Learn how to use a Multimeter - for solar power, DIY and more! #solar #diy #multimeter

this is a digital multimeter it is a double-edged instrument it can Enlighten you with knowledge but it can also trick you with false information it can save you money but it can also cost you money it can increase your safety but in the wrong hands and used incorrectly this meter could also endanger your life [Music] a carpenter has a hammer but a Electronics technician or someone who wants to learn more about electricity and electronics has a multimeter this is by far one of the most heavily used and basic devices all over the world in all sorts of applications and all sorts of professions 24 hours around the clock even if you're not an electrician or a Jet Plane mechanic learning to use this device can really be beneficial to you over the long term even if you only spend a few minutes learning a few basic functions on the meter it will really pay you back in the long term and give you the opportunity to gain more knowledge and more understanding this presentation will do three things simultaneously it will provide beginner level knowledge and introductory information it will also provide intermediate to Advanced knowledge and finally it will include safety related topics okay let's get started with the video one of the most basic and common jobs that you will need a multimeter for is to take a voltage measurement this is the dial of a typical rotary switch multimeter at the top of the dial on this particular model there are two locations for voltage settings the first is right here this is your DC voltage and on the right is your ac voltage the way you recognize the two is usually ac voltage will be represented by what looks like a tilde or a squiggly line that just represents the AC sine wave over here we have a V with Three Dots and a line above it anytime you see there that usually means DC voltage or direct current now it's important to understand that DC and AC are two completely different worlds they are not the same they don't behave the same they don't work the same if you're going to be using a digital multimeter to measure any kind of voltage you should at the very least research and study the differences between DC and AC this is just for General understanding but also for safety reasons to keep this short as possible and encourage independent research I'm going to very briefly explain the difference between DC and AC DC or direct current is a continuous flow of electricity with a positive and negative polarity AC on the other hand is alternating current it usually goes back and forth between positive and negative rapidly 50 or 60 times a second in North America it's 60 times per second or 60 cycles per second also known as 60 hertz and in Europe or other countries it may be 50 hertz or something else or some cheaper multimeters may not measure AC very well if you're measuring the output of say a modified Square wave inverter it may give you an incorrect reading because the meter is not able to deal with the output that it's getting so if you've ever taken a cheap multimeter and stuck it into the AC outputs of a modified Square wave inverter or something similar and were alarmed to find that it didn't read what you thought it should don't worry it's probably just the meter being unable to read the output next thing to understand is that a typical rotary dial multimeter like this will have different scales of voltages that you can select they're also called ranges if you are not sure what you're measuring it's a good idea to start with the highest scale first let's go ahead and start with a DC voltage measurement so we're going to go with DC which is right here on the left let's go ahead and switch it to 500 volts DC which is the highest level that this meter supposedly can measure warning you should never ever try to measure high voltage DC with a entry level multimeter and low cost low quality multimeter probes attached it could literally end your existence but in this case for the example I'm showing you a normal procedure that is generally taught that if you're not sure how high the voltage is you should start with the highest range of voltage that's available on the dial so that's what we will do the meter will first usually jump the numbers around a little bit this is very common it's just the meter's way of calibrating itself it's also called reaching zero or zeroing out so as you can see the meter has zeroed out and the reason you're seeing the polarity sign flash regularly that's right here this indicates positive or negative is because the meter is quite sensitive and it's trying to constantly measure the voltage and believe it or not even when the probes are not connected to anything and are just laying on the ground here's the probes right here they actually can generate a voltage and if you put the meter on a more sensitive scale it's possible to even get that number to change so you'd be putting a tiny bit of voltage into these probes from just your fingers or whatever stray voltage you're picking up now that we're on 500 volts of DC let's measure a voltage source so I'm just going to use this lithium iron phosphate battery here as my voltage source now the first thing to notice about multimeter is it is got a positive and a negative connection and you always want to make sure that you're plugged into the positive and negative on the meter because this meter actually lets you choose which one you want to pick now if you can see here I've made a common mistake this probe here was plugged into the 10 amp range if you look you can see that the common Port there had nothing in it this is going to be a safety warning and a cautionary tale about what not to do with a digital multimeter before you start measuring anything or using the meter always look to see where the probes are plugged into now to make this easier I'm going to take the probes out I'm going to show you the connections on the multimeter we have three connections here it is important to note that the connection between common or ground and the 