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Charging system How do I test an alternator and should I increase the output amps for my winch and install a second battery for my power inverter on a 87 bronco 302

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You Can Test An Alternator By Starting The Vehicle And Then Unhooking The Battery. If The Vehicle Stalls Then The Alternator Needs Replacement. A Second Battery Would Need A Source Of Charge So Unless You Want To Fork Out A Lot Of Money No.

Posted on Jan 05, 2009

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What would cause the battery gauge on a 93 jeep grand Cherokee Laredo to bounce between 14v and 9v. this is also running the battery dead and not charging the battery back up.


Several things need to be checked before an accurate diagnosis can be made, however in general it is most likely your alternator going out OR a bad connection in your alternator/charging circuit wiring.

It's also important to test/verify that you have a good fully charged battery (with no dead cells) before any tests of the charging system. An alternator needs ample battery power into it before it can produce good charging voltage and amps out of it and back into the battery.

If you test the voltage directly out of the alternator's output post/connector (with the output wire disconnected), you will be reading direct alternator voltage output, which should be approx 13.5 to 14 volts, steady. If the voltage is at ~14 volts, then suddenly cycles down to 9 volts (or anything less than 12 volts), then you have a defective alternator.
If the alternator, while isolated, tests out at a constant 13.5 to 14 volts, then the problem is most likely a bad wire or connection in the charging circuit wiring.

There is also the possibility of the battery (how old is it?) shorting out internally, causing the voltage fluctuation. That's why I previously said you need to verify each battery cell is fully charged and good. You can usually test this with a battery hydrometer (if it's not a "sealed" maintenance free battery).

Nov 05, 2014 | Cars & Trucks

1 Answer

1978 chev k10 alternator output 14.4 on bench, reads 9 amps on truck gauge 12.2 on ampmeter at battery with truck running why


amps reading on the truck amp meter is the current that is being generated to run everything as well as charge a battery that will be at best around 80% charged.bench testing an alternator gives these readings as the regulator is feeding into fully charged batteries with no draw on the system. When batteries are 100% charged the charge rate will be as low as 2 amps but in a car where there is a current draw for the ECM , ignition , fuel pump and what ever the alternator feeds these first before it charges a battery. You used a amp meter to get a voltage reading which is reading the voltage drop across the current draw. If you had used a voltmeter (multimeter) then you would see a voltage increase with the rpm increase. The

Aug 14, 2014 | Cars & Trucks

2 Answers

Charging/electrical problem


charging voltage should be 14.5-16..not 12.5.. thats too low.. get the alternator replaced and your charging issues should disapear..

Feb 08, 2014 | 2004 Pontiac Grand Prix

1 Answer

Alternator


Vehicles: any failing to keep its battery charged.

A vehicle unable to charge its own battery has one of 4 problems:
(a) alternator failure
(b) voltage regulator failure
(c) battery failure
(d) wiring problem between battery and alternator/voltage regulator.

One most modern vehicles (including 2002 Lexus RX300 - 2WD and AWD), the voltage regulator is an integral component of the alternator and is not separately serviceable.

In the US, one can get a free "charging system diagnosis" from the popular auto parts chains: AutoZone, Advance Auto Parts & Pep Boys. You needn't remove any parts from the car to get this diagnostic, since they can attach a diagnostic meter to the charging system in the parking lot. This diagnostic aid will tell you exactly which component has failed - battery, alternator or voltage regulator.

