How to Test and Replace a Bad Car Battery (COMPLETE Ultimate Guide)

hey guys chris fix here and today i'm going to show you how to properly diagnose and replace a bad battery in your car or truck now notice i say diagnose first because it's very important to figure out why your battery went dead is it because the battery itself is bad or do you have another problem in the car causing a draw so i'm going to show you how to test your alternator how to test for parasitic draw how to properly clean your terminals to make sure there's a perfect electrical connection that way you know if your battery is bad or if it's something else now if you do have a bad battery don't worry replacing a battery is super simple i know most of you guys could probably do it with your eyes closed even if you're a pro at replacing batteries this video will hopefully teach you something new with all the tips and tricks i have for example when you go to buy a battery like in this case you can see we have a silver we have a gold we have a platinum there's different tiers of battery which battery is right for you can you buy the least expensive battery or do you need to buy the most expensive battery i'm going to talk about the different tiers and which one is right for you another cool thing that i did that i really like is i cut open an old battery that is bad and never do this at home the battery acid is not safe but the acid has been removed and i'm going to teach you how a battery works this is going to be really cool to see because you normally don't get to see this and you can see right there is a bad cell and i'm gonna teach you what causes a battery to go bad from vibrations from heat from discharging it too much that way with that information you could prevent that from happening to your battery and then finally once we go to replace the battery i'm going to show you how to do it in a way that doesn't disconnect the 12 volts from your car so your car's computer doesn't reset the clock doesn't reset you don't lose your radio stations you don't lose any presets it's actually a really nifty thing to do that way you don't lose that 12 volt connection which basically resets your car and i do want to thank advanced auto parts very much for supporting the video and sending me out these brand new die hard batteries that way i could teach you guys the proper way to replace a battery i'll be sure to link all these tools and products in the description so you can easily find them and with that let's go get started so real quick i'm going to begin by showing you what happens when we go to start the cars with the flat batteries we'll start here with susan our previously vandalized car okay let's hit the start button and it tries to start it turns over a little bit let's try that again and yeah this battery is so weak it won't start not even close and this is a pretty new car so what's the problem next up we have the drift sting which unfortunately hasn't been used too much because it's been a cold winter so let's go start her up make sure the car is in neutral clutch in try it again and he could hear it click so this battery is dead as well and finally let me show you what it's like to start my duramax diesel with two batteries sometimes she starts up and sometimes she really struggles now with a diesel turn the key to the run position and wait for that yellow wait light on the dash to shut off and that's for the glow plugs try it again and my daily is dead as well so all three of these cars barely turn over they click when you try to start them what's the next step well the next step is to locate the battery in most cars the battery is located under the hood in the front you can see this one right here but in some cars like this bmw the battery is actually located in the trunk usually in the back corner to help with weight distribution so we have the battery right there and same thing with the maserati if we check out the trunk you could lift up this little access port and you can see the battery is located right there if you can't find your battery just check your owner's manual it'll let you know where it is now once you locate your battery before you grab any tools there's two quick things that we could test out the first thing is to make sure these terminal connectors are nice and tight give them a wiggle that's not budging give this a nice wiggle see if it lifts up and that's not budging either if your connectors move at all make sure you tighten it up and that could solve your issue even just a little bit of looseness here could cause the electricity not to flow properly and that could cause your car not to start the next thing to look for is to make sure your terminals are clean and corrosion free you should see no corrosion on them and they shouldn't look dirty these look nice and clean that's exactly what you want if you do see corrosion or dirt it's important that you clean it so let me show you how so the dirtiest terminals i could find are on my pickup truck and they're not really dirty because they are corroded but they're more dirty because i go off-roading get mud everywhere but this is still a good example on how to clean them so let me show you how to clean the battery terminal so you have a perfect connection first get your safety glasses on then grab a little bit of warm water and some baking soda and make a little slurry so that we can neutralize any acid that might be on the post then just brush down the post in the surrounding area and see that bubbling right there that's a little bit of acid being neutralized if that sat there over time it could cause corrosion and it could lead to a bad connection and that's why we use the baking soda to clean our posts next loosen up the connection so we can remove it and tuck it away against the plastic of