How to Test a Car Battery with a Multimeter
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- Опубликовано: 12 июл 2024
- In this Steve's Garage video I show you a couple simple things you can do with a multimeter to test the health of your car battery and alternator.
I outline how to test 3 basic car battery details:
1. Resting charge or voltage - This is the reading you get with your car off. Your car battery should hold a base level charge.
2. Cranking voltage - This is the reading while you crank you engine. This value is especially important during the winter. The battery needs a lot of juice to crank the engine over in the cold. A weak battery is what will give you a slow or no crank condition.
3. Voltage with the car running - This value shows the health of your alternator more than anything else. The alternator should be charging your battery while your car is running.
These are very simple tests that can be done with any multimeter as long as it has a DC Volt option. These tests can be important when you're trying to diagnose a problem with your car battery or charging system. It can also be a helpful check to perform before winter hits to make sure your car battery is healthy, and you don't get caught with a dead battery.
If you'd like to purchase the multimeter I'm using in the video, check out my Amazon Affiliate link! It won't cost you any extra and I'll earn a small commission from your purchase
Klein Tools MM300 - amzn.to/49c6bZy
If you have any questions leave them below, I try to help everyone. As always, please be careful working on your car! Any damage to you or the car is not my responsibility.
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Chapters:
0:00 - Intro
0:14 - What You'll Need To Test Your Car Battery
0:30 - Visual Car Battery Check and Age
1:04 - How To Test Resting Voltage of a Car Battery
1:29 - How To Test Crank Voltage of a Car Battery
2:03 - How To Test if Alternator is Charging Car Battery
2:22 - Battery Load Testing
2:35 - Outro 
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A very decent video to allow an interested person with a multimeter to see if their battery is ready for the winter season. Thanks
That's the idea! Glad you liked it.
Thanks...super concise...saved me time and money. It was the battery...
Glad it helped! It's always nice to make a proper diagnosis instead of throwing parts at it and wasting money.
Dude, perfect, and i learned about the expiry dates, thanks!
Very straightforward video!
Thanks for sharing 👍🏾
Thanks for watching and commenting!
So concise and useful, thanks bro
You got it! Glad you liked it and thanks for the comment!
Looks like I'm going to have to pick myself up a Multimeter! Especially since winter is right around the corner here in Michigan.❄️
They're handy to have for the car or around the house. You can get one with a little kit that has an outlet tester an no-contact voltage tester. Of course those things are for a house and not a car, but they've come in handy for me and my old house.
Awesome vid man, really helpful
Thank you!
Nice and short. To the point. Thanks!
Thats the goal! Thanks for watching and commenting.
Very helpful, thank you!
You got it! Glad it helped.
Thank you for your help
You're welcome! Thanks for the comment.
Some multi-meters also have a high\low reading function, so when you're cranking the car you dont habe to be looking at the meter, it will store the readings for you.
Hope that helps.
Good work. I like your logo, it's got a cool retro style.
Thank you! It's inspired from the BBS logo 😉
amazing video
Thank you!
Nice1..Stevie * thank u
You're welcome!
Thanks. My wife's car is having issues...I'm hoping it's the battery as replacing the alternator is a pain in the butt!😀
I can't think of a car that's easier to replace the alternator than the battery, so I'll have to agree!
@@StevesGarage99-03 chrysler 300m, Dodge intrepid, Sebring.
@@tylercollins8499I've never owned or worked on one. Do they have the battery under a seat or something silly like that?
Could be worse could be the pcm/ FCM 😂 always can get be worse when it comes to electrical
@@LouiesWorld43 Always have to start simple with electrical. Rule out the easy stuff before jumping to major failures!
Steve great job 👏 I'm the kinda guy that buys tools but don't always know how to use em 😅😂
Thanks for the comment, glad I could help!
Also i think some cars have intelligent charging, eg the ECU can measure the load and voltage and then control the alternator to adjust accordingly.
The battery typically needs about 13.8V to trickle charge but can to around 14.?? Volts
I would start the car and take the reading with some loading on light lights and heater then check alternator output voltage.
I have a 1997 C-280 Benz l bought in 2009, it is now 26 years old and l have never changed the battery, not sure if it's original but I've had the car 14 years.
Probably because the battery is in the trunk protected by weather, so far its still working.
I don't think being in the trunk makes a difference, I've replaced trunk batteries before. Do you live in a climate that has less extreme temperature swings than most places?
this is truly an extraordinarily story.
Hi. I was told by a Mechanic the voltage on a battery when measuring via a multimeter is supposed to be about 11-14 volts. At that time I had an accord with a dead battery and I had to rush immediately to a tech because my power ended up running from the alternator entirely instead. Can you clarify the range and also if its common as to what happened to me with my car?
If the car is running it shouldn't be below 12 volts, as that would mean your alternator is not charging the battery. As far as the upper range of 14v, the alternator is charging the battery while the car is running. The exact reading depends on engine speed and number of things drawing power from the system. I'm assuming your alternator was fine and your battery was just old and not holding a charge?
I guess since you didn’t do a load test is why you never explained it. Whether the old carbon pile type or the current computerized style your looking to introduce a load half the cold cranking amps for a determined period of time, 15 secs usually. The computer ones do it faster. You don’t was to see the voltage go below 9.6 volts. I have no real determination of test time with using a voltmeter but if you hook up the meter and turn your headlights on and the voltage goes below that 9.6 volts quickly then the battery is no good.
Yea, I didn't get into it since it's so easy to get it load tested at a store. Your explanation is perfect though, you can put a load onto the battery yourself and get a pretty good idea of how it reacts.
The car I was testing was reading around 12.3v, I started the car and it was still reading about the same voltage. But as soon as I turned headlights on, it started to read 14 ish volts. I feel this is not Normal right?
