Active balancers have nothing to do with the discussion here.
A BMS is either balancing or non-balancing (just cuts off charging when first p-group hits ~4.25v).
WTF is “MAINTAIN balance”? Is it able to balance or not?
Saying the pack will stay balanced BECAUSE you “pre-balanced” (lol) it implies it does not actually balance at the top of the charge cycle?
You’re reading a fragment of a conversation that probably shouldn’t have been posted to begin with.
They do keep a pack balanced provided the pack is built out of pre-balanced p-groups. After i build my p-groups i balance charge them on a rig i built then weld / wire them into a pack.
What they will not do is fix a pack that’s wildly out of balance. But if a pack goes wildly out of balance, it needs to be repaired or replaced anyway. Chances are there are some bad cells or something else is wrong.
Using solid core 80/20 rn i think, no need for flux at all!
Nice and foolproof, looks great 
I have an off-topic question, what happens if you should ever cut your hair? 
I guess then you would be SHB @shorthairedboy 
I lose my powers.
funny enough, my user name started out as a retort / joke about 12 years ago when a friend of mine, who is a woman, started a blog called shorthairedgirl. She had short hair at the time.
Nice work! Great idea
cool, this spins in my mind for ages as well. nicely done!
@longhairedboy
forgive me if I get this wrong. Not a battery building expert. but would it not be possible to just run the balancing wires through the same xt60’s?
I am planning to build a detachable 12s5p
Not going to work. Balance cables aren’t gonna connect to the modules via xt90s like that…
Suggest read Battery Basics for Beginners [Serious]
Edit - my bad? Maybe this is only a partial diagram…?
This is a pretty extreme version of a sectional travel safe pack, but as far as I can tell this will work. Each group being 1P means you only need one balance wire coming from it to the BMS.
Although, you will need to have a bit of extra wiring on the first/last group integrated into the harness for the BMS charge circuit. The harness will definitely be a pain with that many wires, so zipties, labels, and sheathing would be a good investment for any time you need to remove the groups as well as keeping them safe and organized during use. Also that’s gonna be an absolute truck load of soldering with that many XT connections on a battery, so it will be a long road ahead of you to finish it but for sure possible.
would the balance wires not normally end up in exact the same position when you follow through the connector to the battery?
…
It’s a heap of connectors and wiring though. That’s gonna take a chunk of space
yes, that’s only 3 of 12 p groups
I got some space in the middle between the groups. other than that i have absolutely no space. It’s for a prototipo
should those be xt90 or is xt60 enough?
I am planning on doing this same thing dude!
Problem is I am using 7P 25R cells and I intend to pull as many amps as possible from this, so I would feel much better with dual 3.5mm bullets (2 per terminal/series connection) or twice the current carrying of 1 xt60 with a smaller overall size.
Just thought maybe my plan with 12 separate units are a bit overkill for the purpose. What would be a better choice if I built one? 2s3p p42a or 2s4p 30q? would that roughly come down to the same or would the p42a still win?
Depends on the enclosure. If a 6 2S sections fit better than 4 3S sections then you’ll have your answer. The point of the one i built though was to keep the individual batteries under 99 watt hours for flight. I can see a 3S exceeding that too easily. Even a 2S4P P42A pack would be about 120 watt hours.
thanks, I meant 3p 2s p42a vs 4p 2s q30. I was wondering if 3 molicel would beat 4 30Qs in performance.
3p P42A is better than 4p 30Q in both capacity and discharge
