bluetooth BMS?

flippy said:

the internal resistance adds up with current. this is why you get massive heatsinks on say for example a cpu or graphics card. those thave billions of mosfets running at hundreds of amps. gross simplfication but shit adds up when you push dozens of amps.

Click to expand...

Yeah, sure, but switching is actually a huge part of the heat generation on a CPU. In a BMS during discharge, there should be no switching as long as everything works fine and you don't go over one of the 3 limits I've mentionned before.

parabellum said:

Your BMS is very similar but not same, theoreticaly you should have worse fets if going linear on V ratings but they could potentially be better fets if they are some original reputable make.
Do you have access to fet sink? (the balance sink is apposite one)

Click to expand...

What is different on your BMS? Do you have a link?
There is one sink (actually just an aluminum plate) on each side of the BMS. One is for the balance board, the other for the FETs. So two sinks in total.

flippy said:

What is the max temp you did see at discharge? (the app shows temp at discharge, I believe)

Click to expand...

It was barely above the ambient temperature after a 55km ride.
Ambient temp was around 36-39 degrees (it is terribly hot here these days), BMS was around 42 if I remember correctly.
That's why I say that heating shouldn't really be much of a concern, it just doesn't heat.
One thing to note though is that my BMS is outside of my battery. It has its own 3D printed box with cooling holes. But I doubt this makes for a really huge difference, maybe it would heat 2-3 degree C more in a sealed enclosure? Pretty sure it is not game changing.

flippy said:

How long(seconds in average)you are over 120A?

Click to expand...

I'm over 120A battery draw from 25km/h to the top speed (120km/h). So pretty much everytime I hit the throttle. Of course at stabilized speeds this rating drops down a lot. A few figures at stabilized speeds for your reference:
-18A @ 50km/h
-30A @ 70km/h
-80A @ 100km/h
-about 120A @ top speed.

A few figures during full acceleration:

-50A from 0-10km/h (starting current)
-90A from 10-25km/h
-120 from 20-30 km/h
-150 from 30-40 km/h
-180 from 40-50 km/h
-200-210 from 50-100km/h
Then it progressively goes down to 120A until max speed (120km/h)
My start current is a bit low but unfortunately I don't know if this can be changed on my sabvoton controller

I have a tendency to go really heavy on the throttle, more than anyone I know, so I run at max acceleration most of the time, unless of course if the road is too crowded. To answer your question, I'd say that my motorbike is capable of doing the 0-100km/h in 6 or 7 seconds. So the BMS has to support that kind of load for maybe 90% of this time.

flippy said:

Not confronting your experiences, just need data to understand the whole picture.

Click to expand...

Sure, I have absolutely no problem with that . Ask any question you want, I'll be glad to answer if I can.
If you want me to make a particular test for you or to confirm some figures don't hesitate. I was a bit hesitating too when I bought this BMS (seemed too good to be true to me) so I totally understand. The only thing I've not tested yet it the bluetooth app, I'll hopefully be able to check it this evening.

Dui said:

Yeah, sure, but switching is actually a huge part of the heat generation on a CPU. In a BMS during discharge, there should be no switching as long as everything works fine and you don't go over one of the 3 limits I've mentionned before.

Click to expand...

it does not matter if it switches or not. RDSon is RDSon.

flippy said:

it does not matter if it switches or not. RDSon is RDSon.

Click to expand...

Well, I know. You were the one talking about CPU transistors, hence my remark. They do have to switch a lot of times per sec, and that's probably one of the main reasons why they do heat so much, hence the big heatsinks. I just don't think the RDSon contributes that much to the heat generation in a CPU, but maybe I'm wrong.

Anyway the BMS doesn't heat so I guess we can pretty much exclude the RDSon as being an actual issue here.
I was just saying that the total RDSon should be lower than the RDSon of a single Mosfet if they are paralleled alltogether.

Dui said:

What is different on your BMS? Do you have a link?
There is one sink (actually just an aluminum plate) on each side of the BMS. One is for the balance board, the other for the FETs. So two sinks in total.

Click to expand...

It looks like one you linked, the pictures are of a 24S BMS at least, but yours is 32S and must be longer.
https://www.aliexpress.com/item/Smart-Display-300A-200A-150A-100A-70A-Lithium-Battery-Protection-Board-Balance-BMS-Coulomb-Meter-Li/32826820690.html?spm=a2g0s.9042311.0.0.42f44c4dpwL0XE
I suppose, BMS has a considerable heat capacity and could take even 300A for some period in time but if that period is to long and heat saturation is just under protection level, then it gets funny.
I may be overreacting as usual, 6-7 seconds bursts are nothing comparing to long and constant balance action, where heat is main purpose of the process.
I mean, how much is energy demand, in average, by a 2 wheel vehicle in daily, non racing application? 5KW? (Which is little over 50A at 24S and less at 32S)

flippy said:

Dui said:

Yeah, sure, but switching is actually a huge part of the heat generation on a CPU. In a BMS during discharge, there should be no switching as long as everything works fine and you don't go over one of the 3 limits I've mentionned before.

