Battery issues

Tiny
TIFFANNY1
  • MEMBER
  • FORD ESCORT
I have a 1998 1.3 ford escort with 29000 on the clock. I have never had any problems with it the car is great. How ever I got up Monday an had a dead battery. I called the RAC an they said it was a faulty battery an sold me a new one. The car worked fine I drove it to work an back. Then the next morning the battery was dead again I left it an when I got home my brother (good with cars an reliable) came round checked it over an swapped the battery for a fully charged one he had in case it was a faulty battery. The next morning the same totaly dead. We have check the batterys out they are fine reads 12.3 when cars off 13.6 when engines running how ever it is draining over night. The starter is fine an the alternator is recharging the battery when the cars on. We ave been told the car is grounded some where but how do we find this out. Everyone is saying its the alternator but how do I know this for sure we have just come to sell the car as this has happened an I don't want to pay out for an new alternator if thats not the problem we already have a new battery that wasn't needed. Please help Thank you!
Wednesday, September 12th, 2007 AT 5:19 PM

3 Replies

Tiny
MHPAUTOS
  • MECHANIC
  • 31,937 POSTS
Hi there,

You need to do a current draw test, You need to hook up an AMP meter between Battery Pos + and the battery Pos + terminal ( you will not be able to start the car like this but you don't have to to do the test) Now with the key turned off and doors closed, read what the Amp gauge is showing it should only be about.05 -.5 Amp Max. If it is up around 1 Amp or higher something is drawing current when it should not. Now the really clever bit, remove each fuse one at a time and note what happens to the Amp gauge, If you remove a fuse and the gauge drops back to less then.4.5 you have isolated the circuit that is draining the power, check the fuse cover to see what it is powering, often it is a faulty boot light or glove box light that is at fault, but it bight be a relay stuck on that is draining the power, Remember that the radio fuse will always be active as it need power for the memory as dose the E.F. I. Fuse, so look for one that may have a larger than normally draw and you will be well on the way to locating the fault.

Mark (mhpautos)
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Thursday, September 13th, 2007 AT 1:00 AM
Tiny
TIFFANNY1
  • MEMBER
  • 2 POSTS
Thanks for that how ever I have been told by the RAC today that it is the alternator. How ever my brother doesn't agree as he said he doesn't think its possible for the alternator to do this if the car hasn't been started since the new fully charged battery was connected. I have found loads of info saying the alternator can make your battery go flat by not re charging it so you are running on reserve battery but I have not found any thing saying the alternator can drain the battery if you haven't started the car. I did read something about the diode's being fault can drain your battery but i'm still not sure I fully under stand. Every one keeps saying the alternator as this is the most common cause but the main point we need to clarify is can this still be the cause if you don't even start the car.
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Thursday, September 13th, 2007 AT 2:52 PM
Tiny
MHPAUTOS
  • MECHANIC
  • 31,937 POSTS
Hi there,

I did a bit of home work on this and yes, the alternator can cause the battery to drain if a diode is faulty, the result will be a lower than normal charge rate, so I would have the alternator bench tested to make sure, and the normal cause for this fault is flashing the battery terminals when jump starting, a voltage spike can do the damage.

Mark (mhpautos)
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Thursday, September 13th, 2007 AT 5:38 PM

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