That is so tricky …
It reminds me doing this in a GX connector with 12 pins for external bms … boooooorring
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All the links are the EU site but that have US Site aswell
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Perfect! Exactly what I was looking for.
Nothing yet
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Wonder if and one hear can help
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Is there such a module that plugs into your balance wires and it’s only function is to transmit cell voltages via bluetooth?
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ahh man…that would be sweet.
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I figure it would be a pretty tiny module… and as i would really love to eradicate BMSs from my life, almost necessary.
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I feel you, brotha…
Seen BMS’s kill more batteries than anything else
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Probably because on the forum the lower priced ones from china are seen only.
Im sure if we were using bmss like neptune 15 or some simmilar ones there would be far less problems
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I like the idea of a good smart BMS for being able to monitor cell health. But I also like the idea of fucking big batteries in different boards of different voltages. Most BMS aren’t going to supply balance currents high enough to successfully balance big batteries on a short charge cycle.
Balance charging makes much more sense to me. One charger for multiple boards, multiple voltages and less room taken up in the enclosures by a BMS that could fail for any number of reasons.
Why would you add a critical component into a volatile environment when it is completely unnecessary?
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I agree on all counts. One charger type for any number of toys (skates, bikes,drones, etc?). But I also realize it’s an inconvinience to have a balance charger setup. Most people just want to plug it in and go. The boards I pass onto friends all get BMS conversions.
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I quality battery will not get out of balance from one charge cycle. You can just have an easy brick charger if you want to charge on the way.
There people who where running there boards over years without bms or balance charger just checked p group voltage from time to time with a multimeter.
Edit: I might have gotten that a bit wrong, but still, people could charge there pack with an easy brick charger all week long and put it once a week on the balance charger to double check that everything is still how it should be.
But I get that this is still too much work for the one or the other.
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Thats what I’m thinking. I know that I would wanna open up and check balance probably more often that I need to. Little module would eliminate that.
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Just wondering peoples thoughts regarding bms stuff:
i had a chat with bestekpower recently and they mentioned that the majority of BMS’es these days are without balancing! and he recommended me to go without that function. His argument was that brand cells these days are very stable and as long as they are from the same batch it doesn’t matter too much.
Idk my instinct have always been to always go for balancing but who knows?
I might actually grab myself a few of these tiny ones and go to town and se what happens in a couple of months.
I have also looked at cell balancing boards:
http://bestechpower.com/balanceboard/jh09.html
but if im not mistaken they can’t be compared as apples to apples, to a bypassed bms with a balancing function.
Interesting news ahead :
Physicists Have Identified a Metal That Conducts Electricity But Not Heat
FIONA MACDONALD
30 NOV 2019
Researchers have identified a metal that conducts electricity without conducting heat - an incredibly useful property that defies our current understanding of how conductors work.
The metal, found in 2017, contradicts something called the Wiedemann-Franz Law, which basically states that good conductors of electricity will also be proportionally good conductors of heat, which is why things like motors and appliances get so hot when you use them regularly.
But a team in the US showed this isn’t the case for metallic vanadium dioxide (VO2) - a material that’s already well known for its strange ability to switch from a see-through insulator to a conductive metal at the temperature of 67 degrees Celsius (152 degrees Fahrenheit).
“This was a totally unexpected finding,” said lead researcher Junqiao Wu from Berkeley Lab’s Materials Sciences Division back in January 2017.
“It shows a drastic breakdown of a textbook law that has been known to be robust for conventional conductors. This discovery is of fundamental importance for understanding the basic electronic behaviour of novel conductors.”
Not only does this unexpected property change what we know about conductors, it could also be incredibly useful - the metal could one day be used to convert wasted heat from engines and appliances back into electricity, or even create better window coverings that keep buildings cool.
Researchers already knew of a handful of other materials that conduct electricity better than heat, but they only display those properties at temperatures hundreds of degrees below zero, which makes them highly impractical for any real-world applications.
Vanadium dioxide, on the other hand, is usually only a conductor at warm temperatures well above room temperature, which means it has the ability to be a lot more practical.
To uncover this bizarre property, the team looked at the way that electrons move within vanadium dioxide’s crystal lattice, as well as how much heat was being generated.
