How long before a corroded battery fails?

[Elixer]

Long story short, car wouldn't crank over, just a rapid sounding ticking. Looking at the battery, it had a severely corroded negative terminal on battery (green with tons of buildup). Dealer checked car 4 days ago, said all was fine, but you might want to clean the battery.

It was a Motorcraft battery, installed by the same dealer, the battery was ~4 years old, label on battery says 36 month full, 100 month pro-rata warranty.

Now, since this occurred in a parking lot at a late hour where pretty much everyone was closed, the only choice was to get a battery from the tow-truck driver. They stuck a Bosch Premium Plus, 3-year free replacement, 96-month pro-rata warranty on it, and charged $120.

Question here is, if the dealer saw how corroded the battery was, then, why wouldn't they say, this battery could fail at any time, and instead say it needs a cleanup (actually, unsure why they just didn't clean it in the first place? It was in the shop because of a recall.)?
Is this just coincidence that it just failed 4 days later, and still would have tested OK at the dealer? Car wasn't used for 3 days after the appointment.

The other question is, since that battery had a prorated warranty, but, couldn't actually keep the old battery and had to turn it in (tow truck guy said it was the law) then I assume you can't get anything back since it failed before the 100 month period?

Also, are Bosch batteries any good? I haven't heard of this brand before.


(No, this was not my car, I was just given the info over the phone.)

 

[skyking]

Corrosion does not kill a battery, just the connection. It is due to lack of maintenance.
If you had a crescent wrench and a can of coke you would likely have started it OK.
Loosen and remove affected cable. Pour the coke on the terminal and inside the cable connection, let it fizz. Wipe with whatever you have, a napkin of paper towel.
Put it back on and start.

 

[JulesMaximus]

Why didn't the dealer clean the terminal? If that had been done the battery would probably have been fine.

 

[Torn Mind]

The ticking or clicking sound is the solenoid going up and down. Meaning, power is getting to the starter, but without sufficient amperage for it to crank. The resistance from the corrosion will cause these symptoms.

Cleaning involves a combination of acid neutralization and scraping the remaining material away so that fresh shiny lead is showing.

Batteries are a bunch of 2 volt cells connected in series. The terminals are just something to attach wires to. If the battery fails, it is the stuff in the cells that have failed, such as with sulfation or plates shorting.

Carry a spare starter around anyway just in case. Because while you can "fix" it by cleaning the connections again and again with baking soda+brush, the starter itself WILL DIE.

How do I know this? Well, my mom's Matrix would have intermittent starting problems and every time, I cleaned up the connections and everything seemed to be back to normal. In, fact the starter finally had a long streak of starting up fine. But then one day, the "rapid click" of the solenoid was no more, and that meant it was toast.

In my case, the ignition signal terminal would get voltage and the inside of the motor starts spinning without the fat power "supply" cable attached, which means something is wrong as the inside shouldn't be spinning without the fat 12V supply attached, although I might need to open up the motor itself. I don't think the solenoid is toast now, since it really has a simple task of moving something up and down.

 

[Torn Mind]

Also, just to keep things from being too messy...

A jump start from another car or a pack should have been sufficient to get the car home.

I seriously doubt it is law that someone must turn in the old core. I mean, you can take it to a scrapper yourself if you so desire.

 

[lxskllr]

I seriously doubt it is law that someone must turn in the old core. I mean, you can take it to a scrapper yourself if you so desire.

AFAIK, that's correct. The core charge is the law, but you don't have to turn the battery in if you don't want your money back.

 

[Elixer]

Why didn't the dealer clean the terminal? If that had been done the battery would probably have been fine.

That is what I don't get. They had the car for around 6 hours (recall work was around 2 hours long) before they came and picked it up, so, it was just sitting in the lot.

The tow driver WAS able to jump start it, but, they had to make lots of stops after that, and she just felt it was easier to buy a new battery from the driver.
The tow driver even gave her a printout of the status of the old battery, they had some kind of machine in the tow truck that load tests batteries, and it did say it failed.

 

[Torn Mind]

Was the battery test done while attached to the terminals or directly from the posts? Because with a corroded ground, I have my doubts that it would pass a test.

It probably was a bit undercharged and quietly getting sulfated to the point that it could no longer overcome the bad ground corrosion while the new one had enough oomph to send enough current.

Alternator should be bench tested too just in case. The ones that quietly are dying are the worst.

 

[bruceb]

Just because the terminals are corroded does not mean the battery is on it's last leg. That is a common occurrence on top post batteries (like in Ford or most trucks and some imports) and is due to either it not being a sealed battery or lack of maintenance. This would be cleaning the corrossion with baking soda and water and also removal of the terminal and cleaning with a terminal cleaning tool. Also when you do get battery corrosion their is a good chance the cable itself will start to go bad, as it will wick up into the copper wires and cause problems.

 

[Elixer]

Was the battery test done while attached to the terminals or directly from the posts? Because with a corroded ground, I have my doubts that it would pass a test.