the battery don't let it hit any bare metal now with all the acid removed around the terminal and it's relatively clean we want to sand it down to get a fresh surface to get a good connection so you could use 180 grit sandpaper you could use one of these abrasive pads or you could use a metal wire brush so brush the terminal to reveal fresh metal and also brush the wire end on the outside but more importantly clean the inside where it makes contact with the battery beautiful so with the inside of the terminal and cleaned and our terminal cleaned we have a nice fresh surface so we have a good electrical connection one thing that i like to do ever since i got my drift car this came with the drift car these little felt terminal protectors i didn't think anything of them but they actually work really well to help prevent corrosion and also it makes it really easy to see which side's deposited the battery which side's the negative because they're color-coded plus it comes with the silicone that we're gonna need to make it waterproof and corrosion free inexpensive to buy highly suggest it it just makes the install that much better and these felt pads have a chemical in them to help neutralize any acid that might come out or vent out that way it reduces corrosion so let's reconnect our wires and be sure to push it all the way down and then tighten it down so it's snug but don't over tighten it and give it a wiggle to make sure it doesn't move and the last thing to do is get the packet of silicone grease and get some on the terminal end and coat the entire metal surface the silicone grease is hydrophobic so it's going to prevent moisture from getting in there and causing corrosion it keeps these terminals looking great beautiful and that's all there is to cleaning the terminals on your battery we did the positive i did the negative off camera now with both of these clean the alternator isn't going to work as hard the starter's not going to work as hard the electrics in your car are going to be a lot happier and your battery's going to be a lot happier so even if your car is running fine take a quick look at your terminals make sure they're corrosion free and they look clean i actually did a survey on instagram asking you to check your terminals and see if they're dirty or clean and 44 said they were dirty and that's over 190 000 people who answered this so it's totally worth a quick check to make sure your terminals aren't corroded all right so we're back at the white car with the dead battery we know the terminals are clean so there's a good electrical connection next let's check the voltage and to do that grab your multimeter if you don't have one you could find these pretty inexpensive they're a great tool to have especially if you like working on cars i'll be sure to leave a link in the description and then you're going to want to set the multimeter to 12 or more dc volts so we have 12 volts right there and we're good to go now you can grab your prongs red goes to positive black goes to negative and check it out we have 10.5 volts and that number tells us a lot now when you do this test on your car you want to see about 12.4 to 12.6 volts that means your battery is fully charged if your battery is lower than 12 volts make sure you don't have anything on in the car by accident and if you don't it could be a bad alternator you could have a parasitic draw or the battery itself could be going bad i'll show you how to diagnose that but this number right here that 10.5 volts that specific voltage tells me that we probably have a bad cell in the battery let me show you why now this old battery was also 10.5 volts when it was replaced and it's the perfect example on why a battery goes bad so i cut it open that way i could show you what causes a bad battery and also how a battery works now i want to make sure you guys don't cut open a battery at home these are filled with very strong acid i already neutralized the acid and i recycled it but i wouldn't want you guys to get hurt so instead of cutting open a battery just stick to watching this now you can see this battery has six individual cells each cell creates 2.1 volts of electricity so the reason why when i saw 10.5 volts i immediately thought it's a bad cell is because if one cell's dead that's 2.1 volts out of the 12.6 and that leaves you with 10.5 volts now let me show you inside one cell we'll take this cell out so this is what one cell of a battery looks like it's a bunch of grids there's positive and negative grids in here that's what this is right here this grid actually broke off from vibration and that's what one grid looks like and behind this grid is another grid and this grid is in a plastic sleeve that is very porous so it allows the electrolyte and the electrons to flow through but these two grids can't short out if they touch because they're right next to each other they won't short out they're insulated now each of these grids has a paste on it you can actually see some of the paste has fallen out due to vibration that's why vibration damages batteries this paste helps with the chemical reaction to create the electricity so the more that falls off the less power your battery gets now the more grids you could fit into a cell the more cold cranking amps you'll get and the reason why this cell failed isn't just because one of these grids fell off i mean it's not good that one fell off but if you look here all of these grids are attached to this main piece of metal with very small very fragile pieces and if there's a little bit of corrosion due to heat well guess what over time vibrations will just break that all off and then you lose an entire cell so that's why vibration and heat are the enemy of a battery you want to try to avoid it at all costs and that's what ultimately caused this