in today's video we're going to be learning about how volts amps and watts describes how much electricity is flowing through a wire in an electrical system but this video is geared for beginners so please do not be scared i know there's a lot of jargon and calculations and crazy theories behind electricity but I'm going to try to describe it in the simplest terms possible so first let's talk about electricity we are not going to get bogged down by theory we're just going to understand that electricity travels through wires or conductors or pieces of metal that transmit electrical force over a distance so if I want something to be electrically connected from one point to another point we use wires to transmit that electrical force and what a wire is is a conductor that is sheathed by an insulator and all this means is that the stuff inside the wire can transmit electrical force and the stuff on the outside of the wire cannot and it blocks electrical force and so a wire is kind of like a water pipe the electrical force can transmit in the middle or the water can flow in the middle but it cannot escape the sheath it is trapped inside so it can be transmitted over a distance if you have two wires you can transmit it with DC current and AC current so first let's talk about a DC system direct current what you have is a positive and a negative lead this is like a car battery you have a positive and a negative a red and a black and when you attach two wires to the positive and negative terminal of a battery and you connect it to an appliance that is rated for 12 volts what happens is electrical force or electrical charge will flow through these wires it will go out one side of the battery to the appliance and it will flow out of the appliance and back to the battery so the DC current is like a river the electrical force flows through the whole thing in an alternating current system what we have instead is alternating current so that means that the positive and the negative are switching really fast and what this does is it causes the electrical force to vibrate instead of flow but I do need to explain that it's not a physical vibration the wire does not vibrate at all it's the force inside the wire and this is technically called an oscillation and so the positive and the negative are switching so quickly that nothing in the wire is physically moving but it's transmitting the force across the wire so in an alternating system there is no positive and negative the electrical force is being transmitted through vibrations there is no flow and the best way to actually imagine it is that a DC system is like a river and it flows and an AC system is actually like a wave going across an ocean so when a wave transmits over a long distance in an ocean the force moves but the water does not move it's the same with electrical charge in a wire with a DC system it flows through the wire but in an AC system it vibrates nothing in the wire moves in an AC system but it moves back and forth and it vibrates to transmit the electrical force now that we have that out of the way let's talk about how electricity is measured we use volts amps and watts to describe how much electrical force is being transmitted through a conductor or a wire voltage is like the pressure or the force of the electricity and the amperage is how much electricity is going through the wire and a good way to imagine what voltage is is by using the water hose analogy so what we want to do is in our mind think about electricity as being very similar to a garden hose with water and the voltage is the pressure of the water and whether the water is flowing through the hose or not the pressure is constant and the voltage is always there and this is because voltage is the energy potential or how much force is ready to be used and if you have a garden hose even if it's turned off you know that water pressure is present and the voltage can tell you what appliances you can hook up to your system if you have a 12volt appliance you can hook it up to a 12volt battery if you have a 110vt AC appliance and a 110vt AC plug you can connect them together so I like to think of voltage as a way to understand compatibility so now that we understand voltage and it being the pressure of the water in the hose example or the force of the electrical charge now we can talk about amperage and the amp rating or amperage is how much electricity is flowing through the wire the amp rating will determine how big the wire needs to be when attaching electrical components to each other so let's go back to the garden hose example if you have a garden hose and you want to know the amp rating equivalent it will be how thick the water hose is because the thicker it is the more water you can carry and if a wire is bigger you can transmit more electricity through it so if you have a large appliance that you're connecting to a battery you need a larger wire to transmit more electricity to it and if a wire is not large enough to carry a load to power an appliance it will be given off as heat and that wire will generate lots of heat and it can generate so much heat that it can cause a fire so let's recap the voltage is the pressure or the electrical force in the wire and the amperage is how much electricity is going through that wire and these can determine the compatibility of system components if you have a 12vt solar power system or a car battery you can only hook up 12volt appliances to it when you hook up a 12volt appliance to a car battery you will need a wire that is large enough to carry the amount of amps required for that load now that we understand volt and amps we can move on to the next metric which is watts and all watts are is a combination of volts and amps it is simply the voltage times the amperage and that will tell you the total amount of electricity going through a system so the volts and the amps are kind of proportional or work together to determine what the watt rating is let's imagine with our water hose analogy we have two hoses one hose has high