Do I have to solder on a Y shape?

[Cyclomania]

For a 7P design, that's seven current vectors that are represented by nickel strips.

Does that mean I need an extra diagonal series conection here in green, since I only have six connections between these parallell-groups now?

 

[Cyclomania]

Does it always have to be exactly seven series connections between two parallell groups of seven?

Sof for example in these pics I have 5 connections in the first. And in the second I have nine connections. Is this a problem?

 

[Cyclomania]

So now I am a bit confused
When I read my battery pack one negative side to the last plus side in the other other it reads 48 volts.

But..

When I flip it and measure the negative side the other way around to the last plus side on the other side.. It show like 40 minus-volts
Any idea why this is? Not sure if I forgot something or is this is just normal ?

I guess I eiter made a mistake and there is a weak connection somewhere? Or it is not possible to flip a battery in this way and measure the other way around, as it requires the first and the last group to not have any series-connection on that side ? Am I thinking correctly here?

 

[Diggs]

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?

Yes, add the ones in green. I missed those when I marked up your drawing.

Your understanding of the black and red BMS wires is good. I never thought to use tabs and just soldered the red wires between the first two cells of each group. You should probe your BMS balancing plug with your VOM when done to be sure you have a linear progression of voltage in the balance wires (3.5v, 7v, 10.5v, 14v, etc) as a final check. Be VERY careful. Way too easy to cross the streams here.

 

[Diggs]

Sof for example in these pics I have 5 connections in the first. And in the second I have nine connections. Is this a problem?

In the group of nine, #5 and #7 are redundant and didn't need to be there.
In the group of five you are missing one in the top right.

To have one missing in a group of 5 might be noticeable under very heavy amp draw but isn't a big deal.

 

[Cyclomania]

In the group of nine, #5 and #7 are redundant and didn't need to be there.

Yeah but those could not hurt right?

 

[Cyclomania]

Your understanding of the black and red BMS wires is good. I never thought to use tabs and just soldered the red wires between the first two cells of each group. You should probe your BMS balancing plug with your VOM when done to be sure you have a linear progression of voltage in the balance wires (3.5v, 7v, 10.5v, 14v, etc) as a final check. Be VERY careful. Way too easy to cross the streams here.

Great man.

Any idea why I am reading 40 minus volts when I measure the battery the other way around? I get 48 volts when reading from the first lonely negative group to the last lonely positive cell-group?

Is that because if I measure the first group on the other side, which is negative, it is soldered in series? Or why do I not get minus 48 volts when reading the battery, starting from the other side? In my mind I should get 48 volts both ways ?

I am a bit tired so I probably miss something obvious.

 

[Diggs]

Any idea why I am reading 40 minus volts when I measure the battery the other way around? I get 48 volts when reading from the first lonely negative group to the last lonely positive cell-group?

I don't really understand what you are saying. A pack is measured from the first negative to the last positive. No other way to measure it in total. I don't understand flipping the pack. You can flip your VOM leads and in your case you would get -48 volts. It sounds like you aren't measuring the first and last cell group when you flip it.

 

[Cyclomania]

I don't really understand what you are saying. A pack is measured from the first negative to the last positive. No other way to measure it in total. I don't understand flipping the pack. You can flip your VOM leads and in your case you would get -48 volts. It sounds like you aren't measuring the first and last cell group when you flip it.

So what I mean is this. I thought I would get negative 48 volts but it reads negative -40 when I go from the other side around.

I am new to this so it could be that this is completely normal. I just don't know and my experience in the past has been that when I switch an electric circuits I get the same reading but from the other side. Only negative. But now I get 48 and 40 which are quite different.

In my first video here you can see where I measure from the first negative cell group, which is of course the first lonely negative cell-group of seven cells. There are no parallells going from this negative cell-group, because they start at the other positive end of this cell-group which bridges over to the second negative cell-group. At the other end I mesure the positive cell-group at the end, which is standing alone with no parallell connections(like the first negative did not have either). Here everything reads fine and it shows what it should which is 48 volts:

sinokilovipp33's Video - Aug 29, 2024

www.veed.io

Now, here is the other video. For where I measure the first negative cell group(that also has series connections to the sides so maybe it is in reality a positive cell-group?) to the last positive. This shows minus 40,7. Any idea why this is? Maybe it is just normal I don't know but I find it strange:

sinokilovipp33's Video - Aug 29, 2024

www.veed.io

 

[Diggs]

Any idea why this is?

Exactly what I said. You are not measuring the first negative (and I can't see what is going on with the red probe). The black probe is on a positive and a negative. Your probes need to be on the only two 7-cell groups. One for negative and one for positive. All others are 14-cell groups consisting of a negative and positive.

Someone may be able to explain it better. I'm going to tap out........

 

[Cyclomania]

Exactly what I said. You are not measuring the first negative (and I can't see what is going on with the red probe). The black probe is on a positive and a negative. Your probes need to be on the only two 7-cell groups. One for negative and one for positive. All others are 14-cell groups consisting of a negative and positive.

Someone may be able to explain it better. I'm going to tap out........

Okay so this is normal? That is basically the only thing I wanted to know.

Since I do not want to solder the BMS if this is mistakenly a fire hazard.

So it is not possible to measure what I was trying? From the other side. Because what I thought was a negative is actually a positive, because it has a bridge of series conmections going to the neighbouring positive cell group? Since that is actually a positive cell group? Huh ok, great to know

 

[Cyclomania]

Coming back to this old thread since I now have gotten the BMS and the battery and most of the things in place, and also have some time over finally. The battery is almost finished.

Anyway I have soldered on all the balance leads from the Daly BMS. The reason I asked about an active balancer for the Daly BMS in another thread is because its balance connector, with the 14 holes, is a bit different. So it does not fit the active balancers that I already have. And I want to be sure the cell groups are completely balanced before I put the connector pin from the balance leads into the BMS.

Anyway, the values I get now are as follow and they all makes sense because the cells were ranging between 3,7 to 3,6, when they arrived, and this is a 13s battery. And maybe they are close enough now so that I do not have to use an active balancer before I insert the connector pin, from the balance leads, into the BMS? The cell groups have the following voltages:

3,6
7,3
11
14,7
18,4
22,1
25,8
29,5
33,2
36,9
40,6
44,3
48

I think I could probably hook up the connector right now, don't you think so? I have not soldered on the battery negative main discharge minus or plus yet, but the battery looks like the two images below here.

Best would now be to solder on the Batter negative, then solder on the Battery p-minus and then last solder on the positive discharge wire, to the last positive cell group, correct? Then the very last thing would be to connect the connector pin to the BMS. Is my thinking clear here? Or should it be in another numerical order?