How To Check Alternator Without Meter
Auto alternators provide the electrical energy needed to run all of the electronics and power circuits of your vehicle. It also charges upward the battery to total capacity ready for the next fourth dimension your start the car.
The automobile alternator is a uncomplicated device made up of heavy-duty bearings, electrical copper windings, charging circuits, diodes, and a ready of carbon brushes. Over time the bearings and or brushes can clothing and fail to crusade the charging circuit to non work properly.
In this mail service, we will go over how to test your car alternator both in the vehicle and out of the vehicle to see if information technology is outputting the right voltage.
Tabular array of Contents
- 1 How to test alternator with a multimeter
- ane.one Alternator output voltage
- ane.two Car onboard diagnostics.
- 1.3 How long tin you lot drive with the alternator light on
- ane.4 The battery light is on but the alternator is charging problem.
- 2 How to test the alternator out of the car
- iii How to test alternator without a multimeter
- 3.1 How to exam alternator with a screwdriver
- 4 How Do I Know If I Have A Variable Voltage (Smart) Alternator?
- five Alternator Ofttimes asked questions.
- 5.1 Why exercise auto alternators fail?
- 5.2 Can a auto run without an alternator?
- v.3 Can you jumpstart a automobile with a bad alternator?
- 5.4 Do motorcycles take alternators?
- 6 Alternator replacement cost
- 6.1 Serpentine chugalug noise
- half dozen.ii Alternator belt tension fob
- 7 Conclusion
How to examination alternator with a multimeter
With the vehicle turned off take your favorite multimeter and select DC voltage. Identify the exam probes onto the bombardment terminals and measure the battery voltage. It should read around 12 to 12.7 volts depending on the charge level of the battery.
Any voltage below 12v so yous have a discharged bombardment and it should either be recharged or replaced if it is over 4 years old.
Once you have your base battery voltage start the vehicle and wait 30 seconds for the engine to idle smoothly. Take your multimeter and select DC voltage and mensurate across the battery terminals again.
Alternator output voltage
A good quality car alternator should output between 13.5v and 15v depending on the model and load on the alternator. Anything less than thirteen-volts and you will have a failed alternator. Information technology should also be a smooth voltage and not fluctuate or bound between say 12v and 13.five volts every few seconds.
Equally you lot can see the alternator output voltage on a 2003 Ford Focus is 14.34 volts. This is a good voltage output from the alternator. It will temporally dip downwardly to 12v when a high load kicks in such as the air-conditioner. An inconsistent voltage unremarkably means the carbon brushes are failing on the alternator.
Some smart alternators will actually lower the voltage/electric current to a fully charged bombardment.
Automobile onboard diagnostics.
Oftentimes when the vehicle alternator is failing yous will get an engine, battery, or electric check lite on the dash. The car's onboard diagnostics is testing the output voltage of the alternator and if it dips below a pre-divers voltage so the engine battery cheque light will come on.
You will need an OBD2 tester to further diagnose the problem as information technology could exist ane of 100+ general faults. I utilize a Bluetooth OBD2 tester for my Yamaha Motorcycles which also works on all my cars also. A very handy piece of hardware that is very inexpensive.
How long can you drive with the alternator low-cal on
This will be determined past a number of factors such as bombardment capacity size, battery accuse country, and electrical load on the battery.
To get the best mileage if your alternator has merely failed turn off all non-essential electronics. This means radio, air conditioning, and driving lights if it is daylight.
You should be able to drive around 50 miles with the alternator light on. this is with a total chapters battery. Older cars say 25 years+ old may run longer as they have fewer electronics in them such as no fuel injection.
The bombardment light is on just the alternator is charging problem.
This could be an indication the bombardment is not accepting the charge. If the battery voltage drops nether 12v then the battery has failed or is depleted. I like to supervene upon my vehicle batteries after four years of service life as they become unreliable afterward this.
If the bombardment light is on but the alternator is charging then the problem could still be at the alternator. If the alternator is over 190k miles old or 300,000km I would become it replaced as it is getting close to mean time before failure.
My Toyota highlander alternator was replaced at 200,000 miles and was withal going strong but preventative maintenance is the best.
How to test the alternator out of the car
There are a number of reasons you may need to test the alternator out of the car such as a reconditioned function, rebuilding the engine, scrapyard notice, or but existence curious.
