Building a 3.5kWh DIY Solar Generator for $650 - Start to Finish

hey guys today I'm going to be tearing this craftsman tool box into a three-and-a-half kilowatt hour DIY solar generator so I picked this toolbox up at Lowe's I think it was about 25 bucks it's definitely heavy duty it's very spacious inside there's a lot of room to work with in here so I debated for quite a while what kind of batteries I was gonna use in here and in the end I decided to go with the standard 18 650 so I'm gonna build two packs in a 14 by 13 configuration and there's just enough room here that I can fit 13 cells in this direction and 14 cells wide it would have worked out a lot better if I could have fit 14 cells in this direction because then I could have worked more in this direction but these are the batteries I'm gonna be using for the project these are from some kind of modem there's 130 batteries here which comes out to 390 cells they should be 2600 milliamp hour cells they're currently on sale at battery hookup for a dollar fifty per pack alright so the best way to open this is just to take the two corners facing away from the terminal and you want a big pair of wire cutters and just snip into those corners and the lid should pop off it's very easy and there's your three cells inside and then you can use a common screwdriver to pop mufe you want but the way I've been doing is with some long nosed pliers and just grab the PCB like this and pull out and then your cells come straight out now I just have 129 more to open these cells ended up testing a lot better than I was expecting I knew they were gonna test good but I didn't know they're gonna be this good so out of 390 cells there wasn't one single bad cell in this lot almost all of them tested in the 25 26 or 27 hundred million hour range on average the gray cells did test higher than the purple cells so that actually gave me some extra cells left over only 11 fell outside that range and they're not even bad cells there's some 2421 you know they just have a slightly lower capacity so I was able to pull out these 11 cells that were below the 25 threshold so I'm gonna separate the grey in the purple cells just to make sure I can get an even distribution in each series pack now that cells are separated we can begin assembling our battery packs so for this particular build I decided to use the standard 4 by 5 18 650 cell holders however there are also these honeycomb designs which lessen the amount of space between each cell these holders will allow you to get a more energy-dense configuration and I did calculate you can fit up to four and a half to five kilowatt hours in that tool box if you were to use the honeycomb cells now while a four and a half to five kilowatt hour battery pack would have been preferable there are two reasons why I'm going with dis design instead of this design the first being that the holders in the nickel strip for this design are just a bit cheaper and the second being that if you put four and a half to five kilowatt hours in that tool box it's gonna be way too heavy and there's no wheels on it or anything like that now these holders actually measure 13 by 15 so when I populate these cell holders I'm gonna leave the rightmost lane empty and you could go with like a a hacksaw or coping saw or whatever and cut that off but considering it's only about a half an inch of space or so I'm just gonna leave it in place so now because these cells are all it from the exact same source and they're all the similar capacity I'm just going to use the randomized method of populating this and just fill them straight from left to right I'm not gonna worry about using repack or anything like that to get the capacity similar and because the gray LG cells did test a little higher then the Purple's I'm gonna start populating with those first [Music] now you'll notice when I populate these cell holders I have every grouping of two in the opposite orientation as the previous one and I'll explain why that is when I get to the spot welding step but first I need to get all these boards populated and I'm gonna do it the same way long wise as you see in the first row all right so now these cells are in the holders it's a little easier to explain why I chose to lay them out this way and how the configuration is going to be set up so I have 28 rows of cells total here and every other grouping of two if the polarity is reversed so this is going to be a 14 s 26 P battery so each grouping of cells of the same orientation is going to be wired in parallel and then each of these parallel sets are going to be wired in series so to do a little math here we have 26 cells in parallel times 14 sets that gives us 364 cells so one cell is 3.7 volts nominal times two point six amperes that comes out to nine point six two watt-hours per cell times 364 cells will give us three thousand five hundred and one watt hours of storage now we have 14 cells in series and the nominal voltage again is three point seven so they'll give us the system voltage of 50 1.8 volts nominal so it's slightly above 48 so before we put the top in just double check to make sure all the polarities are correct all right so here we have our two battery packs typically when you're using recycled 18 650 cells there's a little bit of glue left on the wrapper and your stuff left over that causes friction so the cell holders sit on perfectly fine however these cells from battery hookup were so clean coming out of the packs there was no glue on them whatsoever that they're actually loosen these cell holders