battery keeps dying
- Thread starter otis
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Disconnect one of the battery connectors.
Be sure all electrical devices / lights are off. doors are closed.
Measure from the disconnrcted battery terminal to the battery post it came off of. If it reads 12 volts or really any volts other than 0 you have whats called a paridetic load.
To find the culprit, do the same test but disconnect one fuse at a time, if the voltage goes to 0 when a fuse is pulled thats the cir to start tracing.
There are other devices that are not fused so you might have to disconnect lightbulbs or other devices one at a time and check.
Question.
How many times do you start the car?
How long do you drive the car after each start?
Have you checked that the alternator is actually charging the battery?
Be sure all electrical devices / lights are off. doors are closed.
Measure from the disconnrcted battery terminal to the battery post it came off of. If it reads 12 volts or really any volts other than 0 you have whats called a paridetic load.
To find the culprit, do the same test but disconnect one fuse at a time, if the voltage goes to 0 when a fuse is pulled thats the cir to start tracing.
There are other devices that are not fused so you might have to disconnect lightbulbs or other devices one at a time and check.
Question.
How many times do you start the car?
How long do you drive the car after each start?
Have you checked that the alternator is actually charging the battery?
67Dart273
Well-Known Member
Using a voltmeter to check for parasitic draw might be flawed, as many meters are too sensitive and might show the leakage of the alternator including the RF suppression cap. And it might show leakage of just moisture. it doesnt take much
You want to modify your test. START with a large wattage bulb like a tail/ stop bulb and wire that in series with the battery ground wire. If it lights up you have a draw. You are doing this to protect your meter which comes next. Meter protection in current mode is often not complete. Put your multimeter into the high scale current scale and connec that in series as with the bulb. Decrease range switch "safely" to see how much current is being drawn.
BE CERTAIN you have checked things like the glove box lamp, any extra stereo equipment (like a power amp) or any other added accessories, and the trunk lamp
You want to modify your test. START with a large wattage bulb like a tail/ stop bulb and wire that in series with the battery ground wire. If it lights up you have a draw. You are doing this to protect your meter which comes next. Meter protection in current mode is often not complete. Put your multimeter into the high scale current scale and connec that in series as with the bulb. Decrease range switch "safely" to see how much current is being drawn.
BE CERTAIN you have checked things like the glove box lamp, any extra stereo equipment (like a power amp) or any other added accessories, and the trunk lamp
Not to beat a dead horse, for me personally, it's a bit tough to understand sometimes, so Like the members above said...
Simplified, it's also known as a voltage Draw.
A 12V light works fine.
With the battery already charged. Disconnect the negative terminal and place a test light between the ground cable and battery terminal.
If it lights (dim or bright) then there's a voltage draw.
Disconnect circuits at the fuse panel until the light goes out, to narrow down the circuit causing the draw.
Keep in mind the opened door will also show up as a draw (because the interior light is drawing, but won't be visible since the battery negative cable is off).
And yes, common culprits have been mentioned above.
Let us know on your progress.
(My money is on the trunk light)
Over and out.
Simplified, it's also known as a voltage Draw.
A 12V light works fine.
With the battery already charged. Disconnect the negative terminal and place a test light between the ground cable and battery terminal.
If it lights (dim or bright) then there's a voltage draw.
Disconnect circuits at the fuse panel until the light goes out, to narrow down the circuit causing the draw.
Keep in mind the opened door will also show up as a draw (because the interior light is drawing, but won't be visible since the battery negative cable is off).
And yes, common culprits have been mentioned above.
Let us know on your progress.
(My money is on the trunk light)
Over and out.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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Checking for an off-draw is as easy as disconnecting the battery when you get home from work; then reconnecting it next morning. If the car now starts, then you have proven the point that there is an off-draw; you just don't know the actual size of it or where is the source.
Scamp Rhonda
Well-Known Member
Whatever you figure out from this, and you will figure it out, let everyone here know so we can learn from it too. These guys here are top notch and they will help you find the problem.
67Dart273
Well-Known Member
The trouble with lights (I do use them) is that unless the user is experienced, it may be difficult to judge "just what" that draw consists of, in quantity. Many modern test lamps are LED and those can light with nearly no draw. If you are not careful you can be led down the rose colored path
Yea. Just figured, On or Off would help any novice who may be reading this.
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I fought this problem on one of my darts for a while. I used an old school amp meter but could never detect a draw. Had the alternator tested but it tested fine. Tried replacing the new battery with another new battery, replaced the voltage regulator and finally replaced the alternator. The new alternator fixed the problem. Im assuming one of the diodes was leaky.
Is your battery clean? I have seen parasitic loss of 5/6 volts through dirt on the battery. Clean the top with lots of clean water. Clean battery posts while there. Also after fully charging, do a load test on the battery.
roccodart440
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Even after this is fixed, with something like a weekend warrior classic car etc, I like to have a shut off switch and use it. The only downfall is losing your audio settings, which can be remedied with one wire if it really bothers you.
I personally run a lithium battery, which will not discharge at all if disconnected.
I personally run a lithium battery, which will not discharge at all if disconnected.
dartfreak75
Restore it, Dont part it!
Check your trunk light map light dome light etc. I had the same problem in my 75 dart battery kept going dead every couple days I changed batteries alternators coils ecu everything electric I could thing of i ended up buying a battery disconnect and turing it off every night and I found the problem one day I opened the trunk after at the end of the day to get something and the bulb burnt my arm. I thought thats weird it shouldn't be that hot that quick I hit the switch and the bulb never cut off. I took out the bulb and problem solved. I still have not replaced that switch all the years later lol
The old school mechanics have a headlight with some test leads attached to check draw. If it lights a headlight bulb you have issues. Volts don't necessarily check draw. Amps draw. You can have a 12 volt draw but just milliamps and not cause much of a problem if you start and drive your car often enough.
You can check amp draw with a quality multimeter but--- BUT--- you don't know how many amps are drawing and you will often blow the internal fuse. Most fuses are a slow blow type with a 10-15 amp rating. A inductive pick-up "amp clamp" is the best bet.
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