Do I have to solder on a Y shape?

[Cyclomania]

I'm glad you've thought of the safety end of all this. Too many people never give it a thought until something goes wrong and it gets way worse than it needed to be.

I have a lot of fear for this project so I have thought about a lot of scenarios. Therefore I now have sand and an extinguisher available.

If you have any more ideas with which I could increase safety I would be very thankful. I was thinking about a gas mask of some sort since a really bad scenario might be a burning battery pack releasing gases. I do have a kind of filter gas mask that I will have avaliable. But hopefully I will just have to use my safety goggles.

 

[Cyclomania]

Probably used for a state-of-charge indicator. Just use the one that you tested when your charger was plugged in.

I have fixed this one and it seems to work now.

 

[Cyclomania]

The way it’s done in the video is a better method for even current distribution in both connector pins. Your solder blob will work, but it’s not so elegant. And there is more of a chance that a stress fracture will occur in your blob.

I think my Y-connection looks like crap But maybe better than a blob?

 

[A-DamW]

I think my Y-connection looks like crap But maybe better than a blob?

Does not look like a cold joint particularly, I would say double heat shrink, strain relieve the wire so it does not flex at the point where the solder wicked into the wire(metal fatigue failure point), and test!

 

[Cyclomania]

Does not look like a cold joint particularly, I would say double heat shrink, strain relieve the wire so it does not flex at the point where the solder wicked into the wire(metal fatigue failure point), and test!

Something like this?

Nippelmix, 8 pieces

2 pcs. cord strain relief with set screw, male thread 2 pcs. cord strain relief with set screw, female thread 2 pcs. nut 2 pcs. flange nipple

www.biltema.no

I was thinking perhaps that instead of these relieve-wires I could use hot glue, or silicone, to keep the wires from moving inside the pack? Or does it really have to be some kind of strain relieve connector do you think?

 

[Cyclomania]

Probably used for a state-of-charge indicator. Just use the one that you tested when your charger was plugged in.

I also need to solder on this one. The on and off-button. But I do not find any tutorials on how this should be soldered.

Any ideas? Just a ground wire(that goes where on the pack?) or something like that?

 

[A-DamW]

I also need to solder on this one. The on and off-button. But I do not find any tutorials on how this should be soldered.

Any ideas? Just a ground wire(that goes where on the pack?) or something like that?

Do you have a BMS?
That switch would typically be wired to the on/off switch port of the BMS.
I do NOT think that switch can handle the full pack voltage or amperage.

 

[Cyclomania]

Yes

Do you have a BMS?
That switch would typically be wired to the on/off switch port of the BMS.
I do NOT think that switch can handle the full pack voltage or amperage.

Yes my BMS is this one. BMS Daly 13s.

In any case is it only one cable that should be wired from the on and off-switch to the bms? A ground wire or something like that? Or is it both ground and positive somehow? I guess the awg could be pretty thin for that one right?

I also wonder how you guys attach the NTC wire there? Just glue or tape it to one of the cells in the middle, or something like that? Basically monitors heat right?

 

[Diggs]

In any case is it only one cable that should be wired from the on and off-switch to the bms? A ground wire or something like that? Or is it both ground and positive somehow? I guess the awg could be pretty thin for that one right?

I also wonder how you guys attach the NTC wire there? Just glue or tape it to one of the cells in the middle, or something like that? Basically monitors heat right?

Most on and off capable BMSs use one wire. They get a ground from the main ground. Your BMS doesn't appear to have that. Nor do you need to use that switch. You turn your system on and off via the display through the controller. Sure, There's some very small mah current drain but that's why you pull your battery when you're not going to be riding for a long while.

Temp sensor? I've used hot glue, shoe goo, E6000 glue and taped it on. (My early builds/BMSs didn't even have temp sensors.)

 

[Cyclomania]

Most on and off capable BMSs use one wire. They get a ground from the main ground. Your BMS doesn't appear to have that. Nor do you need to use that switch. You turn your system on and off via the display through the controller. Sure, There's some very small mah current drain but that's why you pull your battery when you're not going to be riding for a long while.

Temp sensor? I've used hot glue, shoe goo, E6000 glue and taped it on. (My early builds/BMSs didn't even have temp sensors.)

