Sufficient to say that non of the automakers or laptops use balance chargers. Billions of laptops operate on bms.
Bestechpower is not bms. They make pcm’s - protection circuit module.
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What’s the actual difference between a bms and pcm?
But laptops are not subject to millions of vibrations on a daily basis…
The bms we use balance the cells at 100% state of charge (top balancing), which adds safety during charge and optimizes to fill each cell to 100%.
If any of the cells are weaker than the rest, if top balanced, when the pack is drained to near empty, the weak cells will be lower than the strong cells. Lithium ion cells have a knee in their discharge curve, where as they approach 0%, they sharply drop in voltage.
With no discharge bms, the closer you get to pack 0%, the more likely some cells are above safe minimum voltage, and some cells are below. Once they’re below, and under large loads, they will be doing many large excursions below safe minimums. This is very harmful, and may cause fire. You may not even notice, as it’ll feel like voltage sag at the end of your capacity.
This is just one of the many ways bms can save your ass.
For myself I’m slowly but surely becoming convinced I need monitoring/alerting for cell voltages, leaving plenty of margin on top and bottom. And will balance the cells manually only when needed.
An argument can be made to do bottom balancing, where you balance your pack near 0% and take care when charging not to over charge any groups (charge to 4.1v/cell for example).
Think carefully before you dismiss the safety functions of a bms.
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I have totally thought about it dude… ALOT.
As there is zero chance of me using a discharge BMS, the point you mentioned can be addressed by raising the LVC on the esc to a safer value.
And if I find my unicorn individual cell voltage monitor, I will be laughing.
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By that logic you shouldn’t be using an ESC either. I don’t understand why you would single out the BMS failure and not other components? You should by default mount all components on foam or vibration dampening standoffs.
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Because the ESC is necessary. The BMS isn’t.
Especially if all of it’s work is done at 100% voltage. That means it is working when the board is sitting at home on the charge. The rest of the time it is getting carted around and taking up space that batteries or other ‘useful’ components could fill.
If you run a discharge BMS then this debate is probably not.for you, but if you are bypassing discharge… why even bother?
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You know that a balance charger is a regular charger with a built in bms?
So all those what ifs apply to it as well
Bestech quality has gone shit, the only charge only esc i trust atm is a neptune 15
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Yeah but its a BMS that isn’t in every board and works for multiple voltages… win?
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All things eventually fail. Putting things in skateboards accelerates this failure rate.
The BMS’s (or PCM’s) that came installed in a “very reputable” pack I messed with blew (an electronic component) responsible for balancing a cell group. This caused it to continually try to bleed down that cell and eventually killed it flat, 0 voltage. Because the user had no feedback, he didn’t know until the board stopped working and it was too late. As I understand, this is a common mode of failure with BMS/PCM and is very unlikely to happen with an external balance charger. If something is wrong with the balance charger, the charger throws an error and I just get another balance charger and chuck the broken one.
The waterproofing issue is solved by using waterproof plugs linked above. Has been working great for me since March, some 800 miles and ~100 cycles. IMO it is better in nearly all respects than an onboard BMS and I’ll probably never go back. One exception would maybe be a smart BMS that gives feedback on cell state, but even these do not measure Internal Resistance of the cell groups like my balance chargers do.
Drones and RC cars do not incorporate on board BMS’s and I’ve never heard of issues with external balance chargers in these systems. External balance circuits offer more features, more power, more room in the battery case, more reliability, modularity and does not expose the balance circuit to harsh conditions found in a skateboard.
YMMV
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Well not in my case, I will always pick a bms just because of the balance port that needs to stick out of the enclosure, I just dont like it they are too huge 
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Haha, yes, the form factor argument is legit.
These plugs are massive in comparison, lol.
I had a devil of a time trying to make it look OK that I wouldn’t be embarrassed to ride it, heh.
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What? Tons and tons of posts on rc forums about puffy batteies, burned plales, etc etc otc. 
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Agreed. But for the most part, I appreciate function over form.
@deucesdown a certain amount of responsibility undoubtedly comes when eliminating the BMS, there is bound to be horror stories from stupid people.
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Yeah I say we’re all adults here. Get yer info and make yer choices. I wouldn’t give my builds to anyone for fear of fire perfectly safe for me though!
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That’s true.
But I wonder how many people running these systems are pushing their batteries to the limits, vs sizing the pack appropriately and running well within the limits? The times I’ve blown lipos, I knew I had it coming…
I guess the same control over charging that I enjoy, comes with hazards. I can totally whack 10 amps through it, but should I ? Definitely not for everyone, most people just want to plug it in and go for sure 
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Its healthy debate. What isn’t healthy is when people say that their way is the only way.
I just wanna hear the best and worst of both sides.
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I like the idea of having pass through balance wires via a external connector so you can balance charge without removing the enclosure alot! I think the benefit of having one less component that can fail combined with the fact you get extra space for more cells is a good trade off for a more unsightly connector. It can also be a cost saving feature as well if you own a bunch of boards because you don’t need to keep buying a bms for every build.
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This is exactly my point! 
It may not be for everybody, but I really think that with conscious effort and the right hardware this is the safest way.
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@Acido that’s my point at it.
Doesn’t matter if charge only bms or balance charger.
In my opinion s balance charger can even balance faster and better and monitor the p group voltage. The monitoring with a bms is only possible if you have a smart bms.
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