Surprisingly, they found that the thermal conductivity that could be attributed to the electrons in the material was 10 times smaller than that amount predicted by the Wiedemann-Franz Law.
The reason for this appears to be the synchronised way that the electrons move through the material.
“The electrons were moving in unison with each other, much like a fluid, instead of as individual particles like in normal metals,” said Wu.
“For electrons, heat is a random motion. Normal metals transport heat efficiently because there are so many different possible microscopic configurations that the individual electrons can jump between.”
“In contrast, the coordinated, marching-band-like motion of electrons in vanadium dioxide is detrimental to heat transfer as there are fewer configurations available for the electrons to hop randomly between,” he added.
Interestingly, when the researchers mixed the vanadium dioxide with other materials, they could ‘tune’ the amount of both electricity and heat that it could conduct - which could be incredibly useful for future applications.
For example, when the researchers added the metal tungsten to vanadium dioxide, they lowered the temperature at which the material became metallic, and also made it a better heat conductor.
That means that vanadium dioxide could help dissipate heat from a system, by only conducting heat when it hits a certain temperature. Before that it would be an insulator.
Vanadium dioxide also has the unique ability of being transparent to around 30 degrees Celsius (86 degrees Fahrenheit), but then reflects infrared light above 60 degrees Celsius (140 degrees Fahrenheit) while remaining transparent to visible light.
So that means it could even be used as a window coating that reduces the temperature without the need for air conditioning.
“This material could be used to help stabilise temperature,” said one of the researchers, Fan Yang.
“By tuning its thermal conductivity, the material can efficiently and automatically dissipate heat in the hot summer because it will have high thermal conductivity, but prevent heat loss in the cold winter because of its low thermal conductivity at lower temperatures.”
A lot more research needs to be done on this puzzling material before it’s commercialised further, but it’s pretty exciting that we now know these bizarre properties exist in a material at room temperature.
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Ya kidding right? Very few cells are safe without balance. Even less if you plan to bypass
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I know, I have been under that impression for a very long time myself.
Well not necessarily, most BMS’es work by just chopping off the current when the highest P-group reaches the max voltage cutoff and the same is true for the bottom end. I know that means in theory that the battery can be extremely out of wack but you wont cause any fires. the downside is that you will lose alot of capacity if they really go out wack and that really sucks. (I know I dont like it either)
however what the bestech rep said was that modern cells generally doesn’t go out of wack that much so it isn’t really a problem. I know there is million factors that contributes to that. But there are folks
here who have ran boards for years without a bms. (take whitepony for example)
for us there is a problem however when we are bypassing our bms’es, basically the VESC low voltage cut-off for one doesn’t completely kill the board and more importantly only takes into account the combined voltage, and not the lowest P-group like a bms would.
im more so interested in understanding in testing it out. ofc I will regularly check the cells and balance them if they get too out of wack.
and for example I noticed that @longhairedboy s latest masterpiece uses a non balancing bms.
and looking at bestechpowers as well as most other new bms’es popping up on alibaba and aliexpress alot of them are without balancing.
yeah i’ve been running that BMS in my own board for about six months now with no issues, and sent out a few completes with it as well. As long as the cells are good its good. I used to run 60 amp discharge protected BMSs, but regen braking triggers thier cutoffs, voltage spikes which the cells themselves have no problem absorbing. Since its the voltage spikes that cause it and not over current, using an 80 amp didn’t help. One answer of course is running ridiculously large capacity BMSs (like in a Bioboard) and lose more real estate than a Unity consumes, but i suspect those would also be subject to it under the right circumstances. The other answer is to run 5+ cells per group and and let the pack take the beating, which it will, with pleasure.
Also, the BMS i use ( HCX-D787 ) does have a cell balance / equilibrium funciton.
From the site i buy them at: https://litechpower.com/product-detail/HCX-D727LI12S15A_04.html
“4. With cell balance/equilibrium function;”
in the spec list however they have slashes in the start and end balance voltages. Not sure what that means. Yes, it could mean that thier copy is full of lies, but it could also mean that if i leave a slightly unbalanced pack on the charger over night while it sits on green that the cell groups will slowly balance.
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