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-   -   Help with battery draining gremlins, 83 pontiac with 305 (http://www.hotrodders.com/forum/help-battery-draining-gremlins-83-pontiac-305-a-215642.html)

usaweapon777 02-28-2012 06:42 PM

Help with battery draining gremlins, 83 pontiac with 305
 
Hey guys, Long story short, My friend has an 83 pontiac bonneville that had the alternator go bad on it. I helped him replace it and verified it was outputting the proper voltage and charging the battery unlike the old one. I sent him on his way and a week later he calls me saying the battery is dead. I recheck the alternator and its charging like it should. So i figure something must be draining the battery with the key off. So i hook up my meter to measure current draw and with the ignition off I get a reading of no draw. I'm a little confused right now. So the car is charging and starts fine normally with the battery yet goes dead over the week even though I see no appreciable load on the battery with the ignition off. The only thing I can think of is that my meter can't read the small load thats being put on the battery. It has to have a short or something somewhere for all the power to be drained right? Thanks for any advice
-Taylor

matts37chev 02-28-2012 06:52 PM

I would check to make sure the batt is good first

LATECH 02-28-2012 07:04 PM

X 2 with matt. sounds like a battery on its way out.
Allowable parasitic draw for your 83 pontiac should be 30 -50 milliamps.
anything more than that and I would be looking at the underhood light , to check that it isnt allways on, or the GLOVEBOX light as well. Also GM factory radios of that era, were know to have draw issues with the memory circuitry,and it could be intermittent.

usaweapon777 02-28-2012 08:00 PM

Well he's been switching between two battery's to get him home when it dies like this and both are new. I checked the trunk light and that seems to operate properly. I'll hunt around and see if there aren't any other lights or simple sources for battery drain. The car is very basic so there shouldn't be too many circuits to chase. Also His radio is just an fm/am with knobs. You have to press in these large buttons really hard to get to "memory stations". Are those radios actually digital, I just assumed they were all mechanical/analog. Thanks for the help

LATECH 02-28-2012 08:14 PM

No memory circuit on that ol radio . dont recall exactly when the digital radios came in. Somewhere in the 80s.My 83 bonneville wagon had one.

boothboy 02-29-2012 12:42 PM

Try checking it out the old fashion way. Disconnect the pos battery cable. Connect a test light in series between the batt post and the cable end. If the light lights you have a draw. Start pulling fuses until the light does out. When that happens you will know which circuit to check out. Remember when you open the door to get inside you activate the interior light circuit.You might have to pull the door jam switch out so you check out the remaining circuits.

EOD Guy 02-29-2012 05:38 PM

When you replaced the alt, did the pigtail wires to the alt get switched? If the exciter wire got switched to the sense side of the alt connector, it will appear to charge but when it's not running, the sense wire will ground internally in the alt and the battery will go dead after a few days..... like you are describing.

The sense wire is tied directly into the elec system and ends up at the pos terminal of the battery (allways hot). It tells the alt to produce more or less juice depending on the demands of the system.

The exciter wire is tied to the idiot light on the dash, when you 1st turn on the key the idiot light gets 12v from the dash side of the system and gets it's ground from the voltage reg inside the alt..... light illuminates. After the car starts the internal voltage reg removes the ground and starts producing juice...... light goes out.

If the wires were switched, when the engine isn't running the internal reg will ground out the sense wire that's tied directly to the battery. If this is happening the alt will get extremely hot to the touch when the car has sat for a few hours...... almost too hot to touch.

usaweapon777 02-29-2012 06:52 PM

Quote:

Originally Posted by boothboy
Try checking it out the old fashion way. Disconnect the pos battery cable. Connect a test light in series between the batt post and the cable end. If the light lights you have a draw. Start pulling fuses until the light does out. When that happens you will know which circuit to check out. Remember when you open the door to get inside you activate the interior light circuit.You might have to pull the door jam switch out so you check out the remaining circuits.

Thats a great idea why didn't I think of that!, thanks for the tip.

Quote:

Originally Posted by EOD Guy
When you replaced the alt, did the pigtail wires to the alt get switched? If the exciter wire got switched to the sense side of the alt connector, it will appear to charge but when it's not running, the sense wire will ground internally in the alt and the battery will go dead after a few days..... like you are describing.

The sense wire is tied directly into the elec system and ends up at the pos terminal of the battery (allways hot). It tells the alt to produce more or less juice depending on the demands of the system.

The exciter wire is tied to the idiot light on the dash, when you 1st turn on the key the idiot light gets 12v from the dash side of the system and gets it's ground from the voltage reg inside the alt..... light illuminates. After the car starts the internal voltage reg removes the ground and starts producing juice...... light goes out.

If the wires were switched, when the engine isn't running the internal reg will ground out the sense wire that's tied directly to the battery. If this is happening the alt will get extremely hot to the touch when the car has sat for a few hours...... almost too hot to touch.

I'm pretty sure I wired it exactly the way the old alternator was. I'll be sure to double check. The alt light is on before I start it and goes out once started.

EOD Guy 02-29-2012 07:43 PM

Easy way to ck...... unplug the two wire connector from the alt and see if the battery drains, if it doesn't..... somethings amiss with the connector

#1 terminal goes to the idiot light

usaweapon777 03-02-2012 10:53 PM

Well i tried the light test trick. With the ignition off the light didn't come on. We drove it for an hour and it ran great. He left my house tonight in the rain and by the time he got home he said it was ready to die. He said that it seemed to run a lot better when the heater was off and the lights and wipers got faster. I'm wondering if there's a short in the heater fan circuit maybe?

boothboy 03-03-2012 08:59 AM

I think you have a charging problem. If the charging system isn't keeping up with the amount of power being used while driving, the battery voltage drops. How fast that happens depends on how many accessories you have turned on. By turning off the heater while driving with a low battery the lights would get brighter, less load. If it was raining he probably had the mode switch dialed to defrost .If so the A/C was also in play. More voltage drain. If you had a short in the heating system, you'er be popping fuses. If you had a draw heavy enough to drain a battery while driving it would have to be the blower motor and it would not be putting out very much air flow and it would be making a lot of noise. Pretty soon you'ed smell smoke coming from wiring, the wire insulation would melt, you'ed get a short and the fuse would pop.
If this vehicle is a stock vehicle, when you changed out the alternator you unbolted the heavy hot wire and unplugged a two wire connector. If the wires didn't fall out of the connector its wired correctly. I'd do a load test on both of his batteries. If they check out ok, I'd look real hard at that alternator.

EOD Guy 03-04-2012 10:44 AM

Reason for the connector advice.......... as happens sometimes, things get damaged and spade connectors or after market pig tails are used in place of OEM connectors, and it's very easy to switch the two.......I've seen it happen many times and it has the exact same symptoms as the OP described.

boothboy 03-04-2012 10:57 AM

Your absolutely right but I figured that usaweapon777 would know if the wires came out of the connector. If they didn't you can't wire it wrong.


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