so I'm gonna be very careful how you're moving this around otherwise the lid is gonna come off and the cells are gonna go everywhere so for the nickel strip I'm going to be using this to pee and it's called to pee because it's two cells wide 0.15 millimeter thickness nickel strip this is pure nickel I purchased this from Keith's store which is where I get most of my stuff from and he actually cut it custom to order so I don't even have to spend any time cutting it so Thank You Keith and there wasn't even an extra charge for the cutting and I really appreciate that so I'm gonna put one 2p strip up each parallel group and then you may have also noticed how there is slot in nickel and the reason for that is one probe of your welder is going to go here and the other probe will go here and this slot basically allows the current to go down through the cell and back up the other side rather than taking the path of short resistance and going straight across if this hole was not here now a much better design for this battery would have been to have 4p wide nickel that way these two were connected in series and I didn't have to connect them in series later however the layer of these batteries kind of changed from my original plan and Keith nor anybody else in the u.s. that I could find cells the 4p nickel and I didn't want to wait for international shipping from China which could have taken a month or two so what I'm going to do is weld the top in the bottom of each parallel set and the donors gonna put pieces of nickel going across every couple of cells to then connect them in series but first I need to get all the parallel sets spot welded and to do the welding I'm going to be using my son Co 709 80 spot welder that I modify with these custom electrodes because this is a 240 volt version and I don't have any 240 volt outlets in my garage I'm gonna have to take this in the house to get spot I have the welder set on a current of 7.5 in a pulse of 12 I laid the nickel over the first set of parallel cells and put one electrode on each side of the slot each cell will get four welds now I do have this welder on a dedicated 20 amp circuit but you can still see the lights blink each time I press the welder because of the instantaneous current it consumes the lights and welder are both plugged into an inverter not the power grid you wouldn't see the same dimming if this were the power grid and here's the finished product onto the next row alright so here's the first two battery packs all spot-welded up this is the main positive bus bar there are 26 cells here all wired in parallel and then these 26 cells are wired in series with the next pair of 26 cells and then the way I joined to 26 cell parallel sets is every other cell I just put a piece of nickel across and again it probably wouldn't better to use 4p or four wide nickel strip but this 2p will work just fine and here's just a little close-up so you can see what's going on when I did these series connections I did have to turn the spot welder up quite a bit to get a good weld so if you're doing something similar to this one thing you have to keep in mind is as soon as you start making connections this whole pack is live and you don't want to accidentally drop a screw driver or you know accidentally put a piece of nickel in the wrong location as you're working on this so you always want to double and triple check your connections as I was working across the pack with the spot welds I was covering the areas I had finished with this captain tape so that will prevent any accidents if a piece of metal were to fall on this battery pack or I leaned on it wrong or something like that so on the back here you can see the main negative it's done the same way as the other side so we'll put a voltmeter on here quick so the main negative to the main positive measures 29 point 1 2 volts so the only thing that remains to be done is decide how to terminate the connections from the main positive and main negative and to do that I'm going to use some of this 12 gauge silicon wire 12 gauge wire is rated for approximately 20 amps and we're going to be drawing more than that from this battery pack so I'm actually going to use two pieces of 12 gauge silicon wire on each end and then to make connections easier I'm going to be using standard xt60 connectors I'm going to use both terminals for the same polarities and making these connections is very easy first I'm going to put my xt60 in a vise you can pretend this as a vise and then just strip off like an eighth of an inch of the insulation so usually good and just twist the wires a little bit and slide a piece of heat shrink on each lead and then just carefully insert the wire into your connector and I usually apply heat to the top of these and just carefully insert the solder from the back double-check that you got a good connection and you're ready for the other side and once your connections are good you're ready to slide up the heat shrink all right there we go a perfect connector and I'm gonna connect this connector right in the middle of cells three and four from each end this will give me equal distribution between both ends of the pack however I don't want to solder directly to this nickel strip that's already here and risk damaging the cells or the holders from heat so I'm gonna take a separate strip of nickel and run out the entire length of this battery pack so I'm gonna mark this or I want to solder the leads so just to help make this job a little easier and not burn my workbench I just taped down this piece