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hello everybody i just finished building this diy battery and the capacity test worked out awesome stick around if you want to see exactly how i built it and the test hi i'm david and welcome to my channel where i like to build projects that are diy renewable energy and energy efficiency for this build we are going to use this empty battery box which has the same dimensions as some of the popular brands that you could purchase it is a very nice form factor now it's a completely empty box right now and we're gonna fill it using some of these lithium iron phosphate cells now these are brand new cells from battery hookup and these are 3.2 volt nominal because they're lithium iron phosphate at the end of the project we'll do a capacity test and we'll run through all the numbers and see what it comes out to in the end for cost hopefully we can build it less expensive more affordably than what you could buy it for off the shelf and it should be a lot more fun to build it ourselves so here we go all right everybody let's take a closer look at these cells we're going to be using these are brand new cells from battery hookup 3.2 volts nominal and 5 000 milliamp hour and they were manufactured just a few months ago and if we put these next to each other we can see the new lithium-ion phosphate battery is actually slightly taller which i was surprised by because this says 65 on it and this is also a 65 18 and this is 32 but this one did turn out to be longer so it might be more like a uh 32 by 700 65 millimeters so that's right on the dot with the seven centimeters which is going to be 70 millimeters so i actually wish that they labeled this as a 32 32-700 plan fitting these into something really tight and that might make a difference to you the five millimeters all right let's put this away we're left with about an inch or three centimeters of extra space so as far as how many of these cells can we fit in here i bought a bunch of these two cell holders and three cell holders and they'll fit in this orientation so we have four across the bottom and five tall so we have a little bit of play but not enough to go with the five wide so so this works out fine we're going to get a 20p or 20 cells in parallel and 4s since these are 5 000 milliamp hour cells according to that number right there this will turn out to be exactly a 100 amp hour pack now there is a little bit of space right here the lid is taller than the top of this lip and that extra height will help when we add the bms now the cells and the cell holders i purchased from battery hookup and this case i bought from aliexpress and i'll leave links to everything in the description below if you're going to purchase anything from battery hookup you can use the coupon code davidpaws and that will get you 10 off so we're going to take four of these cells and put them in series which is going to create a 12.8 volt nominal pack which will work really well it's going to have a good voltage range for typical 12 volt applications well all eight cell holders are now done i noticed one little quirk where i have the two cell holder joining in it caused this little oddball where some of the dovetails pop out on the wrong side just on where i have the three and the two lined up with each other now it won't cause any functional difference but that could have been eliminated let's say if i just got all three cell holders only and then cut off the last of the three cells i ordered a case of 100 of these cells because i wasn't sure exactly how many i could fit in here it turns out 80 can fit in very nicely with room to spare for the bms so you can order just as many as you want you don't have to order a case of 100. now something to note the box did get a little damaged in shipping which is a little disappointed right here you know i wish that wasn't the case but when i opened it up the cell itself doesn't look like it has any damage it doesn't look like it has any dents but still i'm not going to use the cells in the four corners and with all the cells in one of the trays we'll take the next one and put it on here and give it a little oh went in pretty easily sometimes you have to shake it a little bit to get the cells to fit in the covers could come off and they could fall apart if i'm not careful so i'm gonna hang this over the edge just a little bit and i've got some of this cap ton tape and this is a high temperature tape before i spot weld these which will parallel the cells i want to double check that all the cells are within one tenth of a volt of each other 3.29 3.28 terrific every single cell is between 3.2 and 3.3 so we're within a 10th i didn't see anything below 3.24 and i didn't see anything above 3.29 yesterday i was spending quite a bit of time mocking up different scenarios i've got different types of nickel strips different thicknesses here's a coil of some nickel-plated copper strip so i've been mocking up different scenarios and trying to come up with the best solution of how i can do this when you plan your series connection there's several things that need to come into play part of it is how this all folds together or gets into the enclosure how are we going to actually make those connections but also how many amps are we going to be carrying this cell group has 20 cells in it this can easily do 100 amps and this bms that i have is a 100 amp bms but in reality you don't want to charge these over 50 amps which would be a half c rate and that's because when you start charging a cell more than a half c rate you're going to start causing excess heat to build up and when these are packed together in a small enclosure that can start to become a problem now not necessarily but potentially and this is why you find even other companies like battleborn