10 amp terminal on the meter is literally a direct short you never ever want to plug your probes into those two sockets and connect them to a voltage source this configuration is meant to be placed in series with a load not across the terminals of a battery which again would be a direct short please note that there are exceptions to this rule for example connecting a small solar panel directly to the 10 amp socket and a direct short through the meter is a quick and easy way to measure the short circuit current that solar panel would be able to deliver as long as that solar panel does not exceed five or six amps of current it should not damage the meter in the few seconds that you have it connected but if you were to try to short say a battery through this terminal it is able to deliver far more current and would quickly burn out the meter in most cases it would probably also damage your multimeter test probes and or test leads so that's something to keep in mind to take a voltage measurement only the bottom two terminals will be used the top one or the third one at the top will never be used for anything except measuring current in series now this is very very common I don't say they're all multimeters are like this some of the newer models may not have this but by and large if you pick up a basic digital multimeter it's going to have these three connections and what's printed here on the face may vary it's common to have different layouts and different icons but this is very basic information it's fairly Universal so first you have a common and there will be some safety warnings here and what these are telling you is basically look this is the maximum voltage this meter is able to measure this is the maximum voltage you should ever put through it here is the maximum amount of current or amps that you should ever put through the meter I would never put through 10 amps but it says it can handle 10 amps for 15 seconds maximum every 30 minutes it's up to you whether you believe that or not I would never put 10 amps through this meter next we have some information here about what this terminal here can do so this is referring to this middle terminal right here and this terminal here is for volts ohms and milliamps it can measure 500 volts DC 500 volts ac or 200 millimolts or milliamps sorry Max and here we have common com and we have ground the symbol here is the universal ground signal it means common or ground or both and that's 500 volts Max so common means that pretty much you'll always be plugged into here and this is also known as negative ground negative common are three things that are pretty much the same thing up to a point generally speaking they are tied together so I'm going to plug my negative probe or the black one into common ground or negative whatever you want to call it this hole here this connection here is for positive even though it doesn't really say that it's just understood that this is positive so folks if you're going to use a Multimeter you always want to start even before turning it on look and see where it's plugged in do that before you do anything else because worst case scenario you could destroy your meter and you don't want to do that and I'll explain why later so first I'm going to take my negative connection and by the way these probes did not come with the meter these are better quality probes the ones that come with cheaper meters are usually not very good and they fall apart for 10 or 12 dollars you can get a new set of probes about like that these are around 10 or 12 dollars I don't remember exactly and they're a great Improvement and I do recommend if you're going to use a meter seriously go ahead and get some better quality probes you don't have to spend a bundle on the meter but get some decent probes just for safety and long-term durability so I've attached my negative probe to common or ground next I'm going to take my positive and I'm going to plug it not here where it was originally my two probes were plugged into these two connections here so I'm going to plug my probe into volts ohms and milliamps which is right here which is also positive and that will enable me to take a voltage measurement okay now that we have the probes properly inserted into the meter and not into the 10 amps connection right here as they were when I first picked the meter up we can go ahead and measure this battery so here's the battery I'm going to use it doesn't matter it's just any old battery for an example now let's take a look and let's measure using the correct polarity so I'm going to use positive and negative correctly as you can see the battery has a red and a blue or a black for negative so I'm just going to take the probes and I'm assuming here that we're measuring a simple car battery it's not high voltage and it's relatively safe and so this is a great way to begin learning how to use a Multimeter just measure small batteries and things like that until you're comfortable okay so next I'm going to take the probes and I'm just going to place them on the terminals of the battery and what we have is 13. so I know this battery puts out direct current or DC I know I'm on the correct range it's voltage in DC and I know 13 volts is kind of close to what this battery ought to be I know at rest it would be around 13 volts and some change if you'll notice here there is no decimal point it just says 0 1 3 which is not very useful when measuring a small battery you really want to know what is the actual voltage so that's where the scales or ranges come in 500 volts DC is not going to be able to show me much information after the decimal place in fact on this range it doesn't have a decimal but if I switch it to 200 which is a smaller range you see the decimal point appears you can see that a small point right there if I put it back on 500 it disappears so it's just showing me a whole number but if I switch it to 200 now we have a single digit after the decimal place now more expensive meters might do better than this this is a fairly basic meter but that is the point of this video is basic equipment