Car Battery Questions

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EEPROM777I
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Car Battery Questions

Post by EEPROM777I » Fri Nov 24, 2006 5:37 pm

I have been through three car batteries in a months time and I'm trying to find answers. My original OEM battery died two years ago. I bought a replacement and it worked fine for the past two years. One day I went out and the battery was dead. I jump started the car and it ran fine. I let it run for 30 mins to recharge the battery and all seemed well. next day I checked the car and it started fine. I let it rest three days and the battery was beyond repair. I was able to verify nothing was left on (trunk and all doors fully closed, dome light off, no acc on, no after market equipment at all and nothing in the cigarette lighter socket). I did a warranty battery replacement. The new battery worked fine for days, provided I started the car everyday. The car sat for four days and again the battery would not charge enough to allow me to start the car. I replaced the new battery two days ago with yet another new battery. So far so good. I did some checking and with the car off I'm drawing 250mA. I left the meter on awhile and after about three mins and having closed all the doors the current draw goes down to 18mA and stays there. Now to my question. Did Walmart give me two bum batteries or is even 18mA to much current draw? I read anything under 25mA was acceptable. I have been able to verify that the car does stay around 18-20mA after the car has been left untouched. It is not cold in my area yet and my battery is stored in my front drivers side tire well, well insulated from cold and heat. Thanks for any info.


I forgot to mention.... With my car off for over 24hrs the voltage was at 12.72 VDC and after being on and running for about 1 minute the voltage is 14.20 VDC.

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Chris Smith
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Post by Chris Smith » Fri Nov 24, 2006 5:55 pm

Most car batteries are made up from used parts from old batteries, rebuilt, meaning you can start with junk from the get go.

Insurance is not a guarantee of the battery condition, just a pro rated pay back scheme.

Second, if your voltage from your alternator is too high the batteries do boil over causing a electrolytic [gas deposit] path across the top of the battery, causing a dead short over a small amount of time.

Then you also have to ensure your charge is correct and not too small to replace the bank account. 55 amps, 100 amps etc at the right voltage,...13.2 to 14.7 volts.

If you continue to remove more amps over all [or volts] out than you replace, your bank account goes dry quickly.

Last but not least you need to know if you are drawing way too much from the battery at idle or stop to handle the over all account, over a 24 hour period or more. {see lesson two}

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Smoke_Maker
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Post by Smoke_Maker » Fri Nov 24, 2006 5:56 pm

If the battery "test" bad than it a bum battery, if the car had a draw that drained the battery you would be able to recharge the battery and use it. The parasitic drain on the battery depends on the size of the battery, Fords group 65 truck battery allows something like 40mA draw per there TSB. The old saying comes into play here, "you get what you pay for". Price dose NOT determine quality -but- quality usually cost more.
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MrAl
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Post by MrAl » Fri Nov 24, 2006 7:11 pm

Sounds tough to fix.
You could try a different brand battery to see what happens.
The voltage readings you are getting sound ok to me.

I have a constant drain on my battery and it seems ok.
LEDs vs Bulbs, LEDs are winning.

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Externet
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Post by Externet » Fri Nov 24, 2006 8:15 pm

Hi.
Seems to me the voltage regulator is kaput, putting too much voltage while charging, destroying it shortly. Anything above 13.8V is to be suspected.
The 25 mA drain appears normal, to keep the computer memory circuits alive and whatever anti-theft is active, plus remote control receiver on.

Remember any lead-acid battery left discharged for over 24 hours will never recover its full capability, and no, you do not need to put a piece of wood under it to prevent self-discharging. :smile:

Miguel

EEPROM777I
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Post by EEPROM777I » Fri Nov 24, 2006 8:30 pm

Externet wrote:Hi.
Seems to me the voltage regulator is kaput, putting too much voltage while charging, destroying it shortly. Anything above 13.8V is to be suspected.
Thats not an answer I was hoping for. How could I test if this is the case? Is the fact thats it's at 14.2 proof enough? My battery is rated for 365 CCA (Cold Cranking Amps) at 32°F if that's any help.