In case the vehicle is immobile, one can DIY (do it yourself) the diagnosis.
(a) inspect the wiring for corrosion/loose connections/loose connectors/etc.
(b) check alternator belt/pulley - if drive belt is properly turning the alternator pulley (no slippage/misrouting/etc.), then the mechanical tests are complete, and you'll need to continue testing the electrical performance of the charging system components.
(c) first component to test: battery
DIY test 1: remove battery from car and put battery on a 120VAC automotive battery charger and charge it fully (or just check it in the car with motor off, since the car's charging system is a type of automotive battery charger).
test parameter: a fully charged lead-acid automotive battery should read 12.45 volts on a VOM/DMM
DIY test 2: disassemble battery out of car after driving it to one of the auto parts chain stores (Advance/AutoZone/Pep Boys) for a free battery test. These testers will test the battery under load, which is not possible with just a DMM.
(d) if wiring is good, and battery tests good under load, then
the failed component is the alternator/voltage regulator - by process of elimination.
(e) DIY test 3: direct alternator/voltage regulator test (car must start and idle successfully to perform this test)
Start the car, and put a VOM/DMM across the terminals of the battery. Since the car is running, you'll be reading the output voltage of the alternator and not the output voltage of the battery. The acceptable ranges for alternator/voltage regulator output are:

ALTERNATOR CHARGING VOLTAGE

Most alternators that are charging properly should produce a voltage of about 13.8 to 14.2 volts at idle with the lights and accessories off. Always refer to the vehicle manufacturer's specifications. Many Asian vehicles, for example, have higher charging voltages of around 15 volts.

When the engine is first started, the charging voltage should rise quickly to about two volts above base battery voltage, then taper off, leveling out at the specified voltage.

The exact charging voltage will vary according to the battery's state of charge, the load on the vehicle's electrical system, and temperature. The lower the temperature the higher the charging voltage, and the higher the temperature the lower the charging voltage. The "normal" charging voltage on a typical application might be 13.9 to 15.1 volts at 77 degrees F. But at 20 degrees F. below zero, the charging voltage might be 14.9 to 15.8 volts. On a hot engine on a hot day, the normal charging voltage might drop to 13.5 to 14.3 volts.

Here are the full specs for installation of the 2002 Lexus RX300 alternator - you may be able to check these specs yourself (with a torque wrench), or pass them along to your mechanic.

Note: the VIN 8th digit should be "F" for the 2002 Lexus RX300 (2WD & AWD)

2002 Lexus RX300 (2WD and AWD) - 3.0L Engine, VIN "F" SFI DOHC

Alternator

Drive belt. Tension the belt to 170-180 lbs. for a new belt or 95-135 lbs. for a used belt.
Adjusting alternator lockbolt. Tighten the bolt to 13 ft.-lbs. (18 Nm).
Alternator pivot bolt. Tighten the bolt to 41 ft.-lbs. (56 Nm).

Glossary of acronyms
--------------------------------
DIY = do it yourself
DMM = Digital Multimeter
DOHC = Dual Overhead Cam
SFI = Sequential Fuel Injection
VOM = Volt Ohmmeter

References
----------------
How to test a Car Alternator - todayifoundout.com

Alternator & Charging System Checks - aa1car.com

Dec 26, 2011 | 2002 Lexus RX 300

5 Answers

I had a the battery light on what does it means


The battery light means your alternator is not charging, so if you continue to drive the vehicle your battery will eventually drain and the vehicle will stop.

You can test this by putting a volt meter across the battery posts. A fully charged battery should read 12.6 volts. Then start the engine and the voltage should increase to 13.5 to 15 volts. If you do not get this increase in voltage, then the alternator is not charging, which can be either the wiring to the alternator or the alternator itself being bad. Good luck :O)

Feb 25, 2011 | 2008 Chrysler Sebring Convertible

3 Answers

Battery wont charge changed alternator and battery still wont charge


fit a new reconditioned alternator and not one from a junkyard

Mar 30, 2010 | 1992 Ford F150 SuperCab

1 Answer

Starter, battery, or alter Promblems.


There seems to be a no charge state in this case. I recommend checking the charging system. use the procedure below to isolate this issue.

Wear protective eye wear and clothing and remove all jewelry when checking your battery and charging system. Jewelry is a good conductor of electricity and is not recommended. Most batteries wear out every 3 to 5 years and need to be replaced. Always replace your battery with an equal replacement battery to assure proper operation. Automotive batteries have a +positive terminal (red), - negative terminal (black). Electricity is stored in the battery and then supplied to the vehicle when the engine is not running. While the engine is running the vehicles alternator charges the battery for future use. (Note: never disconnect the battery while the engine is running. If the battery cable is disconnected from the battery a spark can be generated which can cause the battery to explode or a major electrical malfunction to occur.)

