7aull

iTrader: (2)

Well Bugger-
past couple of weeks if the RX was sitting more than a couple of days the battery was really slo-o-o-owly cranking over(as in: low battery charge), tho it always managed to start. Buzz around town and she was back up to snuff till the next extended sit.
Assumed (hoped!) it was 6yr+ old Optima, so I fully recharged her, disconnected the battery and let it sit a week. Today I reconnected the battery and she cranked over good as new, so battery is obviously holding a charge and I now have a mystery-gremlin draining it while sitting.


Thoughts how to chase this down?

1980 SA, 90,000mi. Electrical is DEAD stock, no recent electrical work done. All the connections to the Alternator look good. No obvious loose wires under the hood. Obviously charges when _driving_ so its the sitting parked that seems to be the problem.

Thanks All!
Stu Aull
80GS
Alaska

-Gamah

iTrader: (1)

Light in glove compartment?

t_g_farrell

iTrader: (1)

Short in one of the systems. Start pulling fuses one at a time until the draining stops.

I would check to make sure all the door activated switches are working right
including the hatch one. I would also check all the running, head amd brake lights for
corrosion that would cause a short to gound.

Jdrift

Take a multimeter, disconnect the positive battery terminal, connect one lead of the meter to the post, and one to the terminal, set the meter to direct current amps. ( Warning do not try to start teh engine with this setup, you'll blow the fuse in the meter) Your amp draw should be minimal. Look for around .02 of an amp. In a car that old that should be all you have at the MOST. And if you have more, start pulling fuses one by one until the draw goes away. Once it does, get yourself a wiring diagram and trace down suspected culprits. But chances are like Gamah said it's probably something to the course of a light not turning off due to a bad or misadjusted switch.

74RX4

iTrader: (10)

I'd check the alternator terminal voltages per the FSM, if you haven't already. Black/white and White/black terminals should have 0V with the ignition off. White/black should have about .5V with ignition on.

DivinDriver

iTrader: (15)

You haven't changed out the stereo to something more modern, have you? Pretty sure I recall your setero being OEM.

Most electronic car stereos have a fairly high current draw on the lead that keeps your stations and presets (and the clock) running with the ignition off. The cheap-as-crap Jensen I have in my SA will suck the battery dry in about 10 days if i leave it hooked up.

Advice above is the right way to chase it: Hook up a meter to read DC amps, then start isolating curcuits by pulling fuses. Once you find the one responsible, you have to figure out which device is at fault.

j9fd3s

iTrader: (3)

this.

if you find nothing, then have the battery checked, it might be a little weak

justinfox

iTrader: (3)

Check the storage compartment lights, the hinges suck.

13x

For whatever it's as my is a 79 with the external voltage regulator ... but if I unplug the alternator my drain is gone. Sorry I haven't traced it down have just gotten in the habit fo disconnecting the battery. Terrible fix but we know how life gets

mazdaverx713b

iTrader: (91)

the 79 and 80 model years do not have storage bins.

7aull

iTrader: (2)

Thanks Guys!! knew some new perspectives here would help.
I have checked:
-lights on that shouldn't be (so far none)
-stereo is stocker, DD - no electronics there (almost tube vintage!
Liking the ammeter idea Jdrift: seems a bit less random way to check
-I have heard the VR in the Alt can go south too and do some weirdness so will pull that and have an electric shop check it out.

Re Ammeter:
have now heard TWO ways to check for draws:
Jdrift:
-disconnect POSITIVE and bridge with ammeter (I assume '+' probe to '+' terminal; '-' probe to '+'CABLE?????)
OR
-disconnect NEGATIVE terminal and bridge THAT to NEG cable with ammeter (not sure which probe goes where yet...), leave POSITIVE connected.

maybe these are both correct?

Any clarification appreciated ! Am no electric geen-yus...

Stu Aull
80GS
Alaska

Jdrift

Use the positive side of the battery. Since I started working on cars that is the way I was taught. Its the way that I go each and every time and it hasn't failed me yet.

One meter probe to the positive cable. ( Some meter probe kits have alligator clips tha twork wonderfully.) and one probe directly to the positive battery terminal. ( You can use an adjustable vice grip to hold the probe end in place, just be gental, but firm on locking pressure to keep a strong contact) As for positive, or negative orientation for the test leads ( red or black) It doesn't matter since most meters will read the amperage as positive, or negative. As long as you can understand the meter, it works. Best of luck.

captainbizzaro

You'd be better off using a clamp meter, makes it a lot less of a ballache.

El Cheapo one here, would do you.

http://www.amazon.com/Sinometer-Prof...9729754&sr=8-2

Then it's just a matter of clamping around each individual circuit cable from the fuse box till you find the one drawing current.

Jdrift

^ that isn't a reliable way of checking for draws. I have one of those with my fluke meter and it's garbage.

j9fd3s

iTrader: (3)

i was taught to use the positive too, but it might not matter, as the current needs to flow thru the negative cable too?

Jdrift

That's true, and to be honest I can't see why you can't use the negative. But, i'm just sticking to my guns. Takes some of the guesswork out of things. lol.

13x

I am lazy so I use a test light ... disconnect positive battery cable and clip the end of the test light to it and jab the top center of the battery post ... if the light is on there is a draw once the light goes out the cicuit has been ID'd using a circuit isolation tecnique. Not pretty or the most precise but when working alone saves and lot of walking back and forth and going in circles lol

I know I know btu it works

7aull

iTrader: (2)

Thanks Guys - something I can now actually tinker with!!
have also been told Volt Reg in the Alternator can fail and draw down the battery too, so might pull and have an electric shop bench it
Will post results...

Stu Aull
80GS
Alaska

DivinDriver

iTrader: (15)

Positive or negative side will work equally well, since you are chasing battery current; the positive side just seems more intuitive for most people.

The electrons actually flow out of the negative side of the battery, through all the circuit branches, and back into the battery on the positive side... but nobody really thinks or cares about how backwards that is, since it's an isolated system & doesn't really have an actual 'ground,' even though we refer to it as a 'negative ground system.'

The alternator VR sounds like a pretty good bet.

Is your dashboard clock working OK? It can fail in ways that make it draw too much current, too.

7aull

iTrader: (2)

Clock's good DD (well, its WORKING at any rate) - thanks for the current clarification

Stu

t_g_farrell

iTrader: (1)

The clock thing reminds me. On my SA, when it was laid up during the long
Pittsburgh winters, I would have to pull the fuse for the clock and such because the
clock would drain the battery in a month easy. I'm sure you know this Stu because
your winters are even longer Just thought I'd mention it.

The amp meter idea is the easiest way to find the drain for sure.

7aull

iTrader: (2)

Thanks tg - battery is out of car thru winter, tied to a charger in the basement

Today-
swapped in a rebuilt Alt - took old (original!) Alt to electrical shop where they benched it aaaaand! - it works (*sigh*) fine! So back to ammeter try-outs. But now noice shiny Alt bling in engine room.


Stu Aull
80 GS, New Alternator
Alaska

Jdrift

Keep going man. I'm sure you'll figure it out. besides, expereinces like these only make you a better person and car owner. Good brother.

7aull

iTrader: (2)

would happily be a "bad" person and no electric gremlins!

Stu Aull
80GS
Alaska

j9fd3s

iTrader: (3)

try the amp meter method, its easy!