UGAd13

[edit]5 months old....[edit]

2003 Max - 126,000 miles - original alternator

I'll try to make a long story short... here goes.

Dead battery this morning, purchased in Aug 2010. Figured it was a bad alternator so I picked one up from AutoZone (b/c I didn't want to get stranded without one) and went to Batteries Plus, where I purchased the battery, to have the battery tested. The battery tested around 6 volts so we couldn't test the alternator. Swapped in a new battery, alternator tested fine. I left the old battery there to fully charge and test. Battery tested fine...

Back to square one. I'm running a small 400w amp, but haven't had any issues before.

I'm going to have them test the alt again before putting in the old battery. If the alt tests fine with the new and old battery, what troubleshooting steps can I do to narrow down the source of the battery drain?

I don't have a voltmeter.

The only thing I can think of now is to check the power light on the amp when the car/radio is off, and check and tighten all connections.

What else?

Scottwax

iTrader: (8)

Definitely check for open circuits when the car is off.

TunerMaxima3000

iTrader: (4)

You need to have a shop hook up an AVR (Automatic Voltage Regulation) Machine with a Carbon Pile. This 'loads' the battery up, forcing the alternator to work, and uses an Ammeter (amp-clamp) to measure the Amperage, it will also sense for any voltage ripple.

That is the only sure way to test the alternator, especially without a multimeter handy. There are less scientific ways to check but this is best.

If the alty is good-----it's likely a bad connection somewhere. Common to have corrosion at positive terminal block where the alternator charge wire hooks up, so check there first. That can cause an ittermittent charge.

Make sure it's diagnosed CORRECTLY that alty is a PITA to change, and expensive if you're paying a shop to do it.

UGAd13

Thanks for the input.

Old "good" battery is back in, they cleaned the terminals and connections for me so I'll check all connections and move forward from there.

If it acts up again I'll have a shop do what Tuner suggested.

timpol

iTrader: (1)

In the meantime, invest a few bucks in a voltmeter. Takes a lot of the guess work out.

TunerMaxima3000

iTrader: (4)

Seems silly to just 'wait and see'. You know there's a problem, the intellegent thing to do would be to address it, before the car leaves you stranded.

I think It's tough for me though because I have the ability to do most of the testing myself, not everyone can do that. I bet you can get a shop to load it up for $20ish, well worth the money, especially if you get stuck and need a Cab or a tow....

UGAd13

I guess I’m just an optimist and hoping the easy solution is the one that works… plus, with a 1 yr old running around it’s tough to find some time to troubleshoot.

However, I was able to do a little research and it looks like the troubleshooting shouldn’t take too long with the right tools. I guess that means I get to add another one to the collection, dammit…

Amave

good way to check for a battery drain is connect a DVOM in series with your neg battery cable with it disconnected.

see here
http://www.youtube.com/watch?v=yFCT-YZbU5o

FrankA33

iTrader: (15)

My collegue had this problem about a month ago but on a 97 civic, he replaced with new battery first, then a new alternator, still died on him.
You know what a good mechanic found in a minute ? the fuse...
Have that checked out. A lot of people forget about this little one, but is essential in the process.

TunerMaxima3000

iTrader: (4)

It would take some pretty crappy mechanics before him to replace an alternator and a battery without testing anything.

But that wouldn't surprise me, most mechanics don't have a clue how to do PROPER diagnosis. They just replace parts.

UGAd13

Off topic slighty, but that's the trend with appliance repair techs as well. The "old dogs" are retiring and the new crop in the field are just parts changers. No one knows how to do board level repairs anymore... just replace the whole board.

TunerMaxima3000

iTrader: (4)

Mechanics are the opposite in my experience, the young guys don't have the experience, but have the proper training when it comes to electronics, etc.

The 'old dogs' don't have a freaking clue how to work on electronics, and they don't usually want to know how either. It's weird and new to them, they fear it.