basic entry level knowledge now I know my battery is nowhere near 200 volts it's just a little 12 volt battery so I'm going to do is I'm going to go ahead and step down to 20. now you see the decimal place jumped over again if you look it's jumping back and forth no decimal place there's a decimal place and again so 20 is very very common on meters like this 20 volts covers a lot of different things it can cover a car battery or just anything a 5 volt power supply lots of things fall under 20 volts and by the way 20 volts is never going to electrocute you it's safe if you touch it with your hand you'll be good generally speaking 48 volts is considered to be the edge of safety but 20 volts you're you're fine you're not going to get electrocuted by 20 volts DC now you'll notice something else this is important to keep in mind the lower you go on the scale so right here I've jumped down to 20. the lower you go on the scale so going this direction the more sensitive the meter becomes and it's probably not a good idea to connect the multimeter probes to a potentially high voltage source when the meter is in a lower scale I'm not saying it will damage it but it could so in this case I know my battery's low voltage 20 volts is fine I'm going to go ahead and make the measurement now here's something else interesting the more sensitive the meter becomes the easier it is to get stray voltage readings now watch what happens when I touch the probes you can see the meter is reacting it can even pick up a little bit of electricity from my fingers so this could be a problem right now it's not a problem but it's just something to be aware of and keep in mind so with that said let's go ahead and measure the battery the probe's on the battery now that's a lot better 13.15 volts this is a lot easier because on a low voltage system even a tenth of a volt matters so this decimal place here is a tenth of a volt and this is a hundredth of a volt or 0.15 or you could say 15 percent of one volt depends on how you look at it so the voltage is 13.15 volts the next thing to be concerned about is that negative sign that keeps flashing on the left side of the screen that's simply telling you polarity now because the meter is very sensitive and it's picking up straight voltage it keeps flashing the negative sign because it's just picking up random noise from the environment that I'm in that's nothing to be concerned about if anything it tells you the meter is awake and it is trying to take a measurement what happens if I take the positive probe and put it on the negative terminal of the battery let's try that and see what happens and this is one of the most useful functions of a multimeter it says negative 13.15 volts now as you can see I've got the red probe positive on the negative of the battery and I've got the negative Probe on the positive side so of course it's now telling me the polarity is backwards this is by far one of the most useful functions of a multimeter it's called a polarity check if you are not sure which is positive and which is negative this meter could save you a thousand dollars simply by telling you hey don't hook that up backwards now that's Universal information it applies to solar it applies to household Electronics any kind of Appliance just a universal piece of knowledge that everybody should be able to know which is positive and which is negative however it's worth keeping in mind that if you accidentally swap the positive and negative connections on the meter itself that test is useless because it's going to trick you now in the interest of keeping this video fairly straightforward and not getting too long I'm not going to demonstrate these last two ranges on the scale so 2000 M and 200m is referring to millivolts these are one thousandth of a volt generally speaking the average person would not care about one one thousandth of a volt but this can be very useful and it's a very sensitive range on this meter you would need to be careful what you plug this into when it's in the millivolt scale and 200 millivolts the very very tiny amount of voltage probably not useful in most cases however when you do need it this is fantastic you can measure voltage drop and all sorts of things I will briefly say that an interesting use of a low scale like this would be to measure the voltage drop across a long wire run or possibly a shunt that's measuring current in a live circuit however this is a rather Advanced topic and won't be covered here for solar and general household use the 20 volt DC range is probably going to be the most commonly used for a very wide variety of chores next let's move on to ac voltage so if you recall earlier this is the AC portion of the scale and it's in 500 and 200 volts ac in North America we generally have 120 volts ac more or less coming out of the wall outlets but in a dryer plug or in a hot water heater you would have 240 so these two scales are going to be the most commonly used in North America so I'm going to go and switch over to 500 volts ac I'm going to let the meter zero out it's a good idea to give the meter five or six seconds to zero out and reach a zero which is what this meter has done if it's jumping around a lot or doesn't say zero then there could be something wrong with the meter you may have a bad battery or you may need to just wait a while for it to settle down I'm going to do something on camera that is probably ill-advised for most beginners nevertheless I'm going to show you how it's done here's a pretty typical AC power cord on the left here it is live it is plugged into the wall there is going to be a time where you might want to measure a cord like this to see is there any voltage coming out at all so I'm going to show you how I do it and this is generally dangerous if you don't know what you're doing now before I take this voltage measurement can you think of something that you should always check on the meter before doing this well there's a number of things but the first is yet again make sure you aren't plugged into this socket right here again this connection here