How to test an alternator the right way!

do you know how to test the alternator the right way for voltage and amperage stick around I want to show you how to do it welcome back my name is Brenna hey I enjoy keeping form it if this is your first time here and you want to learn more about jeeps you've come to the right place now make sure you hit that subscribe button with the Bell and let's get started so today I'm going to be showing you how to test an alternator not just by checking the voltage on it but by checking the amperage output now normally this takes very expensive equipment but today I'm going to show you how to make a homemade amp clamp or a shunt guys did you know that there's a way that you could support this channel by not doing anything other than you normally do not costing you a dime there's a link down below in the description area it's linked to Amazon if you click that link ok any of your normal purchases that you purchase anyway it doesn't have to be anything cheap related anything that you purchase from Amazon if you were to click this link first it'll actually a small portion of that will go to support this channel and it would be much appreciated if you would do that so stick around let's get to it now the average person thinks that chicken an alternator is only by connecting the positive and negative lead to your multimeter starting the vehicle up and see if the voltage is somewhere around 13 or 14 volts now as this may seem like it's good it's not actually a hundred percent accurate now at the dealership or at an independent repair facility they're gonna use something like this is called an amp clamp okay it's simply you just connect it to the negative battery terminal and as you can see here the battery is being charged at 10 amps now the battery might be accepting a charge at 10 amps but what is the alternator actually putting out to find that out you've got to find the dedicated wire coming from the alternator to the battery and when you check that you can see here that there's 57 amps now some of you are probably like whoa which one is right 10 or 57 well they're both right 57 amps is what the actual alternator is putting and 47 amps is what the vehicle is using okay to run lights wipers blower motor anything else electrical and 10 amps is actually being used to charge the battery so this is actually how the independent repair facility or the dealership would actually check your alternator but how would we do it at home when we don't have these expensive tools well let's head over to the bench and find out now you can find these items at a local park house or if you're like me out in the garage with all your junk but what you're gonna need is some large gauge wire and two heavier clamps now we are checking the amperage that comes off of the alternator and goes into the battery so that is some high amperage so we got to make sure that we have a larger gauge wire to be able to carry that current and we don't want to burn up any wires now the wire that I found that would use the best come off of a really crappy set of pair of jumper cables you know the kind that your grandma gets you at Christmas and you're like that's not gonna jump even my lawnmower off I haven't ever used them so I decided to put them to good use now once you get your wires fit you want to make sure this is a good crimp now you could solder it you know and make this connection you know solid and put some heat shrink over it and man really make this thing look nice I'm just doing this the old el cheapo way I'm just crimping the wires on there on this clamps and we're gonna make us a little amp clamp tester here for what three dollars maybe four dollars at the most now before we go and use our little homemade tool here we're gonna have to actually calibrate it to make sure it is accurate some of you are like okay this guy's lost his mind how do you calibrate a piece of wire in two clamps well here we go now the first thing you're gonna need to calibrate this wire is maybe a headlight bulb or some type of filament bulb that carries a load okay now we want to make sure that both works then after that we're gonna take our meter and set it to the amperage setting okay now this amperage setting is is really only for small averages under 10 amps and that's why we're making this tool is because we want to check things for larger amperage than 10 amps because the alternator puts out some of them can put out a hundred and eighty M now we've got our positive multimeter lead on the positive side of the battery going to the amperage spot on the multimeter we have it's the multimeter switch to amperage and then the negative is gonna come out and we're going to attach that to one end of the bulb and then the other end to the battery and this is gonna tell us the amperage that this bulb is actually using now this may seem a little confusing but really all we're doing is putting the meter in between the battery and the bulb to find out how much current the bulb is using now remember your reading might be different than mine but whatever reading you get that's what we'll be using for the reference now what we're gonna be doing is actually connecting the bulb back up to the batteries but we're gonna be using our homemade amp clamp which is actually called a shunt actually this is a real name for it so go ahead and connect one end of the bulb up to the positive and the other end of the bulb up to one end of this shunt and the other end of it up to the negative battery which is going to turn the light on now here's where you can get a little bit technical so make sure you keep watching pay attention and just follow what I'm doing now first you need to have your multimeter it doesn't have to be a nice when just gonna be any multimeter and set to millivolts okay that's the little m and the V DC millivolts then take the negative side of that multimeter and connect it to the negative side of the battery now what I'm using here is like a little needle a little T pin okay you're just going