- Good day everyone,
I woke up with a tickle in the back of my throat
which means I can't go to the office
until I've been symptom-free for 24 hours.
The good news is I get to hang out at home,
the bad news is that I've still got videos to make.
Today we're gonna be taking this battery bank
from 2014 that has served me very faithfully,
but now does not hold a charge the way it used to.
And inspired by accidentally dropping it and realizing
that the plastic casing comes apart quite easily,
I am going to be replacing, ah!
There it is, the four 18650 cells inside it
to give it a new lease on life.
And the craziest thing about this video
is that it is sponsored by Anker,
makers of brand new battery banks that,
well actually no, I think I do see why they were into this.
Because for the vast majority of people out there,
this is too dangerous, not to mention a total waste of time.
This really doesn't make sense,
you should probably just buy a new battery bank.
But we wanted to do it for fun
because it gave us an excuse to make one of these.
This is something that I have wanted
for quite some time for unrelated projects.
A DIY spot welder.
Let's fix a battery bank, shall we?
(upbeat music)
Before I can work on the cell swap,
which is my half of this job,
we need to go back in time and far away
to the (mumbles) Media Group warehouse this morning,
where Colin was working on our DIY spot welder.
It's fairly inexpensive to build one of these.
All you need is a power source, a relay,
a switch and some big old heavy gauge wiring
and a little bit of time.
He's gonna show you how you can build one of these
for yourself step by step, then throw it back to me
to find out if this is actually going to work.
- [Linus] Resistance spot welding
is a pretty straightforward process.
By running a short pulse of high current power
between two electrodes, you can heat up metal enough
to weld it together.
This process is actually how most car bodies are welded,
so those big robotic pincers you see darting around
the frames on the assembly line
are big spot welders fusing the panels together.
What we're planning on doing here
is actually very similar, but instead of body panels,
we're gonna be welding conductive nickel strips
to both the positive and negative terminals
of these common 18650 cells, which we can then use
to refurbish my little pink battery.
There are a couple of other routes we could have gone
for our project, we could have bought
a pre done battery tab welder from overseas,
but we decided that given
the relatively small amount of spot welding
we're planning to do, we could DIY our own solution
for minimal effort and probably less money.
Now there are lots of examples of home built spot welders,
using some sort of high current source,
usually a power transformer harvested from a microwave
but we decided not to go down that route
because it requires not only having to destroy a microwave,
but also having to deal with live AC power,
a danger we didn't feel like dealing with.
Instead, we decided on the safer route
and built an all DC power spot welder.
So for that we need a battery,
we used this 12 volt ATV battery, capable of outputting
the high current needed to make the welds,
while also being a bit more manageable than a car sized one.
But we can't just have to live leads coming out
of the thing, we need to be able
to reasonably precisely control the application of power,
which is where this starter relay comes in.
This relay is able to quickly switch
the high current circuit of our welder
on and off without being damaged.
- So these two terminals are what activate the relay
and these will be connected to hot and ground as well,
but this is where the actual current goes through.
So we wanna bring hot down to here and then hot out
to our little contraption and then negative back in.
- [Linus] If we were to try to use
a little toggle switch for example,
a huge amount of current would flow through the switch,
letting the factory installed blue smoke out
and creating a nasty electrocution hazard.
Instead, we'll let the big relay do the heavy lifting
and use the smaller momentary switch to briefly pulse
the power on and then release it.
With the relay and battery mounted,
it's time to sort out the wiring and the electrodes
that will actually deliver the current to the nickel strips.
We're using big four gauge cables that you can find
at any automotive shop for this.
Four gauge wire is capable of carrying 250 amps
over a four foot distance, meaning we are well
within our safe range here.
With the (mumbles) crimped onto the cables,
the last thing to sort out is the electrodes themselves.
But first, some safety stickers from lttstore.com
nice.
We chose to use copper for our electrodes
because it's able to both handle the power
and high heat at the weld zone
while hopefully lasting a reasonably long time.
Once we had our two pieces clamped in vice grips,
a short trip to the belt sander resulted
in nicely pointed ends that should work great
for our electrodes.
A quick crimp and some heat shrink for safety
and the cable assemblies are ready to go.