and this connection here is a direct short through the meter so if I were to have both of my leads plugged into this socket in this socket and I try to measure the voltage here there's not going to be any voltage measurement taking place what's going to happen is a short circuit straight from the wall outlet through the meter and then back in and so it will burn up your meter and it could actually electrocute you or start a fire but you can see I'm not plugged into this socket for 10 amps I'm plugged into common and volts ohms and milliamps right here so I'm using the meter correctly the next thing is I never use both hands when measuring a high voltage what you don't want to have is you want to have voltage flow up one arm and out the other and through your heart now this is basic Universal safety information it could get really really complicated I could say wear gloves we're a full body suit ground yourself or something like that but I'm just going to give you the basic information you should do research on your own before attempting anything like this what I like to do is hold the probes kind of like chopsticks with one hand and use that to take the voltage measurement that way if I made a mistake or the voltage was very high at least it's only one hand in the circuit and I don't potentially have voltage coming through one hand and going up the arm and then going out the other hand that would go right through your heart that's not to say you're safe but this is certainly something that you can practice uh just to give yourself some discipline and increase your safety so with that let's take the voltage measurement now this is to simulate the wall outlet in a house in this case I have to hold the extension cord to get the footage not sure I recommend that but I'm going to do it first thing I'm going to do is take the probe and I'm going to shove it into one side of the circuit then I'm going to take the other probe and put that in and now for a quick safety warning here I'm taking the measurement from the extension cord which is a substitute for a wall outlet in a house and you can see I've got the probes going in there and those probes are live so the piece of metal you see sticking out there if I were to touch that I would be instantly electrocuted so you can see why this is not really recommended for beginners right at the very start you really shouldn't be doing this until you've gotten some practice and some experience and hopefully have someone around who is maybe an electrician and is more experienced with these matters but I'm showing you this on camera because I want people to see how easy it is to make a mistake and get electrocuted it's important to keep your fingers away from the ends of the probes and that's why they have these finger guards right here you should never have your finger past this guard you should never have your finger down here like you can see right here how easy it would be to slip and touch a live wire okay so I'm taking a measurement of 116 volts ac and you know that's about right it could be 110 it could be 120 it could be somewhere in between not too concerned about it that's about what I expect to be coming out of a live AC cord plugged into the wall of my house now what if I want to measure it from the 200 Volt range what would I do first resist the temptation to just reach up and turn the dial because if you do that this dial is connected to a bunch of copper contacts on a circuit board and you potentially could be switching a heavy load through these contacts these contacts are not meant to switch any kind of load or voltage they're meant to make a setting change and then take a measurement in that order if you take a measurement and then switch this dial while you're taking the measure while current is flowing through these leads and into the meter you could damage the meter also this may not happen immediately it could happen over time you don't want to start having Sparks inside the meter which would over time damage this rotary dial so that's something good to keep in mind and it's also not particularly safe you could have arcing or something like that and we don't want that either so what I'm going to do is I'm going to disconnect the circuit I've taken my meter probes out and now I'm going to switch to the 200 Volt range you can see that we now have a single decimal point which for AC is kind of Overkill but in this case we're measuring the household power so we really don't need a decimal point but as you can see 117.1 volts so once again that's a good reading that's more or less what I would expect and a really interesting use of a meter like this is you can plug your meter into a circuit and then turn on an appliance and see how much voltage drop you get on that same cord if it drops to almost nothing or under 100 volts you know there's something wrong it could be a bad extension cord a bad Appliance and it could mean that there is a bad connection somewhere in this case the court has no load on it and so I'm not going to see a voltage drop there is some variation and that variation is happening on the meter because this is a live household with appliances being turned on and off things are changing things are powering on and off and so there is going to be some variation in the line voltage and having a single decimal place is enough to see even small changes it's very interesting to watch if I turn on an appliance you'll actually see that change so let's do a quick demonstration here if you look in the background I still have my probes plugged into the extension cord and this is on a single 20 amp circuit in my house so I'm going to go and turn on an electric heater on low and you'll see that voltage drop let's go ahead and do that I'm going to walk across the room and leave this here and I'm going to turn on the appliance and Watch What Happens okay I've turned on a basic electric heater to around 600 watts and as you can observe here in the example hopefully you can still hear me over the sound of the heater the voltage dropped to 107.3 volts now why is that