Another boring battery discussion (OR IS IT?)

OK, There have been a whole lot of discussions about batteries in here. Let's talk details here. I'll step thru my story and you tell me what you think.

1998 GTS 23,000 miles

Bought this car with the original battery in it with a battery tender.

Car idled rough, stalled at low idle

Put brand new battery in it, Ran great, I mean great. No problems for three months.

Three months later again rough idling and some choking when pulling out at low idle.

(in one week)Drove the car 200 miles, Ran it to work every day for one week, when for a 70 mile ride then,

I checked the battery, BAD!

I had it professionally checked, BAD BATTERY!

I removed it and returned it to where I purchased it.

Out of the car with a good tester, Tester indicated charge needed, retest.

Charged it.

Tested, GOOD battery.

OK, my time to play with this.

Of course when I took it home it tested good with my tester.

Next I hooked it up to my car, yes a spark, Traced it and the security system has some battery draw. No big deal the alternator should charge the battery enough to get it up to full charge when running the car.

On to more testing. I needed to be sure the charging system was working so I left my lights on for two hours to drain the battery. Yes the charging system is working but with my piece of testing equipment it's charging near the bottom of the scale.

So I disconnected the battery and put the battery alone on my charger. Six hours later the charger had the battery fully charged. Let's calculate this out. It took me 2 hours to drain the battery and 6 hours to charge it.

This is when I realized I may have a week charging system and not a battery problem.

I did not check the output of my alternator.

Here is what I am planning on doing: Remove the alternator and take it to a good alternator shop and have it tested and see what the output curve is. Then I am going to see if there is anyway of boosting the output of the alternator. I need to get more amperage to the battery to keep this battery fully charged.

I feel there should be no reason to run a battery tender unless it's for a full no driving season. I put a new battery in and ran the car for 3 months and put 2,000 miles on the car and the battery is dead. Something is not working properly. I got to figure this out. Do these charging systems go week over time? Most do!


What do you think?

what kind of battery are you useing for your testing, with the car running you could of just took a volt meter and tested the alternator on the car you should be in the 14 volt range. If your useing a Optima red top, I personnaly think they are junk unless you are driveing the car everyday.

"Next I hooked it up to my car, yes a spark, Traced it and the security system has some battery draw."


How much amperage is the security system drawing?

YES and Yes! The alternator can charge and show charge voltage. The gauge reads in volts. Normal charge is 14.5 V. The alternator has 3 postive diodes that divide the Amperage in 3rds. So a 45Amp alt is 15,15,15 a 60 Amp is 20,20,20 and so on. You can loose 1 or 2 diodes and still show 14.5 volts but the Amps are lost in 3rds of rated Alt. output and not enough Amps to keep up with the Cooling fan, A/C, Lights. The A/C is about 10 Amps alone. To test the alternator for full load you need to have an Ampmeter connected to a battery cable turn on everything and see what it's capable of producing at 2000 rpm. Just remember the battery is for storage of excess unused voltage and Amperage and the car should run fine without the battery but charge system will be full out charging without it.(not recommended for very long)There is no way to "turn up" the alternator output without getting a higher rated. The Viper I remember is 100Amp which is more than enough.