mlhaycraft

I have a 68 mustang and I Just replaced the alternator and regulator, but the battery is still running down. I disconected the positive lead to the battery while it was running and it died. Also I have charged the battery and it holds a charge. Any suggestions on what to try next?

JamesW

Not to question you , but how do you know it's holding a charge? Sounds like a weak battery that will charge up but lose it, or..you have a slow 'leak' while the car is turned off (like leaving an interior light on).

First, take your car to Autozone or such and have them run their battery tester. They can tell you if your batter has a weak cell or if there are any other system problems.

Another idea is to start probing your system to see if you've got an inappropriate ground. Try this, disconnect the + terminal of the battery, and then isolate youralternator from your system, either by disconnecting at thestarter solenoid or at the alternator. Using a test lamp or ohmeter, touch one end to the positive batterycable and one end to a chassis ground. If you have an indication, then you've got something drawing power with the car turned off.

LCC

With the car stalling when you disconnect the battry tells me a charging system problem. If you know hiw to use a volt meter, put the leads on the battery car off (aound 12 VDC). Now start the car and check it running, now you shoud have 13.8VDC +-. Take the alt back and have them check it.

69FECoupe

Ditto to what LCC mentioned about it stalling when you remove the positive terminal. It's not a good thing to do but the car should run with it disconnected.

Colorado_Mustang

Mine will stall if you remove the positive terminal. It isn't a real good test.

If the battery voltage goes down while driving, you have a charging system problem. If the battery is going down overnight, you may have a bad battery or excessive drain on the system. Hook an ammeter between the negative terminal of the battery and its cable. You should have just a few mA of current.

It isn't unheard of to get a bad VR or alternator even if they are 'new.'

mlhaycraft

Thanks for your advice, I am stationed in England and I have to order my parts from the States and sometimes shipping gets expensive. I try to exhaust all the options before returning any parts. Unfortunately I dont have Auto Zone or Napa here, cause man that would make life alot easier. And most people here dont know much about this car so Im kinda on my own and your ideas and thought give me other things to try.

JamesW

Mildenhall? Lekenheath?

Does your base MWR program have a garage you can go and use? Rent a bay club or some sort?