voltage so low this is where multimeters really really start giving you information that you might not otherwise have or even be aware of let me turn the heater off and I will explain and the heater has been turned off and you can see the voltage returns to its normal range in this case the reason the voltage dropped to 107 volts which is considered to be below spec you would not want to be lower than about 110 volts in North America it is because the building in which I have this circuit that I'm measuring and the heater plugged into has a extremely long run of wire far out from the main source of power where the power company connects to the house and there's a lot of voltage drop the longer the wire the more resistance it has and therefore when you turn on a heavy Appliance you get what's called voltage drop due to the resistance in The Wire the voltage drops and the current still flows but it's at a lower voltage and this is basically what we would call an inefficiency because you're going to lose some of the power in the really long wire as heat and that goes right into the next function that I'm going to show you on this meter which is measuring resistance electrical resistance is simply an inhibition of current and or voltage flow in a wire the longer the wire the more resistance and generally speaking you want as low resistance as possible because an electrical voltage plus resistance generally equals heat and the heat is simply lost electricity you'll never get it back it's just being wasted and so that's why you generally want a good high quality thick cable with low resistance so that all the power goes through it and into your Appliance instead of just warming up the power cord and this applies to solar applies to household Electronics anything at all same principles works the same way but a hidden feature of resistance is also continuity so what if you want to know if a wire is broken again a resistance check can annuity check are similar and pretty much the same thing if you want to look at it that way in order to measure resistance I'm going to come down here and on the scale you will see that there is an OHM symbol that's the symbol Greek letter ohm or Omega and this means ohm so ohms is simply a measure of resistance and if you want to you can look online and research how to calculate the resistance voltage and current on a circuit I highly recommend learning that right here we have again a scale and this is 200 ohms that's a very low resistance one or two ohms would be pretty low resistance not very much but it goes all the way up to two thousand twenty thousand two hundred thousand and even two million or two thousand thousand I'm going to measure this really long power chord that I have that I was using for this example to see how much resistance it has to do that I only need to measure about 200 ohms or less so I'm going to switch it to the most sensitive range which is 200 ohms and what will happen is the meter will again it should zero out now different meters act different ways mine is a little bit odd it shows a one and it shows a decimal place it basically means okay I'm ready to take the measurement now if you have a dead battery or there's something wrong with the meter it may do something odd I know this meter well and I know it's ready to measure resistance so what is the first step to taking a resistance measurement again you want to make sure you're plugged into the right connections on the meter we already talked about that the first thing you do is you take your multimeter probes and you short them together and the reason you do that is the probes themselves have a resistance in this case the meter says that the probes have about 0.4 or maybe 0.5 of an OHM of resistance in the probes and in the wires so I have to take that account in my measurements now sometimes you will see that reading vary or drop but it's about 0.4 of an O I'm calling it 0.4 of an OHM and I need to know that because the chord is going to be a certain resistance and I want to know what is the resistance of that chord I do not want to include the resistance of my multimeter probes and wires because that would be inaccurate okay here's that extension cord that you saw me use earlier I've unplugged the other end and this is a fairly thin and long cord and I'm going to measure using the ohm setting to see how much resistance it has so first I'm going to take a probe and I'm just going to stick it in one side and I'm just going to pick one side it doesn't really matter now as you know there's two conductors in this type of core it's a two prong chord not a three prong and I can just touch it to one of these prongs and one of them should give me a reading and let's go and touch the probe to this side and you can see I got the right one and what I'm seeing here is about 0.5 so really this chord has about a tenth of an OHM of resistance now what I shouldn't see if I turn the chord around touch the other side I shouldn't get anything and the reason is I'm not connected to that side now if you want to test a bad extension cord using what's called a continuity check you can actually see which side you're connected to and which side still has an intact functioning wire inside and sometimes you have to wait a while for the reading to settle down in this case it takes a while so effectively this chord has a very low resistance as I expect I don't want to see like 3 ohms or 5 Ohms on a cord like this it's about 20 feet long 5 ohms would be very very high in that cord it's either a bad chord or it's going to get really hot in operation and I wouldn't use it for anything important or possibly even just throw it away but this chord is fine and 0.1 of an OHM or tenth phenome is very small and is nothing to be concerned about now what if I stuck my meter probe in one side like this and I got nothing so every time I touch this the meter says there's nothing there just doesn't do anything a lot of times that means the chord itself is bad and you have a broken wire another trick you can use is simply attach the probe get a good connection