battery/wiring/altinator problem

[autoenthus3]

my friend has a 89 escort (i think its an 89) and hes had two new batteries and two new alternators in a week and something just keeps draining his battery. I'm a mechanic and the only thing i could think of is something like a bad ground... i have looked at it yet but i am later today i think. Any ideas?

[Davescort97]

Check for a drain of the battery with the ignition off. Put a test light or volt meter between the negative battery terminal and the negative cable removed. If there is a drain it will show up as a light or meter reading. Then, you can pull fuses one by one until the light or meter reading goes out and you will know what is draining your battery.

[A. Souphound]

Originally Posted by autoenthus3

my friend has a 89 escort (i think its an 89) and hes had two new batteries and two new alternators in a week and something just keeps draining his battery. I'm a mechanic and the only thing i could think of is something like a bad ground... i have looked at it yet but i am later today i think. Any ideas?

Why were the battery and alternators changed? Was it a undercharge or overcharge condition? Does the alternator have a internal or external voltage regulator....which one?

To check for battery drain make sure no accessories are turned on. If the car has an underhood light verify it's working properly and then remove the bulb.
a. Disconnect the (-) battery cable.
b. Connect a test light between the (-) battery terminal (post) and the disconnected (-) cable clamp.
c. If the test light comes on,* there is a short (drain) in the electrical system.
d. Disconnect the alternator wiring harness.
d.1. If the light goes out, there's a problem in the alternator.
d.2. If the light stays on,* pull each fuse until the light goes out. This will tell you which component or wiring has the short.
*NOTE: The testlight may glow DIMLY or BLINK. This is normal and can be due to the onboard computer, digital clock, digital radio etc. If the light burns bright or if you suspect excessive drain, hook-up an ammeter in place of the test light. The reading should not exceed 0.5 amps.
Prime suspects of current drain are lights under-hood, glove box, trunk, etc. not shutting off properly.

Alvin

[chevyn0va1]

Originally Posted by A. Souphound

Why were the battery and alternators changed? Was it a undercharge or overcharge condition?
To check for battery drain:
a. Disconnect the (-) battery cable.
b. Connect a test light between the (-) battery terminal (post) and the disconnected (-) cable clamp.
c. If the test light comes on, there is a short (drain) in the electrical system.
d. Disconnect the alternator wiring harness.
d.1. If the light goes out, there's a problem in the alternator.
d.2. If the light stays on, pull each fuse until the light goes out. This will tell you which component or wiring has the short.

Alvin

I always get confused on how/why that works could you explain it alittle for me?

[A. Souphound]

Originally Posted by chevyn0va1

I always get confused on how/why that works could you explain it alittle for me?

chevynOva1,
You attach the testlight ground clip to the (-) terminal on the battery and stick the sharp point into the (-) ground clamp. If everything is O.K. (no short, (battery drain) the light will remain off....because, there is an incomplete circuit....no power or current flow.
Conversely, if the light comes on there is current flowing because of a short OR, something drawing current i.e. digital clock, even the onboard computer stays on (for memory retention) and draws a very small amount of current. (The combined current flow should not exceed 0.5 Amp.)
Example: You see, with this constant current drain say 0.5 Amp (things which are not disconnected) when the key is "OFF", plus maybe a trunk light staying on, and before long the battery is zapped.
Let me know if I've explained it well enough.
All the best,
Alvin