cell to fail and give us 10.5 volts now the last thing to do to verify that the battery is bad is to put it on a charger now all we have to do is hit charge and it's going to start charging and now if this goes to that 12.6 volts that we need maybe it's not the cell that's bad maybe it just needed to recharge but if the charger can't charge to that voltage then we know for sure our battery is toast all right so i left it on for a couple of hours and you can see we're almost at 12 volts that's pretty good but what happens when we shut the charger watch this charger is shut and immediately that voltage drops real quick and that'll end up settling around that 10.5 volts that we were just at so we know for sure now that our cell is bad now let me show you how to replace this battery so the first thing i do is i make sure i go out and get the correct replacement battery this is important you want to make sure you get the correct one and to do that you can check your owner's manual it'll tell you right in here you could also look on the original battery the old battery that's in your car what you're looking for on here is the group size right there it says group h6 and that's the size of your battery you also want to take a look down here at your cold cranking amps this is how many amps the battery could supply when it's zero degrees out so when it's very cold you want to make sure you have at least the oem number with your new battery in this case it's 600 but you could always go higher the more cold cranking amps you have the more power you have reserved in your battery to start your car and also out of simplicity you could either go to the store or go online input your year make and model and it'll tell you exactly what batteries fit your vehicle and finally when buying a new battery there's two common types now there is your standard flooded battery which has been used forever and then now we have agm batteries absorbed glass mat which is a little bit more durable so they're built more durable to withstand vibrations and higher electrical loads a lot of cars especially newer cars today have tons of sensors they have that start stop technology where if you come up to a light the engine shuts off automatically and then as you press on the gas the car starts and goes if your car has that it needs an agm battery so check if oem requires an agm make sure you put an agm back in and even if your vehicle comes stock oem with a flooded battery you could always upgrade to an agm battery if you want it's not necessary but you can especially if you're running higher electrical loads from maybe you have off-road lights maybe you have a winch maybe you have an aftermarket speaker system it's definitely something to think about if you have anything that adds an extra electrical demand and then finally when you go to buy your battery you're typically going to have a couple of options so these are all the same exact battery size group 24 but we have the lower end the less expensive all the way up to the higher end the most expensive and the biggest differences here are warranty and power so which one should you get it all depends on your car and how you drive for example what i like to do on my daily driver gets the most abuse it gets used the most i want reliability i'll go with the most expensive battery the highest end with the four year warranty this is what i'll put in my hummer this is what i have in my truck and this is a good option for if you need to save some money or you need a battery but you might be getting rid of the car it might not last save your money and go with something like that all right so now you know everything you need to know on what battery to get for your vehicle let's replace it now this is super easy to do in most vehicles i have a couple quick tips the first one being it's very important always disconnect the negative terminal first if you go to disconnect the positive terminal i'm not going to do it but pretend i'm on the positive terminal and i hit the wrench bare metal to bare metal it's going to bridge that gap and it will spark but if we hit bare metal the bare metal on the ground it doesn't matter it's just like grounding out so just make sure you disconnect the negative terminal first good and then we could remove the positive terminal and that's the safest way to do it and now all batteries are held in so they don't become a projectile in an accident this battery is held in right down there so let's unscrew the tie down then we could remove it good and with this removed now we could remove the battery but i did something that you guys shouldn't do and i do this all the time it's a bad habit i put my tools on top of the battery and you shouldn't do this because if the two ends of the tool bridge the gap of the battery it could cause a spark which could create an explosion or a fire you could also heat this tool up a lot which could burn you so never put your tools on top of the battery now out with the old and even though no one will see this i like to make sure it gets cleaned up so vacuum it up spray it down with some soapy water and wipe it down to make it nice and clean good and now in with the new now let's get the tie down in place and tighten it down until it's snug good and that's not going anywhere now we're gonna reconnect the positive side first get one of the red felt pads on there and don't forget to clean the terminal even though this is pretty clean then we can slide it all the way on and tighten it down so it's snug and finally add some silicone grease and work it in there to coat the entire metal surface and one last thing i like to do this battery came with a cover for the positive terminal so i always like to put the cover back over it even though it's not a perfect fit it'll still prevent bare