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good day everyone i woke up with a tickle in the back of my throat which

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means i can't go to the office until i've been symptom-free for 24 hours

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the good news is i get to hang out at home the bad news is that i've still got

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videos to make today we're going to be taking this battery bank from 2014 that

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has served me very faithfully but now does not hold a charge the way it used

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to and inspired by accidentally dropping it and

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realizing that the plastic casing comes apart quite easily i am going to be

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replacing uh there it is the four

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18650 cells inside it to give it a new

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lease on life and the craziest thing about this video is that it is sponsored

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by anchor makers of brand new battery

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banks that well actually no i think i do see why they were into this because for

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the vast majority of people out there this is too dangerous not to mention a

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total waste of time this really doesn't make sense you should probably just buy a new battery bank but we wanted to do

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it for fun because it gave us an excuse

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to make one of these this is something that i have wanted for quite some time

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for unrelated projects a diy spot welder let's fix a battery bank

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shall we

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before i can work on the cell swap which is my half of this job we need to go

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back in time and far away to the lightest media group warehouse

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this morning where colin was working on our diy spot welder it's fairly

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inexpensive to build one of these all you need is a power source

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a relay a switch and some big old heavy

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gauge wiring and a little bit of time he's going to show you how you can build

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one of these for yourself step by step then throw it back to me to find out if

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this is actually going to work resistant spot welding is a pretty straightforward

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process by running a short pulse of high current power between two electrodes you

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can heat up metal enough to weld it together this process is actually how

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most car bodies are welded so those big robotic pinchers you see darting around

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the frames on the assembly line are big spot welders fusing the panels together

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what we're planning on doing here is actually very similar but instead of

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body panels we're going to be welding conductive nickel strips to both the

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positive and negative terminals of these common 18650 cells which we can then use

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to refurbish my little pink battery there are a couple of other routes we could have gone for our project we could

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have bought a pre-done battery tab welder from overseas but we decided that

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given the relatively small amount of spot welding we're planning to do

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we could diy our own solution for minimal effort and probably less money

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now there are lots of examples of home built spot welders using some sort of

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high current source usually a power transformer harvested from a microwave

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but we decided not to go down that route because it requires not only having to

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destroy a microwave but also having to deal with live ac power a danger we

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didn't feel like dealing with instead we decided on the safer route and built an

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all dc power spot welder so for that we need a battery we used this 12 volt atv

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battery capable of outputting the high current needed to make the welds while

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also being a bit more manageable than a car sized one

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but we can't just have two live leads coming out of the thing we need to be

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able to reasonably precisely control the application of power which is where the

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starter relay comes in this relay is able to quickly switch the high current

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circuit of our welder on and off without being damaged so these two terminals are

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what activate the relay and these will be connected to

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hot and ground as well but this is where the actual current goes through so we

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want to bring hot down to here and then hot out to our little contraption and

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then negative back in if we were to try to use a little toggle switch for

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example a huge amount of current would flow through the switch letting the

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factory install blue smoke out and creating a nasty electrocution hazard

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instead we'll let the big relay do the heavy lifting and use this smaller

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momentary switch to briefly pulse the power on and then release it with the

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relay and battery mounted it's time to sort out the wiring and the electrodes

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that will actually deliver the current to the nickel strips we're using big

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four gauge cables that you can find at any automotive shop for this four gauge

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wire is capable of carrying 250 amps over a 4 foot distance meaning we are

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well within our safe range here with the ring ends crimped onto the cables the

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last thing to sort out is the electrodes themselves but first some safety

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stickers from ltdsor.com nice we chose to use copper for our electrodes because

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it's able to both handle the power and high heat at the weld zone while

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hopefully lasting a reasonably long time once we had our two pieces clamped in

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vice grips a short trip to the belt sander resulted in nicely pointed ends

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that should work great for our electrodes a quick crimp and some heat

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shrink for safety and the cable assemblies are ready to go after pairing

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the electrodes up in some brief troubles getting the fence installed colin was

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able to give the welder its first test run and contact

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well i blew through the strip and on that first attempt uh he did not get a

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successful weld but after a little bit of practice he started getting good

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consistent spot welds more than enough for what we need so the rig was packed

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up and dropped off back to me where well this is where we pick up it's night

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time now my kids are in bed and i am ready to fix up this battery bank for

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this project i'm going to need some safety glasses a digital multimeter some

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nickel strips a cutter to actually take it from one big long strip into multiple

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strips my pink battery bank and my diy spot welder of course and some of these

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commodity 18 650 cells these are actually the same ones that i used for

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my diy souped up power wheels battery a

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little while back but fortunately they've been sitting in storage at

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around 3.62 volts which is well within the safe storage voltage for these and

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this is another really critical thing i have checked all of these 18650 cells

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with my multimeter to ensure that they are all the same voltage because you can

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run into some real trouble when you start spot welding together batteries

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that are actually at a different storage voltage because all of a sudden you're

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going to have them equalize nearly instantly and they can

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get super hot that can be very dangerous oh one thing i didn't mention is that

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i've got a couple of dead d-sized cells that i'm going to be using to practice

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my spot welding because unlike colin i haven't actually taken a run at this yet

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so we're gonna go ahead chuck that on there

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cut a nice little tab of nickel and see if we can get a

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spot weld here oh hi

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okay so if you don't go long enough they don't stick together and if you go for

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too long you'll blast right through your nickel strip

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oh not quite dang

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oh hi that is on there the advantage of spot

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welding versus just soldering our battery pack together is that we apply

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heat to join the metals for only a very short period of time when you solder you

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have to heat up the solder itself and flow it onto the materials you're trying

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to join which can mean that they can heat up quite significantly heat kills

