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 going to 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 uh 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 anchor 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
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 lightest 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 going to 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 resistant 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 pinchers 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 going to 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 two live leads coming out of the thing we need to be
able to reasonably precisely control the application of power which is where the
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
want to bring hot down to here and then hot out to our little contraption and
then negative back in 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 install blue smoke out and creating a nasty electrocution hazard
instead we'll let the big relay do the heavy lifting and use this 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 4 foot distance meaning we are
well within our safe range here with the ring ends crimped onto the cables the
last thing to sort out is the electrodes themselves but first some safety
stickers from ltdsor.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 and on that first attempt uh 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 night
time now my kids are in bed and i am ready to fix up this battery bank for
this project i'm going to 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 18 650 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 are 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
going to have them 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-sized cells that i'm going to 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 oh hi
okay so if you don't go long enough they don't stick together and if you go for
too long you'll blast right through your nickel strip
oh not quite dang
oh 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 onto 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 the heat kills batteries
is make sure that you get genuine nickel
strips sometimes you're going to 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 all right
let's go for it shall we now that it's open we can see the configuration of the
battery packs it's 2s 2p which means we've got two cells in 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 captain 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 de-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 strip here strip handle strip here here's where it
gets real wish my luck eh
so close
hi okay yeah you're done that's bad that's terrible that's going
outside now no no why are you going for so long i
let go so the switch flaked out on me but
it 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
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
enough we'll give it one more after it's cooled down
that one's on there though okay that's 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
uh 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 going to
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 spot weld another nickel strip
i'm sure the internet comments are going to be full of why you shouldn't do that
and you probably shouldn't okay that was perfect now we got 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 joins are good i'm going to go ahead and just throw some captain 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
oh i wonder if my ground connection is just no good 7.25 volts that is correct so let's grab
our original one 7.88 point something this is more
charged than this one so yes that our battery is fine where we're running
into trouble 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 gonna probe our solder join here
and our other more different one 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 global solder we got there
we've got sometimes
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 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
what's funny is 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 it's charging
charging we did it read it reassembly time there we go
okay so we glue it shut
and there it is working as intended
you know what i should do if i love captain tape so much i don't
have a dbrand 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 anchor 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
10 000 milliamp hour capacity that charges up to 2.4 amps with their power
iq and voltage boost their power core plus is a 26 800 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 uh it doesn't work very well anymore because the over
current protection on this bms always kicks in um and also these frozen 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 when they're vibrating so you gotta 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
watch that video it's a fun video