DIY Lithium Battery - What could go wrong??
Linus Tech Tips
·Linus Tech Tips
·2019-05-06
·
2,229 words · ~11 min read
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I mean think back to when you were a kid
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What sounds more fun than like one of those cool ride-on power wheels things?
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I've noticed the fact that this is not a brand name power wheels
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This is a cheap Chinese knockoff, but that's not the point of today's video. The point of today's video is what's more fun
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than one of these power wheels ride-on things a
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souped up one and as it turns out
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You can make them go double triple or even quadruple as fast
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Simply by overvolting them
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Now you could do that by just buying yourself a in this case
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This is a 6-volt model so a 12-volt battery at the hardware store and plugging it in
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But this is Linus Tech Tips so instead of that I decided to order myself a
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DIY
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lithium battery kit
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Let's
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see how this goes
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Pulseway Pulseway lets you remotely monitor and manage all of your Windows Mac and Linux machines from one app
1:14
Create your free account today at the link in the video description
1:18
Now I hadn't originally planned to do a video about this
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So you guys are gonna have to forgive me if I am not as prepared as even I normally am
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But I am going away to Disneyland in three days
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And I need to queue up enough videos for a while. I'm gone
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Real talk real talk right now
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And I was telling Ed about this plan that I had to sort of trick out one of our power wheels
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Not actually this one and he was like, oh we should we should do a video about that and I was like, oh, yeah
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I mean, I'm still kind of like learning and I really don't know if this is the most optimal way to do it
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And he's like, oh, yeah. No, it sounds like a video
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so
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basically what I've ordered here
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So these are 18 650s. These are 3,500 milliamp ones. I think they're from
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Samsung it's either Samsung or LG chemical on or whatever. They're like
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Chemicals like division is there's either Samsung or LG cells and then these are high current ones because
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Not on this one, but actually on the two-seater that I am planning to have all of this end up in
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You can actually see some pretty impressive peak power draw so I got a bunch of these
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Then I picked myself up
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this puppy so this is the
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charging
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Controller board that you need any time you're building a lithium battery
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And I can't remember if this is a balance charger or not
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So I'm gonna have to look that up so I can determine exactly what type of charger I need to use on it
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I do have a balance
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Lithium battery charger at home, but I forgot to bring that today
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All right.
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Ah, yes, you can see here,
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this is for seven cells in series.
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So parallel determines how much capacity you have
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and series determines what the voltage is gonna be.
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So this is a six volt model
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and I'm gonna be hitting it with about 24 volts.
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So we're gonna burn it out pretty quickly,
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but realistically I was gonna get rid of this one anyway.
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The idea is to make the Jeep power wheels
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that I have at home go twice the speed
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and we'll making this one go four times the stock speed.
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This is one of the kits from Veruzend,
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V-Ruzend, I don't know what they,
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I don't know how they pronounce their thing,
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but basically resists vibration loosening.
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It's safer.
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Hey, it's safe.
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Oh, yay.
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What we're doing today, building a lithium battery pack.
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It's a modular lithium battery pack kit.
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Just chill.
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It's all good, don't worry about it.
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Fully customizable.
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Where's the guide?
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Don't we have a bunch of like 12 volt batteries
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just like sitting in one-on-one?
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Yes.
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Well, A, I'm building a 24 volt battery,
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which yes, I know.
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And B, I wanted the weight and quick charging
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and I just wanted to do it this way because it's fun.
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Okay.
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To turn this bunch of cells into a battery,
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we need to wire together all of the cells correctly
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to get our 29 volts and 30 amps at full charge.
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To do this, we'll be creating a 7S3P battery,
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meaning there'll be seven cells wired in series
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and then three of those wired in parallel.
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Construction of the battery is pretty simple.
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Although if we wire up one cell incorrectly
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or even just drop a nut or touch a screwdriver
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across the wrong place,
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we risk causing a ShortCircuit that could electrocute us
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or at worst cause the battery to explode.
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Someone's going to blow themselves up.
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Okay, I think we should do the things first
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and then put cells in.
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So then theoretically, we can take your whole thing
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and blippity bloppity.
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Hold on, let me help you get that aligned.
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Okay.
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Do we have a rubber mallet here?
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No, we're not rubber malleting these.
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Why not?
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Because we're not.
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Because that's not a good idea.
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Well, I don't know, maybe.
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It's pretty hard to push on.
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We did this three more times
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and got what seemed like should be a ready to wire up battery
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until we actually thought about it.
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It's really easy.
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Before you begin though,
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make sure you understand how series
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and parallel electrical connections work.
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I want to brush up on the subject,
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blah, blah, blah, blah, blah.
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Don't ShortCircuit, that's bad.
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Got it.
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I wanted series.
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Parallel.
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Wouldn't I need to go from here to here though?
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Oh, that makes sense.
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In order to do that, you need to do every row.
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Oh, this is easy.
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Oh, maybe.
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Well, let's find out.
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Oh, they have videos.
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Okay.
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We'll be back in a minute here.
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We're gonna watch some YouTube to learn.
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Tinted that if we flip around every second cell,
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creating the connections will be super easy
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by just placing the bus bars across the top.
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So the good news is we weren't that far off.