of nickel strip to an old piece of 2x4 so you'll notice how I fanned out the end of the wire just a little bit I'm gonna place it on my mark and when I attach that wire to nickel strip you saw me use a common screwdriver just to hold it down that's just to make sure the wire continues to make contact with the nickel as the solder hardens so now I just got to do the other side so now we can take this back inside and we'll just spot-weld this strip into place and there is our connection I spot welded that strip on the side of my battery pack to splice on my connector and it came out very well and doubling up that nickel bar helps the amount of amps that can carry along with reducing the heat if I would have soldered directly on the existing tabs so now if I stand up both of these battery packs next to each other on the back here is where the series connection will be made between the two packs so there's just two xt60 to plug in and if I take a reading with my voltmeter now I have 58 point 2 volts now I do have some heat-shrink I want to put over this but before we get the heat shrink put on we need to wire the BMS for the BMS I'll be using this Dahle brand BMS it's 14 s 48 volt BMS and it has a maximum discharge current of 60 amps there are multiple versions of the Dahle BMS this one includes balancing functionality and also includes common port and common port means you have one negative lead that comes out if this was not the common port model you would have one negative lead that goes to your charger and a second negative lead that will go to your inverter so this is the wiring harness that comes with you'll notice one of the leads is black we're gonna start with the black lead this is going to go to the main negative of the battery pack and then we'll work our way up to string with the Reds so after the main negative this will go to the first cell the second cell the third cell etc all the way up until the last red will go to the main positive of the battery pack so we're just going to solder this at the top of the battery pack and use these little bits of nickel they're left over at the top I'm going to tin the nickel a little bit first and this nickel is resting on this plastic so you want to make sure you're not heating this up too much and melting that plastic so looking at our wiring harness we connected the black already and this is the next wire in order so because our black wire is connected here the first red is going to go on the other side of the cell so we need to flip over this battery pack and to avoid the constant flipping I'm just going to work on it in the upright orientation all right now we have these two attached we're going to go on to the next wire so it's going to go on any of these terminals because this is the third connection so once you finish attaching all of your BMS leads you'll have something that looks a little bit like spaghetti mess and as long as you all that connections right you should end up with the last positive wire on the main positive of the battery pack now I was thinking I could shorten some of these wires and cut them to the length I needed to be that way this was a nice clean bundle however one of my viewers in the last video commented about leaving the wires the exact same length that way they all have equal resistance and the BMS is reading the cells equally and for security no balance leads in the battery pack I put down one layer captain tape and use the second layer cap and tape to hold down the wires and that first layer of captain tape was just for extra protection in the event any of these wires or cells would heat up now that we got our balance leak connected and our wires sneaking down we're gonna heat treat each with these batteries with this giant heat shrink this heat shrink is designed for a 15 Y battery pack and this is only a 13 Y battery pack so I'm hoping this will shrink down small enough if not we may have to purchase a smaller size and for the shrink I cut it about 3/4 of an inch large in the battery pack on each end all right so here's the completed pack once the heat shrink is on that full package drink definitely does give it a nice look now it would have been nice if there was shrinking enough to go around the entire pack instead having two separate packs I don't think there's one made that's big enough for that so I'm just going to slide this piece of plastic insulator in between the two packs and then I'll prevent the area where these connectors are soldered on from being squished in between and then I'll just use a few wrappings of captain tape to hold the packs together and one last thing before we can put this battery pack in our toolbox is we need to attach the BMS so the BMS has two negative leads one is marked p- and one is marked b - the blue lead marked B - is going to go to the negative terminal of your battery bank and the black lead marked p- is going to go to your inverter and charge controller so on the battery negative I just attached a standard xt60 connector and on the power side for the inverter and charger I am using an XT 90 connector because I wanted to use a bit thicker wire and 10 gauge wire will not fit in the xt60 connector also 40 to 45 amps is probably a lot on the high side for an XT 60 so first I'll plug the negative lead in and then I want to mount it just like this and I'm just going to use some zip ties to hold it down and with the BMS attached now we can plug in our balanced connection okay and lastly we'll plug in our positive connection all right so we should see full pack voltage