Very nice build. I like the enclosures a lot, looks beefy :). Do you happen to have a drawing or pics of how you connected the balance leads?
You could also build some type of simple balance lead board so you can just connect the leads from the LiPo to it, and then have it output the 6s balance lead. That would be a non-invasive (to the LiPos) method. I imagine there may already be a product that does that as well.
Great idea, I just need to find the pin-outs for the 3s and/or 6s balance leads.
you rock out loud sir 
Very nice. The wiring is confusing me but I hope it comes out as well as yours did.
I saw that, very good video. The issue I am having is find the exact connections for the balance wires for 2 battery packs, the connections for the battery POS & NEG & the ESC POS & NEG. I see how to do it in theory, but in practice its fairly complicated.
This is what I have drawn up. The yellow boxes with a question mark are the questions I need to answer. I think the Battery NEG goes to B- and the Battery POS goes to P-. I don’t know where the ESC and the balance wires would connect to the BMS. Any help would be appreciated.
The balance plugs are what is really throwing me. As the 1st & 2nd wires apparently goes to cell 1 and then the 2nd & 3rd wire go to cell 2 and so forth I cant figure out how the 4th wire bridges into the second battery at cell 1.
I am really hoping someone can tell me which wires go were. I’ll then update the drawing and post it for everones future reference.
Thanks
You’re making great progress! I’ll try and address those questions marks.
Let’s start with those on the balance wires. Here’s kind of a general overview of those balance wires. Skip this paragraph if you already understand it. Each battery has 3 cells, so you have 4 balance wires coming out of each one. The first is the negative of cell 1, which is also the negative of the whole pack (so the main black wire coming out of the pack and balance wire wire, most likely black, are connect to the same end of the same cell). The next wire is the spot where the positive end of cell 1 connects to the negative end of cell 2. This wire allows you to measure the voltage across just cell 1, to ensure it is not out of balance (thus “balance” wires). The next wire connects at the spot where the positive end of cell 2 connects to the negative end of cell 3, and serves the same purpose. The last balance wire connects to the positive end of cell 3 (most likely the red wire), which is also the positive end of your pack (big red wire coming out).
So you’ve set up the packs connected correctly to get a 6s pack. The way you did that is to connect the positive end of one pack to the negative end of the other pack. Literally do the same thing with the balance wires. Connected the corresponding ones in the middle. From your schematic, I think that would mean the #4 lead on the left balance plug is connected to the #1 of the right’s. That means you now have a total of 7 leads, labeled like this 1–2--3–4/1–2--3–4, with the double dash being a single battery cell.
Now, as for bigger wires, assuming your BMS is also serving as over current protection, you have 3 wires going through the BMS. The negative of the combination battery (the two 3s cells together), the negative of the charging port, and the negative of the ESC. I think B- is the negative of the pack, P- is the negative of the ESC (the discharge), and Ch- is the negative of the charge port. I can’t quite read what’s on your picture, but I think it may be something similar to that. The positives are all connected together.
Edit: Removed “As a note, a 6s BMS should have a 7-port balance jack.” …total brain fart, it should be 6, as is pictured.
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Im gonna go back and read this a couple of times, just to make sure I understand. I really appreciate all the help.
Just becareful when connecting lipos together. Ensure using multimeter to know there are no shortings.
Here ya go! I went off this following page for the wiring of everything involved. The ESC is directly connected to the battery because it overrides the current limit of the BMS.
Just to confirm my messy paint skills, the battery on the left is NOT connected to the BMS via the balance lead, and two of the pins between the two batteries are connected.
Please be careful while setting this up, while I am pretty sure what my diagram is correct, I have had a lot of people screw up because they thought polarity didn’t matter/I might have made a simple mistake.
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That is AWESOME! I will update the drawing when I get back to work Monday and upload it for everyones use. It will likely be a month or so before the BMS arrives, but at that point Ill test and post the results. This could be a really cheap way to get very simple battery management fir our boards. Thanks to everyone for the help.
I have never setup a BMS,
but this seems really strange because you bypass the bms completely when running your board. Is this a special way of wiring? Thought you had to have the BMS inside your “main” loop. This way your bms won’t be able to cut off + the fact it’s rated for 60A is not being used, the amps the esc is pulling is not going through the bms.
Or am i wrong?
Like I said, I bypassed the current limit of the BMS in that wiring diagram. The BMS is rated for 30 amps and an eboard can draw quite a bit more than that.
I’m stupid, didn’t read what you wrote ! My bad !
Not stupid, just learning. We’ve all been there!
Just for reference, I (200 lbs) draw about 40 amps, going 15-20mph uphill on my dual setup. So you may actually be okay with 30, but I would probably follow the wise advice of @VladPomogaev, 30 is a little low. I may add to that, if you are going to bypass it, then I’d see if you can save a few bucks and get the same one but just with as low of a discharge current as possible, since you’re not going to use it anyways. I did that on my board. I’ve got a 10A BMS, but since I bypass it going to the ESC it doesn’t create an issue.
I don’t want to step on anyone’s toes but you really want a more stable chemistry when using a BMS. Stick with cells that have an internal fail-safe like a123’s or 18650’s if you want something you can just plug in and walk away.