metal from touching it and shorting it out now we're going to do the same exact thing to the negative side tighten it down so it's snug and coat the terminal with silicone paste like so beautiful so with that installed there's one more thing left to do all right moment of truth let's start her up and she starts out with no problem at all and a lot of the new cars have awesome gauges they'll actually give you there you go your battery voltage right there 14.4 volts that's because the alternator is spinning giving you the extra juice and that's perfect so there you go that's all there is to replacing a battery it's one of the easiest things to do if your car battery isn't in an easy location comment below let me know the car and the model and i'd like to hear where that battery is but for most cars five minute job and you're good to go now what happens if you don't own a multimeter or you don't know how to test your battery or you just want the convenience of somebody else testing it well you could head over to your local advanced auto parts and they'll test your battery for free with no obligations to buy anything at all they have a high end load tester and that'll let you know for sure if it's bad and in this case just like we tested this battery has a bad cell and it won't charge above 10.5 volts so it needs to be replaced and just to let you know they will come out to the car as well to test the battery in the car that way you get an idea of how strong your battery is so you don't get stranded all right and it's that simple to diagnose and replace a bad battery but this is just one scenario and in this scenario we did have a specific voltage which gave us a hint that a cell was bad in the battery that 10.5 volts told us to check the battery and we did find out that the cell was in fact bad so we're able to easily diagnose it but it's not always going to be that simple it's not always going to be that type of problem a lot of times you're going to go and park your car and then a day later it won't start or a week later it won't start or maybe even two weeks later you go to start your car and it won't start and it should start no problem if the battery's healthy if not we're gonna have to diagnose the problem and to do that it's really easy it could be a bad alternator it could be a parasitic draw or it could be a bad battery so the first thing we're going to test is the alternator really simple to test we need to start the car and in this case the battery voltage is about 11.8 volts not enough to start the car we want to make sure we charge the battery all the way up to 12.6 that way we could start the car and properly test the alternator so a couple hours later we're all charged up at 12.6 volts so now we could disconnect the battery charger and let's go start the car to test the alternator all right so we have about 14.3 14.4 volts that's perfect you want to be anywhere between 13.6 and 14.6 volts that means your alternator is outputting the correct voltage if it's higher than 14.6 let's just say it's 15 volts it could be a bad voltage regulator in your alternator so you might have to replace that and you don't want to have too many volts more voltage isn't good over 14.6 volts could damage your battery so if you see that that's one problem now let's just say you see the opposite problem you see something below the 13.6 volt threshold well we're testing the voltage at the battery so that doesn't mean your alternator is bad necessarily it could mean that between the positive post and the alternator there's a bad cable or a bad connection so how do we verify that it's actually the alternator that's bad if you see low voltage you test the voltage at the actual alternator now you want to be careful with your test leads here don't get any of the wires wrapped up in the belt that's spinning that would be very bad but on the back here we have a positive wire and then our alternator case is our negative that's our ground so scrape it a little bit like that to get a good connection and you can see we have 14.1 volts which is perfectly fine so if you find your voltage is low at the alternator you could be pretty sure that your alternator is the problem if you find your voltage is normal at the alternator but low at the battery then there's probably a connection issue from your alternator to your battery there's a wire and there's connections this connection right here could be loose it could be corroded or the wire could be damaged or corroded so check that so that's how you test an alternator super easy to do and in this case our alternator is working great so now let's shut the engine and test for parasitic draw now a parasitic draw is an electrical component in your car that's drawing on the battery when the car is shut off and there really shouldn't be much of a draw the only things that should really draw on a battery when the car is off is your security system maybe like the clock on the radio and maybe your computer a little bit but it shouldn't be more than 50 milliamps if you have more than that your battery could drain overnight it could drain in a couple days it could drain in a week depending on how big that draw is so let me show you how to identify if you do have a parasitic draw and then where that draw might be coming from the first thing you're going to do is make sure everything in the car is off there's no interior lights on there's no headlights on and if your hood is propped open like this make sure your car doesn't know the hood's open some cars have a hooded jar switch if it does press it down tape it up whatever you need to do make it think that the hood's closed you basically want the car to go to sleep if you have a key fob especially a keyless entry fob or your car starts with a push button make sure you move this