today I'm going to show you how to use a multimeter to test the battery on your car to see if it's bad Some symptoms that you could have with a bad battery or a bad alternator Is that your battery light is on the dash the engines cranking slowly or not cranking at all there's clicking when you turn the engine on But the engine doesn't start so just clicks the battery seems weak or is it dead the interior lights or a [headlights] seem weak?
And stuff like that these symptoms could be a bad battery or alternator this video right [now] is going to focus on the bad battery aspect of it to See the alternator tests . [one] of the first ways you could tell if your battery's going bad is you put your key in the ignition you [turn] it to the run position and you can see Right there is the battery light That lets you know that the battery light is working most cars test the voltage of the battery through the battery light
So if that blows out you won't be able to tell if your [battery's] bad or not and a lot of times I could trigger Another light like a check gauges light so what should happen is when you start the car. It'll shut off if it shuts off Then your battery is good to test the battery
what you want to do first is you [want] to turn the headlights on for about? two minutes this will get rid of any surface charge the battery may have as We wait what you want to do is you want to turn on your voltmeter and right now? I have [it] set to Ohms you want to set it to 20 volts or something above fifteen volts So 20 is what my voltmeter has and that's ready to go two minutes later We're going to shut the lights off and make our way over to the battery This is our positive lead, and this is our negative lead our negative is our ground now
I'm going to connect our red to our red and our black to our black and you can see the voltage goes to twelve point eight five you want to have around twelve point six volts So this is good now Just because this is a good voltage doesn't mean your battery's good the battery could be holding a charge but doesn't have the cold cranking Amps to start the car.
That's what we're going to test [right] now So I'm going to go start the car with these attached and this shouldn't drop below ten if this drops below ten then we have a battery problem You can see it dropped down, and then it popped back up, and now it's at 14. That's because the alternator is charging the battery Now you saw this drop down to about [ten] [ten] and a half and rose right back up, so that's good This battery checks out has enough cranking amps and the cells are good and I knew this this battery is good
I'm just showing you as a test of what should happen if this drops down below ten then your battery starting to go Below five your battery's garbage You need a new battery cold cranking amps CCA is the measurement of how many amps a battery can deliver? at zero degrees Fahrenheit for 30 seconds and not drop below Seven point two [Volts] batteries are supposed to last about four years
And that's what most of them are warrantied to but only 30% of the batteries that are sold today reach that four year mark Now if you are having problems with your battery and this doesn't solve it you also want to see to make sure your connections here Aren't corroded you can see here There's a little bit of corrosion But nothing bad what you might want to do is get some sandpaper some WD-40 [sand] it up if there's corrosion on here You see like this blue green crystal and stuff you want to make sure you use goggles and gloves [plus] that stuff is corrosive
it Could hurt your hands and it could hurt your eyes you can see that these terminals are actually pretty clean Obviously, I told you I had no problem with this car But let's check out a battery at bad terminals that are dirty So here's a good [example] of what I was talking about and if that happens you want to clean off [your] battery terminals Really good. So I have a piece of sandpaper, and that'll do the trick.
[you] just loosen this up Once you get all that dirt [and] everything out of here just sand the post down So you can see I clean the post off pretty good Clean the inside of this very good, so they attach Slide that back on [I'll] tighten this completely with a ratchet [you] [know] the battery terminal is done as well that looks good So I'm going to tighten them up, and then we'll take a reading now I know this battery is going to be low, but this will give you an idea of a bad battery Two volts that's bad this battery is garbage.
It's six years old, and it can't even hold the charge anymore I charged the battery last night to twelve point six volts and now it's two volts I kept the terminals Disconnected to make sure there wasn't any draw from the car So that's an [example] of what a bad battery looks like one more thing after you done cleaning off the posts hit it with some WD-40 and That will prevent it from rusting and getting corroded again. So we're going to look at one more battery.
This is my truck battery this batterys [six] years old and you can see it's perfect twelve point Seven volts So I ran the headlights for about two minutes now, we're going to see what happens when we [started] up This [battery's] running really [strong]. You saw it dropped down to 11 volts when I was starting it and The alternator is running well, and it's going a fourteen point two five volts running that is excellent So you saw two good batteries and one bad battery the one bad battery won't even be [able] to start a car These batteries that I showed you in this video are all maintenance-free batteries
They don't need any water if you have battery that needs water you'll see they'll have caps up here And you want to make sure that they're not filled to the top of the cap But there are a quarter of an inch over the Electro the metal piece that's inside there And if you need to fill it fill it with bottled water or distilled water so you don't have any extra minerals or anything That's in your water getting into the lead acid battery The other thing you should remember is that you could take your [car] to a major part store And they'll test your battery for free.
