My bad, I meant to say ground I think? I guess it’s okay if you have a 2 prong charger
Against all advice here, I think the 8s and 4s combo to make 12s will work. Use an 8s and 4s bms. And when you connect them in series make sure the cells are all at the same voltage since over time you might get drift between the two packs. However this can be fixed easily by just checking the cell voltages about every 6 months between the 2 packs.
I think people are too paranoid about unbalanced cells, and as long as one cell doesn’t die and take the whole p-group with it. They should stay reasonably balanced just by themselves.
Or ribbon cable to bring the 4s balance wires up to the bms in the 8s case. If you use some balance lead extension connectors it shouldn’t be too big of a headache to build. Instead of 2 thick wires down the middle you’ll just have 2 thick wires and 5 little ones.
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@marsrover Exactly, we’re speaking the same language. I thought about both options, but wiring the BMS would be intense. When you say ribbon cables you mean extensions from the separate pack to (one) BMS right?
Kind of like a flex battery, but one bridge with longer cables at the split?
lmao I was just thinking of getting that from Keith to play with
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Behold the power of 12am drawing. Note the +leg from 8s pack going into the 4s cells, then coming out again at full voltage.
NICE lol thanks. which setup do you think is safer for the battery? Two packs would be easier though, and swappable. If both packs died I can insert a spare into the chain, and be fine right?
Obviously all on one bms would be “safer”. And now that I think about it more, most likely easier with these.
https://www.amazon.com/dp/B0757GBSY2/ref=cm_sw_r_other_apa_i_yXTEEbZNE3TMD
Hack up those to make the extension. Use large bullet connectors for the thick wires. Hardest part honestly is going to be the enclosures. It’s going to have to be custom. I’d start with a 3d model, then print a mold for fiberglass or kydex to form around.
Perfect Thanks, Yeah I’m thinking Carbon Fiber custom from another vanguard build online it was very stealth.
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Damn that’s she’s tightly packed, don’t think I could fit another cell if I tried…not sure what to do about the charge and discharge ports though
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So the most space I have is enough to put an XT90s in the corner side which is good enough for the discharge…but I can’t have a proper charge port (I have a beefy 3 pin connector because 8a)…is it reasonable to have a third wire to the ESC case for charge negative and have the charge port, voltage display, and anti spark in the ESC enclosure?
Also, is it better to…
- A) glue all the p-packs w/ silicone and wipe away the majority with a credit card, then sperate with fish paper, relying on shrink wrap to hold everything
- B) just glue them all as a block w/o the fish paper then shrink wrap it all
- C) just fish paper and heat shrink the thing
- D) glue the fish paper to the cells then heat shrink, even if the paper delaminates eventually
0 voters
It’s a long fucking night and I’m not in a state to make decisions anymore
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I vote not-B. Always gotta have something in there for abrasion resistance, and fishpaper is that thing.
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Why not making 12s3p + 12s2p and connecting them in parallel?
This way, if you decide to change your setup or whatever, you will have 2 usable batteries which can be separated. You can do nothing with 8s+4s setup except using it as is.
Also, you will need only 12s charger and you can charge both batteries at the same time
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@tinp123 OK, I didn’t know that I can do it that way, but I guess I have only seen most people changing the (series) combinations, and (parallel) stayed constant, but you’re right any combination is possible if you know what your doing. So, let me ask? can I have 6 cells double stacked (12s) in Series, and 6 packs of 5 cell double stacked Parallel. Are you saying that if the Parallel packs goes bad I can replace them with touching the Series pack? Last question does the (series) pack have more stress put on it. Than the (parallel) packs?
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Look at this this way. You are building two separate 12s batteries, each with its own bms. One battery can work without another, you are just connecting them together in parallel to get more Ah = more miles.
If I was in your place, I would build each battery with charge only bms (since it is smaller and you need space) and I would wire charging port on each battery. One charging cycle I would charge on one port, next charging cycle on second port. That is so that each battery would use balancing function of bms when it’s charging through its charging port. Those are not strickt rules, but for peace of mind. I hope this is understandable, if not, I will try to describe in more details.
Every time you charge one battery, another one connected in parallel will also charge; they will always have same voltage.
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I don’t quite understand what do you mean about stress? More cells you have in parallel, lower will be stress on each cell. It doesn’t matter if all those parallel cells are in one 12s pack or if they are divided between few 12s packs, if those packs are connected in parallel.
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That whitepony build is one sexy beast
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I understand, I was under the impression that connecting two batteries together would increase voltage only. I can wire the packs both in 12s and when I connect the packs together it will increase the Capacity miles. Right? Ex. 12s3p pack connected with a 12s2p pack makes a 12s5p. Correct?