pressure but it's a very small hose and let's say another one is low pressure but it's a very big hose let's say that the two hoses even though they vary in pressure they still fill a bucket in the same amount of time you would say that they still have the same watt rating because in an electrical system you can have a wire that carries a very high voltage but a low current and another wire that's very low voltage but a high current but at the end you have the same amount of power that can go through these two wires they're proportional and they determine how much electricity can travel in a wire the total amount so let's imagine this for a second let's say we have a solar panel that produces 10 volts but only 1 amp that means that together if you multiply those two metrics the volts times the amps you'll have 10 watts 10 * 1 equals 10 watt now let's say a solar panel produces 1 volt but at 10 amps if you multiply those two together you will again get 10 watts both solar panels produce the same amount of power or wattage but at different volt and amp ratings the difference in these components is that one will require a much larger wire to carry that power the larger the amp rating the larger the wire but you can see that even though there's different volt and amp ratings they still produce the same amount of power so let's do another example let's say a solar panel produces 50 volts but 2 amps it still will produce 100 watts let's say we have another solar panel it produces 10 volts and 10 amps that means that it will still produce 100 watts so it's very simple you multiply volts times amps you get watts but and with that information you can also go the other way so we can take the wattage of a solar panel and determine the voltage and the amperage if you have one of those metrics so let's say we have a 100 watt solar panel and we know that the voltage is 10 volts but we don't know the amp rating so we will take 100 the wattage and divide it by 10 and we will get 10 amps and let's do another example if we have a 50 watt solar panel and it produces 25 volts if you divide 50 by 25 you're going to get two so that means it produces 2 amps at 25 volts so even if a sticker on the back of an appliance shows the wattage and the voltage but it doesn't tell you the amperage you can figure it out also if it tells you the amperage and the wattage you can figure out the voltage and the wattage gives you a good idea of how much power something is using it doesn't tell you the compatibility or what wires to connect to it or the fuse size at all the wattage only tells you how much power overall it's generating or consuming and we can use the wattage with time to determine what are called watt hours so if you look at your electricity bill it will tell you how many kilowatt hours or thousands of watts of hours you have used and this is very simple too okay it's just the wattage times the hours so if you use 100 watts for 1 hour that's 100 W hours if you use 1,00 watt for one hour that's 1,00 W hours or one kilowatt hour it's very simple and the W hour is really good to understand how much electricity an appliance or a solar power system is generating or consuming over time but you can also use W hour to determine how much electricity a battery can store so let's say we have a battery that is 12 V and it can produce 100 amp hours if we times 12 by 100 we will get 1,200 W hours that's how it works if you have an amp rating for a battery in amp hours and then you have a voltage you multiply the two and you get the WH rating and the W hour is the best way to compare two batteries and so first let's talk about how batteries are rated so if you go to the store you will find a 12vt car battery and let's say it has 100 amp hours that means that it can produce 100 amps for one hour at 12 volts but you need to understand that the amp hour rating is at that specific voltage it is variable so a lot of people when they see a 6volt battery they'll say "Wow 225 amp hours but that's at 6 volts." If you were to series connect that battery with another 6volt battery the amp hours will not change and when you know the Watth rating of a battery you can determine how long it can power your appliances for and how long it will take to recharge with a solar power system or an AC charger so let's say we have a,00Wh hour storage battery and we want to power a 100 watt load what we do is we take a,000 watt hours and we divide it by 100 watts to tell us how many hours we can power it for so a 1000watth battery can power a 100 watt load for 10 hours very simple guys now let's do a second example let's say we have a 100watth battery and we want to power a 50watt load we can only do it for 2 hours and you guys need to compare things with watt hours and watts because easier to wrap your mind around so use volts and amps to figure out the wattage and then use watts with time to figure out Watt hours and then use Watt hours to determine how big a battery is how long it takes to recharge that battery how long you can use that battery to power your loads and everything else that's the best way to figure it out and this can really throw people off if you do not use the W hour in watt ratings like for example my 24volt Tesla battery produces 250 amp hours at 24 volts if I were to run this system at 12 volts it would be producing 500 amp hours so people will see 250 amp hours and say "Oh that's not that great." But when you double that number you'll be like "Wow that's a lot." Because they're trying to compare the amp hours do not compare the amp hours find the watt rating or find the watt hour rating and use basic arithmetic to compare i have to drive that point home and so now we can talk about parallel and series connecting system components so when you parallel and series connect you can change the voltage and the amp rating of certain components including batteries and solar panels by connecting them in various ways so if you connect things in parallel what that means is that you connect all the positives and all the negatives