battery the kilovault the victron energy when they have these modules that are already built as a 100 amp hour lithium iron phosphate they recommend in the user manual not to go beyond a half c not to go more than a 50 amp charge and that's because of the heat buildup now when you take all these factors into account i have decided to limit the amp capacity of this pack to 50 amps so i have here a midnight solar brand circuit breaker of 50 amps so that is going to be the weakest link now i want to make sure that all of my series connections are capable of 50 amps continuous without overheating now for example this nickel strip is 0.15 millimeter by 8 millimeter this is good for about 5 amps now this is a double wide nickel strip made for 32 millimeter cells which is what we have here now if you look at just this part of it just one stretch now this is about what was it 15 millimeter by 0.2 millimeter so this is good for 12 amps so if i use five of these strips that is a 60 amp capacity continuous and i know that the series connections won't be the limiting factor i won't overheat them now i've mocked up how i'm going to fold these accordion style here just with tape right here in the middle we have put down some nickel strip and it's not yet spot welded and i just put a piece of cap on tape to hold it in place and a straight edge to make sure that we're lined up so i have a temperature sensor here and it's just jammed into this xt90 connector and i want to stop when we start overheating we're going to change the joules and we're going to go to 50 joules now 50 joules is about right for 0.2 millimeter nickel that's what we're using here so we're at 50 joules now we press this once i'm going to go down to calibrate we're going to hit calibrate it's going to tell me open i click to say yep i'm open now it says to short so literally going to hold these two probes really tight together and press and hold you saw the wires jump because it actually sent some electricity through there and then we can release when it said okay now i'm going to press this again i'm going to go up to mode enter and auto if you can hear that clicking now so we just finished that row and they all look good 50 jewels let's see what our temperature is whoa 84.4 degrees celsius and that probe is right there in that xt connector if i take off a glove and check yeah yeah that is that is hot so i'm going to take the tape off and reposition this and that will give the xt90 a chance to cool off a little bit see it drops pretty quick but that's a lot for it 50 joules it's not as big of a deal when you're using thin material because you can turn down the power setting now this is finished being spot welded and i put a layer of kapton tape on it i want one more layer because these are going to fold in and touch each other now this is some paper with adhesive on one side and i did a search for battery paper and this is what came up i think i've heard somebody call it barley paper before it kind of feels like a thick construction paper adhesive on one side peel off the backer now i'm going to stick this on the negative battery right down the seam this is a the exciting part turning it up bend this in so yep so i think that will work well here you can see the nickel right there and i'm just kind of pressing these two sides together to make sure that nickel has a good crease on it right at the intersection [Applause] nice there we go here's the positive side i set this up yesterday where i oriented all the nickel strips on a piece of plywood i then soldered them to four layers of copper strip so that i could get the amp carrying capacity that i want and then i just soldered on a pair of 10 gauge wires now i used a pair of 10 gauge because that's the same gauge wires that the bms has i still have some more spot welds to do up here but i have to wait till the spot welder cools down and these positive wires are going to come off and come up the side and i still have to do the negative on that one okay all the spot welds are done up top so now let's fold this over this is the wiring harness for the bms now the main positive wire is this red one it needs to go over here onto this positive bus bar and then each one needs to tie in subsequently now i'm letting the usually i'd want to put this on first but i'm letting the spot welder cool down right now so i'm going to go ahead and solder these on while i can and then we'll spot weld the last main bus bar later okay so if i open this up then i can see right here is some so let's go ahead and try to solder to that all right so this worked out fine now i'm sorry i just couldn't get a good camera angle to show you while i did it but i just peeled back a little bit of tape and put that on there i'm going to tape this over again now there's a little recess in the plastic see there's a high point in the plastic here and here and there's a recess that's where the wire is coming out okay so i put a little tape on there and now i'll close this back up and you can see there's plenty of space that it's not going to short out to the next cell like it's not going to rub by doing that so that's in place this one's in place next i'll go right here to that one because it's nice and convenient so i'm going to take the plug and the first two wires are done so i'm going to grab the third wire and now run my fingers along it so that i don't screw that up and this is the one that's going to be soldered on here this is a little bit of flux so the first thing is just to get a little bit of solder on there there we go alright so now we've got the now we have the bms and it comes over here and i want to attach it right at this point okay so what i did is i just took a little strip of nickel and i jumped it over these two wires and spot welded it and that will help keep them