ALEV8

740 CCA or 900? What's everyone buying these days? I usually get Interstate or Continental....I have my Fluke meter and wondered if I can text the battery at the poles in the engine compartment or do I go under the seat for the most accurate reading? Anyone have a procedure for the alternator test?

duh

If you want high cca, the agm at oreilley is the highest i found and best cost. Its made by east penn. East penn and johnson controls make most of the batteries in the world. At work we use interstate (johnson) with no issues, factory batteries for warranty replacements only. Ive always tried to use optimas in my vehicles, but they dont fit in the pig

duh

And for alternator test, just watch voltage at the poles. As long as its staying above 13.5 or so it should be good, but thats just the high view test . A true alternator test will test full loads and no loads at differnt rpms and compare them to the specifications and make a determination for you.

ALEV8

I get a discount from Continental due to family connection....so they always give me about 50% off. Just want to get an AGM batt. 49/8H? Might just check that OReillys out though as it likely is less even with my discount....

ALEV8

Test @ the battery correct? NOT the jumper leads in the engine compartment IIRC...

extanker

you should be okay at the jumper leads.imho

CaptJim

Resistance in the wire with the minor current a meter will generate is not that significant to warrant a test at the battery. You will discover the same potential or voltage at the poles under the hood.

Read the voltage before you start the car, key out, door closed. You will see 12.5-12.8 depending on the material you are using and the current state of the battery.

After you start the car, it may take a minute or so, you will eventually see the regulator kick in and provide a higher voltage, 13 - 13.8. Now turn the lights on, fans on high, defrosters, high beams..... Everything. Make sure the voltage is above or higher than the voltage reading than when we started this little experiment.

ALEV8

12.6v key in doors closed etc...so battery is definitely going to be replaced.
Engine running 13.8-9v
Engine plus accessories blazing 12.8v

duh

12.6v is the max a battery can have-anything higher is simply surface charge that will dissipate on its own, or quickly if you turn the lights on for a couple dozen seconds.

ALEV8

Actually the car sitting there sleeping should have 12.7v, ie remove battery and sit it on your bench, it should test 12.7v at bare minimum. That is the threshold I have been taught by extremely knowledgeable mechanics and one battery company owner who sold his business to Continental, and I stick to it.

mcbit

12.6v is the de facto norm for a fully charged battery quoted by the majority of battery manufacturers.

duh

A battery cell can only hold 2.1 volts. 6 cells per battery.
If you want more details on auto batteries you can read about them on wikipedia http://en.m.wikipedia.org/wiki/Automotive_battery

CaptJim

Your battery and alternator doesn't sound bad. Everything sounds good. The next step would be to put a Load test on the battery to see how the capacity capability is doing. Regardless, relative to the size, you want to fit the largest possible in the hole under the seat. Note I have not had to do this yet and have no experiencing changing the battery in the Cayenne. I don't know what Group (size) Porsche recommends in the car.

CCA is typically a measure of the Surface area of the plates. The larger the surface area, the more CCA hence, the bigger the battery.

Did you know that the voltage is determined by the Half Reaction of the materials used. different chemicals have different properties.

There is a good list in the following link.http://chemed.chem.purdue.edu/genche...20/electro.php

West marine does a really good job of putting choice into perspective.
http://www.westmarine.com/WestAdviso...torage-Battery

mcbit

What problem do you have that makes you feel that you need to change the battery?

CaptJim

The correct statement would be that a single cell of conventional Led Acid battery, when fully charged has a combined reaction potential of 2.1 volts. All cells in series will yield 12.6-12.7 volts, the math says 12.66. Different chemicals will yield different reactions and have different voltages. Remember, a battery is nothing more then a chemical reaction.