[JFP in PA]

Originally Posted by vipola

Cold cranking amperes (CCA) is the amount of current a battery can provide at 0 °F (−18 °C). The rating is defined as the current a lead-acid battery at that temperature can deliver for 30 seconds and maintain at least 1.2 volts per cell (7.2 volts for a 12-volt battery). It is a more demanding test than those at higher temperatures.


If a Boxster Battery is rated 600 CCA, that's the amount of amp it can deliver for 30 sec without draining itself..

A Battery Tester put a high load on a battery for 10-30 sec, and you look how the battery recover from that load..

look like the same specs for me.. from what I understand you should test a battery with the closest possible of it rated CCA to get a valuable result..

You want to know if you kill the battery with that test, and if you do, then it show you that the battery is not able to deliver those promises CCA anymore..

Testing a 800 CCA battery with a 150 Amp tester won't give much info about the true performance of the battery..
If a battery is supposed to be able to deliver me 800 CCA, it dosn't mean much to know that it can deliver 100 CCA :P
isn't just like asking a body builder to bench press 5 lbs?


(This is all from what I understand, I'm always open to learn better )

OK, let’s start simple: Think of the battery’s amperage rating as you would a fuel tank’s capacity (around 18 US gallons for the 986/987). Much like the battery, the fuel system is never called upon to deliver all the fuel instantaneously, but it does have the total capacity of 18 gallons, and could do so under the correct circumstances, although that outcome would also be disastrous.

Most of the non-momentary electrical loads (lights, stereo, etc.) only draw a couple of amps each, so they really do not place much of a load on the battery, particularly while the car is running. This is why a car with a weak battery will run fine after a jump start, but be incapable of restarting on its own. A typical car, with a good battery and charging system, is running down the road with only a few amps load on the system. Placing a momentary high amperage static draw on a battery using a proper 130 amp rated load tester for 10-15 seconds (I have never seen a shop load tester capable of doing it for more than that length of time, because they do get hot; although much larger liquid cooled units are used by the battery manufacturer’s to test the battery’s) pulls the battery voltage down and shows how capable the battery is dealing with the high momentary load, much as it would when trying to spin the engine over. After 10 seconds of static load (engine not running), the tester will read out the battery voltage, with an 800 amp rated battery that is in good condition reading in the 7.2-7.8 V range. If the battery goes below that level, it is either only partially charged, or defective (in our shop, we always run a specific gravity check on a battery to make sure it is fully charged prior to load testing).

The 130 Amp load tester we use on our client’s cars has regularly identified batteries that were becoming questionable before the owner’s even knew there was a potential problem. We recently had a 911 in that periodically refused to turn over, but otherwise ran fine. Every time it refused to spin over, a quick jump got the car running, and it would then act normal for several starts, but would eventually again refuse to spin over. The dealer told the owner he needed a new alternator, battery and starter. Not wanting to spend that kind of money, he brought it to us for a second opinion. When we looked it over, the battery specific gravity said it was fully charged. But after only about 5 seconds under a 130 Amp load, the battery voltage dropped to 4 volts. We immediately suspected the battery, but jumped the car to start it, and ran a “dynamic” load test (130 Amp load testers are also capable of testing the alternator’s response to high current draws in a similar manner, but while the car is running. The load period is the same 10-15 seconds, and should cause the charging system to jump to maximum output to offset the current drain. Some of the better 130 Amp load testers also have a separate lead that attaches to the alternator’s power terminal, which allows you to see the diodes and regulator respond in real time to the brief load in separate digital display.) and saw that the alternator responded well, but again the battery voltage momentarily dropped very low. We checked the starter for current draw, and it was also in spec. As we suspected the battery, we replaced it, and the car repeated the tests without incident, and has run fine ever since.

130 Amp load testers do work, and can often find otherwise elusive problems………