Author Topic: Automobile batteries  (Read 2286 times)

drone on

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Automobile batteries
« on: January 27, 2012, 04:18:11 PM »
Hello all, I was wondering if someone knowledgeable about cars could answer this question for me.  I've been Googling and researching but still wondering.  My situation was:  my 2010 car was having very weak cranking on a cold start (after engaging the key, the engine wouldn't start up right away, there would be a delay of a couple seconds after the key was fully engaged) that got worse over time.  I suspected it was the battery, based on my research.  The dealer service dept. stated my battery was in "good condition," yet when I took the car to a trusted independent mechanic, they said the battery was bad and to replace it.  The mechanic gave me a printout of the battery test showing the voltage was 12.57v (apparently "normal"); however, a "capacity test" done showed the battery failed and the battery life was 0%.  Recommendation: replace now (which I did). 

My question is, do you think the dealer just didn't check my battery at all, or did they only possibly measure the voltage, and because they didn't do the "capacity test," they couldn't tell the battery was in bad shape or get a complete picture of its health?  In other words, are some methods of battery testing not very comprehensive compared to others?   Please let me know somebody as I'm trying to determine whether to return to the dealer service dept. in the future.  If you think they f'd this up let me know.  Thanks!!!

sraymar

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Re: Automobile batteries
« Reply #1 on: January 27, 2012, 05:29:42 PM »
Wild guess - if your car was still under warranty then they'd have to replace it for free, whereas the independent guy can charge for a new one plus installation.

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Re: Automobile batteries
« Reply #2 on: January 27, 2012, 06:16:03 PM »
Hard to say, at the Shop I work at we do what's called an "AVR test" which shows the cranking power of the battery, measures alternator output, and measures the draw from the starter.   If the battery cranking power is less than 50% of new, and the other two components pass, then the battery automatically fails.  The dealer might have been lazy, or didn't want to pay out a warranty....

Bill Binkelman

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Re: Automobile batteries
« Reply #3 on: January 28, 2012, 05:26:04 PM »
I can't offer any advice except to say that I have NEVER heard of factory installed battery failing in so short a time....unless you let it completely discharge numerous times. When a car battery "dies" each recharge brings it up less and less to its "full" strength. Why a dealer would refuse to simply put a new battery in, when the vehicle is under warranty, is a mystery. Dealers are compensated by the manufacturer for warranty repairs. Could they have simply made the mistake and misdiagnosed it? Sure. But I'm more concerned why the battery had zero capacity in so short a time. Out of curiosity, what make and model did you buy? I ask because the service dept. for dealers can vary depending on make as some car companies are more lax in rating their dealerships' service depts.
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drone on

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Re: Automobile batteries
« Reply #4 on: January 29, 2012, 12:58:52 AM »
Thanks for feedback everyone.  It's a Mazda 3.  I have read about other owners batteries being short lived.  Is it possible the factory batteries are cheap?  If not, I'm a little concerned perhaps something else is wrong that may have caused the battery to fail prematurely.

Bill Binkelman

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Re: Automobile batteries
« Reply #5 on: January 29, 2012, 03:52:46 PM »
It's possible the factory installs less the good batteries as a cost saving measure. You can try Googling for info. Here is a quick result of a Google search I did about bad batteries in Mazdas

http://forum.mazda6club.com/mazda6-atenza/217537-another-shitty-mazda-battery.html

The only thing that can cause a battery to die that soon, from what I know, are:

(1) Recharged so often due to frequently letting it discharge so battery loses effectiveness over time (unlikely if you don't remember at least 10-20 times the battery died because you left lights on, etc.)
(2) Bad cells in the battery or just a bad battery...cells can go bad before the whole battery dies
(3) Charging system operating at less than normal output (unlikely, IMO....usually the charging system just flat out dies, e.g. the alternator goes out)
(4) Something is draining the battery because the device is still "on" when it shouldn't be, e.g. overhead dome lamp never shuts off, etc.

If you put in a a good aftermarket battery and it happens again in a short amount of time, then it's something in the car itself. I'd be willing to bet it's the battery. Sorry I can't be of more help.
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APK

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Re: Automobile batteries
« Reply #6 on: January 29, 2012, 05:22:00 PM »
"(4) Something is draining the battery because the device is still "on" when it shouldn't be, e.g. overhead dome lamp never shuts off, etc."

