ok i have an alternator question i have a alternator on my car but i dont know what amperage it is, but i need a larger one. heres the deal i have power everything, ac, 1500 watt stereo, about what amperage alternator would i need, any konwledge would be helpful

,kevin

 

It depends on the year, but you probaly have a 63 amp alternator. Which might be good enough, but if you really want to put on a new alternator, go no higher than 100 amps. any higher, and the battery will blow when you turn the accesories off without running.

 

Sorry, thats turn the accesories ON without starting it that will blow the batt.

 

seems like you're confusing voltage with current. i wouldn't worry much about "the battery blowing" since most all modern alternators are regulated to around 14 volts and have a negative chassis ground.

When alternator shopping, make sure that the alternator mounting points line up with the engine brackets and that the pulley is compatible with the alternator drive belt.

also, this TSB may be of intrest:

"Low Voltage Reading Or Dim Lights At Idle
Bulletin No.: 43-64-07A
Date: January, 1997

INFORMATION

Subject: Low Voltage Reading or Dim Lights at Idle

Any vehicle may have a low voltage reading (if equipped with gauges) or lights that dim, when electrical loads are heavy at idle, or under very slow driving conditions. This condition may be worse with owner added electrical accessories, or with a discharged battery. THIS CONDITION IS A NORMAL OPERATING CHARACTERISTIC OF THE VEHICLE, AND NO REPAIRS SHOULD BE ATTEMPTED UNLESS A PROVEN FAULT HAS BEEN FOUND.

At idle, vehicle electrical loads may exceed the low speed output of the generator, but the battery can make up for this shortfall from its reserve capacity for short periods. During normal driving conditions, the generator is designed to do two things: supply the necessary vehicle loads, and recharge the battery. Long periods of battery discharge due to high accessory loads at idle will cause the electrical system voltage to drop as the battery continues to deliver the electrical power. Increased generator temperatures from extended idling can also contribute to lower electrical system voltage. As temperatures rise, the voltage setpoint is reduced to avoid battery overcharge, and the generator's output capability is reduced due to increased electrical resistance.

Depending on the vehicle application, normal generator output at idle can be as low as 35% of the full rated output (see Figure 1). With enough electrical loads, it is easy to exceed the low speed generator output at idle. This is a NORMAL condition that the battery can compensate for during short periods. Items that affect the vehicle system voltage at idle are driving conditions, the number of electrical loads being used, add-on accessories, and extended idle times. Normal driving conditions will recharge the battery and restore the charging system to its normal state.

Some typical electrical loads are:

Load Amps
Rear window defogger 25
Headlamps (low) 15
Headlamps (high) 20
High blower 20
Windshield wipers 6
Ignition 6
Brake lights 5

Dimming lights at idle may be considered normal for two reasons. First, a vehicle with a low state-of-charge battery or under a discharge condition will have a normal low voltage condition. As vehicle speed changes, so will the output of the generator. As a vehicle slows, the output of the generator may not be sufficient to supply all demanded loads, so the vehicle system voltage will drop, and the lights will dim. Secondly, as high current loads (blower, rear defogger, headlamps, cooling fan, power seats or windows) are operated, the regulator can delay the rise in output. This effect, usually at lower engine speeds, can take up to ten seconds to ramp up the generator output. This is done to avoid loading the engine severely, so that engine speed variations caused by the increase in generator output are not noticeable to the driver.

Component Functional Tests

Make sure all battery and ground connections throughout the engine compartment are secure and tightened. The battery and generator performance can be checked as follows:

Battery
1. Turn the ignition switch and all accessories "OFF."
2. The battery should have a "green eye" and the terminal voltage should be greater than 12.0 volts.
3. If not, the battery should be charged and tested following the instructions in Section 6D1 of the appropriate Service Manual before testing the generator.

Generator
The regulator lamp circuit provides the best diagnostic indicator for generator faults. Confirm that the lamp is operating properly, and isolate the unit with the Universal CS Generator Tester (J 41450-B).
1. WITH ALL ACCESSORIES OFF, run engine above 2500 RPM.
2. Diagnostic lamp should remain off. Voltage at the battery terminals should be between 14.0 and 16.0 volts when cold, and between 13.0 and 15.0 volts with engine at normal operating temperature.
3. Install a carbon pile tester (VAT-40 or equivalent equipment) across the battery and an inductive ammeter on the generator output wire(s).
4. Run the engine above 2500 RPM and load the charging system until peak output is reached.
5. If the peak measured current is within 70% of its rated output and the diagnostic lamp remains off, the generator is good.

If the generator does not perform to the above tests, refer to Section 6D3 of the appropriate Service Manual."

 

Got to dispell this myth. An alternator will NEVER cause a battery to explode. To understand this you must know how it works. The alt. has no idea how much charge the battery actually has. An alternator looks at battery terminal voltage to determine how much it will charge. For example, if you cold start the car in the morning the current required may bring the terminal voltage down to 10.5-11 volts. The voltage reg senses voltage and adjusts the field intensity to charge up to a predetermined level as is it set for. AS a battery charges it's terminal voltage will rise, hence the regulator will cut back the field and alt. charging will drop off. The tricky part is understanding how a battery reacts to charging. A new fresh battery will charge LESS than a lazy battery, and that is because a new battery will take less time to come up to terminal voltage whereas an older batt. with a lazy cell or two may never come up to the reference point that the alt. looks for. In that case the alt. will indicate a hard charge and mislead you. And that is why many alternators fail. They are NOT battery chargers, they will maintain a charge if all things are working. I recommend that everyone trickle charge thier battery every couple of months. You would be surprised how much longevity you will add to your batt. No BS, my 89 ROCK's ORIGINAL battery is still running a neighbors car. A 105 amp alt is a nice unit for almost all applications and should handle most modern loads. I suppose that if an alt. ran WILD it may cause the batt. to pop, but in most Delco alt's they have a safety provision to protect against anything over 17 volts. Hope this helps