To check a battery surface voltage, remove the positive terminal protective cover. Connect the +positive side meter lead (red) to the positive side battery terminal. Connect the - negative (black) side meter lead to the negative battery terminal. With the vehicle not running and the car sitting over night the battery voltage should be between 12.5 and 12.8 volts.(You will need to use a voltmeter for this testing procedure)

The alternator is rotated by a drive belt driven by the vehicles engine while it is running. Electrical voltage and amperage are generated to recharge the battery and supply voltage to the electrical system of the car. The alternator is held in place with mounting bolts. There is a main electrical wire on the rear of the alternator that supplies voltage to a main voltage junction box. If your alternator is not charging properly, your battery will slowly drain down from operating all the electrical systems in your car and stop the car from running.(most non charge states will be the cause of a loose belt or a low tension rate, due to a mis-adjusted alternator. make sure you have enough tension in the belt for full rotation of the alt pulley)

Next, you will need to check the alternators output with the Amp meter.

Testing the amperage output of the alternator is good for measuring the amount (not the level) of voltage the alternator can produce. This test can be tricky because if the alternator is weak it can still show it as producing amperage. Which is good, but if the voltage is low, it will still allow the battery to go dead. To check the amperage output of an alternator an amp meter is needed. Once the meter is connected start the engine. Next turn on all electrical accessories and raise the engine idle to about 1200 RPM. The alternator should output the max amperage it was designed to produce. Example: a 90 amp alternator should output about 88 amps. Note: An alternator cannot sustain maximum output for long periods of time. If the alternator is forced to operate at maximum output it will overheat and fail. An alternator is designed to operate at max amperage output only for a reasonable amount of time.

((Connect the voltage meter lead the same way you would in a battery static voltage check, Start engine (do not drive) at engine idle the voltage should be between 13.6 to 14.3 volts. If not the alternator may need replacing.)))


Additionally, If the above inspections prove that the charging system, and battery are ok, This will lead to a battery drain issue.

Here is a procedure I use to isolate a battery drain. Remove the negative battery cable from the battery. Using a 12-volt test light, hook one end to the negative battery post the other end to the negative battery cable you just disconnected. The test light will glow or "light" if there is a drain. If the "light or glow" is faint, that is probably normal draw for the clock or computer. If the "light or glow" is bright, this will indicate a large drain is present. That should be corrected,asap. Now start removing and replacing the fuses one by one until the light goes out; The one fuse that causes the light to shut off, will be the circuit with the drain. Remember to close the car doors, when testing. If not, the interior doom light will interfere with the results of the test.

Dec 15, 2009 | 1995 Jeep Wrangler

2 Answers

How do I troubleshoot the charging system?


test battery and alternator battery may be loosing charge or alternator output enough to run vehicle but not enough to keep battery charged some auto stores such as auto zone/advanced auto can bench test both for free

Oct 30, 2009 | 1991 Toyota Corolla

1 Answer

Battery problem


Check the battery for a draw, if you know how to use a Ampere meter, put it inline and make sure all doors are closed, and if the car has a lamp under the hood disconnect it. With the Ammeter in line, you should see a reading on the meter.
If there is a reading, disconnect the amp power connector and the reading should drop. If it does, you may have to install a power relay to control the amplifiers to ensure they do not drain them in future.

The second possibility is that the power consumption of your amps is preventing the battery from charging completely. Especially if the battery has bad cells. It would be helpful to know what amprerage your alternator is putting out and what the amperage draw of your amps are while in use.
Of course if demand is higher than supply then the battery will have difficulty keeping up.

One quick check is to check battery voltage with a meter, start the car, check the voltage is it around 13 volts and increasing, turn on the amps, again check the voltage, is it still increasing or decreasing. Rev the car up a few rpm's If it is decreasing then you are taxing the charging system.
Replace the battery and try these tests again.

Hope this is of some help.
Ed

Apr 20, 2009 | 1995 BMW 5 Series

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