NEED HELP....BATTERY PROBLEM

judeo · 09-17-2009, 07:26 PM

Hey everybody, I've been having problems with my battery. I bought a new one a while back for my 88 mustang and it seems to be drained everytime I let it sit for like 5 days. I changed the battery cables thinking it was that but its not and I'm not sure what else to check since I am new to cars. If someone could give me a few ideas of what to check it would be greatly appreciated
thanks

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sleeper_inc · 09-17-2009, 09:12 PM

Make sure the battery is holding a charge. If it is then check to see whats draining your battery (stereo, lights, relays, etc)

judeo · 09-17-2009, 11:34 PM

Thanks. Ill check for those things and write back if I still need help. one thing though what would I look at? should I check the wirering to see if its cracked

sleeper_inc · 09-18-2009, 10:07 AM

See if there is a big drain on the battery when the key is off (there will be some but nothing too big)

dreamer1uk · 09-23-2009, 05:39 PM

Hey,

Sleeper is right

(again lol). You can check the battery for parasitic drain by using these following steps (I cut and pasted these from a website as it does a better job in explaining the process than me typing it out).

1 - Remove the negative side battery cable from the negative battery terminal.
2 - Attach an ammeter (this measures amperage) between the negative cable and the negative battery post. Wait a few seconds to several minutes for the car to go into sleep mode - i.e. when you make the contact with the ammeter, the cars computer systems "wake up". After a bit of time they will go back to "sleep".
3 - If the ammeter is reading over 35 - 50 milliamps, something is using too much battery power.
4 - Go to the fuse panel(s) and remove fuses, one at a time. Pull the main fuses (higher amp ratings) last. Be sure to observe the ammeter after pulling each fuse.
5 - Watch for the ammeter to drop to acceptable drain. The fuse that reduces the drain is the draw. Consult the owners' manual or service manual to find what circuits are on that fuse.
6 - Check each device (circuit) on that fuse. Stop each lamp, heater, etc. to find the drain.

Hope this helps.

I know the OBD2 computers may use a drain between 50 and 70 miliamps (i found this out in my electrical diagnosis class) so i would assume anything over 35 milliamps is an issue on the OBD1 computer.