Ok. Thing is my battery pack has that on and off switch so I do not think it looks as professional when that switch cannot be used. For example if I need to sell this battery pack in the future it would be nice to have that On and Off-switch so people do not think this is a hack battery. But maybe would not work with my BMS then?

Any idea what I could fill that hole with instead so the pack still looks goods? A plastic connector of some sort perhaps? Just siliconed glued in there? If the ON and OFF-connector does not work I would prefer to not have it in that place if possible. So change it out with something else.

Did you strip the NTC-wire before you attached it to one of the cells(n the middle of the pack?) or did you just glue the top on like it is in this picture?

 

[Cyclomania]

So I am planning on spot welding the pack pretty soon. But there were two videos that made me pretty confused about the soldering of the balance wires.

So in this first video with an indian guy he seems to weld on the first positive balance wire on the first positive cell group which sits on top of the first negative cell group. This is how I learned it should be done. This is shown in the picture below with the name "bms wiring one" and in this video:

Now, in this other video with an american I think he says he is soldering on the first positive wire on the first positive cells group as well. But in the video and picture below "bms wiring 2" I think it looks like he solders on the first positive wire on the second cell group. It is approximately 27.20 into his video:

I think they use similar BMSes only the indian guy uses 13s and the american 14s.
Could someone please let me know why they solder the first BMS positive cable differently? I thought you were supposed to solder this one on top of the first cell group, which means on the cell group that also has the first small negative cable in the other end, as the indian dude does?

 

[Cyclomania]

Also, now I am very close to start spot welding. Can you guys please review my soldering schedule and setup of the cells here below which is same order drawn out as they will go into the slots.

Let me know if the nickel setup looks good, or if I have missed/misunderstood something there. Also let me know if I am thinking correctly about the BMS wires. I have drawn metal strips of nickel that will go out over the side there, where I will solder on the BMS balance wires, after I have taped everything else over with capton and fishpaper. So these will be the only thing of metal sticking out on the sides.

 

[Cyclomania]

The schedule I am doing is the same as they do in this video around the mid section which they have ready around 11.37 into the video on both sides. Which is what I have drawn up in the post previous to this one. Here is the video of the schedule I am using around 11.37 into the video-

Never mind the rest of the video because they seem to be all over the place one time having a picture of a 10s pack and then after g to the 13s-pack. But it is the 13s pack I am trying to imitate regarding my nickel layout.

Now, I am a bit confused about one nickel strip-group that they have welded on there. But I guess I am just overthinking it right now and it has its reason. But I was thinking about this one that is kind of drawn the other way around, in contrast to the other ones, that are dawn from left to right. But this one is drawn from right to left.

But this is probably as it should be correct? They have not done a mistake there?

 

[Diggs]

Any idea what I could fill that hole with instead so the pack still looks goods?

Put the switch in and don't wire it. I sometimes glue a small piece of black plastic over the hole from the inside.

Did you strip the NTC-wire

Leave the wire as is. Do not strip it.

 

[Diggs]

You are missing some nickle strip connections (in red) -
(It's early here, let me look through your other questions....)

 

[Diggs]

Could someone please let me know why they solder the first BMS positive cable differently?

They are wired the same if you look at the details. The pic wiring2 has the first two rows of cells connected at the bottom where you can't see. Although it looks like he is connecting to the second row of cells with the first BMS wire but the first two rows are connected (on the bottom) he is actually connecting to the first positive in the pack. Whether you connect the BMS to a little tab that hangs over the edge or connect in the middle of the row of cells it makes no difference.

 

[Cyclomania]

You are missing some nickle strip connections (in red) -
(It's early here, let me look through your other questions....)

Yeah your drawing makes much more sense to me. I do not understand why it did not have that layout in the video and why there were all these loose ends in there it seemed to me.

But so basically if I add the nickel strips in red, and then solder the rest exactly as I sent it in my previous post, the battery pack should come out fine probably, right?

It is easy to get confused about it when everything is diagonal .
Also, I don't understand why they do not show that in the video as well. But I trust your judgement. So I will go with that plan and also solder the red ones.