and then start moving the cable around move the wire around and see if the reading changes if it starts turning on and off you know you have a frayed or broken wire inside the cord and you need to dispose of it now to further demonstrate the value of a simple multimeter like this one I'm going to show you how to do a continuity check and an ohms measurement all in the same run in addition to that I'm going to show you how to identify which cable is which so in addition to a polarity check a multimeter like this can help you identify which cable goes where if it goes through a wall or underground it can be very difficult to tell which one is which because they come out the other end and they all look the same so here's some old solar panel cable I have you can see the end has been cut off this is a use cable and what I'm going to do is check this cable to see which one is which I don't know it's a pile of cables and this could be running underground or it could be in a large installed system or anywhere but I'm going to go ahead and touch my probes to one side of a wire that I see exposed and you want to make sure it's not a live wire in this case I know it's not it's just sitting on my work table here then I'm going to take the other end of it and I'm going to put my probe in now I can touch this wire and see if that's the same wire and you can see that it is and this wire has again about two tenths of an OHM to a tenth of an OHM measurement so you can see that a multimeter has a lot of value you can use the resistance or continuity check to see if a wire is broken or has high resistance or a bad connection you can use it to identify which cable is which and by switching it to voltage you can even find which one is putting out power if for example I had a array of solar panels and I had 20 or 30 wires coming through I could disconnect the solar panels and use the ohms setting or the continuity check setting on the meter if it has one to determine which of these wires goes where and then Mark them with a colored tag at either end and by process of elimination I could identify every single wire without actually seeing where they go underground or through the conduit or through the walls or wherever they're going in this case I know I just have a couple of solar panel cables on my workbench but it's a great way to demonstrate how it works so this cable here goes to this plug and I know that because this meter told me that I don't actually have to go and look at the entire wire foot by foot to see where it goes okay next I'm going to talk about the probes themselves most basic multimeters come with a very cheap set of probes and they're actually quite hazardous to use as the wire that's inside here can actually fall out or come loose and generally speaking they're not very good quality so if you have a chance it's a good idea to spend 10 or 12 bucks on a nice set of probes they're just a little bit better quality than what the meter comes with they generally cut corners on the probes and it really shows but I want to point out that at the end generally speaking you would have about you know this much metal which is exposed and that is one of the most hazardous things about using a multimeter these metal probes here can actually get you electrocuted and they can also cause a short circuit they are conductive and if you shove this piece of metal into the wrong place in a live circuit that's functioning you can actually destroy it and worse still you wouldn't even know you did it it may not necessarily make a spark but you would have quietly destroyed that circuit causing even more troubles so probing a live circuit with probes like this is generally a No-No unless you're really an expert now some probes come with a set of shrouds which will cover up this metal and only leave a little piece of metal at the end exposed if you have those available you should install them and use them in general and only take off the shrouds off of these metal probes when you need to do that for example when measuring an AC power outlet you need the full length of the probe to get into the outlet to get a contact and measure the voltage otherwise you should keep the probes covered up as much as possible to minimize the chance of a short circuit or an accident another common mistake is when measuring something that's close together and then accidentally contacting the pros together once again it makes a short circuit so very risky and it's very easy to do that it's so easy to slip with these probes and touch them and it just takes a split second and you've made a short circuit and you can see that these probes here have a little point at the end and that's actually intended for penetrating wire and it's also intended for getting a good connection so if you wanted to and I'm not saying I recommend this you could actually take the multimeter probe and actually push it in to the wire through the insulation and make a connection I generally avoid doing this because I don't want to damage the insulation on my wire but in some cases in Desperate situations you may be forced to actually push through the insulation jacket of a wire use the sharp point of the probe to get a voltage reading of a wire that is live and in circuit this is mainly an FYI I don't necessarily recommend doing it and it's generally only for advanced users of multimeters and keep in mind you are damaging the jacket or the insulation of the wire and I would not want to really use an extension cord that had a hole poked in insulation for any reason whatsoever another reason for the very pointy end of the probe is actually so that you can get a good connection sometimes there will be some oxidation or some corrosion on a measuring location and by taking this probe and sort of scratching with the sharp end you can actually get a good connection and take a voltage or resistance measurement at the end of the probe or near the end of the probe you can see where my fingers are there's a finger guard and generally speaking you're not supposed to put your fingers past that line there that's