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Posted by: KaptKaos Jul 16 2012, 09:39 PM

It might be old, I need to go check the date code. Are there any tests I can run with a multimeter at the battery to see if there is a draw when its off??

TIA

Posted by: CG-914 Jul 16 2012, 10:01 PM

just drive to a local auto parts store they can test it for free with a load test too!

Posted by: ruby914 Jul 16 2012, 10:03 PM

I went through a crazy witch hunt on that not long ago with the WRX914.
Some thought it was all the WRX electronics, some the alternator.
In the end, I think, some of the 3 wires to the front turn lamps may have been switched and that may have had something to do with it.

You ever get that targa top cleaned up?

Posted by: Cap'n Krusty Jul 16 2012, 10:05 PM

And, if you're lucky, their test will actually work, giving you an accurate and truthful result.

The Cap'n

Posted by: toolguy Jul 16 2012, 10:11 PM

the idiot proof test is pull off the battery lead and see if it still goes dead. .
I didn't think I'd have to say without the engine running. . but yes no engine running. . .

Posted by: McMark Jul 16 2012, 10:57 PM

If you have a multimeter with an Amps setting, you can use that. Just pull the negative battery cable and touch one lead to the cable and one lead to the battery - terminal. Just make sure you don't have an amp or any other high draw components turned on. My meter maxes at 10A.

Of course, I don't have a baseline for you, but I can if you PM me as a reminder.

Posted by: kerensky Jul 16 2012, 10:58 PM

Don't do that with 914's, it can burn out the exciter diodes in the alternator. Happened to me in the mid 80's. I believe it even says so in the owner's manual, if I recall correctly.

Posted by: Dave_Darling Jul 16 2012, 11:09 PM

I think he means without the engine running. That will definitely tell you if the battery itself is toast; if it starts out the evening charged and is dead by morning even when not plugged in!

IIRC, the draw on the 914 with the key off is on the order of 50-100 milliamps (0.05 to 0.1 amp) or less. I forget what the amp-hour capacity of the batteries usually is, but I think it's over 50 A-H. And 0.1 amps would take 500 hours to drain a 50 A-H battery completely.

--DD

Posted by: ThePaintedMan Jul 17 2012, 07:19 AM

Having worked at Autozone, I'd try the overnight test that Dave and the guys suggested first. The load-testing equipment most FLAPS use is shotty at best. I had known bad batteries test good multiple times.

Posted by: KaptKaos Jul 17 2012, 08:17 AM

Oddly enough, it started up fine this morning.

I think I need to go through and check all of my grounds and connections.

More to follow.....

Posted by: McMark Jul 17 2012, 09:04 AM

Poor/corroded cable connections can cause problems like this as well. I had someone call me because their car wouldn't start. I had them loosen and twist the battery connections and it fired right up.

Posted by: toolguy Jul 17 2012, 09:06 AM

Joe
. that's not so strange. . . I had an almost new OEM battery in my truck go dead overnight once, and didn't leave anything on. . had me stumped. . I recharged it and it's never done it again and that was 5 years ago. Go figure. .

.If it happen again to you, you'll need to figure out what is drawing current. . another way is to remove all the fuses, and replace one every day till the problem re occurs. . this will give you a general clue. But there are a number of wires that are un-fused also. Like the interior light or an unswitched radio left on.

Maybe this is an opportunity to learn to use a multimeter real good. . . the meter method described above is looking for a wire that has a current [miliamp] draw with the ignition switch off.

Posted by: brant Jul 17 2012, 09:57 AM

I really don't trust the test equiptment at FLAPS

I've had many batteries fail their tests and even when the batteries seem to not be bad yet....

I always assumed that those tests were skewed to sell new batteries.
you can make a brand new battery fail if you set the thresh-hold high enough