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Pretty much these bars go on
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and we make all the parallel connections between ourselves.
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Oh, yeah.
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Like it ain't no thing.
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I'm, hold on.
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I'm just trying all my contacts here.
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We good, we good, we good, we good.
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Yep.
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Beautiful.
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Now we have to attach the...
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These ones?
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Yeah. I don't know.
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I don't know.
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So let's, we're gonna watch,
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we're gonna watch this other video now.
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BRB.
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All right, so we ran out of time yesterday.
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It's day two, but there's some good news.
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I was able to bring in the actual car that I intend to use.
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So this one shouldn't fry immediately
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when we hook this battery up, but there's some bad news.
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So I had planned to either hook this up
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with the battery management system
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for a single input charging, or I had planned
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to hook it up with this doodad
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and then use a balance charger like this one.
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But I forgot this is a maximum 6S balance charger.
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So this won't work,
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which means we're gonna have to use the BMS,
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except for one small problem.
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We can't find a single power adapter in the building
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that is, so you don't take the 3.7 volt nominal voltage.
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You take the 4.2 volt charge voltage.
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So this thing can't take magically like a 12 volt input
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and turn it into 30 volts.
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You need an actual like 30 volt charger.
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And 7S as far as I know is a pretty oddball configuration.
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So I'm not sure how we're gonna charge it,
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but I'm gonna start to wire it up anyway.
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I found a 33.6 volt one.
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Do you think it would work?
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33.6?
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Yeah.
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I don't know.
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What do you think?
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What do you think the tolerances are like
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on something like this for input?
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Probably fine.
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We have 29.4, is that what we were looking for?
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29.4, yeah.
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I knew those stupid hover shoes
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were gonna come in handy for something.
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We're gonna cannibalize the charger.
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Cannibalize it?
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Well, yeah.
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Well, yeah, cause I don't have a socket for this.
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So first things first.
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All the balance wires are on.
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There we go.
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And my negative,
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I believe this is negative.
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Negative charging, yep.
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My negative charging wire is soldered.
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Now what I need to do
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is throw on two positive wires
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to the opposite terminal here.
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So to the positive terminal
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at the other end of the battery.
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One of those will be for charging.
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One of those will be for discharging.
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Now I realize I'm opening myself up
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to some soldering technique critique here,
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but this is how it's going on.
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Alex, do you wanna solder me?
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I'm sorry.
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Let's go for a solder bath.
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Okay, that's lots.
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Oh man, I can feel the cringing.
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Just wait till The Verge does this.
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That'll make me feel better.
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So we've got our eyebrow tweezers
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and our butter knife.
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Okay, don't include that last bit.
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We don't wanna be too mocking of The Verge.
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We're not trying to make enemies in the industry.
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I don't have Captain Tape.
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We really need to get some more electronics project crap.
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So I'm gonna go get packing tape
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just cause I need to keep those wires out of the way.
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For all the viewers out there
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who know what they're doing with this stuff,
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make it better or worse,
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that in many cases I know the right way,
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but I'm doing it this way anyway.
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Now they say in their guide,
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you don't have to solder this,
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but I think that's really stupid personally.
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I think advertising, stop it.
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Okay, stop doing that.
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Oh, nice.
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Now typically hat nuts aren't reusable,
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but I managed to kind of crush it back on there.
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Okay.
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All right.
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So we can test then.
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Well, first I'm gonna have to show you guys
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the before of course.
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Here we go.
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See, pretty boring.
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This is not the recommended way of doing this.
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Again, if you wanted the recommended way,
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would you be watching my video?
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Oh, we're gonna ruin our floors.
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Here we go.
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There's no steering on this floor.
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How's my phone?
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Is my phone okay?
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Oh, it sticks out of my pocket sometimes.
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It's okay.
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So that hat nut, not a great solution,
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just bending it back.
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So this is our pre-test.
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This is with the original battery,
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which has like a somewhat fresh charge.
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It's not super fresh, but it's not like the worst either.
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So reverse, first gear, second gear.
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Now it's really important for a reliable operation to install,
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people do either 30 amp or 40 amp breakers in these things,
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but I'm gonna do that later
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when I do my whole ESC upgrade
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with the sewing machine pedal and all that kind of stuff.
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So this stock connector no longer has any use.
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We are wired up now, baby.
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Oh, that's reverse.
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It's definitely faster.
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That's first gear.
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And we need to move over to unit 101.
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Let's turn it up to high gear.
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Woo!
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Oh! Oh!
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That was an undesirable.
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This is really hard.
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I can't even use, I can't even use my foot.
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Oh really?
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No, I'm just using my hand.
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Oh Lordy.
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There we go.
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Oh yeah.
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J-turn.
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Oh, I tried to throw it in forward.
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Wow, the traction's actually pretty good out here.
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So there she is.
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She's a little toasty.
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She's definitely ready to be left to cool and then charged.
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And that's it.
14:44
That's a DIY battery for better or for worse.
14:50
And this whole mess is brought to you by Memory Express.
14:54
Memory Express is the place to go
14:55
if you need any kind of electronics products in Canada.
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they will beat any price both in-store and online
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So go check them out.
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You can get them at the link in the video description.
15:15
So thanks for watching guys.
15:16
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15:21
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