It probably was a bit undercharged and quietly getting sulfated to the point that it could no longer overcome the bad ground corrosion while the new one had enough oomph to send enough current.

Alternator should be bench tested too just in case. The ones that quietly are dying are the worst.

The guy cleaned the old battery first with some kind of a tool, and then tested the battery, where it showed it failed.

How do you test if the alternator is going bad or not? I am going there next week, and I got a meter I can use, but, unsure if a meter will find if it is going bad or not.

 

[Torn Mind]

The guy cleaned the old battery first with some kind of a tool, and then tested the battery, where it showed it failed.

How do you test if the alternator is going bad or not? I am going there next week, and I got a meter I can use, but, unsure if a meter will find if it is going bad or not.

Well, if it failed the test with the tester, the battery might have just reached a point where the sulfation just built up and enough cranking amps were lost to have if fail their test. The receipt should have the results with CCA, battery voltage, internal resistance, etc on it.

The meter won't find every possible failure point as quickly as taking it off to a store to bench test. But it can find a some failure points without taking the alternator off. The voltage output and regulation can be tested without taking anything apart. Ripple in the system can also be found with a multimeter. Excessive resistance in the wire between the alternator and battery can also be tested.

If you do take the alternator off and crack it open, you can check windings and diodes, but you'll need a service manual for the exact resistance specs. Probably, it would take too much time to be worth it in this case.

The simple checks would be first checking the DC voltage. It should idle around 13.6-14.4volts, maybe at little more at either end depending on the vehicle. If you see anything voltage that is in the 12.x or below range, something is wrong. Most of the time, if everything else in the system is good, the alternator is toast and you should replace the whole thing. Chances are that the rotor is dead.

Just make sure that the engine is not idling too slow while making your determination, because that can also create a low voltage output situation. If you want, you can check the brushes before tossing out the whole thing and service them if it is convenient and you know for sure it is just the brushes. But if the brushes are good but the voltage output is low, time for a new one.

Then, you want to push the accelerator pedal to around 2000-2500 RPM and see how the voltage goes up. If the voltage holds at around 14.0-14.6 something, then the alternator is fine. If the voltage keeps increasing with idle into the 15+ volt range, the voltage regulator is bad and the alternator either needs the regulator replaced or the whole thing replaced.

Also, you can switch the meter to AC voltage to see if there is any ripple in the system. In my experience, an AC voltage of around .02 volts is okay.

If your friend's car is used for short trips a lot, then it might just be a case of the battery not being charged enough and a float charger needs to be applied to it to keep the battery voltage up.

http://easyautodiagnostics.com/misc-index/how-to-test-a-bad-alternator-1
http://www.samarins.com/glossary/alternator.html

 

[bruceb]

With alternators these are the most common faults:

1): Brushes worn out

2): Bad diode in the diode trio

3): Defective voltage regulator -- you usually replace it with the diode assembly

4): Bad bearings -- they will make noise when you spin the shaft

So far I have yet to have an alternator with a bad rotor or field coil. It can happen
but it is very rare.

 

[Torn Mind]

And of course, I just happen to be one of the rare ones to come across an alternator with a bad rotor. Of course, it had to happen after I tried putting in a new voltage regulator and diode assembly, but it was definitely toast since the voltage output would not go above 12 volts or something. Once I tested the windings and the ohms were below the spec in service manual. Used Camry. 249-250K. Must have seen salt in Illinois or something. It also sat for a year before I really put it into use.

 

[Elixer]

Then, you want to push the accelerator pedal to around 2000-2500 RPM and see how the voltage goes up. If the voltage holds at around 14.0-14.6 something, then the alternator is fine. If the voltage keeps increasing with idle into the 15+ volt range, the voltage regulator is bad and the alternator either needs the regulator replaced or the whole thing replaced.

Thanks, got a chance to do that today, and it was steady at 14.25.
Is it true that using petroleum jelly on the terminals prevent corrosion in the first place?

 

[razel]

Putting anything to cover the positive terminal will help prevent corrosion. The majority of the corrosion comes from the fumes (hydrogen) coming up from the vents off the top of the battery. Most cars, past 15 years do have a stock cover over the positive terminal. If you don't buy the felt covers. A felt ring goes underneath then you wrap the rest around the top of it.

Otherwise PlasticDip also works great. You don't want anything permanent on the terminals. You will reduce conductivity if you do so. You will easy access to bare metal when you jump the car. PlasticDip and the felt are great at this. The PlasticDip you just rip off and respray when you get home.

 

[Elixer]

Only the positive terminal? Why not both?
From what I was told, the negative terminal has the crap all over it, the positive one was clean.

 

[razel]

Yes, you do use felt on both positive and negative. When I was editing it, I matched the fact that nearly all 21th century cars have a stock cover over the positive terminal and just focused on that.

 

[lxskllr]

Yes, you do use felt on both positive and negative. When I was editing it, I matched the fact that nearly all 21th century cars have a stock cover over the positive terminal and just focused on that.

I always assumed the covers were there to prevent possible short circuiting due to the tighter clearances in modern cars.