in this connection now and we're at fifty eight point one so we're good to go for the remainder of this video I'm going to explain why I picked each component and then I'll show you how they're wired at the end I'm not necessarily going to include all the drilling and layout and assembly process because this video is already 20 minutes long and the primary reason for this video was the battery build and the choice of equipment so at the heart of this build will be a reliable electric pure sine wave inverter this is 48 volt 1500 watts you can see there are two battery lugs in the back and in the front we have to stand 115 volt outlets and just an on/off power switch now I already had this inverter from a previous project if I was purchasing a new one I would still go with reliable electric because they are a low cost and as the name States they are fairly reliable the only difference I would have done is I probably would have gone with the 2000 or 2500 watt and for the output connection on the generator I went with these recessed outlets each one is rated for 12 amps at 125 volts and they have tea receptacles so I have a total of four receptacles installed and each one also includes two USB charging ports they do come with a fairly lengthy cord and I obviously don't need more than a foot or so of cable so I may try taking this apart and see if I can shorten that cord or not because I really don't want all this bulk in a tool box if I can help it so for the user interface I went with this Drock brand energy meter the voltage supply is good for five to ninety volts of DC and it has a maximum rating of 200 amps so because we all need four twelve volts in our system as well this is a fairly standard buck converter and this is good for 240 Watts it will take in 36 or 48 volts I forget the maximum tolerance I believe it's like 62 or 65 or something and it will output 12 volts DC at 20 amps and the 12 volts will feed into to standard 12 volt outlets these are first standards cigarette lighter plugs like you would find in any automobile additionally that 12 volts will feed into this temperature fan controller it's just a small PCB that you can set a preset temperature on and it comes with this remote temperature sensor and once you have a set temperature on this board it will control this standard 80 millimeter case fan from a computer to ventilate the toolbox and ensure it stays cool the main on/off for the tool box will be this blue c-systems 50 amp circuit breaker I am questioning whether or not I can use this though because I see it says that the UL rating on it is for up to 32 volts DC however I noticed that the max voltage listed on it is 65 volts DC and I noticed on the website for blue C systems it also includes an interrupt rating at 65 volts DC so I did reach out to the manufacturer to see if I can use this for a 50 volt battery bank or not and hopefully I receive a reply on that fairly soon and last but not least I'm using this generic MPT 7210 a solar charge controller and I already have this controller as well from a previous project one reason I chose this over other options available in the market is that this is really a DC boost converter I don't think it's a true MPPT controller however I do like that this takes an input lower than your battery voltage so I can put anywhere from 12 volt panel a 24 volt panel or as a standard MPPT controller might take 100 to 150 volts to turn it on and since this is a portable build I don't want to have to carry around that many panels I want to be able to take just one or two panels out plug them in and charge away so while this is not the best option in the market it is the best option for my particular use case so that's where I'm gonna stop here at the video I'm gonna go ahead and get this stuff assembled and then I'll review the wiring and how I set everything up alright so I'm in the final stretches to get in this thing put together and before I start closing it up to where you can't see what's going on inside I thought I would do a quick overview of where I'm at so on the right hand side I have almost all the components mounted and I'll go over all of these later but for right now just know they're on the right side on the left side I have a fan so the right side fan is blowing air in and the left side fan is blowing air out so airflow is in this direction so then on top of this battery I just cut another piece of white plastic insulator that's going to fit in like so right on top of the battery and that gives us a nice insulated and flat surface and to mount the inverter on which will sit right here so if you have a look down in there I have four holes drilled on each side where I'm going to zip tie it into place there is plenty of room for air circulation in the back so the inverter will blow air out the back and then it will get sucked out by the lower fan and the case down here and on the right hand side there's plenty of space for air to come up as well and get sucked in through the inverter most of the wires are gonna be routed along the back back here I do still have to fit in the MPPT charge controller which will likely sit down in here I just have a little bit more fitting to do so that's where I'm at I'm gonna finish up the wiring and then hopefully we can turn it on pretty soon alright guys so it's finished and it is great I've done some basic testing with it but I have not hooked up solar panels yet before we do that let's take a look on the side and see what we got so we got 410 volt outlets each receptacle is good for 12 