Re: Generic Battery Testing Question......

Ok, my car is a 2009 and has the original battery in it and I am facing very low starting temps here over the next few days. So.....

1) Can a battery be tested for "wear" and therefore be able to recognize that it will most likely fail in 7 degree temps?
2) Is there any indication, via normal use, for me to tell if my battery is at risk of failing in these low temps?

Peace
Bruce in Philly

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Bruce In Philly (2000 S Boxster, now '09 C2S)
Ok, my car is a 2009 and has the original battery in it and I am facing very low starting temps here over the next few days. So.....

1) Can a battery be tested for "wear" and therefore be able to recognize that it will most likely fail in 7 degree temps?
2) Is there any indication, via normal use, for me to tell if my battery is at risk of failing in these low temps?

Peace
Bruce in Philly

I took my 08 328i over to Autozone to get the battery tested (free). Tested out at 84% (good--I hope). The test took about 30 seconds to complete once we got to the battery.

I had a very slow crank the other day at 5 deg F. temps that that prompted the trip; given the age of the battery I'll have to make an attempt to drive this car at highway speeds more often and make sure it is locked after I exit the car.

The standard tests are called voltage test and load test. Requires a fully charged battery and just a few minutes. Once they know it is a 5 year old battery any shop selling batteries should be eager to test it for you.

I bought the tester for less than $100 but it has never been out of the box and sits with lots of other similar tools on the storage shelves.

You could grab a manual from [www.actron.com] and see how it works.

As Mike says, you must first get it good and charged.

Then they apply a load and test the voltage fluctuation with load - this effectively measures the output impedance which is a proxy for the reserve capacity.

Simple no-load voltage measurements are marginally helpful, but not veyr good.

A good load test is cranking in 10 deegree weather. Just listen.

Grant

Grant

gee-lenahan-at-gee-mail-dot-com

Could a load test be performed by measuring the voltage variation while putting a load on the battery like starting the car ?

What metric should be acceptable ?

"A good load test is cranking in 10 degree weather. Just listen."

But i have no idea what metric should be acceptable. I would guess under full cranking no more than 2-3 volt drop.

But over time, if the cranking becomes slower, that's you drop right there. We know it is getting worse.....

Grant

Grant

gee-lenahan-at-gee-mail-dot-com

Cranked my Audi in COLD weather last week in VT and looked - never fell below 10.something volts (its analog don;t push for too much precision)

Grant

Grant

gee-lenahan-at-gee-mail-dot-com

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grant
Cranked my Audi in COLD weather last week in VT and looked - never fell below 10.something volts (its analog don;t push for too much precision)

Grant

Thanks Grant,

I'm assuming your Audi has a good battery

I will have to do the test, these days with our weather variation, I can probably crank it at any points between 10C to -20C...

be able to generate a spark.10 volts or above is a good voltage reading as it provides a bit of margin over the 9V minimum.

Grant

gee-lenahan-at-gee-mail-dot-com

If you are an AAA member they will come out and test it for you. When mine was dead the AAA came and said the battery they had wasn't right for the Boxster so he wouldn't sell me one, but he could test mine. He did, and said it just needed a charge (somebody left light on I guess). I gave it a deep charge and it has been good for over a year. In your case, you may need a new one. Tom

Although it is not N rated you can buy a decent battery tester from Harbor Freight for $20. I use mine to test our car batteries as well as the battery in our home standby generator.

You guys have got your priorities wrong. The Boxster is a convertible. Right? So why would any of you live in 10 degree weather? Come on out west. When the weather is warm enough to lower the top, rent a new apartment, lower the top, and THEN test the battery. :-)