Make certain to clamp the alternator to the demote deeply.
Locate the positive terminal and make clean up the commodities post with a fine bit of emery paper. Place the alternator in a vice and make sure information technology is clamped securely. Spin information technology past hand to make sure it moves freely. As the frame of the alternator is the negative ground clean up a spot to place the negative of the multimeter on to.
The simply style to exam an alternator charging correctly is to use another 12v machine bombardment. Connect the car battery up to the alternator and get a small 12v globe and connect it to earth and to the lamp concluding shown in the flick above. The lamp will plow off when the alternator is charging the battery. The lamp will plow on then the alternator slows down or stops.
Now find a socket the same size every bit the flywheel bolt and adhere it to a battery drill. On my Toyota Highlander/Kluger 130A alternator I used a 10mm socket fastened to a one/4 inch drive extension slice. This is what we will use to spin upwardly the alternator fast.
At present get someone to help you lot as yous spin upwardly the alternator. You should have the drill at its fastest speed to measure out the voltage betwixt the positive and negative of the housing. It should be between 13.5v and xv volts. Make sure to use the fastest drill speed possible.
This is one of the best ways how to bench test an alternator off the car. The video below explains information technology well.
How to examination alternator without a multimeter
There are a couple of bush-league mechanics ways to examination if the alternator has failed without a multimeter.
Start the car and look at the battery voltage on the nuance display if it has one. Then rev the engine to effectually 3000 RPM and plough on all the accessories such as airconditioning, radio, and lights. Check the bombardment voltage in the nuance to come across if it is the same, increases, or decreases in voltage.
If information technology decreases below 13v you lot have a faulty alternator and must have it replaced.
Another style is to utilise a cheap iii-48V excursion tester. These can bank check for 12v power and equally it is digital it volition give your the exact voltage as the alternator kicks in to accuse the machine battery. They are small enough to keep in the car glove box and come in handy to find electrical faults.
1 end gets clamped onto the metal frame or negative battery concluding and the other tin be used to detect voltage. I like that it has a sharp signal so that you can push it into the insulation to access the copper wires underneath.
How to test alternator with a screwdriver
The screwdriver exam is a quick test to meet if the alternator is making an internal magnetic field. This won't test for the correct output but will only test that the internal windings are not shorted out or broken.
Find a long thick metal screwdriver and place it near the copper windings on the non-drive terminate of the alternator. It works amend with a screwdriver that is magnetized.
With the vehicle off you lot will non feel any magnetic field or a pulling sensation on the screwdriver. With the car turned on and running practise the same test but this fourth dimension you lot should feel a slight magnetic force pull the screwdriver into the windings.
Be careful as there are a lot of moving parts and belts effectually this area.
How Do I Know If I Have A Variable Voltage (Smart) Alternator?
Variable Voltage Alternators are at present becoming a standard issue in most modernistic vehicles. These only run or output a large voltage over 13v when the power demand becomes large. Another name for a smart alternator is called Computer Controlled Alternators.
Variable voltage alternators reduce the load put onto the engine by only operating when required to charge the battery or a large load is applied like the loftier beam headlights, electric heaters, and the sound organization. They assist to reduce the emissions of vehicles to pass strict laws in many countries.
Smart alternators require battery sensing technology to decide the load coming from the battery. This is done past a battery sensor which is establish on i of the battery terminals often it is on the battery negative connection point.
To examination a smart alternator commencement the car and turn off all of the electronics such as light, radio, and heaters. Use a multimeter to test the battery voltage. It should be under 13v if the battery is total or close to 100% charged.
At present plow on all of the electric systems of the vehicle such as headlights, sound system, heaters, and internal lights, and test the bombardment over again. The output of the alternator should now be over 13.5v with a proper functioning smart alternator.
You can too remove the small-signal wire from the negative final. This will trick the vehicle estimator that the battery needs charging to always output over 13v to 14v.
Alternator Frequently asked questions.
Why do car alternators fail?
As a motorcar alternator uses carbon brushes these volition article of clothing out over fourth dimension. Alternators as well have metal bearings that are nether a side load due to the serpentine belt. These can neglect if the belt tension is likewise tight.
The flick above shows the carbon brushes from a 2005 Toyota Highlander/Kluger alternator. These only had well-nigh 1mm of carbon brush left earlier they would have failed. The car had been driven for 300,000km on the original alternator.