if I have 10 solar panels and I connect all the positives and I combine them into one wire and I combine all the negatives and combine them into one wire that's a parallel connection if instead I daisy chain these solar panels and I connect the positive of one to the negative of the one next to it and then the positive of that one to the negative and I make a string or a daisy chain of these 10 panels that's called series connection so in a parallel connection what happens is that the voltage does not change or the force of that electrical charge like the push will not change but the amps will so if you parallel connect all of those solar panels and you connect 10 panels and each one produces 10 amps you add them together and you will get 100 amps so if you parallel connect the amps will go up and the voltage stays the same in a series connection when you daisychain them together what will happen is that the voltage will rise but the amps will stay the same so let's say we still have those same 10 solar panels and they all produce 10 amps but instead of producing 100 amps with a parallel connection they will still only produce 10 amps with a serious connection but the voltage will go up so let's say each panel produces 10 volts instead that means that altogether when series connected they will produce 100 volts instead so you can change the voltage and the amp rating by series or parallel connecting different components so now that we understand the basics we can design a solar power system from scratch and this will give you guys a good idea of how to plan out your own system if you plan to build one so first we need a battery we're going to use three 12vt 155 amp hour sealed lead acid batteries the batteries are going to be in parallel so we want to add the amp hours together so 155 + 155 + 155 is 465 amp hours at 12 volt if we have this battery bank of three batteries and it gives us 465 amp hours if we multiply that by 12 volt we will get 5,580 W hours total but because this is a lead acid battery we need to cut this figure in half because sealed lead acids can only be discharged to 50% if you want a long lifespan for the batteries so the usable is actually 2,790 W hours now that we have a battery bank we need to charge it with solar panels so we're going to hop on Amazon and we will find a solar panel and the data sheet says 17.2 volt and also produces 5.82 amps under ideal circumstances and if you combine those figures it will give you 101.1 watts and we are buying four of them so altogether it will be 404.4 watts now we need to figure out what size solar charge controller we need and solar charge controllers are rated in amps so we need to figure out how many amps at 12 volts our 17V solar panel set will actually produce so get this we're going to take 404.4 4 watts which is the total solar panel array wattage and we're going to divide it by 12 volts and this will give us how many amps our solar charge controller needs to be able to handle and so 404.4 / 12 gives us 33.7 amps so that means we need to buy a solar charge controller that is slightly bigger so to be able to handle a 33.7 amp load we need a 40 amp solar charge controller and this will also allow us to add an extra solar panel in the future if we want to it's always best to size your solar charge controller larger than you need okay so now we have a battery bank and now we have solar panels how long will it take us to charge up this battery bank so if the battery bank is 2,790 W hours we can recharge it with a 404.4 W solar panel array in 6.89 hours in ideal circumstances because solar panels typically output only 70% of rated wattage so what you will do is take 404.4 and multiply it by 7 and you will get 283.08 watts so realistically it will take 9.85 hours to recharge this system under most realistic circumstances with solar panels so let's say we have a 100 watt load that we want to power with this system because we have 2,790 W hours available in our battery bank you will divide that by 100 and you will figure out how many hours you can run it for so 2790 divided by 100 will give you 27.9 hours that means that our battery bank when fully charged can power a 100 W load for 27.9 hours if instead we want to power a 1 watt load we can only do it for 2.79 hours and if you can't find the watt rating of an appliance you can take the volts times the amps figure out the watts and then compare it to the W hour capacity of your battery and then divide it and it will tell you how many hours you can run it for also keep in mind that flooded lead acid batteries and lead acid batteries in general they are typically rated at the 20our rate so if you're trying to run a large load you need to understand that it's not going to give you nearly as many amp hours sometimes it can be as much as half it's also dependent on temperature and lots of other factors i have a whole other video that's just as long as this video that talks about the discharge rate and what's called the pukeert effect so you guys can check out that video if you want and now we're going to learn about how to size a fuse and the wire gauge for an appliance and so all a fuse is is a small wire that heats up at a certain amp rating and if too many amps goes through it it will disconnect that appliance or the wire so if something bad happens to that wire or the appliance shortcircuits internally what will happen is that fuse will disconnect power so a fuse is like a switch it's a self-destructive switch and whenever you connect an appliance or a charging method to a battery the battery is an amp source the battery can produce hundreds of amps so you need to make sure that it's protected because if all of that electricity flows out through the wires of a DC system it will generate lots of heat and you can catch things on fire so you need to size the fuse and the wire gauge size accordingly for your application so if you're connecting appliance to a battery we are going to learn what size wire to use and what size fuse and how to calculate that in a very