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1997 626 Mystery Short - Killing Batteries
06-01-2017, 02:46 AM
Post: #1
1997 626 Mystery Short - Killing Batteries
Mazda 626, 1997, LE, 2.5 liter V6, Automatic Trans, 156,000, live in Los Angeles.

Problem: Mystery Short - battery will die if just parked. 2 mechanics, no joy.

1.Took it to get smogged, turned it off for 4 minutes and it suddenly would not start again, jumping did not work, the starter would just click - mechanic #1 said starter was bad, changed.
2. Got it home, a week later the battery was dead.
3. Mechanic #2 examined car and just put in a new battery.
4. Got it home and it died a week later - dead battery.
5. Took it back to Mechanic #2 - he kept it for 2 weeks and said he "checked everything" and could find nothing wrong with the car, it sat for a long time and did not lose power. Installed new battery.
6. Got it home, took the positive terminal off the battery to keep it from murdering the battery (it's not a deep cycle) and posted here.

I don't know what to do about this one. I'm humbly asking for any and all advice here. Stupid question I suppose but: Would it help if I took it to a Mazda specialist instead of just a general mechanic?

Thank You.
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06-01-2017, 03:33 AM
Post: #2
RE: 1997 626 Mystery Short - Killing Batteries
Have the alternator checked. The alternator is supposed to put out 12.9 volts and may only be putting out 12.3 volts. Now if this is the case and let's say you are listening to the radio or running the ac at same time then the alternator will not put out enough volts to keep the battery charged. I have had this happen to me before on one of the cars I owned.
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06-01-2017, 03:39 AM
Post: #3
RE: 1997 626 Mystery Short - Killing Batteries
I thought that also at first but, no, not the alternator. 1. I was not using the car the times the battery went bad, it was just setting and died on it's own. 2. The mechanic (#2) in total had the car for about a month and I have to assume he checked the obvious. It's a mystery short.
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06-01-2017, 06:19 AM
Post: #4
RE: 1997 626 Mystery Short - Killing Batteries
First; as a safety precaution, you should take the negative post off the battery, not the positive. That said, have you checked things like the dome light, glove box light, or trunk light coming on? One way to check for a draw is to take the negative wire off of the battery, put a test light between the negative wire and negative post. If the light is lit, there is a draw. You can pull one fuse at a time to see when the light goes out. When the light goes out you found the circuit that is pulling current.
Keep in mind that while doing this you must close the doors so the dome light isn't on because it will light the test light.

I also had one that the battery kept going dead on where it was the key fob. Any time the key fob was near the car it was working the door locks and killing the battery.

Hope something there helps. Please keep us posted as to what you find.

Thanks for using the forum,
Garner

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06-01-2017, 10:16 AM
Post: #5
RE: 1997 626 Mystery Short - Killing Batteries
This is a 20 year old car so let's dig a little deeper and talk about failing alternators, poor connections, etc.

An alternator can "partially fail" where bum diodes can cause a low charging rate, or if shorted internally, can drain the battery like leaving the lights on. It can also be intermittent in that respect, but not usually. The automatic voltage regulator can also fail to turn off and cause a battery draw, although usually that goes back to a bum diode problem. Either way you can do Garner's check with a test light while removing the wires from the alternator to see.

On the issue of poor connections, people seldom check the other ends of the battery cables where they bolt to the body or engine. A bad connection here will cause the same symptoms as a dead battery and a jump may not do anything either because the power is not reaching the end of the circuit. The easiest way to get a feel for your direction is to try starting the car with the dome light on and a meter on the battery terminals. When it fails to start / crank notice what the voltage is. If you began with 12 volts and it drops like rock then the battery is low due to some issue with charging or draw down. At 12 volts and no change the next question is... did the dome light go out while trying to crank? This condition means the battery still has juice but there's a bad connection elsewhere. IOW a high resistance connection causing voltage drop.

Fill in these gaps of the story and we can talk you through a few more simple tests.
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06-01-2017, 02:44 PM (This post was last modified: 06-01-2017 02:44 PM by Kitfox.)
Post: #6
RE: 1997 626 Mystery Short - Killing Batteries
Yeah, can't get the bat terminal off I don't have a socket wrench, mechanic put it on tight.

Again, the car was parked and not being used so the alternator is not an issue here. As for lights that might be on, etc..the mechanic had the car total for a month and said he checked the lights, checked current draw, etc. He found nothing.