They are easy to replace merely remove the back black plastic cover and remove the iii screws holding the carbon brush cake in place.
The alternator electric excursion has a full-wave bridge rectifier inside to convert the AC voltage to a DC voltage. Sometimes these diodes fail but it is rare.
Can a auto run without an alternator?
Aye but not for very long. Often part of the alternator circuit is a range of belts and pullies. Sometimes these belts run other car items such as water pumps, air conditioning, and power steering. If you are fully removing the alternator and wanting to start the car make sure these other items or non going to be affected.
Equally mentioned earlier you may only go effectually 50 miles of car run miles before the vehicle volition run out of battery power due to non having a working alternator.
Tin can you jumpstart a car with a bad alternator?
Yes, you can bound-start a car with a bad alternator but if the car won't get-go with its own battery and so it won't travel very far because the battery is already depleted. You may merely get a few extra miles before the voltage in the battery is so low the fuel pump fails along with the fuel pump injectors or the onboard engine direction circuit.
I tin recommend any of these wireless bound starters for your vehicles.
Do motorcycles have alternators?
Yes, they do only the alternator of a motorcycle is more commonly chosen the "stator." It is oftentimes located on the opposite side of the clutch plates and includes a stator and rectifier/regulator circuits.
Testing of the motorcycle stator will exist the same procedure as the car alternator battery voltage examination. Any voltage between 13.5v and 15v with the motorcycle engine running means the starter is good.
Alternator replacement cost
Depending on the make and model of the vehicle a new alternator replacement price volition be between $400-$1000 for just the part. Mechanical labor costs will usually exist another $200 on superlative due to a few hours of labor.
Yous can save this labor cost by changing out the alternator yourself as this is non a difficult job. Just make sure to gear up the tension correctly of the alternator belt otherwise it will bleat and or slip.
I too like to replace the alternator chugalug also chosen the serpentine belt if I replace the alternator.
Serpentine belt dissonance
Sometimes when the serpentine belt gets erstwhile and worn it can start to slip. This causes a bleat that may or not go abroad as the belt heats upwards. This indicates either an over-tightened or slack serpentine chugalug.
With the automobile engine off use your fingers to cheque if there are whatever cracks in the alternator belt. If you find lots of cracks in the ribs or there are chunks missing it is time to replace the serpentine belt.
If it is slipping due to just existence slightly worn you can tighten the chugalug slightly so the belt noise will go away. Virtually adjustments will be done via the alternator adjustment screw check your workshop manual for the verbal instructions for the model of your motorcar.
Alternator chugalug tension play a joke on
To gear up the correct tension on a serpentine chugalug that has a manual adjustment spiral tighten the belt until you lot can simply turn it 90deg on the longest belt run.
Only use your fingers to turn the chugalug from horizontal to vertical. The quick video below explains information technology well. It'southward a handy tip.
Conclusion
Alternators are a deadening vesture part on your vehicle and should be replaced according to the service schedule. I have seen alternators reach over 250,000 miles with no trouble with older model Fords, Toyotas, and GMC cars.
Sometimes you tin can just replace the brushes and get another 200k miles out of the alternator. Although you run a risk the bearings failing over fourth dimension.
I like to supplant alternators every 200k miles merely to be on the safe side. Zippo worse than breaking downwardly in the heart of nowhere considering yous have run out of bombardment power due to a faulty alternator.
Almost cars may take 20 years to go to these loftier milages where the alternators demand replacing. But if y'all are pulling a large current out of your battery like running spotlights or car fridges the alternator life may be less.
A discussion of warning delight don't buy the cheap eBay alternators from communist china as many don't last as long as proper aftermarket OEM parts. In my research, over the years I have found that the alternator carbon brushes are much shorter and the bearings smaller. In that location is a reason why they are so cheap and will fail just over 100,000 miles.
A bad alternator will not charge the bombardment and is one of our meridian sixteen reasons a motorcar turns over but won't start.
I am a qualified Industrial Electrician for the by 20 years and I love to share my knowledge on dwelling house repair jobs.
I honey fast toys like Motorcycles, Cars, Jetskis, and Boats then writing well-nigh them is like shooting fish in a barrel.
To keeps costs downwardly I do all my own mods, repairs, and servicing. These skills I want to share with everyone. DIY is a skill everyone tin can acquire.
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