down and in place getting some solder in from the back side so so now we have the bms attached to this which i pre-made in the right orientation all these nickel strips need to be spot welded up here onto the battery but i'll go ahead and solder on the last wire for the bms voltage sense which is this black one so that soldered on fine there we go all right so now i've got all the voltage sense wires i'm not yet done i still have more spot welds to do but this is overheating so i'm going to let it cool over here we have the voltage sense wires so what i like to do before ever plugging this into the bms we need to make sure that i haven't crossed a wire i haven't jumped one in the wrong location so to do that let's take a multimeter and we'll set it to volts dc 3.2 you have to be careful not to touch your two probes of the multimeter now this should go up by another 3.2 and it did another 3.2 yes and the last and final 13 perfect it's easy to keep track of the wires when it's only a 4s but when i'm doing my big 14s or 16s battery packs this you can sometimes cross these so but we've got them all in the correct location now if you do cross them and you plug it into the bms you will likely blow out the bms you'll burn out one of those little chips on it now i've taped this top end and we have the bms attached which is back here so let's go ahead and put a little bit more paper on this assembly all right well this is looking really good now it's a solid package okay there we go i have to put spacers in so that the wires on this side don't get crushed and then over here and probably over on this side too i'll just add some some block or something so i want to use this half inch cutting board as a spacer on this side and i want to prevent then all these wires and stuff from hitting the side of the box so i'm going to route out this part right here for this cable now probably if i did it again i should have just put the positive wires up here but my thought was you know diagonally because that helps even out the flow but i don't know probably not necessary anyways let me route this out all right i routed out the board and i'm going to put it on here like this i need to cut this tape because the tape's in my way as much as i like having that tape right down in here you can kind of see getting it in so i'm just reaching in with my finger and pushing it into that groove and then i can push it against there and now i'm going to tape this in place i have half inch cutting board on each end i also have a piece of half inch cutting board down here and it's routed out for that positive wire all right let's uh let's tip it up right i think that's going to work yeah that should work uh-oh sticking a little bit okay snug fit all right when i plug this in i'm gonna put a bluetooth dongle on here now this may or may not work with android but i'm going to try it now this bluetooth dongle is a separate part that you can purchase it doesn't come with the bms i was able to download the app from battery hookup's website opened the app on my phone and i was able to discover the bms but i couldn't actually get the bms to open inside the app instead an error message was coming up on the screen saying that it doesn't work with the version of android that i have on this phone this is a google pixel 3 so whatever version comes with that now this is my wife's apple phone and it looks like it has discovered the bms so let's go ahead and see if we can get information from the bms it says waiting for data and it looks like it opened hey that's great so here's the bms bluetooth dongle we have a blue light and it looks like it has connected to the apple so in this case we're looking at 21 13.13 that's great well let's see what the settings are from the factory let's see here if we hit configure writing parameters to bms costs more money hmm uh i guess the free version of the app will let you look at the cells look at maybe the watts coming in and out that says power there but it won't let me set the parameters so what voltage to overcharge what voltage to balance those types of things we have the circuit breaker rated for 150 volts dc and 50 amps and i'm going to get it as close to this positive terminal as possible so that the rest of this room won't interfere with the bms so if i put it up like this you'll see i'll just be flipping the lid on here and i want the circuit breaker and the bms to be on different sides so they don't interfere i start by cutting this close inside because i can always go wider you see i need two holes for the two screws it's going to be a little bit offset but i think it it'll go in like this i'm not sure yet if they're going to reach they're fairly short but let's give it a shot alright so here's the screw and i use this thread checker and i found that it's a 6 by 32 5 16 right now let's see if we can get one a half inch going through my pile of random screws i was able to find a couple of 6x32s but these are too long so let's go ahead and put them in and then we'll measure how much we have to cut off so now we have the circuit breaker in place and if i flip this over we can see how much the screws protrude out now i have the screws bottomed out inside the circuit breaker so now i can measure this distance and that's how much we have to cut off and it looks like we have to cut off three tenths of an inch if i cut these off just using a hacksaw that would leave a rough edge that would then have to be cleaned up so instead there's an easier way to cut these off this is just a pair of wire strippers it's just a i don't know a generic one that i've had for as long as i can remember but it has 632 printed right there so what you can do is open it up and we'll screw this into the 632 hole and there's threads on this upper piece of metal and then the bottom