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batteries so this is a way for us to much more safely assemble our multiple

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cells into a battery one other thing to note to do with the heat kills batteries

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is make sure that you get genuine nickel

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strips sometimes you're going to see steel strips with nickel plating

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advertised as pure nickel strips and the problem with that is that steel is not

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quite as conductive as nickel so what happens is especially if you've got a

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high current battery pack probably not a concern for us here today but if you're

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working on like an e-bike battery pack or something like that it can heat up

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more which can heat up your battery pack more and slowly kill it with the

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pre-done ones you can just sort of dial in how long it goes for and then kind of

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play around with it until it's just right but here i just gotta kinda eyeball it

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come on yep nailed that one all right

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let's go for it shall we now that it's open we can see the configuration of the

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battery packs it's 2s 2p which means we've got two cells in series and then

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two of those in parallel so series gives you voltage so you need at least two to

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get about five volts for usb charging and then parallel gives you capacity so

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this gives us the total capacity of two 18650s i lied there's more stuff we

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need captain tape solder flux

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soldering iron these old cells were a little less worried about damaging with

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heat because they're like kind of dead already anyway so we're just gonna de-solder them real quick like that you

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can see here i'm gonna have to do a total of four plus four spot welds with

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three strips so a strip here strip here strip handle strip here here's where it

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gets real wish my luck eh

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so close

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hi okay yeah you're done that's bad that's terrible that's going

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outside now no no why are you going for so long i

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let go so the switch flaked out on me but

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it seems to be behaving properly again

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oh got it yes

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okay but while one of those did burn through on this one here the other one's

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good so we're just gonna give it another spotty spot

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oh yeah oh yeah we good ladies and gentlemen

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nope that's a little hot one of those burnt through a little bit but the other one seems okay i think that should be

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enough we'll give it one more after it's cooled down

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that one's on there though okay that's a little harder

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okay i think i got it it's not the finest workmanship ever but it's the

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same configuration as our original battery so we should be good to go

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oh no the original battery

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had extra length on these two strips to

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solder to removing these is not going to be easy

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uh basically you can't we have a couple of different approaches

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that we can take we can either solder directly to this

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strip right here which is probably fine except that it's going to

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heat up the battery which is not what we had intended to do or we can try to

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spot weld another nickel strip on top of the original one

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what do you vote for spot weld another nickel strip

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i'm sure the internet comments are going to be full of why you shouldn't do that

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and you probably shouldn't okay that was perfect now we got we got

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tabs on the end for soldering now all we need to do is solder the electronics to

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the original pack good enough so we just fold these tabs down

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make sure they're still on there real good and we can

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solder the pack back on okay good good good good hold it now

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that our solder joins are good i'm going to go ahead and just throw some captain tape over

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all of those solder points you know last thing we want is this strip coming loose

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and shorting something on the pcb or something dumb like that let's pop that

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in there we're gonna go pcb side first that's it hey all right cool okay

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to check our sanity we're just gonna put a couple of probes into a usb port on

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here and see if we get five volts it doesn't power on

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oh i wonder if my ground connection is just no good 7.25 volts that is correct so let's grab

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our original one 7.88 point something this is more

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charged than this one so yes that our battery is fine where we're running

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into trouble seems to be where our bms is connected to the battery pack

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this to here should be seven point something volts and it's wonky it's all

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over the place so there's just a bad connection so now

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we're gonna probe our solder join here

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and our other more different one now there's your problem if we go to the

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back of the cell we've got 7.2 volts if we go to that global solder we got there

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we've got sometimes

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also on this wire we have

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not get this off

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okay i just checked the solder points on the bms and it seems like it is now

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attached better everything that i can see says there's power to the board got

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my 7.2 volts but i pressed the button and

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it just came alive you know what it probably was it's only got one bar so it's actually a

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very narrow voltage range that most of these types of batteries operate within

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so we were probably at the threshold where the thing won't turn on at all

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what's funny is i had planned

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to bring this out as my kind of last resort you know

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cut my life into pieces and all that and see if i could charge it up and then

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it would come to life so it might have just been so dead that the battery

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indicator wouldn't even work so let's plug this it's charging

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charging we did it read it reassembly time there we go

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okay so we glue it shut

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and there it is working as intended

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you know what i should do if i love captain tape so much i don't

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have a dbrand tutorial to watch or anything but well i hope this was as fun

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for you guys as it was for me once again to be clear though i'm not recommending

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doing this at all if you have a five or six year old battery bank instead i'd

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recommend taking a second and checking out our sponsor anchor they've got a

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huge array of portable charging solutions that aren't nearly as hacky as

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this their power core lineup has a few that i thought you might be interested

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in the powercore 10000 is their best-selling classic battery bank with a

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10 000 milliamp hour capacity that charges up to 2.4 amps with their power

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iq and voltage boost their power core plus is a 26 800 milliamp hour battery

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bank that features usbc power with up to 45 watts of delivery so it can fully

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charge a 13 inch macbook pro or dell xps 13 and their power core fusion is a

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two-in-one hybrid charger so it's a wall charger for everyday use and a battery

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bank for on-the-go charging it even has a foldable plug so you can keep it nice

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and compact so check out these and more at the links in the video description if

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you guys are looking for another video to watch maybe check out the one where we built this battery pack for the

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souped up power wheels uh it doesn't work very well anymore because the over

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current protection on this bms always kicks in um and also these frozen things at least

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the version i'm using doesn't have like a compression thing so it's easy for

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them to come loose when they're when they're vibrating so you gotta kind of like squeeze it on every once in a while

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but it's a way to build a battery pack without any

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welding now that i have this and given how easy

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and cheap this was i wouldn't do this again but hey there it is

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watch that video it's a fun video