Please help! pulled all fuses but still have battery drain

Ultrastar

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Hey all,

i've been dealing with a really bad battery drain for the last few months

the issue became a major problem when i stopped using the car as my daily driver.

If i leave the car overnight it will drain the battery out.
I have to jump it everytime when that happens, so i started to disconnect the battery everytime the car would not be used, but even doing so the battery would still die eventually.
measured voltage with car running and was pulling 14.xx volt

so my battery died last week, most likely from jumping it too many times (every few day for months), so got a new battery in, and it also died overnight.

so today it was a bit less cold so I pulled out my ammeter and measured a draw of 4-5amp, pulled out every fricking fuses and relays (under hood, under passenger side and trunk) but I still have a constant draw...

what next???
what should I do?

im out of hope, i already bought another car i just want to fix this battery drain before selling it, any help would be great!
 
Any time the battery drains all the way it gets damaged the battery is probably junk. There's a good chance seeing as it was disconnected and drained that battery was bad to begin with. Buy a new battery and you should be fine.
 
If you really pulled all the fuses, then the starter and the alternator are the two thing that are left.
You may very well have a bad diode in the alternator. I would disconnect the power wire at the alternator and see if the drain goes away. If so, you found it.

Also if you put your voltmeter on the AC range while the engine is running and see more than 0.something volts AC, you have a shorted diode or two in the alternator.
 
Any time the battery drains all the way it gets damaged the battery is probably junk. There's a good chance seeing as it was disconnected and drained that battery was bad to begin with. Buy a new battery and you should be fine.

yea i already bought a new battery last week, and it drained it overnight
 
If you really pulled all the fuses, then the starter and the alternator are the two thing that are left.
You may very well have a bad diode in the alternator. I would disconnect the power wire at the alternator and see if the drain goes away. If so, you found it.

Also if you put your voltmeter on the AC range while the engine is running and see more than 0.something volts AC, you have a shorted diode or two in the alternator.

yea I pulled out every single fuses and relay, and it was not fun at all lol, especially the passenger fuse box

on the flip side i found 2 blown fuses; for my cig lighter and for the driver power seat, cant believe i drove with no seat adjustment for over a year!

so anyhow, how would i test the starter?
and would disconnecting the power to the alternator mean getting under the car where the alternator is located?

its already night out so i'll have to resume working on it tomorrow.

ill try measuring AC when I can and report back!
 
If the drain isn't the alternator, then disconnect the battery wire at the starter to see if that's where it is.
 
alright so i plugged the voltmeter and got a reading of 30vac?

i attached some pics just to be sure i did it correctly :p

also uploaded pics of the reading of the drain (5.7amp)


so what do you say joe? bad alt?

IMAG0255.jpg


IMAG0256.jpg


IMAG0258.jpg


IMAG0259.jpg
 
noooooooooooooooooooooooooooooooooooo

@#*&$^*#@&%

oh well, I'll get it replaced monday and report back!

thanks for the help btw, really appreciate it
 
Have fun with that if you do it yourself. Just went through it at the beginning of the week. And be sure to buy only Motorcraft alternator even if you do go used.

Trust me / us. Don't go aftermarket.
 
Have fun with that if you do it yourself. Just went through it at the beginning of the week. And be sure to buy only Motorcraft alternator even if you do go used.

Trust me / us. Don't go aftermarket.

haha who said I was doing it? :p
im extra rookie, cant do none of that stuff!

going to the garage...
 
alright,

i tested the voltmeter on my mdx and also getting the same reading? :confused:

am I doing something wrong or could my meter be busted?

attached pics of the reading on the mdx
can someone confirm if my settings are right lol

IMAG0260.jpg


IMAG0261.jpg
 
Yeah, but the alternator makes AC, hence the name Alternator. Diodes block one direction of the alternating current flow thus making direct current. Bad diodes can cause AC voltage generation, or battery discharge. I dont know why his MDX is outting out 30 VAC.
 
It's possible that your meter is too cheap to correctly measure AC voltage in the presence of a DC voltage.
 
The regulator uses several diodes in order to rectify the voltage down. Perhaps only one diode is fried? I could see a single bad diode allowing part of the AC to bleed through, and it would only take one bad diode to backfeed the battery through the alternator to ground. Now this is assuming that the engine is running while this reading is being taken. If the engine is off I would say the meter is not reading correctly.

One thing I'm confused about, what kind of car is this? Thought all LSs had the battery in the trunk?
 
Whoops, didn't realize WTH was going on. I never thought of trying that to detect a bad diode - brilliant! At least if the meter is good enough.
 
alright,

did some further research and i've concluded that it must be indeed my meter;
this guy was having the same readings:

http://www.garagejournal.com/forum/archive/index.php/t-75551.html

and as per this post:
"At one time it was extremely common for AC meter ranges on analog meters to read about double the correct value when DC was applied.
What you are seeing is almost certainly somebody using the old style circuit. "

http://electronics.stackexchange.co...eter-readings-measuring-12v-lead-acid-battery

so it would make sense that i was getting 30vac on both car batteries, i tested some regular 1.5 AA batteries and also getting some 2.x vac on them.

I will head to the store later to get another meter and report back (mine was real cheap at like 4$, last week i bought 2 cheap meters on ebay as backup but i guess they'll be junk too)
 
update:

ok finally some breakthrough in my ongoing problem,
went to canadian tire (canadian equilvalent of autozone) and bought another dmm, a reviewer said the meter was able to read ac, plus it was on sale (60% off):

http://www.canadiantire.ca/AST/brow.../Autoranging+Digital+Multimeter.jsp?locale=en

so I tested the meter on the mdx: 0.000vac (once in a while went to 0.001)

then i tested it on the ls, and the readings kept oscillating, it would never settle to 0.000v, definitely something wrong there!

so ill be changing the alternator this week, im not screaming victory yet, but i'll keep you guys posted!

stay tuned
 
Good luck! I was real happy when I got my charging issues resolved.
 
alright well I've called a few alternator places and tomorrow this guy will be coming to pickup my car and rebuild the alternator for 195$

tomorrow is the day i'll finally know if the problem is fixed....

so tired of it
 
alright well I've called a few alternator places and tomorrow this guy will be coming to pickup my car and rebuild the alternator for 195$

tomorrow is the day i'll finally know if the problem is fixed....

so tired of it

Sounds shady, especially being in QC. Aren't Motorcraft alternators also close to $250? Sounds too cheap :shifty:
 

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