amps there are two cigarette plug later so this is like your car charger stuff like that that you might want to take out your car and use with a generator there are four USB ports each USB port is good for two point 1 amps of charging there's an xt60 connector for your solar input or an AC to DC adapter can also be plugged in here and then a 50 amp circuit breaker which also serves as our own off switch I did hear back from blue c systems and they did confirm that this breaker is good for up to 65 volts and once it's turned on the display on top will light up this basically shows the state of charge of the battery I'm not really sure how it's calculating this display here it shows the current voltage accumulative watt our display and it shows the amount of amps and watts being charged or discharged from the battery it's not super fancy but it's simple and it gets the job done now that being said it is not super accurate so when we open it up the main positive is coming up out of the battery and it goes into the battery side of the circuit breaker the load side comes at the bottom and this positively goes all the way back to the positive side of the inverter and then you can also see the negative lead coming up here as well except bypasses the breaker this is just a single pole breaker and the negative lead comes over and goes to the negative side of the inverter and then on the univers side we have a set of red and black leads to come off as well and they come up here to this nest of wires so we have a pair of red and black leads that come up to the DC to DC convertor this steps down the 48 volts down to 12 volts a second set of leads comes off and goes down to the charge controller and then two other leads come off of this controller and go straight down to the xt60 connector we saw in the front we have a black lead that comes off of the 48 volt splice and goes into the Drakh voltage display and we have a red and yellow that both come off with a positive and go into the Drakh I believe this is good for up to 90 volts if the voltage you're measuring was over 90 volts you would have to supply one of these wires with a voltage within the acceptable range and then the other wire would be the sense wire for sending the voltage of the battery because our battery bank is under 90 volts we can attach both of these to the same positive also I did make a mistake this is the 12 volts place and these are the 48 volts places so then the 12 volts that comes off of the buck converter comes down to these two splices you see one lead goes down to the fan controller down here and this fan controller is actually very cool might be difficult to see the display on the video but it is showing 16.7 which is temperature in Celsius and basically you just use these buttons to set the temperature for which you want this really to engage so you can switch any voltage within the range of acceptable voltage is printed on the relay because I'm also switching 12 volts I just have a little jumper lead going over to the input on the relay and then the output comes out to these two white leads which go over to the fame over here and the fan over here and then all three blacks are tied together on the ground lead and then that last lead that comes off of this board is the temperature sensor which I just have running up to the top and it's sticking off right over here where it's going to get a good reading away from any direct airflow so it additionally coming off a 12 volt rail we have both of our cigarette lighter outputs and they just run down here they are individually fused 10 amp fuses and they come down here to both of the cigarette lighter plugs and last but not least we have the AC wiring from the AC outlets now I was able to open these boxes up and cut and race out of the cord so I've only got about a foot a quarter in each one instead of having the full 10 feet or whatever it was times 2 rolled up and stuffed in here so I just tucked those underneath the inverter nice and sound so then the one thing I wanted to mention about this Drock display is this is the cable that came with it's a very thin two conductor cable with the shield and then the shield is used as the Center ground pin on here so it is shielded but it is very susceptible to interference that is any time this wire was ran along the wire or even when it was closed the lid and it was against this inverter this display was picking up all kinds of interference now this does have a way to zero out the display so you can account for the interference but the problem is any time this wire moves or the slit is open and closed the amount of interference changes so first I took this gray wire and I ran it through this ferrite coil and that was actually an idea that Keith had given me so thanks and that definitely helped with the interference but it was still not perfect so what I ended up doing is I replaced this wire and made a new wire this is aircraft wire three conductor twisted and braid shielded and I twisted it around three times twice Oh No making three passes through a smaller ferrite coil and then clamped it down with heat shrink and once I put this fairy as close to the display as possible it gave me a near-perfect reading and you can see where that wire attaches down here it's just a little coil that you pass your positive lead through and that just sits there reading the amount of current using a magnetic field so yeah that's pretty much an overview of the wiring on this thing and so before we wrap this video up I want to plug in a few appliances