hole is just open so it will scissor that off it'll just snip it off for us you can see it coming through there now if i apply pressure it's going to cut it off but i haven't measured it yet so we know that we want to cut off three tenths of an inch so we'll come over here to the back side now remember it's going to cut it off right in the middle between the two so we'll go like this now that would cut off too much so i'll back it out a little bit so now i'll just squeeze this like that there's the piece that came off and we'll unscrew this and as we i'll have to unscrew it using a screwdriver because that'll come out of the there we go so that should thread in okay now those screws are shorter we were able to screw the circuit breaker in place i mocked up what i needed with this piece of nickel and now i am putting it on this scrap piece of copper that i have [Music] now drill out these holes and what this is going to wind up doing is making the connection between the circuit breaker it's going to go on like that and then fold down and go on to there let's see if this double layer can fit on here yep fits over that stud looks like that's off a little bit i just think it's the bend let me try to re-bend it now one layer could probably handle the amps no problem serrated flanged bolt thread locker there we go on the circuit breaker great okay both of these are torqued down nice and tight i threw down some paper in between the battery cells and the bms just one more layer of protection i marked here the distance that this edge of the plastic comes out so they won't interfere and i'm going to tape down this bms and kind of get it right up like that real close to this edge so that i have enough space for the slack of this wire all i need on this edge is enough space for the lip of the lid there's a two layers of the lid here so this can get real close up to that side the temperature sensor is under there the voltage wires come over here so let's get this taped down so the next thing to do we're going to cut this off we're going to put some ring terminals on here with the hydraulic crimper that's going to be on both sides and then we'll finally be able to attach it to the lid section now each one of these wires is a fine strand 10 gauge wire with silicone insulation so it's high temperature insulation they're nice wires i think i can fit them into an 8 gauge ring terminal so i have some eight gauge ring terminals here there we are nice so both wires can get in there at the same time now we can crimp that i'm going to try a number 10 die we'll see if it works pull on each wire individually and i'm not getting any movement so we're good okay so now these three have loctite on them i threw on just a little bit of electrical tape over those terminals so now we have plenty of slack in there now we just have to crimp on the ring terminal for this one this is the ring terminal that i had and i drilled it out to accept the larger bolt for the brass terminal now i'm not happy with that so i'm not going to put any loctite on it i've already gone online and ordered a new crimp ring for this so i'll fix this as soon as it comes in but i want to finish testing this battery and get the video out for you [Music] guys and no loctite because i have i'm going to replace this ring terminal that red wire there i have to miss the bms so i'm just going to reach in with my fingers and pull it to the side a little bit and we should be okay i'm just going to put a layer of electrical tape on here right now because i have to get in here in a few days when the new ring terminals arrive well the battery is complete but we still need to test it so give me a minute and i will clear the workbench because i have four days worth of tools piled up on here it has taken me four days to build this probably will take you guys a lot less if you do it yourselves because you won't have the camera and the lighting and trying to get all that so i have these wire leads that i've built previously i have a whole collection of different adapter wires that i've had to build for different projects this one here is ring terminals on 10 gauge wire to an xt60 connection circuit breakers on so this is now charging this is about 100 watts so i put this to 6.5 amps just because i want to see the balancing function and we had two for a second there and then one shut off let's uh let's see if we can get the cells any closer right now we're 43 millivolts so it looks like it stopped before the cells actually reached 100 percent it says over voltage protection it looks like cell group number two must have went over and it's not balancing right now the bms turned it off but i wasn't sure about being absolutely a hundred percent so i turned it on again just at one amp that's the i i programmed this to one amp and the purpose there is to allow for the balancing to take place it looks like cell group number two is a little bit higher in voltage so it's balancing out but it probably the bms shut it off probably before we actually hit 100 percent because this probably went into over voltage protection so the more times that i cycle the battery the more chances this will get to balance now it looks like it's not balancing when it's just in storage mode it's only balancing while charging so it will eventually allow for more capacity but if i was to do a capacity test right now it would be a little bit low so i'll probably cycle this a few times and then try to do a capacity test for camera so that cell group two is definitely at a higher state of charge than the other three cell groups and right there we hit over voltage and it shut off and it i heard this beep and shut off but the bms internally is what shut it off this guy didn't hit pac voltage so that's a good thing that the bms is working when you hit over voltage