What kind of car do you have?
This video doesn't cover the behavior of variable voltage or "smart" alternators. Those style alternators can behave like you described.
My multimeter doesn’t show 20v under the DC.
It shows 4000m, 40, 400, 600.
40 should work fine. You just don't want to use anything less than what you'll be measuring.
@@StevesGarage thanks. Battery was so dead. Was ready at 4 volts! No cold crank amps either.
@@americandude3825 Oh wow, definitely time for a replacement!
So anything under 13 voltage while car is running get a new battery or charge it ....
Not necessarily. If it's running and below 13 volts it could be a battery not holding a charge, or your alternator not charging the battery.
One way to test is with your battery fully charged and the car off, turn the headlights on for a minute. Then turn them off and check the battery. It should still be above 12 volts. If not, chances are your battery is shot.
You can also have parts stores test the battery, and they'll even bench test alternators if you can get it out of your car.
I have The same multimeter, you can also turn it to the bottom right where it says BATT (battery) 1.5 v Show same numbers. Before and after turning over the engine
It's showing in the 14s when I turned over the engine. Was in the 12s before but every third start the car struggles to turn over Like I put it on the charger Overnight till it turns, green starts right up to go to work starts right up 8 hours later when I leave work but if I stop anywhere. I have to sit there as it goes Agha. Ag uga ago gaaga for like 15 seconds before it actually turns over. So based on the numbers, the alternator is charging the battery.
But somehow the battery isn't holding a charge ... wierd!!!!
Just tested a theory. Same thing even happens when you turn it over 3 times back-to-back to back the third time. It struggles to turn over. Turn it on, turn it off fine. Turn it on second time. It struggles, turn it off, turn on the third time. It almost doesn't turn over , but still shows same numbers before and after all , three turn overs 12s then 14s 11 months old. Guess I just got a dud battery Unless It's the computer 2004. Honda Accord got a lot of electrical on it. I'll try going to O'reilly and getting a new battery cheapest fixed. I can see just a pain not being able to go anywhere other than work home work home without being afraid. It might not start
@@JNicholsKnows Good to know about the BATT setting, thank you!
As for the car starting - If it was slow on the 3rd start in quick succession I'd say the battery was just getting drained from starting and not charged up from running. But interesting that it happens every 3rd time. Is the battery old and needs to be replaced? Is it possible it's a different problem entirely? Maybe a fuel or air issue?
@StevesGarage I'm new to working on my own vehicles just tired of paying other people. The outrageous fee for labor and the parts themselves are so cheap. Comparably. I just ordered a code scanner and battery load. Testershould be here in a couple of days. Based on videos I've seen. And things I've read online. It's either a cell in the battery. That's gone bad or it's the starter.
The batteries only 11 months old. But I did Leave the car in the garage without starting it for about 2 and a 1/2 months through the heavy winter.
Without turning over the engine.
Out of sight out of mind that was my bad Use the multimeter to test the alternator and it was showing fine
Battery load tester only shows 118 of 580 cold cranking amps I guess it is the battery weird, though that it's still showing the 12.4 to 12.6 V. Then we turn it over jumps to 14. Something just like a real or good battery.
How about telling us where to plug in the leads?
Black is always plugged into black. Red has the option of amp, or volt/ohm. Since we're measuring volts for this test, plug it into the one labeled with the V and ohm icons. You can see in the video that my lead is plugged into that port, and the A port is open.
how to check CCA?
You won't get a specific reading from a multimeter for CCA. The best way to do it is to pull the fuel fuse so the car won't start, and crank it for a bit. If it doesn't drop below 10V while cranking, your battery is probably fine. That being said, temperature will cause that number to vary. So if you did this test while warm, you might get a different result than when it's really cold.
Your finger was in the way of seeing things you were pointing out--like the ac and dc.
DC Volts is a V with a dotted line, AC Volts is a V with a curved line.
ok
Alright
This guy know just enough to be dangerous I would take advice from him on how to repair a bird house 🙄
Want to share some advice? I love learning.
I remember when batteries lasted 10 years 😑
I guess I'm too young to remember that!
Now you done it! Jinxed me that is . My battery is 9 years old this September, date in service when I bought my truck.
@@buffystclair9042 Wow, that's impressive! I've never had a battery last me that long. Sorry for jinxing you! 😆
Seriously? Battery connections were wrong... You CAN load test a battery with a voltmeter. Dude - so wrong.
How are the connections wrong? As far as a load test, cranking/starting the car with a multimeter connected is sort of like a load test, but you're relying on capturing a split second reading from a multimeter display. The better way to load test is hooking up a load tester. They will give you a better reading of how the battery is handling a constant load.
@@StevesGarage The meter leads must be on the battery POSTS - not the terminals. Corrosion between them will cause a flawed reading. Auto part stores sell batteries misusing their load tester by failing to isolate the battery. Your test would fail if the terminals were corroded. It would erroneously show a failed battery. Voltage drops add up.
@@bivideo7 You're right about reading from the posts and not the terminals. I was working by myself shooting this video which is why I stuck them between the terminal and the post. I'll have to get someone to help me next time!
Fancy multimeters can set to capture high and low voltage for your crank test of the voltage?
@@tedlahm5740 MIN/MAX setting
A parasitic test can also be done with a multimeter.
It can! And it's an important test if the battery health is good and you're having problems with it holding a charge. Maybe I'll make a video for that test as well.
Very helpful! If the battery cable has some corrosion where it attaches but I touch the probes on the top of each post like you did, would the reading still be correct?
Yea that should work fine. But definitely clean up that corrosion and use some dielectric grease when you put it back together!