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Battery keeps being drained somehow...

J

jonward786

Member
I am still having an issue with my battery. Last time it was the alternator draining the battery (or so i thought) so i replaced it. Now the battery is still going dead after about 3 weeks of running around town, this time it wouldnt start the car in a cosco parking lot. I had to get a jump to drive home. Where could it be losing juice from?

If its relevant, i put the battery in backwards for a couple seconds which probably fried the alternator, which is why i replaced it. Could that momentary dumb move have damaged anything else that would cause the battery to slowly be draining down to zero after a couple weeks of starting and stopping?

Also after i did that my radio stopped working mysteriously? could be related...i had a blown fuse but replaced it, radio still wont work

Also i was a little fuzzy about how to wire the choke, so i just took it to the fuse marked ACCY and stuck a flat connector in? dont know if that could be related?

ughh
 
First of all, I would take the car to a local Auto Zone or like place and have them do a test on the elec. system. This will tell you if all the major components are in proper working order. Be sure the battery is fully charged when you go there....
 
You may have fried the volt. reg. or since you hooked the battery up backwards maybe you just have to re-polarize it.( if this is possible anymore). I haven't messed with a reg. for ages so I'm not sure. Also, what you are thinking is a charging problem because you have to have it jumped may only be a bad starter causing a huge current draw on the batery. I thought I had a bad batery at one time and all it was is a bad starter. Just throwing out some ideas to look at. I would do what Pete mentioned since you now have electrical troubles since the battery being hooked up backwards.
 
You also could disconnect the Mustang battery completely and use jumper cables from a known good battery that is charged and check the starting circuit.

Choke can be wired to the STA connection on the alternator. This should not be a hot wire when the key is off.

Yep, you may have screwed the radio too......
 
Is the voltage regulator something that can be removed and brought in to them to test? or should i just drive the whole car in?
 
Drive the whole car in. The voltage regulator is not really testable by them as a separate item, but if not working when in the system it can be seen. FYI, it should be located on the drivers side of the radiator wall, held on with two screws.

You can test it your self with a volt meter when the car is running.
 
"jonward786" said:
Also i was a little fuzzy about how to wire the choke, so i just took it to the fuse marked ACCY and stuck a flat connector in? dont know if that could be related?

ughh
Click to expand...

Unless it is a key on only accy term, this could be your draining the battery prob.
Run the choke wire to the sta term on the alt.
 
"AzPete" said:
You can test it your self with a volt meter when the car is running.
Click to expand...

What's the best way to test the regulator? My alt light came on and stayed on this weekend. Never had a cranking issue and we tested the battery and alternator. Alternator only showed 12 but never dropped when we cranked the stereo up or flipped on the brights. 5 hour drive home with no problem but 30 miles away we stopped and had to get a boost. Drove the rest of the way home with no problem but once I shut the car off it was dead. Symptomatic partly of battery, partly of alternator. It's been on a charge and I'm gonna give it a look today but how do I nail it down to the vr vs. the alt/batt? Not meaning to hijack the thread but seems we have a common problem.
 
Been a bit since I did this but....(I have an 100 amp internally regulated alt. now)

If you put a volt meter on the sta output of a stock Mustang alt....you should get a reading of over 12 volts with an increase from idle speed.....around 14-15 volts. If that is what you get, the alt. is working. If not, it is bad.

With that test done, you next check the power level at the battery as you did. If it does not change with an increase of engine speed, it looks like the voltage regulator is bad.

You also need to have the battery with a full charge. Now, a battery with a cell bad and shorted or grounded out could alter any of these readings.

From the indications you (blue65coupe) gave, it sounds like you have a bad alternator. With no other power being used, a good battery can last for that drive home with the alt doing onl;y 12 volts.

I would charge the battery and drive it to a local auto parts like Auto Zone and have them do an elec. check for free. Those are normally accurate.
 
Thanks, I was thinking along those lines but have never had an alt. go "slightly bad". Typically when they do they'll drain the battery upon driving. However, the only thing that was being powered for the whole ride was the coil. Possibly not a big enough draw to effect it. Just wondering if there was a way to determine the reg. vs. the alt. before I run it up there. The one thing we didn't do is change the rpms of the engine. We just loaded it. Thanks again and back to your regularly scheduled program.
 
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