I have a '91 Escort with a 3 y.o. DieHard battery that keeps dying. Sears tested the battery and said its ok. Dealership couldn't find any problems - says battery is ok, and charging system is ok. Will drive the car maybe 3 days in a row, 4th day, the battery is dead , car is garage kept. Something must be draining it. I assume I can disconnect the battery cable from the starter, and test with a meter between the cable and the post on the starter, to see if there is a minor short in the starter. Same with the alternator.

Any other suggestions on finding the culprit?
thanks

 

got any little light bulbs glowing while you are away?
Under hood, glove box, etc.............

 

It wouldn't be a short in the starter that would drain the battery. You have the switch and solenoids between it and the battery. The alternator is always a possibility when all else has been exhausted. You can check that by removing the battery feed wire on the back of the alternator and check for drain in the manner you suggested for doing the starter.

I would make sure all the cables are in good shape with clean connections and all accessories are turned off and not drawing on the battery.

Hope this helps,

Bob

 

Systematic aproach

Remove one battery terminal and insert a test light. If it glows at all the draw is greater than normal. Start pulling fuses and disconecting wires until the test light go's out. Now you know which circuit has the culprit. While the fuse is out note what doesn't work. It's one of those. Good luck.

 

thanks to all
thanks circus... didn't think about pullin fuses one at a time, good idea.
wingnut

 

ok, here's what I did. Disconnected ground from the batt, inserted multimeter between batt cable and terminal. Showed current right away. I began pulling fuses in passenger compartment, and none of them caused the current to stop. I then pulled fuses from the engine compartment fuse box, and the current stopped when I pulled the one labeled "charging system". I then put the fuse back and disconnected all wires to the alt. - still had current pulled thru meter. Anyone know what else might be on the "charging system" circuit? The only other items I can think of to check are the volt regulator and the starter maybe.
Battery now dies overnight.
many thanks

 

when you say multimeter, which function did you use? it has to be an ammeter, not a voltmeter or ohmmeter. make sure you do this part correctly or you (and us) could be chasing your tail. the etst light works well becasue you can see it easily from inside the car (reread mcircus' post). if you do this test again, which fuse (how many amps) is it that you are pulling under the hood. I can look at the power distribution schematic and tell you what else is on the circuit...but need to know exactly which circuit.

it might also be helpful to post what engine is in it...

PS, the voltage regulater is inside the alternator and you wouldn't have any type of short in the starter that would cause this.

 

i feel for you, friend. hope, you'll get it figured sooner than later

in the meantime, get 2 things - and maybe you have one already. get electrician greese and lubricate both battery terminals. keep negative terminal slightly lose, then simply remove the cable as soon as you parked for longer period of time.
2nd thing - i'd just connect battery charger to it and keep it charged overnight. at least, you won't get cought by surprise somewhere. it's a small hassle that might save you bigger headache later.

just an observation: if your battery is dying faster now, it means it's taking less charge or is charged less. under the circumstance that your poles and terminals are perfect clean from oxydation, either your alternator is not doing it's work anymore, or something in circuitry does not operate properly. drains don't get bigger over time. it either drains at some rate, or does not. your battery might be going kaput as well.

not that i know much about electricity, but isn't something supposed to be WORKING to drain battery overnight? otherwise, there's no power usage, right? you can't just drain on chassy, unless it's grounded, tires are perfect insulators. why do i keep having a mental picture of a light bulb with + and - elctrodes in it shortened? got to be something that runs on resistance priciple, like light bulbs, so even if it's shortened, it's still "working" without making any obvious signs, like fan does. my gps killed my battery overnight once, but then, again, i had to replace that battery few mths later anyway.

 

focus on the draw first...then, because your battery has been charged and discharged so many times, you should slow charge it at a low rate and then have it tested, preferably by conductance (find someone with a midtronics battery tester). this is most accurate. i find that the DIY stores don't know how to test a battery and use inferior equipment (50/100 amp bread toaster type load testers won't cut it). charge and discharge cycling is very hard on automotive lead acid batteries. don't get hung up on the charging system not working properly until you determine the source of the draw.

 

how many amps draw are we talking about, I assume when you say current you mean amp draw not volts. If your meter has an inductive pick up you can take a long jumper wire and make a loop of 10 coils to help pick up low amp readings, just remember to divide by 10 to get the correct reading. Any thing over 1 amp will kill a battery over night usually. On some cars the alt main charge wire also powers the fuse block so when you see current with it disconnected from the alt that just means you need to trace the circuit to find out what each componet is that feed off of it. You may have to unplug each circuit to issolate where the draw is.
remember Murphy was an optimist

 

My gut tells me its not the battery. I had two different shops load test it, and they claim its OK. The battery has been dying overnight, so I drove the car for about a half hour, took it home and pulled the ground cable from the batt. I waited a couple days, reconnected the batt., and the car started right up.

I also performed the test with a test light (between ground cable and ground post). I got a slight glow (the battery is half dead at this time mind you). I pulled each fuse in the passenger compartment one at a time, the light continued to glow. Pulled fuses in the engine compartment, and one made the bulb go out. Its a 40A fuse marked BTN that powers some of the lower amp fuses in the pass compartment (the ones I already checked) and the "charging system".

carguy, if you can tell me what else is on this circuit, I'd appreciate it. Now, not to confuse you any more, but in the owners manual, the illustration and chart calls for a 60A fuse in this slot, but the car came equipped with this 40amp fuse, and the cover of the fuse box illustrates a 40A fuse also. The fuse has nothing to do with the problem, I just wanted you to know in case your schematic shows a 60A fuse instead of the 40A I have. clear as mud?
Also powered by the 40A fuse is belt, stop and tail, and a few other things I can't remember.
thanks

 

I looked at the wireing diagram that is on the autozone website, sorry it is not detailed enough to tell me what else is on that circuit. you might have to just start unplugging connectors and see what stops the drain. Then check from there.
life begins when the kids leave home and the dog dies

 

It could be a bad diode in the alt. Check for continuity from alt. batt. term. to the case with an ohm meter if it zeros the meter the alt has a short. and it will still charge. But also drain the batt.

 

Thats weird!!! Maybe electrical problem makes the battery drain fast... Grounded?

 

you disconnected all wiring to the alternater and your sure nothing else was on like the door being open or under hood light, using an ampmeter usually allows you to see lights come on and off per example like dome light from opening the door to access the fuse box all these things will affect your amperage reading how many amps is your meter showing also do you have anything plugged into the cigarrette lighter.