fast easy way so first let's think about the size of wire that we need to connect your appliance to a battery so first you need to find the distance that the wire is going to be and also the amps that that wire needs to carry with these two variables you will jump on the internet and find a chart and it will tell you what gauge of wire to use for that size of load at that distance it is very simple and easy to find these charts now that we know the gauge of wire used to connect your appliance to the battery we need to find the size for the fuse and the fuse needs to be able to protect the appliance and the wire itself and so in order to do this you need to find the right size fuse and if you have a wire gauge that is appropriate for an appliance what you can do is size the fuse to 125% of the amp rating there are different codes some people say 135% for certain circumstances with special types of fuses you want only 100% but 125% of the amp rating is the best in my opinion it's very easy and most people agree that it works for most things so what you do is you take the appliance amp rating and you times it by 1.25 and it will give you the amp rating of the fuse that you need to connect to that system and if you use the proper gauge of wire and you also calculate to 125% of the amp load the wire and the appliance should be protected also keep in mind that when you look up these charts some of the charts will say 3% loss and some will say 5% loss and this is just the efficiency this is because all wires give off a little bit of heat and if you use a wire that's too small it will give off more heat and will not be as efficient if you have an appliance that's connected to the battery and it's always turned on like an inverter in standby or a solar charge controller what you need to do is make sure that the gauge of wire is larger than necessary so it's more efficient and you have less losses if your load is infrequently connected you can use a slightly smaller wire but you still need to make sure that the fuse is calculated for the appliance and the wire so if you're using a smaller wire than necessary because you just have to for whatever reason you need to make sure that that fuse is sized to the wire and not for the appliance in that situation because both the appliance and the wire need to be protected with that fuse so let's imagine that we have a 100 amp load and it's 10 ft from the battery if we look at our wire gauge chart size it will say that we need 4 gauge wire and this is copper wire not aluminum wire aluminum wire does not carry as many amps you need pure copper to be able to use these charts right if not you're going to have to find an aluminum wire chart and they're a pain in the butt so now that we know that we need to have four gauge wire we need to calculate the fuse size for with this 100 amp load so we will take 100 amps and multiply it by 1.25 and that'll give us 125 amps so we'll go down to the store and we'll find a bolt-on fuse or an inline fuse holder or something that can hold a 125 amp fuse and we will connect that as close to the battery as possible so we'll go battery fuse wire appliance and that's on the positive lead of the battery and then the negative it doesn't matter the negative does not need a fuse the negative will have its own four gauge wire going to the negative terminal of the battery and typically when you build systems it's nice to over gauge your wires i usually build stuff that's under 3 ft with six gauge wire even for 24vt systems because I will have practically no losses and if you feel the wires after you build your system and they are getting hot that means you need to make your wires bigger because they're generating too much heat you want the wires to be as efficient at carrying that load as possible also if the fuse is too small what will happen is it will put resistance on the load if you're pushing 100 amps and you have a 105 amp fuse that fuse itself will generate heat and this can cause a bottleneck situation and produce quite a bit of energy loss in your system so let's recap first find the wire gauge size for the amp load you need distance you need to know how many amps are going through that wire then take the amp load of the appliance and multiply it by 1.25 or 125% of the amp rating and you will get your fuse size as long as you follow that you should be good if you have an appliance that is constantly connected and there is always power going through it use a larger gauge wire than necessary but still have the fuse size calculated for the appliance no matter what gauge wire you use because you also need to protect the appliance and there are lots of other circumstances and codes that we could talk about where some of these numbers can change a little bit but for DC 12VT everyday people this will cover pretty much 99% of it if you do have an inverter and you have a very high surge and your circuit breaker or fuse keeps tripping then you'll have to just make it bigger but you don't want to make it that much bigger so try to calculate it out to the most common surge that it will experience so if your surge is like 3,000 watts try to calculate it for that and now we're going to have one more example for inverters because that can be kind of confusing so let's say we have a 1,500 watt inverter we need to divide that by 12 volts and then we will get 125 amps and then we take 125 amps and we multiply it by 1.25 that will give us 156.25 amp so I'll have to use a fuse that's around maybe 160 amps because that's probably the size I can buy at the store and then also with the surge we could add another 20% onto that so I would say maybe around 170 180 there's also slow blow fuses and other things that could actually work better for that some people like to size their fuse really big and use large gauge wires for an inverter so it really depends on the application but if you use 1.25 it works pretty well and that's how you size a fuse or a wire gauge it's not that hard just use a chart and then times by 1.25 bam you're done