What´s the difference between a BMS with a C- and P- wire compared to one with a shared wire for C/P?

[leffex]

What´s the difference between a BMS with a C- and P- wire compared to one with a shared wire for C/P? (C- Charger in minus, P- Power out minus)

Please if someone can shed a light on this. Thanks

There are of course other BMS functions as well but focus on the security side for hazardous events what is the best BMS to go for as a standard?

Also as you´ve got a motor and controller connected to your battery would a shared wire for C/P be better if that controller has function for regen.

In the end anything can be connected with wires to function correctly but explained in the easiest way possible. How would that explanation go for the topic question?

 

[batteryGOLD]

Maybe the best is allways to use a common port bms C-/P- or C+/P+ common
paralleling batteries & regenerative veicules careful, better use common port bms (dont put reverse current @ a discharge port, its unsafe..)

dont put a fire at your own electric veicule bcause of a faulty bms or separate C/P ports... make sure U know what Ur doin!

 

[batteryGOLD]

CN dudes found an invention at separate port bms's to apparently transform it into a safe common port bms! guesss...
that trick is used at millions of batteries 60V 20Ah and 12Ah worldwide for tha famous citycoco escooters! those scooters have 2 batteries connect in direct parallel. one battery at tha scooter floor and other battery under seat (some people connect randomly a fully charged battery to a discharged battery in parallel and don't understand whats happening at tha citycoco scooter.. )

the CN scientists invented tranforming a separate port bms into a commun port bms by just connecting input charger to C port and also discharge link connect to bms charge port! Is this chinease magic? tha bms Discharge/P port is left alone no cable connected to it

guess?? it works for city cococo scooters even at 30A peak current, no bms heat..! is this is science?

 

[amberwolf]

The separate port BMS C- and P- uses C- for charging, and P- for discharging. Each one can only protect against current flow in the direction it would normally flow--there is nothing to stop current flow back the other way in the event of some type of problem. So a controller with regen on a separate port BMS could keep charging the battery even if the BMS is trying to stop this due to some limit being exceeded or some problem with a cell, etc. You can still use them this way, just be aware of the potential.


A common port BMS with only one input/output protects both ways, so is safe to use in situations like regen, paralleled batteries, etc. The only real electrical disadvantage in this type is the two sets of FETs (charge and discharge) are in series, so there's twice the resistance, voltage drop, heating--it's small, but there.


Keep in mind that for the *controller* part of things, the separate port is safer, *because* the BMS can't disconnect the controller during a regen event. If the controller gets disconnected during a regen event, the current has no where to go, and voltage rapidly spikes across the FETs and everything else on the battery-side bus (and because it's there the controller doesn't turn off, either). If this voltage exceeds the ability of any of those parts to tolerate it, they can be damaged or destroyed, and it's a very very fast thing--too fast for protection systems to do much of anything about it, most likely.

It's even possible for a non-regen event to cause this issue, if you have a DD hubmotor and go downhill faster enough than the motor can be driven by the system, so that the voltage it generates is higher than the normal system voltage--this *forces* regen, so the controller can't even turn this off if it *did* have protections fast enough for it.

 

[leffex]

Maybe the best is allways to use a common port bms C-/P- or C+/P+ common
paralleling batteries & regenerative veicules careful, better use common port bms (dont put reverse current @ a discharge port, its unsafe..)

dont put a fire at your own electric veicule bcause of a faulty bms or separate C/P ports... make sure U know what Ur doin!

Thanks dude

I mean these common wires are easy to understand how the connections may be

How about a bms s with two cable connections? They are connected to controller input and then the other cable C- is connected only to the charging lead? When this vehicle is using regen the current then goes back to P- as the C- is not connected. So in a sense, can a dual connection bms work or will it cut power and "break into destruction" in this normal regen instance or will it only break when currents are high enough and outside the paramteters of the electrical system?