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dacflyer
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Post by dacflyer » Fri Nov 24, 2006 8:52 pm

not that this would help you any, but i heard a bizar story long ago,,
its long,,but here it is in a wirecap :P no nutshells inthis forum :P

a guy goes and buys a new car..next day its dead,, dealer comes to jump it,,its fine all day..
next day same story..car goes to shop for inspection,,nothing found..
owner takes it home...next day its dead again... nothing is on each time.
after going around and around, they finally discover the problem,
the owner lives on a hill with a steep driveway..
the incline is so much that it triggers the hood light. the angle is just as if the hood was up...
so to remedy the problem the owner pulls out the bulb and thats the end of the mysterious dead battery.

perhaps you might have same problem ??
but i bet you its the cheap wally world batterys.. i don't trust them have the battery load tested somewhere..then go from there.
good luck

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Crowbar
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Post by Crowbar » Fri Nov 24, 2006 9:34 pm

Anything above 13.8V is to be suspected.
Not true! 14.2 v is the typical spec for a healthy charging system, over 14.5 is reason for suspicion.
Keep Prying...

Crowbar

EEPROM777I
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Post by EEPROM777I » Fri Nov 24, 2006 9:37 pm

Thanks Dacflyer for the suggestion but I have no under hood light, no tilt switch and my driveway is almost dead level. That must have been a tough one to solve though. He must have gone out for midnight chocolate run and saw a mystical glow from under the hood.

EEPROM777I
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Post by EEPROM777I » Fri Nov 24, 2006 9:38 pm

Crowbar wrote:Not true! 14.2 v is the typical spec for a healthy charging system, over 14.5 is reason for suspicion.
Sorry Externet but I hope Crowbar is the right one. Just for my sake.

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MrAl
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Post by MrAl » Sat Nov 25, 2006 12:41 am

Hi there,

Yeah mine is 14.2 also. I dont have the kind of problem being
talked about here either. I think 13.8 is ok, but 14.2 is ok too.
I could double check and measure it again with the digital meter
next time i go out if you like.
LEDs vs Bulbs, LEDs are winning.

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Chris Smith
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Post by Chris Smith » Sat Nov 25, 2006 8:02 am

Re read my letter and stick to the print, the specs have been used in the industry since the invent of the starter and battery.

13.2 to 14.7 is what my professor taught us, some thirty years back.

Its never failed any one.

Too much voltage will cook a battery, [ high voltage regulation or even AC in the lines /bad diodes] ,....acid on the top can short out a battery, ......and over discharge at stop or idle will drain the account.

[Have you looked for AC in the lines?]

It’s a simple job to find out the problems associated with a battery that even first year students are taught to find. Its one of the basics.

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Smoke_Maker
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Post by Smoke_Maker » Sat Nov 25, 2006 8:32 am

They are correct 13.5 to 14.7 volts is the normal working window for a vehicles alternator voltage regulator.

You can discharge a battery "many" times then recharge the battery and it will still have a useable service life in starting the vehicle, it is also true that the battery will never recover to full capacity after being fully discharged, but a "good" battery will accept a charge and still pass a load test and start the car.

I suspect that you got bad batteries, most auto parts stores charge and test the battery before replacing it under warranty, if the battery accepts a charge and shows a good load test they give you the battery back and say you have another problem with the car.
Richard Furniss
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philba
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Post by philba » Sat Nov 25, 2006 9:36 am

my bet is with externet - the likelihood of 2 bad batteries in a row is very low. I'd have the regulator looked at.

First, though, I'd check the alternator belt to see if it's loose or glazed and slipping. Maybe under loaded conditions, you just aren't charging the battery.

EEPROM777I
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Post by EEPROM777I » Sat Nov 25, 2006 12:56 pm

philba wrote:First, though, I'd check the alternator belt to see if it's loose or glazed and slipping. Maybe under loaded conditions, you just aren't charging the battery.
I've checked the belt and all seems well. With lead acid batteries voltage is a good indicator of charge? Right? So if after running the car and letting it sit for over 24hrs the voltage is 12.72 VDC does/nt? that show it's charging normally ?

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