good laugh, after all my issues with getting the car running correctly as in my last post, guess what happens yesterday? The starter went out! Ugggggggggggg!!

Thus is life! Now over 70% of the car has new parts. But it's a almost perfect 5.0 lx coupe ?!?!? and those are very hard to find! esp with only little milage!

lol.

 

[Roland69]

Typically it is something draining the battery. Small things like glove box or courtesy lights are often the culprits. If you have an aftermarket stereo or alarm system, it is also suspect.

The ideal method is to disconnect the positive terminal on the battery, and connect a Digital Multimeter (DVM) between the positive terminal on the battery and the positive cable. Set the DVM on a low current scale of 2-5 amps if it doesn't auto range. Watch the current draw, and then start pulling out fuses. When you see a sudden drop in the current, that circuit is the likely culprit. Note that the computer, radio & clock will draw less than 1/10 amp to keep the settings alive.

that is how I was tought except I was told to use the neg side...I don't know why but I would think you could use one or the other couldn't you

 

[BullittAndy]

Check the sunvisor lights if you have them.

 

[Roland69]

we have run into that before, or a glove box light, ashtray light, hood lights ect

 

[jrichker]

that is how I was tought except I was told to use the neg side...I don't know why but I would think you could use one or the other couldn't you

Using the negative side prevents nasty accidents like shorting the wrench to ground while disconnecting the battery cable. It probably is a better method.

 

[onefstsnake]

I know stangs dont have On Star, but I knew a guy who found that his On Star transmitter was drawing 2.5 Amps with the car off...

Bulbs dont draw much and neither do bad connections, but they add up quick.
Check the grounds?