I'm trying to figure out failure scenarios and take those in comparisson between these bms so se which bms is good for which.

Most ebikes have no regen
Most e-scooters have regen.
Faster and stronger vehicles may have regen

 

[leffex]

The separate port BMS C- and P- uses C- for charging, and P- for discharging. Each one can only protect against current flow in the direction it would normally flow--there is nothing to stop current flow back the other way in the event of some type of problem. So a controller with regen on a separate port BMS could keep charging the battery even if the BMS is trying to stop this due to some limit being exceeded or some problem with a cell, etc. You can still use them this way, just be aware of the potential. ...

Thanks

So in the above example how does the wiring look like as it seems to be very hard to visualize this one. Golden guy gave an example that the coco emopeds did parallel the c- och p- connection in essence doing an override to keep the system going but what mechanism of protection did they lose by doing this and what did they "gain" by doing it?

I have an emoped going but no regen activated yet. How should I be on doing with my BMS cables that has separate ports for charge and discharging? If I activate regen with only P- connected will I destroy my BMS? or will it just charge it but charge without protection?

In the above example of the coco's couldn't they just put a diod from the P- to C- to get it working with increase safety or do the regen current, if high, kill a diod fast here?

If I was to build batteries it would be good to have a BMS that I know the ins and outs off fully so to say, that I can make my builds the best way I can possibly do. If the end product is not working as specified or I am installing a bms for protection that doesn't work the way I think it should that is a dilemma for me. I guess no person would be proud pushing out products into the market that is beeing hazardous.

 

[batteryGOLD]

How about a bms s with two cable connections? They are connected to controller input and then the other cable C- is connected only to the charging lead? When this vehicle is using regen the current then goes back to P- as the C- is not connected. So in a sense, can a dual connection bms work or will it cut power and "break into destruction" in this normal regen instance or will it only break when currents are high enough and outside the paramteters of the electrical system?

I'm trying to figure out failure scenarios and take those in comparisson between these bms so se which bms is good for which.

I don't know the answer to Ur question..

and add more electric veicules to tha list
"Most ebikes have no regen
Most e-scooters have regen.
Faster and stronger vehicles may have regen"

Patinete/trotinete Xiaomi m365 has regenerative braking.. plus many other trotinetes, some don't have fisical brakes, just a throttle for electronic brake..
Are those veicules real regenerative or where is going braking energy? most trotinete/patinete batteries have separate charge/discharge port

 

[amberwolf]

So in the above example how does the wiring look like as it seems to be very hard to visualize this one.

For a separate-port BMS, you just wire it exactly like it's suposed to be wired. Charging to the charge C- port and discharging to the discharge P-port.

That's it. Regen is going to go backwards thru the discharge port, uncontrolled by the BMS.


If you use a common port BMS it only has one connection, so both charging and discharging go thru that connection...and they are both controlled by the BMS as needed, including regen being blockable.

Golden guy gave an example that the coco emopeds did parallel the c- och p- connection in essence doing an override to keep the system going but what mechanism of protection did they lose by doing this and what did they "gain" by doing it?

If you connect C- and P- on a non-common port BMS, you bypass the whole BMS protection, since neither port can block current flow in or out of the battery anymore, since the other port can't be turned off for reverse current flow.

I have an emoped going but no regen activated yet. How should I be on doing with my BMS cables that has separate ports for charge and discharging? If I activate regen with only P- connected will I destroy my BMS? or will it just charge it but charge without protection?

The latter.

In the above example of the coco's couldn't they just put a diod from the P- to C- to get it working with increase safety or do the regen current, if high, kill a diod fast here?

There's no way to insert a diode in there if they're paralleled, in a way that would block one current without blocking the other. You either prevent discharge, or you prevent charge, and in either case it makes it pointless to have paralleled them (which is unsafe, anyway).

