Charging system help needed: - somewhat needed: - somewhat urgent
10-03-2005, 12:33 PM
#1
Burning Brakes
Thread Starter
Charging system help needed: - somewhat needed: - somewhat urgent
Symptoms
1) Battery has been leaking fluid at the negative terminal for some time (assuming this is from overcharging, but car is a race car - so cornering/braking loads are high)
2) While driving, voltmeter at the last race on the dash went to 0 volts - returned to the paddock where the car died.
3) Pulled the battery, it read 8-ish volts on the multimeter
4) Replaced battery, car ran fine but showed that the battery was not charging - showrd just under 12 volts and went progressively lower and showed low 11.x volts after the session. This was verified on the multimeter at the battery. Voltmeter used to show 13 or 14 volts on the dash when running.
5) Connections at the battery are clean - cleaned the terminals on the new battery and the leads of the battery cables with a wire brush prior to battery install.
6) Charged the battery on the charger - car ran fine for the race
7) Went home (after a pole position and two wins for the weekend ;-)
8) Battery was showing some fluid at both terminals. Sprayed down battery and compartment with baking soda/water.
9) Pulled alternator and took to autozone - they ran the test and showed the battery failed all three test - Alternator, Diode, and Voltage Regualtor - i.e. toast!
10) Put in a Bosch OEM voltage regulator in the hope that autozone was wrong.
11) Started the car - voltmeter on the dash showed just under 12 volts. Voltmeter on the battery showed 12.7 volts with the car off, and 12.5 volts at idle. Revved the car up to 3000-ish, and voltage did not increase either at the voltmeter on the car or accross the battery
Ok - understand that the alternator is bad - have a new one on the way. Assuming that it comes with a new voltage regulator and diode pack - but if not, I'll get those as well. However, I'm trying to figure out what would cause a potential overcharge? Or, is my cheap die-hard battery just leaking from cornering and braking forces.
Help on tests or ideas would be appreciated.
1) Battery has been leaking fluid at the negative terminal for some time (assuming this is from overcharging, but car is a race car - so cornering/braking loads are high)
2) While driving, voltmeter at the last race on the dash went to 0 volts - returned to the paddock where the car died.
3) Pulled the battery, it read 8-ish volts on the multimeter
4) Replaced battery, car ran fine but showed that the battery was not charging - showrd just under 12 volts and went progressively lower and showed low 11.x volts after the session. This was verified on the multimeter at the battery. Voltmeter used to show 13 or 14 volts on the dash when running.
5) Connections at the battery are clean - cleaned the terminals on the new battery and the leads of the battery cables with a wire brush prior to battery install.
6) Charged the battery on the charger - car ran fine for the race
7) Went home (after a pole position and two wins for the weekend ;-)
8) Battery was showing some fluid at both terminals. Sprayed down battery and compartment with baking soda/water.
9) Pulled alternator and took to autozone - they ran the test and showed the battery failed all three test - Alternator, Diode, and Voltage Regualtor - i.e. toast!
10) Put in a Bosch OEM voltage regulator in the hope that autozone was wrong.
11) Started the car - voltmeter on the dash showed just under 12 volts. Voltmeter on the battery showed 12.7 volts with the car off, and 12.5 volts at idle. Revved the car up to 3000-ish, and voltage did not increase either at the voltmeter on the car or accross the battery
Ok - understand that the alternator is bad - have a new one on the way. Assuming that it comes with a new voltage regulator and diode pack - but if not, I'll get those as well. However, I'm trying to figure out what would cause a potential overcharge? Or, is my cheap die-hard battery just leaking from cornering and braking forces.
Help on tests or ideas would be appreciated.
Last edited by Matt Marks; 10-03-2005 at 01:04 PM.
10-03-2005, 01:01 PM
#2
Mexican Ambassador
Lifetime Rennlist
Member
Lifetime Rennlist
Member
seems like the voltmeter was off, but the alternator is just shot if when you replaced the voltmeter it was somewhat normal (under 12). i had my voltmeter go bad and my voltage was completely unregulated, i went to like, 16 and it almost cost me a battery. replaced voltmeter, all was well. 
10-03-2005, 01:06 PM
#3
Burning Brakes
Thread Starter
951 Obsession - Updated bullet 4 above to make it clearer. Voltmeter on the dash showed 12 volts with the new battery slowly falling in to the low 11.x range. Should be reading 13-14 volts if the alternator was charging. Voltage on the voltmeter with the new battery is consistent with the voltage accross the terminals checked with a multimeter.