Yes, it can be something as simple as the glove compartment light not switching off when closed.
Happened to me once. Hard to spot. Worth a check.
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drone on

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Re: Automobile batteries
« Reply #7 on: January 29, 2012, 08:42:46 PM »
Car starts perfectly now with new AC Delco battery (72 month).

drone on

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Re: Automobile batteries
« Reply #8 on: January 31, 2012, 01:17:33 PM »
I spoke too soon.  It started perfectly for two days, now it's back to weak/delayed cranking after sitting out all night.  I think something is draining my battery overnight.  Taking it in for alternator/electrical system test, and if that checks out OK then it must be a "parasitic drain" from somewhere in the car.  Can't afford a new battery every 21 months. 

sraymar

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Re: Automobile batteries
« Reply #9 on: January 31, 2012, 05:24:24 PM »
I hate electrical problems because one appliance can affect several others. Like Bill mentioned the alternator could be going.

Years back I had an old '69 VW bus and I took it out for a long drive and stopped at a drug store near my place one night. When I got back in the bus it wouldn't start. I popped open the engine compartment lid in the back only to discover the battery was gone! The metal it sat on had rusted clean through and I must've lost it on the freeway somewhere.
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Bill Binkelman

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Re: Automobile batteries
« Reply #10 on: January 31, 2012, 06:46:03 PM »
I spoke too soon.  It started perfectly for two days, now it's back to weak/delayed cranking after sitting out all night.  I think something is draining my battery overnight.  Taking it in for alternator/electrical system test, and if that checks out OK then it must be a "parasitic drain" from somewhere in the car.  Can't afford a new battery every 21 months.

I kinda doubt it's the alternator, but I could be wrong. My money is on something...some kind of accessory...is permanently "on" due to a short or a glitch. If you lived in a cold climate, like Minnesota, that drain at this time of year would drain the entire battery overnight, most likely. In southern/warmer climates, an accessory left on wouldn't drain the battery completely for a while, especially if you are then driving it now and then and recharging it. But maybe the alternator is "kinda" bad...if it is, it has to be under warranty...HAS to be. Unless you have put on more than 50K in two years. A thorough diagnostic check of the entire charging system will reveal if it's at all related to that. OTOH, if the charging system is okay, it has to be something else...something draining the battery, I'd have to think. But, yeah, as Steve just wrote..electrical problems are the worst...they can be almost impossible to diagnose without tearing a car apart and costing a LOT of money in diagnostic fees. My power door locks are fidgety as hell on the driver's side but my mechanic, who I have used for about 15 years, said it would be cost prohibitive to track down the problem (likely a short or loose wire). Sucks, man. I feel for ya...seriously. I've owned about 20 cars in my life and repairs will just frustrate the shit out of anyone.
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Seren

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Re: Automobile batteries
« Reply #11 on: February 01, 2012, 05:46:36 AM »
I once had a 1600cc VW camper with a 2500cc gearbox - was great if you enjoyed taking an hour to get up to 50 miles an hour.

Sold it to a friend who used it to learn mechanics - really enjoyed it until it broke down on the motorway and when he opened the engine compartment the crankshaft was sticking out through the casing.....

drone on

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Re: Automobile batteries
« Reply #12 on: February 01, 2012, 11:20:03 AM »
Getting the charging system tested Friday.  If that's not it, it freaks me out it'll end up being some wiring issue Mazda will never be able to find and the car will continue to have weak cold starts and the battery will fizz out quickly again.  I really love driving this car and it looks great but I've had so many little problems (bad CD player, squeaky power locks, creaking seats, and now this electrical problem) that it's my first and last Mazda product.  The service dept. at the dealership I bought it at is horrible and so is corporate Mazda when you try to get help from them. 

drone on

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Re: Automobile batteries
« Reply #13 on: February 01, 2012, 06:19:58 PM »
If it was something like the trunk light not going off when closing the trunk, wouldn't the bulb burn out quicker than 2 years (how long I've had the car)?   

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Re: Automobile batteries
« Reply #14 on: February 02, 2012, 11:02:03 AM »
I just got a clue to this mystery:  2 days ago my glove box light was on when I opened it.  This morning it wasn't on.