to protect your hands from slipping and making contact with the metal part of the probe it's for safety but I'll tell you when I'm measuring a higher voltage or I'm worried in any way for my safety I usually hold the probe back here and I keep my fingers and hands as far away from what I'm measuring as I can just for instructive purposes let's take some resistors and these are supposed to be 15 000 ohms and let's measure these to see what they actually are so let's take the probes and put them right on the resistor here and you can see that I don't really get anything on the meter and that's because this is supposed to be a 15 000 Ohm resistor let's bring it up to 20 000 ohms and then let's try measuring the same resistor and I get a reading of 14.78 it's jumping around a little bit which is not a problem let's call it 14.8 so this is 14.8 000 ohms it isn't quite fifteen thousand ohms but it's pretty close and it's probably still useful even though the resistor is showing as less resistance than what it's supposed to be it doesn't necessarily mean it's a problem it's pretty close it's not super perfect this higher range right here obviously is useful for measuring higher resistances now if you were to plug the meter into an extension cord and you had to come all the way up here to get a reading it's time to throw that cord away because the extension cord would never be 20 000 ohms or ten thousand ohms you want it to be under 1 ohm and a tenth of an OHM a half an OHM would be probably the very most I'd be willing to accept another useful tip for using a digital multimeter is if the battery is not fresh and is low on charge the meter may or may not tell you the battery is low but I will tell you that it is a fact that when the battery gets low these meters start to read inaccurately the readings can change quite a bit depending on the status of the battery inside in this case I'm sure the battery is at least half charged and I'm just showing some examples so I'm not too worried about it but if you're very concerned about the accuracy of the readings make sure the meter has a fresh and charged battery installed first another obscure fact about this type of multimeter is it's very common that people will just take the dial and flip it over to what they want and they don't pay a lot of attention it's very possible that the meter can get stuck in between so you can see right there I've stopped it in between two different settings and if you do that the contacts inside this rotary dial here may not give you the results you expect since this dial is actually part of the circuit inside the meter so if you're ever getting strange readings one of the things you can do is put it back on the setting switch it over and watch the dial and what should happen is the meter should zero out you can also trade things like pushing on the dial sometimes if you push on the dial you'll see the meter change its behavior and that's usually a red flag it could mean that the switch in here needs to be opened up and cleaned out with electronics contact cleaner or perhaps it is faulty the next function I'm going to cover is measuring current or amperage amps is a measurement of how much electricity is Flowing or the quantity of electricity that is flowing through an electrical circuit this information is fairly Universal so I'm going to use a simple battery which is a 12 volt battery it can pretend this is a solar panel a battery a DC power supply it really doesn't matter it all works the same to measure current there's two ways to do it you have Micro in milliamps here and then you have 10 amps now I generally pretty much never use these the most common one I use is this one here which is 10 amps and I would not put 10 amps of current through this meter but you know three or four amps for a few minutes or seconds to measure your circuit and see what's going on should not be a problem so in order to measure amps you will use the common connection which is right here and instead of plugging it in here which is for volts ohms and milliamps so the very tiny fractions of an amp that are measured here I'm actually going to plug it in here at 10 amps and in order to make this easier I've replaced my probes with alligator clips that are able to be plugged into my meter so here are my alligator clip probes I'm going to plug the negative into common and I'm going to plug the positive side into the amps now at this point you don't want to try to take a voltage measurement or you will short out the current right through the meter and destroy the meter so I'm going to switch it over to 10 amps let the meter zero out now I can go ahead and take a current measurement for this example let's use a fan that is an electric fan or a blower and I'm just going to connect it to the battery here that I showed you earlier when I connect the fan to the battery it's going to turn on and you can see that the fan is running it's blowing air and I can measure the voltage of the battery which I did earlier but what if I want to know how much current is flowing in order to measure the current flowing in a circuit you will no longer be placing the meter in parallel when you place the meter over the terminals of a battery you're effectively placing the meter in parallel with the output of the battery to measure its voltage but in order to measure the current or the quantity of current flowing through a circuit you have to place this meter in series with the item that you're running whether it's a fan a light bulb a solar panel a charge controller it doesn't really matter the principle is always the same so it's important to keep that in mind earlier I connected a fan to my alligator clips and the fan turned on what I need to do is I need to run that power through these two connections here and then to the fan then I will be able to see how much current that this fan is burning I've set up for the experiment I have my cables going to my battery which are right here this is positive and negative so this represents the output now I have two Thin wires coming from the fan that would