Thanks for taking the time and helping me with this. It is much appreciated.

I might start the build tomorrow. Do you think it would be a smart idea to solder everything in both series and parallell first, and then work my way outwards(in my case from right to left)?
In that case if something goes wrong I do not short a finished pack of 48 volts, but instead I might short a 36 volt-pack or a 7,2 volt-pack but hopefully no shorts at all of course. But if i connect everything and work my way out towards the other end, then I will at least build something that is functional which I can test with my multimeter all the way out. So 3,6, 7,2 and so on. And then keep on going if it works, and gives the correct reading, like it should.

 

[Diggs]

Watch a few other videos of battery builds. There's a lot of them out there. They can make it so much clearer -

 

[Cyclomania]

Watch a few other videos of battery builds. There's a lot of them out there. They can make it so much clearer -

I am now spot welding the parallells. Looks like this. I plan on spot welding all of the parallells and then start to connect them in series.

Do you have any extra tips or precautions I could think about when doing the series?
And does it look okay so far?

Why is it that you sometimes get sparks flying from the spot welding? Some cells more than others?
Also, would it hurt to put an extra weld in green (see picture "Extra weld?), or would that be stupid?

Thanks

 

[Cyclomania]

I also wonder when I make the series connection.. In theory only one series connection would do, correct? The reason I do as many series connections as I do parallell connections is because I want more current flow right?

 

[Cyclomania]

Video Unavailable

This video is unavailable.

streamable.com

This is what it looks like now and I am going to head on over to the series connections. Let me know what you think and if you have any additional tips. (sorry about the shaky camera) I also turn the battery over to the other side when you see it go dark in the middle.

 

[Cyclomania]

Here is how I have set up my nickel strips for where I am going to solder on my balance leads. Since I was a bit unsure of this one before, please let me know if this is correct?

It cannot be another way as I see it? First negative to first negative. First positive to first positive and on and on. Until I hit the last positive on the last positive on the pack. 13 positive balance wires and one negative. Looks right?

 

[docw009]

Nope. Theory requires as many series connections as cells.

Series connections are the most important as that is where all of the current flows. Ideally, the positive end of a cell goes directly to the negative end of the nearest series cell. For a 7P design, that's seven current vectors that are represented by nickel strips.

For your layout, that is easily done except for a few spots where s positive end of a cell is surrounded by two other positive ends, and a few negative cells are surrounded by other negative ends. Use your best judgement and double up on the nickel strips in those areas. It's a visual process, no magic to it. If it looks like the current from two cells gets concentrated into one strip, just add another strip.

 

[Cyclomania]

Nope. Theory requires as many series connections as cells.

Series connections are the most important as that is where all of the current flows. Ideally, the positive end of a cell goes directly to the negative end of the nearest series cell. For a 7P design, that's seven current vectors that are represented by nickel strips.

For your layout, that is easily done except for a few spots where s positive end of a cell is surrounded by two other positive ends, and a few negative cells are surrounded by other negative ends. Use your best judgement and double up on the nickel strips in those areas. It's a visual process, no magic to it. If it looks like the current from two cells gets concentrated into one strip, just add another strip.

Great what do you think about where I have put my nickel strips for the BMS wires?

So it is the first black small one goes to the first alone negative cell group. On the OTHER SIDE of this same cell group I will have my first positive small balance lead. And after that I will work my way up and put a positive lead on every positive side of the cell groups. The last one will be my final positive cell group where I will also have my positive main wire coming from the battery side.

 

[Cyclomania]

Nope. Theory requires as many series connections as cells.

Series connections are the most important as that is where all of the current flows. Ideally, the positive end of a cell goes directly to the negative end of the nearest series cell. For a 7P design, that's seven current vectors that are represented by nickel strips.

For your layout, that is easily done except for a few spots where s positive end of a cell is surrounded by two other positive ends, and a few negative cells are surrounded by other negative ends. Use your best judgement and double up on the nickel strips in those areas. It's a visual process, no magic to it. If it looks like the current from two cells gets concentrated into one strip, just add another strip.

A bit tired now so not sure if my mind is clear, but what about here in green? Could I add extra nickel there to bridge? Or would I do something stupid?