far away from the car so it could go to sleep and now what we're gonna do is we're gonna disconnect the negative terminal on the battery some people like to test on the positive side i like to test on the ground side that way if you ground out by accident it doesn't cause any damage so unscrew and disconnect the negative battery cable and what we're going to do is we're going to bridge this gap right here with our multimeter but first what we need to do is we need to take this positive cable from the regular spot and put it into the dc amp spot and then we're going to turn the multimeter to dc amps right there you can see it's 10 amps now we need to use the leads to bridge the gap so i want to get one lead on our cable here it doesn't matter which color and then the other lead on our post here but to make a good connection i'm going to just use one of these hose clamps that way it's nice and tight against the post and right away you can see we have about a .07 amp draw so 70 milliamps now a rule of thumb is you want to be 50 milliamps or less that varies from car to car but 50 milliamps is an average since we're pretty close at 70 milliamps i'm not concerned we don't have a parasitic draw if you had 100 milliamps so 0.1 amps of a draw or higher then there could be a problem now we just connected this so what we want to do is we want to wait at least 15 minutes to make sure the car goes to sleep and then double check that number okay so 15 minutes later our draw is still the same 70 milliamps on older cars they basically go to sleep right away but if you have a newer car definitely wait that 15 minutes because it needs to go to sleep to make sure that your amp draw is accurate now let me show you how to tell where the parasitic draw is coming from so again our draw is solo we don't have a parasitic draw i just want to show you as an example what you would do is you'd watch your multimeter and you'd pull out a fuse so let's just pull out this fuse right here and we'd see does that affect the amperage no it doesn't okay so put the fuse back and let's move on to our next fuse we'll pull that fuse no it doesn't affect it and so on and so forth until you see your amperage drop so let's pretend i pull this fuse and our amperage drops well now we know whatever this fuse is for that is where our problem is located so take a look there the other thing is if you pull all the fuses in your car and you still have a big draw check this cable on the alternator pull this cable off disconnect it completely and see if your draw stops sometimes there's a draw in the alternator and you wouldn't be able to find it just by pulling fuses now we know the alternator is working fine we know we don't have a parasitic draw so that leaves us with a bad battery so now let me show you how to replace the battery without actually disconnecting it from the car you're not going to lose 12 volts so your radio stations don't disappear your clock doesn't reset any presets in your car don't reset and the computer of your car won't reset and real quick just to prove that this works if we take a look at the clock you can see it says 216 if the battery resets that'll go all the way back to 12 o'clock and also if you look at my channels here for the radio those are some of my favorite radio channels they are in there if the battery disconnects those channels will reset so let me show you how this works first get your new battery and put it nearby next you're gonna need some high quality jumper cables and by high quality i mean the only parts of the alligator clip that is actually conductive is the tip you can see the tips are conductive the handles here are not conductive they're coated and that's going to be very helpful because we do not want these to touch and it's also a good idea to have a second person helping now we take our first cable the black ground and connect it to a chassis ground a bare piece of metal on the car next grab your red and connect it to the positive side of the battery on the cable if you can try not to get it on the post it'll make it easier later on you'll see why and finally with our last two jumpers connect the red to the positive post and the black to the negative post and be very sure not to mix this up okay so let's do a quick review real fast we have our old battery right here i disconnected the battery tie down that way we could easily just pull this battery out also the terminals are slightly loosened so that we could easily just pull these off so we have our red to the positive we have our black to a chassis ground and then on the other side we have our brand new battery and then black to negative red to positive and right now if we disconnect our battery here we still have juice going to the car with our new battery so basically now we just transplant it now is when your helper comes in handy to remove the positive wire from the battery and you can remove the negative wire and then remove the old battery from the car make sure that positive wire is held in place and doesn't come in contact with any metal parts otherwise it could short out so now with the new battery still remotely connected to the car carefully put it into the holder and then we can connect the negative cable first and don't remove the jumper cable until the negative cable makes good contact like that same for the positive make sure you get good contact and then slide the positive cable the rest of the way on then we can remove the positive jumper cable and finally remove the negative jumper cable from the chassis ground now tighten down the negative cable and tighten down the positive cable and finally tighten down the tie down all right give that a wiggle that's not going anywhere you could always add your silicone right after this i'm just super excited i want to show you