If I was to build batteries it would be good to have a BMS that I know the ins and outs off fully so to say, that I can make my builds the best way I can possibly do. If the end product is not working as specified or I am installing a bms for protection that doesn't work the way I think it should that is a dilemma for me.

If you define *exactly* what you want the system to do in each specific situation, then you can find parts that do those things, or can be made to do them with some redesign. The more specifics you have, the harder it is to find a single part that does that thing unmodified, however. (I literally can never find anything that just does what I want it to--*everything* has to be customized to do what I want, no matter what kind of project or usage it is).

I guess no person would be proud pushing out products into the market that is beeing hazardous.

But many many people do exactly that, unfortunately, so they can make greater profit.

 

[Batteryrepair]

I don't know the answer to Ur question..

and add more electric veicules to tha list
"Most ebikes have no regen
Most e-scooters have regen.
Faster and stronger vehicles may have regen"

Patinete/trotinete Xiaomi m365 has regenerative braking.. plus many other trotinetes, some don't have fisical brakes, just a throttle for electronic brake..
Are those veicules real regenerative or where is going braking energy? most trotinete/patinete batteries have separate charge/discharge port

How would those scooters even regen when the battery is fully charged? Or is there a charge limit to make sure the brakes work? Very likely not it would seem.
I've already fried a lab supply from testing a controller on a xiaomi and accidentally touching the brakes.

 

[leffex]

I don't know the answer to Ur question..

and add more electric veicules to tha list
"Most ebikes have no regen
Most e-scooters have regen.
Faster and stronger vehicles may have regen"

Patinete/trotinete Xiaomi m365 has regenerative braking.. plus many other trotinetes, some don't have fisical brakes, just a throttle for electronic brake..
Are those veicules real regenerative or where is going braking energy? most trotinete/patinete batteries have separate charge/discharge port

Yes. So in a sense a BMS with separate ports can charge when regen is still at a full battery, question is for how long, (what I measured on one scooter I had was 4,12- 4,15v fully charged so maybe that's why it works. Also because some other functions in the BMS that I want to know as well as you that let's the regen or charge from the output P- through untill "event" fire hehe or whatever happends.

Yes e-scooters like m365. Scooters can be large also and even called bicycles by the law in my land. Allthough some new rules have set in to make it less appealing to drive around on these small and lightweight foldable e-scooters and those for hire / rent.

 

[leffex]

For a separate-port BMS, you just wire it exactly like it's suposed to be wired. Charging to the charge C- port and discharging to the discharge P-port.

That's it. Regen is going to go backwards thru the discharge port, uncontrolled by the BMS.

...


But many many people do exactly that, unfortunately, so they can make greater profit.

Thanks. I think I get it a lot better now.

Yes. The world we live in people sell their soul for some money.

 

[leffex]

...

the CN scientists invented tranforming a separate port bms into a commun port bms by just connecting input charger to C port and also discharge link connect to bms charge port! Is this chinease magic? tha bms Discharge/P port is left alone no cable connected to it

guess?? it works for city cococo scooters even at 30A peak current, no bms heat..! is this is science?

Yes, Aliens scientists invented the common port bms I believe.

I started this thread to get an answer as you had given a reply to someone about bmses that was dangerous and that it was a security issue that can become dangerous and as such lead to a fire.

I also like to know which bms to choose first and foremost so that whenever I make a battery it will be build with quality items. These bms's can be as low as only 1 euro or a dollar each so they can't be the only thing protection batteries "out there". Maybe we can find some new and better bms and get better protection for our batteries and so not build batteries with bad invented bms' nor cells.

 

[leffex]

I installed and replaced a broken BMS today. It was a 48v 15A rated with temp fuse. One of 6 feets on the plate had gone kaput and burnt through the plastic sheeting so it had the standard look. A fuse was missing or non existent on the charge port so that needed a fix.

Common port BMS 15A replaced with a new 48v 30A BMS with two ports, one charge and one discharge port.

https://imgur.com/a/GuMbDFq