hey guys Frank here just wanted to follow up on the questions that I had
asked during the holiday season I had two specific questions that I wanted to
get answers to one is why do di wires build all of their battery packs in
large in large chunks you know 80 to 100 cells and question number two was if I
were to build my battery packs from my power wall should I build them in large
chunks like that just as one cell so you'd have 80 cells in a pack and that's
3.7 volts or should I build it out where I have it like this where it's parallel
and serial this is a 48 volt pack instead of a three point seven volt pack
like this so I had the answer
the first question is why do most di wires build large cell packs like this
this is a three point seven volt I don't know how many amp hours are actually in
this one but there are quite a few in two cell packs like that well I did get
an answer back from battery DIY on YouTube if you have eight cells like I
have here eight cells these eight cells would be one one battery piece or one
cell configuration and one fails one of these cells fails twelve percent of the
module is failed then you start to think about that and that could be pretty
important especially if I have one that fails here and then I have another one
that fails down here and I'm down here because aren't we using harvested cells
we're going out finding cells and battery packs and in tool tools you know
shop tools and that we are finding old cells and in that process sure we test
them and we try to do the best we can to vet them but you know what they're still
going to fail eventually they will even brand new cells will fail I get new
cells and I've seen them fell so cells will fail we just have a better chance
of keeping our things together if we can figure them correctly and that's why I
ask the questions all right so this or this this makes sense to me so I've
decided that when I build my power wall I'm not going to use cell packs like
this is convenient as this would be for many different reasons one with having
the cells all grouped together like this in series and in parallel I wouldn't
need to use very large cables because my amperage is up are my voltage is up I'm
running higher voltage and so I can actually use a thinner gauge wire so
that would cost me a little bit but I'm just talking about having it in a
controlled area so it doesn't make that much of a difference
in a controlled environment like that I still will probably end up having to
spend more money on wire and connectors but the risk of cell failure is just a
little bit too high to be playing with and I think I'd rather spend a little
bit more money on wire and and that to make sure that I don't lose all this
work all this work that we're doing okay so based on that I'm gonna go with back
to this style of battery pack now I'm not sure what size I'm going to do at
this point I still haven't vetted that out yet the other portion of this is BMS
and I didn't ask the question and I'm not gonna ask it now but I do I'm
bouncing around my head BMS why should I you know there's been those who've gone
before that say no you really don't need it but I think we've seen with like DIY
power wall where it's you're better off having some some BMS and so I'll address
that is I get a little bit farther down the road and I'll talk more about BMS
how to set it up what it is but for now we're just gonna we're focusing on the
battery packs and depending on how we built battery packs because if I were to
do this style would be a one type of BMS and this requires a different type of
BMS basically they still manage the batteries but it's just a little
different system so we'll talk about that later cuz I do have more questions
I'm not done with my questions they're on to question number two question
number two was should I build my badge batteries as a single volt this is a 48
volt battery this is a three point seven volt battery this would be my full
voltage size this would be what I was actually shooting for for my power wall
but I'm gonna have to do 14 these instead so the question going back to
question number two should I build my PAX like this the answer is actually yes
then oh yes when it comes to power walls power wall
you're gonna have a lot of cells to deal with you're gonna have a lot of voltage
you're gonna have a lot of amperage which means a lot of watt hours and so
on and so forth yes you're gonna want to build out packs like this you're gonna
make them low-voltage but you're gonna have a lot of them and that will give
you your volume so that you get your watt hours out of your out of your power
wall but when it comes to smaller kits like the one I showed you that I used my
red blanket in and I can do cell phone charging and fits in my backpack and I
can carry with me I don't have much choice but to make myself packs the
actual voltage I'm striving for so where do I draw the line I think what it comes
down to is if it comes to a power wall I'm doing big I'm doing big bricks of
low voltage three point seven volt batteries and trying to get my amps up
inside these cells but when it comes to the portable stuff you have to build
them out at the voltage you need a mat and you may not get as many amps out of
them but that really comes down to space quite frankly I mean it's just a matter
of how much can you pack into a little tiny kit and so based on that the answer
is yes and no question number two well guys I hope this I'm hoping that this
was helpful to you I hope that you've been able to get something from this and
it wasn't just a bunch of psychobabble but it has been helpful for me to really
think this through to make sure I'm doing this correctly because I really I
don't want to go back and I want to have a reason for doing each of the things
that that I've done or I'm trying to do and it still may not be right but I'm
gonna give it a good go and hopefully it was helpful to you if you do have more
questions or comments please leave them in the comments below and subscribe to
the channel subscribe to my channel and then tell your friends about me so that
you can help me out I'm trying to just share what I'm doing if you guys have an
interest I think I'm hope this is helpful to you so till then I
will catch you around thanks for watching
why do most di wires build battery packs like this or not like