so the bms is doing its job and the more times i cycle this the more this can bring it back together i've had this inverter for a long time i just use it in my car if i need something but otherwise i don't have a lot of 12 volt stuff i prefer the bigger inverters so here's the shunt for the meter and so we'll go ahead and turn this on now this is a 300 watt inverter and i think this was a 250 watt heater and we'll do a little bit of a load and then we'll try to charge it up again a little bit more okay so the heater did kick on we're over 300 watts on the dc side that might cause this to overheat we'll see i've never actually done a capacity test on this inverter to see where it actually overloads it shows 21.46 amps 21.2 amps so they are close this is showing 286 watts and 281 watts so if anything this is reading a little bit lower and as you can see the cell differential dropped really close to each other as soon as you put a load on it because this is in that plateau of the voltage curve if you're not sure what i'm talking about these are lithium iron phosphate cells and they have a voltage curve that is very steep in the beginning plateaus and then falls off really steep at the end so when you're in this middle range here between about 3 volts and 3.4 volts it's all plateau and you only see it go really high up right at the very top end and very bottom end which is why we typically recommend you either top balance or bottom balance now i did not top balance or bottom balance these cells or the cell groups specifically because i wanted to see this bms do its balance function i mean sorry i'm holding the cell phone cell phone is just my monitor with the app for the bms but i wanted to actually see it do its balancing i wanted to make sure that occurred and it does if i had top balance these cell groups the bms would not have seen a differential and it wouldn't have done any balancing and i could not have verified then whether or not that worked we haven't started balancing yet so that means that the differential is not large enough yeah so it's at 15 millivolts that it starts balancing you can see it jumping between 14 and 15 millivolts as soon as it hits 15 it begins balancing now the balancing is just little tiny resistors that are built into this thing we are almost ready to over voltage here 3.65 there we go and it did it so the bms shut off and that means that beeped so fantastic we caught it on camera all right we're ready to begin the discharge capacity test so let me turn this off here and i'll just unplug this so we don't have anything else going on that side over here on the meter we have an extra 17 watt hours so we want to get rid of that here we go zero turn on the inverter turn on the heater now we're going to ramp up okay great let's check what time it is 11 16. we're discharging excellent so we'll let this run and we'll see what our capacity is so this will take four or five hours to discharge and then we'll be able to come back and find out what our capacity is at this point we're probably around two hours into the test everything is still running so this is showing that we've used 40 amp hours let's see boom we're still rocking and rolling let's take a look at the numbers we're over 1.2 kilowatt hours right there that's awesome we're almost done as far as this is concerned we've almost hit the 100 amp hours but we still have room left in the cells so i'm really excited to see what this actually turns out to be i hope the bms doesn't shut down when the bms thinks it's at zero i hope it just keeps going i'm not sure yet if it's going to stop i haven't programmed it i haven't configured it to anything it's just making an assumption that it's 100 amp hour battery we are almost done the beeping just started on the inverter so the inverter is telling us that we're at low voltage uh we are at uh 10.67 volts one of the interesting things is how the voltage just drops off a cliff after three volts per cell there's really not much power in a lithium iron phosphate cell below 3 volts the cutoff is 2.5 volts per cell so we're gonna go until the inverter shuts off or we hit 2.5 volts per cell which would be 10 volts all right it just shut itself off at two point uh 10.3 volts let's take a look now our cells are going to bounce back a little bit here they were a little bit lower but we got 1478 watt hours 1478 watt hours ah that's just incredible these cells from battery hookup are listed as 5 000 milliamp hour cells but i got an extra 15 percent more than what i should have gotten out of these things which is just incredible i love it when a company is able to over deliver i mean that's really fantastic i love having a circuit breaker built into the battery oh and temperature uh let's check what the temperature is we got up to 27.3 degrees celsius 33.2 pounds a friend of mine has a vinyl cutting machine so i'm going to put a logo on here and this will be my 12 volt battery here we go there we go there we go awesome i am proud to put my name on this battery i like having the circuit breaker built in you know it's it's in a clean package nice thank you everybody very much for watching if you enjoy the videos please like and subscribe to the channel in the description below is going to be a parts list and please leave a comment below if you can think of a better way to do this or something that i should include in a future video thank you very much you

Channel: DavidPoz

Views: 971,375

Rating: 4.8445234 out of 5

Keywords: battery, battery hookup, 32650, 32700, 3.2v, volts, amps, mah, ah, 100ah, 115ah, testing, diy, build, make, nickel, kweld, spot weld, BMS, smart bms, low temp, cut-off, cells, 12, 12.8v, LFP, lithium, iron, phosphate, lifepo4, marine, rv

Id: 6Ai5IRQbLcc

Length: 41min 57sec (2517 seconds)

Published: Fri Oct 09 2020