And stuff like that these symptoms could be a bad battery or alternator this video right [now] is going to focus on the bad battery aspect of it to See the alternator tests . [one] of the first ways you could tell if your battery's going bad is you put your key in the ignition you [turn] it to the run position and you can see Right there is the battery light That lets you know that the battery light is working most cars test the voltage of the battery through the battery light
So if that blows out you won't be able to tell if your [battery's] bad or not and a lot of times I could trigger Another light like a check gauges light so what should happen is when you start the car. It'll shut off if it shuts off Then your battery is good to test the battery
what you want to do first is you [want] to turn the headlights on for about? two minutes this will get rid of any surface charge the battery may have as We wait what you want to do is you want to turn on your voltmeter and right now? I have [it] set to Ohms you want to set it to 20 volts or something above fifteen volts So 20 is what my voltmeter has and that's ready to go two minutes later We're going to shut the lights off and make our way over to the battery This is our positive lead, and this is our negative lead our negative is our ground now
I'm going to connect our red to our red and our black to our black and you can see the voltage goes to twelve point eight five you want to have around twelve point six volts So this is good now Just because this is a good voltage doesn't mean your battery's good the battery could be holding a charge but doesn't have the cold cranking Amps to start the car.
That's what we're going to test [right] now So I'm going to go start the car with these attached and this shouldn't drop below ten if this drops below ten then we have a battery problem You can see it dropped down, and then it popped back up, and now it's at 14. That's because the alternator is charging the battery Now you saw this drop down to about [ten] [ten] and a half and rose right back up, so that's good This battery checks out has enough cranking amps and the cells are good and I knew this this battery is good
I'm just showing you as a test of what should happen if this drops down below ten then your battery starting to go Below five your battery's garbage You need a new battery cold cranking amps CCA is the measurement of how many amps a battery can deliver? at zero degrees Fahrenheit for 30 seconds and not drop below Seven point two [Volts] batteries are supposed to last about four years
And that's what most of them are warrantied to but only 30% of the batteries that are sold today reach that four year mark Now if you are having problems with your battery and this doesn't solve it you also want to see to make sure your connections here Aren't corroded you can see here There's a little bit of corrosion But nothing bad what you might want to do is get some sandpaper some WD-40 [sand] it up if there's corrosion on here You see like this blue green crystal and stuff you want to make sure you use goggles and gloves [plus] that stuff is corrosive
it Could hurt your hands and it could hurt your eyes you can see that these terminals are actually pretty clean Obviously, I told you I had no problem with this car But let's check out a battery at bad terminals that are dirty So here's a good [example] of what I was talking about and if that happens you want to clean off [your] battery terminals Really good. So I have a piece of sandpaper, and that'll do the trick.
[you] just loosen this up Once you get all that dirt [and] everything out of here just sand the post down So you can see I clean the post off pretty good Clean the inside of this very good, so they attach Slide that back on [I'll] tighten this completely with a ratchet [you] [know] the battery terminal is done as well that looks good So I'm going to tighten them up, and then we'll take a reading now I know this battery is going to be low, but this will give you an idea of a bad battery Two volts that's bad this battery is garbage.
It's six years old, and it can't even hold the charge anymore I charged the battery last night to twelve point six volts and now it's two volts I kept the terminals Disconnected to make sure there wasn't any draw from the car So that's an [example] of what a bad battery looks like one more thing after you done cleaning off the posts hit it with some WD-40 and That will prevent it from rusting and getting corroded again. So we're going to look at one more battery.
This is my truck battery this batterys [six] years old and you can see it's perfect twelve point Seven volts So I ran the headlights for about two minutes now, we're going to see what happens when we [started] up This [battery's] running really [strong]. You saw it dropped down to 11 volts when I was starting it and The alternator is running well, and it's going a fourteen point two five volts running that is excellent So you saw two good batteries and one bad battery the one bad battery won't even be [able] to start a car These batteries that I showed you in this video are all maintenance-free batteries
They don't need any water if you have battery that needs water you'll see they'll have caps up here And you want to make sure that they're not filled to the top of the cap But there are a quarter of an inch over the Electro the metal piece that's inside there And if you need to fill it fill it with bottled water or distilled water so you don't have any extra minerals or anything That's in your water getting into the lead acid battery The other thing you should remember is that you could take your [car] to a major part store And they'll test your battery for free.