dead battery again...

[87poopcoupe]

sigh.... where to start ?

went to take the 95gt for a spin

and dead battery- not even a click

charged it on my charger for an hour and it started up, drove it around a bit
battery gauge shows it is charging..

turned it off and let it sit for 4 hours came back out to check and nothing

not even a click... now i'm super ticked off( brand new battery):HYF:

now I'm at a loss... what should i check first...

I did a tune up on the car on Saturday bit I don't see anything loose or un-connected.

[chris91]

I know its a shot in the dark but check to make sure your glove box light is turning off when you shut it. I had that happen once.

[jktruckin06]

just cause it happened recently on a buddies vert. his voltage regulator on the alternator was draining it big time. there is some checks you can do with a multimeter to maybe narrow it down

[mustang_gt88]

I agree with jk, start check the systems and see what ones draw power with car off.

[87poopcoupe]

if they regulator is going out shouldn't the battery light come on though ?

[mustangjon]

Run it. Y an advanced have them test system

[jktruckin06]

probably poop... (had to)... his cluster was out or not functioning at the time i think

[87poopcoupe]

Run it. Y an advanced have them test system

humm, i'll most likely run it up in the morning and have them hook it up to the machine...

[DSSKing68]

You can also feel your alternator...if it is warm, one of the diodes has failed and is probably passing current. If Advanced doesn't find anything, put an multimeter in series with your battery to read current. Start pulling fuses until the current draw goes away. My guess is somewhere you have a circuit passing current and over time it is draining your battery.

I am assuming it isn't a battery issue, because it is new. I have a battery tester, but Advance can test those too.

One other thing, put a volt meter on your battery and make sure your alternator is putting out the correct voltage. ~13.8VDC

[87poopcoupe]

went and had the battery and alt tested.. everything tested fine ?

went ahead and pulled the glovebox bulb since i couldn't be sure...
also checked a few connectors..

i figure I,ll give it a few hours and see what happens and start from there...

[Goober]

I've had brand new batteries drop cells and it not show on a test until it sat for 30 minutes or so.

[87poopcoupe]

on a side note...... i just found a blown fuse for my driver side seat.....

woohoo i now have a moving seat again...

[87poopcoupe]

Ok.. just checked the car...

wont start again..

Now i am really at a loss...

voltage looks good and i dont see anything wrong ?

[DSSKing68]

Does it try to crank or nothing? No click when you turn the key? Interior light going dim when you try? Have you checked your ground? What is the static battery voltage?

[87poopcoupe]

Does it try to crank or nothing? No click when you turn the key? Interior light going dim when you try? Have you checked your ground? What is the static battery voltage?

once it sat for 8 hours yesterday = no click , dim dome light... ground and connectors look good..

I was hoping to look at it again this morning but its pouring down rain ..sigh

battery is back on the charger.....

[DSSKing68]

You are going to have to find your current draw that is draining your battery.

Put an multimeter in series with your battery to read current. Start pulling fuses until the amp draw goes away. That will be your circuit with the problem.

[87poopcoupe]

found the circuit ( drl,horn,fog) it showed a 28.8 draw... took fuse out and voila no draw...

but cant find anything unusual on those wires...

still looking though..

[87poopcoupe]

found the circuit ( drl,horn,fog) it showed a 28.8 draw... took fuse out and voila no draw...

but cant find anything unusual on those wires...

still looking though..

[87poopcoupe]

anyone have an idea on what an acceptable draw is on a mustang ? 5 mili-amps ?

[redfirepearlgt]

anyone have an idea on what an acceptable draw is on a mustang ? 5 mili-amps ?

This would be a very, very minimal draw which I would conclude to be acceptable. 0.005 Amps or 5 milliamps is nothing. That equates to 69 Milliwatts (0.069W) of power consumption per hour @ 13.8VDC (ExI=W). Now all you have to do is detemine which one of those components are the source.

[87poopcoupe]

To me it still seems a bit high considering the lack of features on my 95 gt... but we'll give it a day or 2 to be safe... if so i'll be taking ugly betty out on sunday....

[Black Horse]

Sounds like a short to ground somewhere

[87poopcoupe]

so far so good....

it started this morning and only showing a nominal draw...

[redfirepearlgt]

To me it still seems a bit high considering the lack of features on my 95 gt... but we'll give it a day or 2 to be safe... if so i'll be taking ugly betty out on sunday....

Depending on the meter (even an annually calibrated high end Fluke meter) there will be some error. Nothing is 100% accurate. So unless you are reading the meter incorrectly and you are seeing .500 amp and not .005 amps (5 milliamps) what you may be measuring is insignificant.

The reserve rating on a battery is based on a 25 amp discharge time. Therefore if the discharge time is 90 minutes it can be assumed that the battery theoretically has a 37.5aH capacity. This means that the battery can deliver 37.5A of current for one hour before it is completely discharged.

Sooooooo.... If the battery is disharging 0.005A (or 5 mA) of current how long will it hold up theoretically on a 37.5aH battery? 37.5aH/0.005A= 7500 hours or 312 days. If you are misreading the meter and the actual reading is 0.5A then the number would be 75 hours or 3.13 days. At your former rate of 28A the battery was liekly discharging completely within 1-2 hours of full capacity. Check the amp hour (aH) rating (not CCA rating) on your battery and divide it by 0.005A. This will tell you how long it will theoretically last.

Keep in mind that CCA (cold cranking amps) is only a rating stating that the battery can generate that amount of current for 30 seconds. Don't confuse that number with aH which is a different measure. Hope this helps you out.

IR=E, E/I=R, E/R=I, EI=P - where E=voltage, I-current, R=resistance, P=power or wattage

[mustangjon]

The fog light circuits are notorious to short out check for chafed wires. Or hot sockets

[maverick]

Is it that the car will not start or is it that everything has no power?

[87poopcoupe]

well the battery was just getting drawn down to where it couldn't turn over the car...

darn battery draw.....

[maverick]

If your still getting power to everything else, it may be a starter solenoid or a corroded cable under the insulation going to the starter

[87poopcoupe]

its all good now guys....

thanks

[maverick]

Thats good, what did it end up being?

[87poopcoupe]

horn relay/fuse... it was draining the battery

[redfirepearlgt]

horn relay/fuse... it was draining the battery

Beautiful. See you Sunday them.