Click to expand...

it does not matter if it switches or not. RDSon is RDSon.

Click to expand...

It does matter...RDS on isn't the only heat source. The back diode is probably far worse than Rds. Partially on or off puts the mosfet in a semiconducting (high resistance state) where it generates lots of heat. Mosfets just sitting there on only have to contend with Rds and nothing else that generates heat. Rds by itself is fairly negligible on decent mosfets. It's why most BMS don't have a giant heat sink...there's no need for it.

parabellum said:

Dui said:

What is different on your BMS? Do you have a link?
There is one sink (actually just an aluminum plate) on each side of the BMS. One is for the balance board, the other for the FETs. So two sinks in total.

Click to expand...

It looks like one you linked, the pictures are of a 24S BMS at least, but yours is 32S and must be longer.
https://www.aliexpress.com/item/Smart-Display-300A-200A-150A-100A-70A-Lithium-Battery-Protection-Board-Balance-BMS-Coulomb-Meter-Li/32826820690.html?spm=a2g0s.9042311.0.0.42f44c4dpwL0XE
I suppose, BMS has a considerable heat capacity and could take even 300A for some period in time but if that period is to long and heat saturation is just under protection level, then it gets funny.
I may be overreacting as usual, 6-7 seconds bursts are nothing comparing to long and constant balance action, where heat is main purpose of the process.
I mean, how much is energy demand, in average, by a 2 wheel vehicle in daily, non racing application? 5KW? (Which is little over 50A at 24S and less at 32S)

Click to expand...

I have a couple of these in 24S and 32S. Both are pretty small, but yes the 32S version is definitely larger.

parabellum said:

It looks like one you linked, the pictures are of a 24S BMS at least, but yours is 32S and must be longer.
https://www.aliexpress.com/item/Smart-Display-300A-200A-150A-100A-70A-Lithium-Battery-Protection-Board-Balance-BMS-Coulomb-Meter-Li/32826820690.html?spm=a2g0s.9042311.0.0.42f44c4dpwL0XE

Click to expand...

They are exactly the same. Just a different version, but they should be the same size and mostly all the same specs.

parabellum said:

I suppose, BMS has a considerable heat capacity and could take even 300A for some period in time but if that period is to long and heat saturation is just under protection level, then it gets funny.

Click to expand...

The point of a BMS is to let the current pass through, not to act as heating system. So, as I said, during discharge, they do not resist much to current. Maybe a tiny bit more than a normal wire, but thats all. Their whole point is to be as efficient as possible during normal use, if you generate heat then you're basically wasting your precious pixies.

Since all of you guys seem to be panicking about heat, I had an other look yesterday: no matter how hard I tried, accelerating at full throttle from 0-top speed dozens of time, using the regen, etc, I could not make it heat above 43Degree C (outside temp was around 36 degree).
So I'll say it again, this time being 100% sure: heat isn't an issue during discharge, at least at 210A. I think this case should now be considered closed

parabellum said:

I may be overreacting as usual, 6-7 seconds bursts are nothing comparing to long and constant balance action, where heat is main purpose of the process.

Click to expand...

It is just absolutely not the same thing. While discharging, you let the fets opened. Fets don't heat much when they are fully opened, their whole purpose is to let current pass through them as efficiently as possible.
During balancing, the heat is generated by bleeding resistors who are here to discharge each cells who needs it.
I've checked yesterday, using the Android app for the first time, to balance my pack and here is what I can share:
-It works fine
-BMS reached 59 Degree C at maximum (heat generation varies depending on how many cells are being discharged at the same time)
-You can set whatever current discharging rate you want for balancing. In my case it was set to 200mA by default, but if it heats too much and if you are not in a hurry to balance your pack, you can lower this value.
-You can set a temperature limit for balancing: when the BMS reaches this temp he will temporarily stop balancing, then start again once the temperature dropped enough. Both limits are programmable.