represent my load now if I just want to run the load I just connect it to the positive and negative on the battery and it will turn on but that doesn't show me how much current is flowing through the circuit I know I can get the voltage by placing my meter across positive and negative of the power supply in order to get the current I'm going to attach the black alligator clip which represents the negative of the battery to the fans negative and that makes half of the connection now I have the battery which is this alligator clip here and the Fan's positive connection so what I'm going to do is instead of connecting it straight to the fan I'm going to insert the multimeter in circuit and I'm going to close this connection here using the multimeter this will cause the power to come out of the battery into the meter out of the meter and into the fan and it will give me the measurement this is going to be a little confusing I have two more alligator clips that looks slightly different so before beginning the demonstration let's be clear these two alligator clips are attached to these two connections on the meter common and 10 amps so now this is a series connection it's going right through the meter and out the other side the meter is just measuring between these two points to see how much current is going to flow this meter has changed its operation it's important to keep that in mind and understand it power is now going to flow through the meter through these two alligator clips so I'm going to attach the positive alligator clip from my meter to the positive power source now that leaves me with a positive wire to the fan and this black alligator clip which is actually going to be positive because this is actually connected to the positive terminal of the battery but going through the meter so let's see what happens when I connect the positive fed meter to the positive of the fan and now you can see that the fan has turned on and it's drawing about 150 milliamps or 0.15 of an amp 150 milliamps is very small amount of current and I can leave this meter attached all day as long as the battery in this meter doesn't run down it's perfectly safe there's not going to be any heat generated that is a very very small amount of power but if you're measuring five or six amps you would only want to do that for five or six seconds and then you would want to stop because a meter like this really isn't intended to be a high amperage meter and it will get hot eventually it could melt or blow a fuse inside if it has one so when I disconnect the meter the fan stops and the reading stops what if I want to know the voltage coming out of the power supply into the fan while the fan is operating obviously when the fan turns on the reading could change and here's where a number one mistake is often made you switch to dial straight to 20 volts and you start taking the measurement the problem is your meter is now in a short circuit so I got to remember to always unplug this connection here and put it back where it belongs so I can take a voltage measurement and if I don't I can burn out the meter so I went ahead and made that change I've gone to 20 volts now I'm going to change the setup again here is the battery output or the solar panel or the power supply or whatever you want to pretend that it is I'm going to connect that to the fan without the meter being in circuit the fan has turned on now I've checked my meter I'm verifying that it's currently back in common and voltage ohms and milliamps and not in the 10 amp range right here or the 10 amp socket I put the meter on 20 volts DC now I'm going to take the measurement of the battery or the power supply or whatever it is while it's in operation so in order to do that I simply take the power connection for the negative and I'm going to attach my meter to that then I'm going to take the positive side right here which is feeding power to the fan also and I'm going to attach my meter to that side and you can see that the loaded voltage present at the terminals of the fan is 13.22 volts or 21 volts it's jumping around a little bit and that's perfectly normal and it's nothing to be alarmed about now this is all on a very small scale in a lab environment but the principles are still the same let's disconnect the fan while leaving the multimeter attached and see if the voltage changes and you can see that the voltage actually crept up just a little bit it went from about 21 to 22 to 0.23 you know it was about 0.01 volt higher than it was with the fan running and that's normal and that's caused by the battery's internal resistance or the loads power draw which is going to pull the voltage down just a little bit in order to fully get everything out of this multimeter that you can it's highly recommended to study the relationship between resistance voltage and current you can do that online in your free time and it may take a while to understand but once you understand it it will change the way you look at electrical circuits of any kind whether it's solar energy household Electronics or anything similar even working on your car could be different if you know how to use this meter and you understand resistance current and voltage it will change everything I hope this video helps someone it does not cover all of these settings or functions on a typical multimeter all multimeters are different and may have different scales ranges voltages functions and features thanks for watching and I'll see you later

Channel: Solar Power Edge

Views: 11,083

Keywords: solar, multimeter, digital multimeter, how to use multimeter, multimeter concepts, voltage drop, continuity check, multimeter probes, multimeter safety, multimeter for solar power, check solar panel short circuit with multimeter, multimeter troubleshooting, learn multimeter, multimeter tutorial, multimeter how to check continuity, multimeter how to check amps, multimeter how does it work, multimeter how to check voltage, multimeter how to use, multimeter how to check battery

Id: F-L4pT5FvM0

Length: 44min 4sec (2644 seconds)

Published: Mon Nov 21 2022