to need something sharp to pierce through the insulation of that large wire that we made okay so now we're going to poke into this wire until we find C there until we find the four point three that we're looking for okay so I had it on volts they're just millivolts so there's four point nine we're looking for four point three now there's four point four and I'm I'm just piercing through the insulation to find that sweet spot of four point three and pretty close right there so as you can see if you come further out look at that there's seven point three so that's inaccurate you want that that sweet spot of four point three or whatever your reading was mine was four point three so this is where I'm trying to find that sweet spot of four point three now after you found that spot you want to take a razor blade and just pull back a little bit of insulation there so you can gain access to the bare wire now this is gonna allow you to put an alligator clip or the the positive end of your meter on to the wire which will give you the reading that you need to check for amperage now once that is done you can take your positive end of the multimeter lead and stick on that bare spot of the wire and now we got four point two now that is not the four point three that we showed before but it's only one tenth of a amp off so it's really not that big of a deal when you're measuring 50 to a hundred amps one tenth not that big of a deal now once we got our homemade tool this shunt calibrated now we can go ahead and disconnect it from the bulb and now we will test the battery to see how many amps the batteries charging without using that fancy amp clamp we're gonna use our homemade one and we're gonna see how well it works now let's go ahead and disconnect the negative battery cable and grab our homemade shunt here and go ahead and connect it to the battery going on connect one side to the battery terminal and the other side to the actual battery post now make sure you have a good solid connection when you connect these terminals up because all the energy is gonna be flowing through this large terminal now you can connect your multimeter leads up to your little special tool that you made and you can see that while the engine is running this battery is being charged here at 18 amps now I know that we have the multimeter set to millivolts not amps but we can't use this multimeter for large amperage like that that's why we made this tool because the the meter can only go up to 10 amps here we can see is charging clearly at 17 so let's check the alternator and see what it's actually putting out it's gonna be putting out sixty basically if you had 17.5 millivolts that's gonna equal 17.5 ants that this is charging that all right check this out this is a plus 17 point oh now I want to cut the engine off we go to negative 3.1 now why is that the reason for this is because the engines not running so the alternator is not charging the battery the battery is being drawn three amps so something's own drawn this battery down now you can use this to check for a drama battery but remember our multimeter can already do that if it's under 10 amps so that's not really why we made this tool we made this tool so that we could check the high current that the alternator puts out and to verify that this alternator is working now let's go ahead and disconnect our shunt reconnect the negative battery cable and let's move over to the alternator now I'm going to be removing this large main wire that comes from the battery so just make sure you have it secure and away from any ground because you don't want any large arcing that could damage anything so we're gonna go ahead and connect our shunt up to the alternator terminal then also to the that wire that was coming off there the main wire and we're gonna go ahead and start the engine up and we're going to connect our tool to see how many amps this alternators actually put now so let's go ahead and connect it really doesn't matter which way you connect it up it's just gonna read negative one way or positive the other way so connect there's a positive up to that one and then the negative up to that bare spot and you can see here that the alternator's charging at 48 and 47 amps now that's pretty cool huh so we've just eliminated about a hundred and fifty dollar tool by just a few bucks there now as you can see it's charging at 46 amps right now so let's see what happens when I turn the headlights on let's see if it should go up so the headlights are on and look at their 57 so that added another 10 amps just to run those headlights now all the current is flowing through that wire there so this is definitely something you don't want to leave on there this is just for temporary testing purposes only now I want to verify how good our tool actually is and compare it against this $150 amp clamp against our three dollar homemade shunt so check this out guys accurate very very accurate so I'm very impressed in place of how this small simple little tool here can be made at home and be so accurate guys just remember this three to five dollar wire and clamps is just as accurate is this 150 dollar amp clamp now the amp clamp is nice to have but if you can't afford one then this makes for a good alternative thank you guys have a great day I hope you're smarter now than you were when you started this video take care have a great day you [Music]

Channel: Brandon Haneline

Views: 331,124

Rating: 4.7950187 out of 5

Keywords: how to test an alternator, how to check alternator, how to check alternator is bad, how to check alternator voltage, how to test an alternator with a multimeter, how to test an alternator amperage output, alternator testing, how to test an alternator with a voltmeter, how to check your alternator, how to check your alternator with a multimeter, how to check alternator with multimeter, how to make amp clamp, how to make a shunt, how to make a high amp shunt, alternator test

Id: Q849H1s-g1o

Length: 13min 12sec (792 seconds)

Published: Sat May 19 2018