Battery was old and seemed like it just died overnight. Jumped it checked for charge(14.5 volts no load). Was ok the rest of the day but was dead again in the morning. Took battery to be tested at parts store and it was junk. Put in new battery and was good gor a couple days,now dead again. What do I need to check?
When was the last time you did any electric work on the car (add a stereo, add lights, etc.)? Sounds like you have a source pulling a load while the key is off. (using amperage) Nearly nine times out of ten, when you take a battery to a store to be checked, they will try to selll you a new one.
Had to replace temp sensor for cooling fan also replaced fan relay. Working on 86 skyhawk no regulator. Hooked multimeter between neg cable and neg post. Set for 10 amps and showed no draw which I thought was odd because computer and clock should show some draw. Correct? Battery replaced same day as fan parts 2/25/10
Think I will recheck draw with a different meter. Brother has a new one and mine has been dropped a couple times.
On a 72, just pull the negative battery cable off with the engine running... if it dies, the charging system is bad. If it continues to run, suspect the battery.
Sounds like your meter has a blown fuse. If you ever exceed a 10 amp draw while checking for a draw, the meter will blow its internal fuse.
In place of an ammeter connect a small bulb in series between the negative terminal post on the battery and the negative cable. If the light lights bright there is a heavy current flow, if dim a light a little flow. If no light there is no flow. To make sure the connection is good turn on the headlights and the bulb should light. Turn lights off and ignition on and see what the difference is. Turn ignition off again. If the light is on at all pull fuses until it goes out and you will have found the source of current flow causing the battery to discharge. On the older cars the clocks were generally a source of dead batteries because they used a magnetic coil to wind the works. If the contacts burned closed it would discharge the battery but not blow the clock fuse. Good luck.
replaceing fuses in DVMs stinks. i like to make a test lead for the DVM that has a fuse holder holder inline with a 5 or 7.5 (i like fuses to be fast-blo) fuse in it. that way replacment is external.:Smarty: my vote on this whole drainage problem is debris in the lighter recepticle.....LOL
Guys, For the record, NEVER disconnect the battery with the engine running, for ANY reason. The resulting surge can destroy a good alternator, and damage other components. The alternator MUST have the load the battery provides, or the voltage can exceed 20 volts. The procedures outlined in the manual are GOSPEL. Ray
Hooked up test light between neg cable and neg post. Lit up like a Christmas tree. Pulled all fuses and was still lit up. Started pulling connections in engine compartment. When I pulled the heavy wire off alternator,test light went almost out. Hooked up another known good alternator and light stayed very dim. Had alt tested and showed bad. Is this common. Charges good but shorted internally?
quote=455 Powered;1597769]Hooked up test light between neg cable and neg post. Lit up like a Christmas tree. Pulled all fuses and was still lit up. Started pulling connections in engine compartment. When I pulled the heavy wire off alternator,test light went almost out. Hooked up another known good alternator and light stayed very dim. Had alt tested and showed bad. Is this common. Charges good but shorted internally?[/quote] Probably charged, but not good. Testing with volt meter only leaves a lot to be desired especially if not under a load. Test with volt meter, amp meter, and ripple test would have shown a bad alt .
I'm glad the test light pointed you in the right direction. It is a simple old school trick that is low tech but works. It was probably the diodes in the alternator which convert the AC power it produces to DC which the car uses. They should operate like a check valve, allowing flow in one direction only. If they fail they will allow current to flow both ways, charging a bit when the engine is running and draining the battery when the engine is not running.
A faulty trunk light mercury switch, or leaving interior courtesy lights on via the headlight switch are also conditions that may drain a battery over a short perod of time, but they are fairly easy to detect and correct. :TU:
