Do I have to solder on a Y shape?

[Cyclomania]

So I have a Polly DP9 case with which I hope to build a battery. 13s7p.

Now in the youtube instructional they solder on a y-shape, from the inside of the battery case, approximately 4.02 into the video here:

Any idea if it has to be a y-shape there? Or could I just as well solder on more of a blob there as I did when soldering the bottom bracket(see picture of my own soldering in the last picture with the blue soldering mat in the background). Or is it a reason for this small y-shape-soldering on the inside as you can see in the first pictures?

 

[AGS]

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.

 

[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.

Hmm any tips on how to make this happen the same way it does in the video? This was my first solder with the Weller 80 since I got the tips earlier that this relatively large solder iron would be enough to melt the blob and heat the pins enough to create a strong connection.

Also, I used flux and I think the connection is quite good and strong. But now from the inside I am looking at perhaps creating this Y-connection instead. So if you have any ideas on how to do that it would be much appreciated. I think it heats up everything really quickly this soldering iron, which is good, but I am not the best at creating these finer solder connections.
Perhaps touch the material for shorter time durations, or how do I best go about creating this detailed Y-connection without blobbing all over the place?

 

[AGS]

It’s just a skill that you have to learn with practice.

 

[Diggs]

Hmmm.... I just went through this. I used a U-shaped 14 ga. piece of solid copper wire. Laid it into each trough on the connector and soldered it in place. I then slightly flattened the 12 ga. stranded wire and soldered it across the width of the 14 ga. solid already in place. I used tiny alligator clips to be sure the 14 ga. stayed in place while while soldering the 12 ga. stranded wire to it. Use some type of heat sink on the other side of the connector in between the connector tabs to pulls some heat away from the plastic. I first used screwdriver tips but changed to a flattened 12 ga, solid copper wire.

(How is wire thickness (i.e. 12 ga., 14 ga., etc.) expressed in Europe? )

Soldering the male (blade) connector was a bit easier. Each blade has a small hole in it that fits a piece of 14 ga. solid. I put a ~10mm long straight piece through the two holes on two adjacent blades and soldered in place. Then I wrapped the 12 ga. stranded lead around the 14 ga. solid and soldered in place. Again I used heat sinks (tiny Vice Grips with heat transfer pad) on each blade to pull the heat away from the plastic. I wish I would have taken pics.

We discussed this recently here -

Soldering cradle terminals to controller

This is probably a stupid question, but I can't find any specific instructions and am curious as to how others do it: What's the best practice for soldering my grin baserunner to the terminals in my downtube battery cradle? There are 4 pins (2 +ve, 2 -ve) and of course two wires. Should each...

endless-sphere.com

 

[docw009]

Never thought of that, but the Y-shape males it easier to solder because arms of the Y are half as thin. And since the current splits into each arm, halving half the wire doesn't matter.

But what I do is run the wire to both terminals, so it's a harder task with the thicker wire and I have to do it twice, risking the melting of those terminal pins.

 

[Diggs]

but the Y-shape males it easier to solder

...and I never thought of that.....heh

 

[Cyclomania]

Ok thanks for those tips.

Now, I am also a bit unsure of the charging port and how it is supposed to be soldered. Around 5.15 into the same video she talks about it and says "I soldered the charging port" and then you see a picture of how that looks like in the first pics below. But as you can see on my pictures I just see three pins there so I am not sure where to solder on the red one and where to solder on the ground/negative.

Any ideas here and if someone knows a tutorial it would be helpful as well. So in short, I see the metal pins there but not sure which one is for ground and which one is for positive.

Video:

My pics are here below. First is from the video and the last ones are on my charge port connector from the backside.

 

[Diggs]

The red will go straight to the positive end of your pack. Of the three pins on the connector probe conductivity to see which one goes to the middle pin on the front and which one goes to the outer wrapper. The center pin is usually positive while the outer wrapper part is usually negative. Plug your charger into the wall so it's in float and probe its plug to see which is positive and which is negative and be sure you are wiring your charge port on your battery the same way. Be very careful not to short the charge plug on your charger.

 

[Cyclomania]

Plug your charger into the wall so it's in float and probe its plug to see which is positive and which is negative and be sure you are wiring your charge port on your battery the same way.

You mean I could see which one is the positive one with a multimeter or something like that, correct? Plugged in and then conect to the pins? Hmm i haven't done that before. How do you set the multimeter for that one?

Also, I don't think I received the cables in the pack that she is using in that video. What do you think would be suitable awg for these charging cables? 14 awg maybe, or could I go even thinner? Looks like most people use a bit thinner wire there.

 

[Diggs]

Depending on the ranges available on the multimeter but set high enough to cover 75 volts? There should be a setting of 200 DC volts which most meters have.

16 ga. is fine for charging.

 

[Cyclomania]

Depending on the ranges available on the multimeter but set high enough to cover 75 volts? There should be a setting of 200 DC volts which most meters have.

16 ga. is fine for charging.

Then you put black on one of the pins and red on the other or something? Never done that before but figure it should be something like that right?

How do I know which one is which by looking at the multimeter? Not too bad if I happen to put the black on the charging pole for red, or the other way around? The only way to short this is if I connect them somehow right? Like normal common sense probing?

 

[Diggs]

If you switch the leads on the multimeter it will give you the same number but negative so it makes no difference. A negative number means the positive of the charger is the black lead on the multimeter. Your charger plug will look like the picture and almost all have the positive on the inside barrel and the negative on the outside.

Yep - Just don't cross the streams..... Hmmm..... never mind. That may be a states thing ( who ya gonna call?)

 

[Cyclomania]

If you switch the leads on the multimeter it will give you the same number but negative so it makes no difference. A negative number means the positive of the charger is the black lead on the multimeter. Your charger plug will look like the picture and almost all have the positive on the inside barrel and the negative on the outside.

Yep - Just don't cross the streams..... Hmmm..... never mind. That may be a states thing ( who ya gonna call?)

Hmm I have checked now and it gives a reading of 42 since I hooked it up to a 36volt-charger.

But how do I know which one is ground and which is positive? It gives the same reading both ways. Black on top or red on top.

The pin I have circled does not seem to do anything. It looks like one of the others pins but does not seem to lead current. Any idea what that one does do? Could that one act as a bridge/support for the other one when I solder on the wire there or is it best left entirely alone with no wire on it?

 

[Cyclomania]

( who ya gonna call?)

Ghostbusters?

 

[Cyclomania]

16 ga. is fine for charging.

The ones I am thinking of soldering on to the actual battery terminals as a Y-connection are these 10awg cables which should be enough right? I have an xt90 cable at home as the picture shows so I think I will steal those cables. Or do you think 12 would be enough there?

I am building 13s7p.

 

[Cyclomania]

I might as well post the rest of the setup so it is easier to understand it. This is a picture of how I plan to set up the battery in the battery slots. And also a picture of the HG2-cells I am using.

Since the nickel strips are quite long on these cells and they came like this I plan to cut them off a bit as well. And use my own nickel strips on top of them.

Let me know if something is off here or if I am thinking correctly.
Also, I have heard it is safer to connect everything in series first. Before the parallells. To see if to something is wrong. What do yu think?

 

[Diggs]

It gives the same reading both ways.

They are not the same. The pic multi2 is correct. The pic multi4 is reversed as it has a negative sign showing.

I wouldn't worry about the extra pin at this point. Use the continuity test on the multimeter (orange arrow with the WiFi symbol next to it) and that pin may connect to one of the others when the charger plug is puller out. (Just a guess but it may provide the BMS with notification when the charger is plugged in or out. Test continuity without the charger being plugged into the port.)

12 ga. should be enough but I don't know how many amps your controller can draw. 12 ga. is usually fine for 40 amps and under unless the draw is continuous.

As far as the rest of the build. Are you soldering or welding the tabs? An inexpensive pair of flush-cut nippers will get rid of the old tabs completely. Don't weld/solder on top of the old tabs. I didn't think there was a preference between doing the series or parallel connections first. Just be sure all the cells are within .1 volts or so of each other.

Did you buy a battery kit that has the case and cell holders? If so did it come with pre-made cell connectors?

 

[Cyclomania]

They are not the same. The pic multi2 is correct. The pic multi4 is reversed as it has a negative sign showing.

Ah so solder the red/positive wire to where I have my red pin in multi2 and solder the ground/negative to where I have my black pin in multi4, correct?

 

[Diggs]

Red and black should be as in multi2.

...and please, if you are unsure about something ask or see a professional. There's enough energy in that pack to destroy a house, garage, apartment, etc. Don't let it be yours.

 

[Cyclomania]

12 ga. should be enough but I don't know how many amps your controller can draw. 12 ga. is usually fine for 40 amps and under unless the draw is continuous.

BMS is 60 amps. Plan on using it on bikes that do not draw over this current.

 

[Cyclomania]

As far as the rest of the build. Are you soldering or welding the tabs? An inexpensive pair of flush-cut nippers will get rid of the old tabs completely. Don't weld/solder on top of the old tabs. I didn't think there was a preference between doing the series or parallel connections first. Just be sure all the cells are within .1 volts or so of each other.

I am spot welding the tabs. But I don't think I will rip them off completely. If they can be used I will probably spot weld them between the cells. If they are not long enough I will probably trim them a bit.

A bit afraid to rip them off completely since I heard that could lead holes in the cells in the worst case scenario. So if they are not long enough to bridge the gap between the cells I will trim them with a scissor and spot weld new nickel on top of them.

 

[Cyclomania]

Red and black should be as in multi2.

...and please, if you are unsure about something ask or see a professional. There's enough energy in that pack to destroy a house, garage, apartment, etc. Don't let it be yours.

I plan on having it in a zinc bucket like this picture. With sand in the bottom and kind of raised up on a wooden surface like a small table within the surrounding bucket. I plan on building close to the my main entrance door that leads outside. If something goes wrong. A short or something. I then plan on throwing sand all over the pack within my zinc bucket

Then carry it outside with welding gloves. I will also have protective glasses. If the sand does not extinguish an unwanted fire I also have a lithium extinguisher to spray water on it on top of the sand.

Let me know if I can do something more to be even more safe.

 

[Cyclomania]

I wouldn't worry about the extra pin at this point. Use the continuity test on the multimeter (orange arrow with the WiFi symbol next to it) and that pin may connect to one of the others when the charger plug is puller out. (Just a guess but it may provide the BMS with notification when the charger is plugged in or out. Test continuity without the charger being plugged into the port.)

These two in the picture have continuity. The two pins that looks the same. But other configurations does not. The big one does not have continuity with the smaller ones connected to each other in the picture. Is it then as you thought? And should they be soldered in any particular way because of this?

 

[Diggs]

Ah so solder the red/positive wire to where I have my red pin in multi2 and solder the ground/negative to where I have my black pin in multi4, correct?

Correct

afraid to rip them off completely

That's why I recommended the flush-cut nippers so you can cut them off instead of ripping. If they are in good shape with good welds and they fit with what you are doing then keep them.

These two in the picture have continuity.

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

more safe

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.