any recommendation?
All of my jst connectors are intermediate and can be replaced, the charging cable too. But that is good info in your post.
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I skimmed the pdf and interesting but for the min cycles of the plug your stating (didn’t see it)I think they’re being used w a servo where the voltage drop from increases resistance over cycles could effect the communication w the servo but when used with balance wires it wouldn’t be a problem.
Replacing the balance plugs the bare wires get so close I sure don’t want to ever do that.
When I’m messing around with my hobby chargers with “NIST traceable voltmeters”, the voltages always seem a bit all over the place. Granted it’s showing 3 digits of precision, and that third digit might as well be fiction. but we’re trying to hit 2 digits of precision so the 3rd digit actually matters… And it always seems to be a little off from my “nice” multimeter.
Anyway, I feel like the balance leads are not consistently good connection. I’m always doubting what I see.
Bottom of first page 
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” We highly recommend using only gold terminals for your connectors. Tin plated contacts usually have a life of about 10 cycles (a cycle being plugging in and unplugging) before the contact goes outside of its rated specs (possible specs being contact resistance and holding strength). Basically, the plating starts to rub off and the contact becomes prone to oxidation, and the contact(s) start to lose their springiness, increasing contact resistance. “Contact resistance” refers to electrical resistance, which can impede power going to the servo and possibly disrupt the servo signal. In most electronics applications the connector would be plugged in once and never touched again, so 10 cycles would be fine, but they’re simply not meant for the repeated use seen from hobbyists. Gold connectors have a life of 50-100 cycles, offer lower contact resistance, and are extremely resistant to corrosion. These numbers probably still seem low but keep in mind that the contact isn’t going to fail after 100 cycles, it will just gradually increase in contact resistance and decrease in holding strength (the springiness of the contacts is reduced). You might notice the same thing happening to the outlets near your kitchen counter. If your connector doesn’t plug in firmly anymore, that’s a good indication to replace it.”
I’ve never replaced a plug on my kitchen counter and never heard of anyone doing that!
I have had balance plugs break though but almost always from losing their connection to the battery, at that end.
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Question for those that have the smart BMS.Does it come with the balance cable? Also I’m tossing up between the 100a model and the 20a model. Still not sure if I want to go charge only or not. For those that have the 100a version did you struggle to fit it in your enclosure? It seems quite large
Mine came with, like all bms I got from bestech had them included too.
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Mine too came with a balance cable.
What are peoples thoughts on this bms I’m hoping to use it in a mountain board so in would like to have a high current discharge.
I woud say it´s the same
I just came across the Neptune Lite and I like it a lot. It’s not exactly a BMS. It merely monitors cell voltages and sends out the data via BT, but then again it’s really small (41 x 35 x 7 mm). It comes with a very cool looking Android app with a ton of features. Unfortunately no iOS (yet?). Still, I wish I have known about it before I started routing all the balance wires out of my enclosure. 
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Hey I’m gonna propose a scalable and working solution, it was a work made by an E-S member (AfdhalAtiffTan) back in the days. He called it an active battery balancer (compared to his previous passive dissipative one with shunt regulator).
Claimed accuracy was 99.99% with him using various used laptop 18650 cells. It is built around 2S daisy modules between each cell so you can scale the voltage up as much as needed, no limit.
Main con is : cost adds up quick for bigger batteries.
Plugging in parallel if possible might be an efficient way to shave down price from expensive to super affordable (circa 40$ for 12s4p for example). But I don’t know if it is doable or relevant? Is it how classic BMS usually work ?
Here is a link to his page 
Edit : This might deserve a separate build thread!
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I looked at it and I don’t understand it. Could anyone translate it to a 5-year-old language for me?
My (possibly wrong) understanding is that it can balance 2S by charging both cells by using the average voltage. So for example if one is 4V and the other is 3V it would charge at 3.5V and the charger voltage would gradually increase as the weaker cell is getting charged and it would converge to 4V. Right?
Now, how is that helpful for more than 2S? I also still don’t quite understand how exactly the charging works.
In not exact terms, it kinda transfers exceeding energy from most charged cell toward less charged cell insured to balance it. Reference voltage is external voltage.
So both will end up charged at same level ; under discharge I think it still does same job (balance is made at few mA current) but I was only interested in charging aspect.
You need 1x module “between” each cell in série. So 4s = 3 modules, 6S = 5, 12s = 11 etc…
It daisy chains. So your cells are always watched in regard of their immediate neighbor, which forms a group…
Hope my half assed explanation is not too confusing (it is not a scientific description lol)
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Does this mean all cells are being continuously balanced? This is not necessarily good. Hmmm but I guess that’s the situation with cells in a parallel-group. Let me go into a hole and reconsider…
That’s a great explanation. Thank you! That sounds really useful. Unfortunately nothing to do with measuring cell voltage, so somewhat misplaced in this thread. Thanks for sharing the link anyway. It’s definitely an interesting approach to balancing cells.
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I’m still unclear on a few things. IIUC, there’s a buck converter for each 2 cells that acts as a charger. It charges at the voltage that’s equal to the mean of the two cells. I guess it takes energy from the 2s pack and transfers it to one of the cells. Does it always charge the weaker cell though? It looks like it’s hardwired to only one of the cells, so in case that cell is lower of the two, it can balance the 2s pack, but if it’s the higher one it can’t. Is that a wrong interpretation?
Well from what Adfhal told me back then, there was a minimum voltage thresold to reach before balancer triggers ON so under voltage thresold it will let cells charge first then balance on “top” 
Positive aspect is : cells won’t drift to overcharging state no matter what.
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Not sure to have understood everything ; are you asking if it can bring a higher cell down to a lower voltage level (ex : 4.15 instead of 4.2) instead of just bringing both cells to higher cell voltage ? IIRC yes there is a way, need to dig in my ES PMbox to check infos.
But basically it will try it best to bring down/up to reference voltage level so it might need to be set on charger firsthand.
Hm, so the buck converter is connected to the first cell of the 2s pack and it either charges it or discharges it to achieve balance with the second cell? That would make sense.
You would then need 11 buck converters for balancing a 12s pack and that would be pretty bulky, wouldn’t it? A bit like the “Frankenstein charger”?
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