After pairing the electrodes up
in some brief troubles, getting the fence installed.
Colin was able to give the welder its first test run.
- And contact.
Well, I blew through the strip.
- [Linus] And on that first attempt,
he did not get a successful weld.
But after a little bit of practice,
he started getting good consistent spot welds,
more than enough for what we need.
So the rig was packed up and dropped off back to me
where, well this is where we pick up.
It's nighttime now, my kids are in bed,
and I am ready to fix up this battery bank.
For this project I'm gonna need some safety glasses,
a digital multimeter, some nickel strips,
a cutter to actually take it from one big long strip
into multiple strips, my pink battery bank
and my DIY spot welder, of course
and some of these commodity 18650 cells.
These are actually the same ones that I used
for my DIY souped up power wheels battery
a little while back.
But fortunately,
they've been sitting in storage at around 3.62 volts,
which is well within the safe storage voltage for these.
And this is another really critical thing,
I have checked all of these 18650 cells
with my multimeter to ensure that they're all
the same voltage.
Because you can run into some real trouble
when you start spot welding together batteries
that are actually at a different storage voltage
because all of a sudden you're gonna have
them (mumbles) equalize nearly instantly
and they can get super hot, that can be very dangerous.
Oh, one thing I didn't mention is that
I've got a couple of dead D size cells
that I'm gonna be using to practice
my spot welding because unlike Colin,
I haven't actually taken a run at this yet.
So we're gonna go ahead, chuck that on there,
cut a nice little tab of nickel and see if
we can get a spot weld here.
(welds)
Oh, hi.
Okay, so if you don't go long enough,
they don't stick together and if you go for too long,
you blast right through your nickel strip.
Oh! Not quite, dang!
Whoa! Hi!
That is on there.
The advantage of spot welding versus just soldering
our battery pack together, is that we apply heat
to join the metals for only a very short period of time.
When you solder, you have to heat up the solder itself
and flow it on to the materials you're trying to join
which can mean that they can heat up quite significantly.
Heat kills batteries.
So this is a way for us to much more safely assemble
our multiple cells into a battery.
One other thing to note,
to do with that heat kills batteries,
is make sure that you get genuine nickel strips.
Sometimes you're gonna see steel strips
with nickel plating advertised as pure nickel strips,
and the problem with that is that steel is not quite
as conductive as nickel.
So what happens is,
especially if you've got a high current battery pack,
probably not a concern for us here today
but if you're working on like an e-bike battery pack
or something like that, it can heat up more,
which can heat up your battery pack more and slowly kill it.
With the pre done ones you can just sort of dial in
how long it goes for and then kind of play
around with it until it's just right,
but here I just gotta kinda eyeball it.
Come on! Yep!
Nailed that one.
Alright, let's go for it, shall we?
Now that it's open,
we can see the configuration of the battery packs.
So it's 2S, 2P, which means we've got 2000 series
and then two of those in parallel.
So series gives you voltage, so you need at least two
to get about five volts for USB charging
and then parallel gives you capacity.
So this gives us the total capacity of two 18650s.
I lied, there's more stuff we need Kapton tape,
solder, flux, soldering iron.
These old cells were a little less worried
about damaging with heat because
they're like kind of dead already anyway.
So we're just gonna solder them real quick like that.
You can see here I'm gonna have to do
a total of four plus four spot welds with three strips.
So a strip here, a strip here, a strip here
and a strip here.
Here's where it gets real, wish me luck aye?
Oh, so close.
Whoa, whoa, whoa, whoa whoa whoa, whoa!
Hi.
Okay, yeah, you're done.
That's bad, that's terrible.
That's going outside now.
No, no, no, why are you going for so long?
I let go.
So the switch flaked out on me
but it's seems to be behaving properly again.
Oh, got it! Yes!
Okay, but while one of those did burn
through on this one here, the other one's good.
So we're just gonna give it another spotty spot.
Oh, yeah! Oh yeah!
We good ladies and gentlemen.
No, that's a little hot.
One of those burned through a little bit
but the other one seems okay,
I think that should be enough,
We'll give it one more after it's cooled down.
That one's on there though.
Okay, just a little harder.
Okay, I think I got it.
It's not the finest workmanship ever
but it's the same configuration as our original battery
so we should be good to go.
