@Acido thatās my point at it.
Doesnāt 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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And how much of them even donāt balance the pack but just cut off over and under voltage?
Itās not an argument to say because xy % use one application, an other one canāt be same efficient or even better.
With all my arguments I donāt want to say that using a bms is shit or worth.
Just there are good reasons for not using a bms and rather external balance your pack.
There always multiple ways.
Thatās why laptops donāt use balance charger, because the average Joe doesnāt want to plug in two wire and setup the charger just to get the charging done.
On the other hand, I build my packs by my own, so I might be that self confident to say in this part Iām not like the average Joeā¦
I totally respect the argument that an external balance plug doesnāt look nice or might be harder to waterproof ( donāt think the last is really an issue) and I also think that people who want to have a discharge protection will benefit from a discharge bms,
But if to compare a charge only bms vs external balance charger just from the functional side there is no real advantage in the bms and to say a balance charger doesnāt do anything is just not right.
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He grinded my gears too. I donāt think he is really invested in the spirit of this thread bro.
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A Discharge BMS will stop at any p group been over dis charged
A VESC is only looking at the hole pack voltage
Charge only BMS = a balance charger only BMS (if you ignore idiots using the wrong settings)
The only exception to this (as fare as I know) is the FlexLight BMS Under development that is a charge only but over can will be able to tell theVESC to shut off if any p group is about to be over discharged
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Yeah i get that, my post really should have read ābypassed or charge only BMSā
Do you have any links to read about the BMS you just mentioned?
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if it ever arrives.
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I have height hopes and some very promising things by some of the top codes on the forum involved. so I think it will be up there with the DieBieMS possibly better.
Iām a pessimist so that saying a lot
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Time and testing will tell, there is a lot of thorough testing happening, so much that itās hard to keep up with without having one here to tinker with myself
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Prity awesome idea why double up on monitoring curent and mosfet switching when the VESC is all ready doing it. Get the VESC to do it saves a lot of fotprint.
Avoids peak over discharge discrimination (BMS shouting down when a short spike happens that the VESC is dealing with)
On over discharge VESC Keep running at a reduced level instead of just powering off and having nothing
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ESC does nothing. It sees overall voltage and current. Thats it. It cant tell you SOH of the pack. Its a weird discussion. Every single automotive, motorcycle, tool, computer, medical manufacturer uses BMS. Perhaps they are stupid and average Joe here is more clever, i donāt know, i tend to look towards direction where engineers engineered the fuck out of it. No 300USD bike will do proper DH, you would kill yourself. Why would someone expect 30USD dollar PCM will be reliable? Its just stupid. People getting branded expensive cells and then shaving on proper BMS?
Tiny BMS is from someone who worked on EMUS BMS which is automotive grade reputable system used by many in cars(just do a search). Go to the website: https://www.energusps.com/shop/product/tiny-bms-s516-150a-750a-36,
read the manual and compare it to your cheap Chinese PCM, then argue.
You donāt have to discharge through BMS. BMS has output to control your ESC ignition/activation input. You set your discharge current on the ESC and BMS is left to monitor, balance, disconnect your load/charge based on HVC, LVC, temperature. Lots of parameters could be programmed via BT or wire, audible signal for errors etc. Logs could be accessed occasionally and quickly to ensure the pack is in good SOH.
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bascially a flexi bms that talks with the vesc so the vesc can act as a discharge type bms and limit the current to minimum if theres a bad p group or any error is the best deal 
This is all possible and probably will be added in the firmware in the future
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You still donāt get the point of our discussion.
Great write up thou! Agree with most of your points there.
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Whatās the discussion? I have done all 3 types.
- Use a charge balancer
- Use cheap China charge only BMS $10
- Use expensive discharge DiBieMS $100
I prefer cheap China BMS currently. Iāll replace with smart charge only BMS that can relay information to my phone(through metr pro) or give inputs to the VESC so that it can stop me gradually and not abruptly like DieBieMS does when one weaker parallel group voltage drops below minimum. I do like that I can see individual cell voltages in my phone with DieBieMS, but donāt want to use it as discharge BMS.
Using a balance charger was okay, but they are usually meant for 8s batteries. Probably expensive ones go higher. Also I donāt like lots of connectors outside. I want my board to look like a finished product and not some diy havkā¦
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@iamasalmon uses 2 6s batteries in parallel. So its cheap to balance charge. I like that method. @mishrasubhransu
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it was more or less just, why use a charge only bms (Simple one without CAN communicate or bt and also not a discharge bms) if you can just route out balance wires and do balance charging. Thatās all.
In our discussion we had valid points as advantage for both options.
So as result, itās up to personal preference what you are going to use.
If you think your external plug is optical not pleasant or canāt be waterproof and you like the simplicity of just plug in your brick charger, but you donāt mind that you canāt monitor the individual p-group voltage and also donāt mind that there is a very real possibility that the bms could drain one of your groups till 0V due to a component failure, than go with a charge only bms.
If you might not have space in your enclosure for a bms (Tayto enclosure with a 12s4p for example), you want to see individual cell voltage and like higher balance current, plus use one charger for different boards with different S count, than external balance charger might be fit you.
I by the way have a 6-12S balance charger and very happy with it.
As I use LiIon as well as lipos in different S counts, routing out balance wires are the way to go as I can use that one charger for just every pack. Again, thatās my way, because itās most convenient for me, not saying itās the best and definitely not the best way for everybody.
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The conveniece is with BMS as you can have laptop style brick for charging, smaller one to take it with you on the road and single small dc plug.
You can do that without a BMS as well 
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Thatās me
At least I tell people I check the pack every week, it must be at least 3 months that Iām saying ānext week I will check itā
But to be honest, every time the cells were perfectly matched. Would I recommend for the average Joe that built his first battery? No way, but with proper current sharing in the pack and quality cells they should stay in balance
But things can go wrong really quickly if a cells fails and gets overcharged, as per data sheet tests it should never catch fire, but there will be heat and smoke
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hi,
is this looking ok so far? or am I destined for a fiery death?
any input gratefully received!
next step is solder 12awg silicone wire to the nickel then spot weld that to the battery + & - and join the 2 x 5s4p packs (once Iāve practiced soldering the wire to nickel and Iām happy itās secure enough)
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