and test it out and see what it can do and then it's windy and cloudy today so hopefully tomorrow it's bright Sun and we can take it up back and plug some solar panels in and I'll show you how I do that Oh two more things I want to mention before I do that if you don't have fan holes cut and you're not going to be using fans for ventilation this is a watertight enclosure it's very important that you remove you can see there's a little gasket going along the outside the case here it's very important that you remove this gasket if you're not going to have ventilation holes cut because you don't want an airtight seal in this box if something were to happen you don't want this to turn into something where it's gonna get pressurized and could potentially you know blow up or anything like that the second thing is you'll notice there is no AC adapter in here to charge this you know most controllers most people don't realize that these controllers do not need to take a solar panel source you can plug any DC source into this and this actually has something like 10 or 20 profiles you can set up on it and so what I have here that I'm using is just a standard laptop charger I think it's 130 watts and ice place the next T 60 connector on it so I can just go ahead and plug it in the side in the xt60 port and you'll see the controller turns on and it's going to begin charging shortly so this controller is going to serve as both my AC charger and my solar charger I just have to remember when I plug this in and I'm switching between sources I need to make sure to set the correct source on this charge controller and this can handle a maximum of 10 amps input and/or output so this is a good balance between by having to buy an expensive controller and have a separate component installed in here taking up more space and generating more Heat so now the fun thing is we're going to plug a few things into here and see what it can do so the first thing up is just my cheap black and decker hammer drill and this is rated at 6.5 amps in nominal so I'll just plug it in here [Applause] that's pretty cool let's take a look at the amps over here and see what it's doing that's a lot of amps and the last thing I want to try is my craftsman shop vac and this has a rating of 7 amps so it's slightly above the hammer drill but again it's in the same range [Applause] alright so that was pulling about nineteen amps when it was running but you did see it took a big spike when it started so we're gonna do that Clint meter test again you can see I have it set on inrush and the display is zeroed out and that pulled 70 amps from the battery when it started that motor that is sweet that's actually incredible when you think about it alright so I'm gonna run a few loads on this tonight to run down the battery a little bit since it is full charged right now and hopefully tomorrow we can take it outside and show you a little bit of the solar charging all right so out here I have a 270 watt SunEdison panel the VMP or maximum power point voltage is around thirty point two volts I just took the positive and negative leads off of this and I splice them on to an xt60 connector and plugged it right in there front in the charging port now today is a partly cloudy day it's kind of sunny but it's not really full Sun and off that single panel I'm getting about 180 to 185 watts of charge this controller would have no problem handling two or three of these panels total I can put these in parallel I can't do it in series because that would exceed the voltage of the battery keeping in mind because this was an MPPT boost converter versus the traditional MPPT buck converter the operating voltage of the panel needs to be equal or less than the voltage of the battery and because this has been sitting out in the Sun for a little while charging I can hear the fans have turned on because it is heating up inside so this just further solidifies the point that you need to have some sort of active cooling if you're going to be building one of these generators and leaving it outside that being said we have reached the end points video I do apologize for it being so long however I wanted to make sure to include as much detail as possible if you found the video helpful please don't forget to hit the like and subscribe button any questions or comments please leave them below I do appreciate any feedback or constructive criticism as far as the build itself and my video editing if there's anything specific you want to see more of please leave that below as well otherwise thank you very much for watching

Channel: undefined

Views: 3,690,376

Rating: 4.9230614 out of 5

Keywords: solar generator, diy solar generator, diy battery pack, battery hookup, emergency solar generator, diy solar generator build, solar generator portable, diy solar generator box, diy solar generator cheap, solar generator diy, diy emergency solar generator, off grid solar, off grid, off grid cabin, off grid homestead, portable power, portable power station

Id: PVnQ87Fvsk4

Length: 33min 0sec (1980 seconds)

Published: Fri May 15 2020

Reddit Comments

[u/Hamilton950B]

I wish people would stop calling these "generators."

[u/Methadras]

This video exemplifies 18650MR

[u/goeielewe]

Is this your channel? Nice build.

[u/reddittwotimes]

I loved this! Thank you so much for posting it. The title is a bit misleading, but it was well worth the watch.

[u/allen06390]

Does it run by solar power? or it can be power by gas?

[u/FourTwentySixtyEight]

This video lead me to this sub today, cool stuff.