this we're going to do this live i'm not going to do any cuts here we're gonna get right in the car excuse the camera shakiness okay turn it to the run position and check it out we have our clock here good we have our radio stations boom we didn't lose any connection at all that is awesome now you might be wondering why did the old battery go bad and i'm pretty confident the reason why is because i didn't have this car on a trickle charger and all winter long it was basically sitting there i had it in storage there was no electricity i forgot to disconnect the battery so over time that 70 milliamp draw that you saw when we did the parasitic draw test that is gonna drain the battery and batteries don't like getting drained and not recharged when a battery sits and it's drained you decrease the lifespan of the battery and the reason why is because lead sulfate crystals bond to the grid of the battery and that won't let the chemical reaction inside the battery happen efficiently the lead sulfate crystals block the electrolyte from contacting the grid and you lose cranking amps and your battery degrades so you always want to make sure you keep your battery fully charged and since this is a nice new battery i don't want it to go bad so what i suggest is at least once a week start your car and go for a ride not only is it good for the battery but it's good for the car too cars are meant to be driven don't just start it and then shut it off in a few minutes you actually want to go for a ride and have that battery charge up or another option is to install one of these trickle chargers that way you just plug it in after you park your car and to install the trickle charger it's actually really easy this part doesn't get installed this stays at your house this little connector right here is what gets installed very simple black goes to the negative red goes to the positive so get the black ring terminal on here and then get a nut on there and tighten it down to hold it in place same with the positive use a nut and tighten it down to hold it in place then all you need to do is plug in your trickle charger when you go to park your car for a while so i highly recommend setting up a trickle charger for cars you don't use very often you can set it up just like that nice and easy to do that way when you go to use your car your battery won't be dead it'll start right up and that battery will last for years to come alright so as you saw multimeters give us a ton of information and help us diagnose a bad battery but the one thing they don't do is load test the battery so we're gonna use my duramax hummer as an example and i'm gonna show you how to use a load tester to load test your batteries so let's run through this real quick just like any car we're gonna start by removing the negative terminals first good and now let's disconnect the positive terminals beautiful and now all we need to do is remove that bracket so now both of our batteries are loose and ready to be removed but before we do that i want to show you how to load test these and we're going to be using one of these load testers they're basically a cheaper version of the good load testers they use at the parts store so connect the tester to the battery like so this is a regular flooded battery then pick sae for our measurement of coal cranking amps and this battery is rated for 800 cold cranking amps so set it to that and you can see it tells us that we need to replace our battery we have about 350 cold cranking amps compared to the 800 that we should have now let's test the other battery real quick and this also is telling us to replace the battery according to this this is saying we have 70 cold cranking amps compared to the 800 the battery charge is a little bit low so i'm sure it's a little bit higher than that but at least it's telling us these batteries are bad and need to be replaced so out with the old and in with the new now don't forget to add some silicone paste to the terminal ends and with two brand new batteries installed there's one last thing to do all right moment of truth let's see what we got oh man she starts right up no lag at all that is beautiful that's even better than when i got the hummer so there you go that's my ultimate guide on how to diagnose and replace a battery in your car or truck now what do you do with the old battery that you just replaced well anytime you go buy a new battery there's an extra charge called a core charge and you get that money back when you bring back your old battery now if you didn't buy a new battery so you don't have a core charge but you do have an old battery just sitting around you could actually recycle it and make some money bring it to your local advanced auto parts and they'll give you a 10 gift card you can bring it to your local scrapyard they'll pay you for it because batteries are filled with lead which is valuable and easily recycled actually did you know car batteries are one of the world's most recycled items 99 of a battery is recyclable so it's a good thing to do plus you make some extra cash now i hope this video was helpful remember you want to try to avoid vibrations avoid heat and avoid draining your battery and keeping it drained always keep it topped off and that'll keep your battery lasting a good long time hopefully the video was helpful if it was remember to give it a thumbs up if you're not a subscriber consider hitting that subscribe button and all the tools and products i used in this video are linked in the description below

Channel: ChrisFix

Views: 1,093,542

Rating: 4.944881 out of 5

Keywords: ChrisFix, How to test a car battery, 12v car battery, car wont start, clicks when I start the car, parasitic draw, alternator test

Id: YC--MLNIbik

Length: 28min 50sec (1730 seconds)

Published: Thu May 06 2021