New battery, new terminals.

Oddly I went out this morning to try and disconnect the battery and there is battery acid pooled on the top part of it - (confirmed by baking soda test) brand new battery, only drove it home from the mechanic 4 miles. What could this indicate?

FYI I don't have any tools or equipment, I'm having to go through mechanics and they are stumped - hence, mystery short
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06-01-2017, 07:39 PM
Post: #7
RE: 1997 626 Mystery Short - Killing Batteries
If that was battery acid then the battery needs to be replaced
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06-01-2017, 09:06 PM
Post: #8
RE: 1997 626 Mystery Short - Killing Batteries
(06-01-2017 07:39 PM)sandman Wrote:  If that was battery acid then the battery needs to be replaced

Right, that's what I think also. However since it's the 2nd brand new battery in this venture, I wondered if the leaking might be caused by whatever is causing this issue. I've never seen a new battery leak, its literally just came from the mechanic who installed it fresh. When I asked the mechanic he only volunteered to wipe the acid off of it....but admitted at first it was not normal but later would not admit it and just said "bring it in, I'll look at it".. This after the last 2 week stint "inspecting" the car.

My impression is to have him replace the battery and just try to sell the car, I don't have time or money to spend on it any longer and already put in a lot of money, to no effect. Some cars are cursed, this appears to be one of them.

I doubt it's true, but I was always told growing up in the '70's "Never buy a green colored car..British racing color, bad luck.".. this one is green. I call this one the green goblin ..and no I won't be buying any green cars in the future!
(lol)
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06-01-2017, 10:27 PM
Post: #9
RE: 1997 626 Mystery Short - Killing Batteries
Color of the car has no real meaning unless you are superstitious. The same parts go into a red car or a black one, only the black one shows the dirt more easily.

Back to your issues.... the acid was pooled up on top of where? Is this a sealed battery? (flat top without caps) Acid on top may mean LOTS of chemical reaction going on, such as high charging or excessive draw, but sealed batteries typically can't leak out the top. These are things we need to know in order to make sense of everything.

The car is parked (how long?) but you didn't say if it will start at the moment. Some problems with an alternator can show up when the engine is NOT running so what I posted earlier about diodes and voltage regulators is important in your case.

BTW, these mechanics you are using should know these things if they are worth their salt. Batteries seldom go dead without an external cause so the guy who said there was no draw is missing something.

Side note: Years ago I had a customer who shared a car with his wife who went bowling once a week. The hatchback they drove had an extra courtesy light in the rear under a covered area that could not be seen when the hatch was closed. The problem they ran into was her late night return from bowling in the winter caused her to use this extra lamp and forget to turn it off. (a seasonal situation) Since it couldn't be seen easily it was accidentally left on quite often, causing an intermittent dead battery problem. Could your problem be that simple? (glove box, trunk, under hood light?)
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06-02-2017, 06:12 AM
Post: #10
RE: 1997 626 Mystery Short - Killing Batteries
The more that I read the more I am leaning towards a faulty alternator or a bad ground. If the alternator is Overcharging it will boil the battery causing the acid on the top of the battery. A poor ground at the engine; as Rupe mentioned, can cause that to happen. Or just the alternator itself not having a good ground. Or; also as Rupe stated, a faulty regulator or diodes in the alternator can cause overcharging. And in CAN be the alternator even if the car is just sitting. Again; as Rupe stated, if there is a problem in the alternator juice can flow through it while the car is sitting and drain the battery.

I guess my point here is to have this checked by someone who knows alternators instead of dismissing it as it "Can't be the alternator." It CAN be the alternator. Both Rupe and I have seen this condition many times. If you don't have the tools to follow our test procedures it sounds like you need to find a mechanic more knowledgeable with electrical issues.

Another thing to keep in mind if you are attempting any of this on your own. A battery can explode and kill you! I know 2 people who are blind due to auto battery explosions. Wet cell batteries generate Hydrogen gas, the stuff that was in the Hindenburg. Sparks from shorting a wrench against a ground or from smoking near the battery can cause it to explode. That's why you remove the Ground wire First and install it Last. A wrench on the ground post that touches metal elsewhere won't arc like it will if you are on the positive post. At the very minimum you should wear a good pair of safety glasses while working around the battery.

Hope that helps. Please let us know.

Thanks for using the forum,
Garner

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