battery or alternator: Please help

[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 )

[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………

[ARModen]

600amps over 30seconds=20amps per second. 150amp rated tester is rated for 150amps per second, well in excess of your maximum battery discharge rate. If you managed to get near 600amps per second out of your battery, you'd completely ruin a wrench and have purple spots in your vision for several hours... just trust me on this one.

[Paul]

So are you saying that our starter motors only need 20 amps x 7.2 volts or 144 watts of power? Since 746 watts are needed to produce 1 hp, that seems to be very low.

[stephen wilson]

IIRC, the starter on my Formula Ford 1600cc required 140-160 Amps.

[mptoledo]

UPDATE:

Got the Alternator from Oreily's auto parts for $204+tax. It has a lifetime warranty. It was fairly easy to put in, but you do want to take that bolt off by the bottom bracket screw as this gives you more room to work it into place.

It works great but the oil check thing still doesn't work. I am getting 12.x for the battery and when I start it I get 14 so the alt is doing its job.

Questions:
1.) my radio doesn't work and I checked all the fuses except the radio(next)
2.) my oil check thing only blinks and doesn't perform its test.

Everything else seems to work fine. any ideas on the oil check thing?

[ARModen]

Originally Posted by Paul

So are you saying that our starter motors only need 20 amps x 7.2 volts or 144 watts of power? Since 746 watts are needed to produce 1 hp, that seems to be very low.

Power's another beast altogether. 20A at 14v=.5hp more or less. That sounds about right to me. 150A at 14v would be 3hp, which would make your starter about the size of a large pool pump, which might be necessary on a higher compression vehicle.

As Voltage goes down, the impedance of the motor goes down, which causes current flow to increase. So if you're starter pulls 20A @ 14V, it'll pull 40A @ 7V. You're rolling an unloaded engine. You can roll the engine by pushing the car while it's in gear fairly easily with 1 person and we generate much less power than a horse.

[Klimo]

I just retrieved my car from the winter to find out that my battery was complete dead. The battery was about 2 years old and I know they drain fast on these cars. So I put a new one in and everything seemed to work fine. I took it out to re set the electronics and realized the radio or wipers didnt work. I was also getting to flashing oil lights as well. The battery light never went off. After about 30mi of driving I started seeing all the warning lights come on and the car eventually died (about a block from my house) I was able to jump and get in going for another few minutes until it dies again. First guess was alternator. Did you get everything working again? Any help is greatly appreciated.

[ARModen]

That does indeed sound like an alternator problem Klimo. You could take the battery to a parts store and have them check it to make sure it'll hold a charge, but the battery light being on is a good indication that it's something on the alternator.

[Perfectlap]

My alternator died at slightly higher mileage too.