Oh, no.
The original battery had extra length
on these two strips to solder to.
Removing these is not going to be easy.
Basically, you can't.
We have a couple of different approaches
that we can take, we can either solder directly
to this strip right here, which is probably fine,
except that it's gonna heat up the battery
which is not what we had intended to do.
Or we can try to spot weld another nickel strip
on top of the original one.
What do you vote for?
- [Woman] Spot weld it.
- Spot weld another nickel strip?
I'm sure the internet comments are gonna be full
of why you shouldn't do that, and you probably shouldn't.
Okay, that was perfect.
Now we got tabs on the end for soldering.
Now all we need to do is solder
the electronics to the original pack.
Good enough.
So we just fold these tabs down,
make sure they're still on there real good.
And we can solder the pack back on.
Okay, good, good, good, good.
Hold it.
Now that our solder joints are good,
I'm gonna go ahead and just throw some Kapton tape
over all of those solder points.
You know, last thing we want is this strip coming loose
and shorting something on the PCB
or something dumb like that.
Let's pop that in there, we're gonna go PCB side first.
That's it.
Hey, all right, cool, okay.
To check our sanity,
we're just gonna put a couple of probes
into a USB port on here and see if we get five volts.
It doesn't power on.
I wonder if my ground connection is just no good.
7.25 volts.
That is correct.
So let's grab our original one, 7 (mumbles) or something
this is more charged than this one.
So yes, our battery is fine.
Where we're running into troubles seems to be
where our BMS is connected to the battery pack.
This to here should be seven point something volts
and it's wonky, it's all over the place.
So there's just a bad connection.
So now we're going to probe our solder joint here
(mumbles).
Now there's your problem, if we go to the back of the cell,
we've got 7.2 volts, if we go to that glob of solder
we got there, we've got sometimes (mumbles)
also on this wire, we have not, get this off.
Okay, I just checked the solder points on the BMS
and it seems like it is now attached better.
Everything that I can see says there's power
to the board, I've got my 7.2 volts
but I pressed the button and--
It just came alive.
You know what it probably was, it's only got one bar
so it's actually a very narrow voltage range
that most of these types of batteries operate within.
So we were probably at the threshold
where the thing won't turn on at all.
You know it's funny because I had planned
to bring this out as my kind of last resort,
you know, cut my life into pieces and all that
and see if I could charge it up,
and then it would come to life.
So it might have just been so dead
that the battery indicator wouldn't even work.
So let's plug this in, it's charging.
Charging, we did it Reddit.
Reassembly time.
There we go.
Okay, so we glue it shut and there it is,
working as intended.
You know what I should do?
I love Kapton tape so much,
I don't have a D brand tutorial to watch or anything but,
well, I hope this was as fun for you guys as it was for me.
Once again, to be clear though,
I'm not recommending doing this at all
if you have a five or six year old battery bank,
instead, I'd recommend taking a second
and checking out our sponsor Anker.
They've got a huge array of portable charging solutions
that aren't nearly as hacky as this,
their power core lineup has a few
that I thought you might be interested in.
The PowerCore 10000
is their best selling classic battery bank
with a 10000 milliamp hour capacity
that charges up to 2.4 amps with their power IQ
and voltage boost.
Their PowerCore+ is a 26800 milliamp hour battery bank
that features USBC power with up to 45 watts of delivery,
so it can fully charge a 13 inch MacBook Pro or Dell XPS 13,
and their power core fusion is a two in one hybrid charger,
so it's a wall charger for everyday use,
and a battery bank for on the go charging.
It even has a foldable plug
so you can keep it nice and compact.
So check out these and more at the links
in the video description.
If you guys are looking for another video to watch,
maybe check out the one where we built
this battery pack for the souped up power wheels.
It doesn't work very well anymore
because the over current protection on
this BMS always kicks in and also these (mumbles) things,
at least the version I'm using doesn't have
like a compression thing, so it's easy for them
to come loose when they're vibrating.
So you can kind of like, squeeze it on every once
in a while but it's a way to build a battery pack
without any welding.
Now that I have this and given how easy
and cheap this was, I wouldn't do this again.
But hey, there it is.
So watch that video, it's a fun video.