There are a lot of options you can configure in the app, but unfortunately I only have the chinese version so it's a bit hard for me to know which parameter does what. If any of you guys could post a screenshot of the whole "Setting" page, it would be really awesome. Or even better: post the english apk file! (for the BMS-Ant please )

Steu851 said:

It looks like you have a better translated app than mine. I have some parameters in chinese. Do you have a link where download the app? Thanks

Sent usingTapatalk

Click to expand...

Here is the latest version of APP app, you can download it

Dui said:

Or even better: post the english apk file! (for the BMS-Ant please )

Click to expand...

I tried other apk, similar but other maker and they did not connect to my BMS,s. So, there is a chance this one not going to work with yours.

Is there any APK or mode in existing one to have nice dash on the phone screen?
Something similar to 1st BMS screen, just with basics like TotalV, Ah, lowest cell, highest cell, maybe speed.
My APK has 3 screens that are useless for anything but programming and deep analysis.

1 is log screen with some reset options
2 is programming
3 is all info at ones with tinny characters

I think you are asking about these 24 and 32S smart BMS and the LCD....which is the only real dashboard.






The app is intended for setting up the BMS and logging, but not for use as a dashboard.

VBMS can do that, hit "run" after connecting.

ElectricGod said:

I think you are asking about these 24 and 32S smart BMS and the LCD....which is the only real dashboard.

Click to expand...

The LCD is nice, I have 2 now and the info on first screen is about all I need but unfortunately I did not find any space to mount it, with access to the buttons.

flippy said:

VBMS can do that, hit "run" after connecting.

Click to expand...

Do you mean the app from Vortecks for USD6.62?
My is called VBMS to but no RUN button, screen looks like one above, posted by ElectricGod and I have PARAM2 button instead, with dozens of parameters in 2 columns.

i will post my version of VBMS during the weekend.

flippy said:

i will post my version of VBMS during the weekend.

Click to expand...

Please, I still have hope. I printed enclosure for the screen but there is no way to get it on and still use buttons. A cell holder will work, it is optional and there is front access.

P.S. If anyone wants the box with buttons for the screen module I can post it. You just need to add some 3mm plexy or PC screen silicon in, it gets like CA in waterproof compartment.

parabellum said:

flippy said:

i will post my version of VBMS during the weekend.

Click to expand...

Please, I still have hope. I printed enclosure for the screen but there is no way to get it on and still use buttons. A cell holder will work, it is optional and there is front access.

P.S. If anyone wants the box with buttons for the screen module I can post it. You just need to add some 3mm plexy or PC screen silicon in, it gets like CA in waterproof compartment.

Click to expand...

Why don't you just unsolder the original buttons and use wires and stuff to put the buttons elsewhere? That's what I plan to do on mine, shouldn't be very difficult.

I put the buttons externally so no problem there.

parabellum said:

flippy said:

i will post my version of VBMS during the weekend.

Click to expand...

Please, I still have hope. I printed enclosure for the screen but there is no way to get it on and still use buttons. A cell holder will work, it is optional and there is front access.

P.S. If anyone wants the box with buttons for the screen module I can post it. You just need to add some 3mm plexy or PC screen silicon in, it gets like CA in waterproof compartment.

Click to expand...

Button on the side if they have hinges are going to do the trick. Lots of things do buttons that way. THe horizontal pushing motion through the hinge, translates into vertical movement and the physical switches get pushed. I don't know how well 3D printed plastic hinges would hold up, but it might do OK. another way to make this work would be very small rocker arms. Push the exposed arm down and it lifts it's internal end upwards to push the switch closed. It's just a tiny see-saw action.

Or do like Dui, ni shuo de dui suggested and just move the buttons.

here is mine:

flippy said:

here is mine:

Click to expand...

Thanks, but it looks exactly the same I have, there is no RUN button or I am to dumb to find it. :?

If you are conncected the button is at the bottom right.

flippy said:

If you are conncected the button is at the bottom right.

Click to expand...

I know what you mean (I have seen screen shots with RUN button https://play.google.com/store/apps/details?id=com.vortecks.vbms&hl=en_US, there is also 4th screen mode I can not find), but I still have PARAM2 button there(like this http://i1055.photobucket.com/albums/s515/rkenders/EV%20Stuff/BMS/24S%20smart%20BMS%20-%20LCD/24S%20main%20page.png picture from ElectricGod).
Maybe different android versions trigger different interfaces in the APP?
Mine is Android 5.1 (Lollipop) with Bluetooth 4.0, A2DP, will try with Android 6 after work.

flippy said:

here is mine:

Click to expand...

I'm a little slow apparently...
Does this VBMS app work in place of the Chinglish app we get for the 24 and 32S smart BMS's?

I have a 32S LIPO pack sitting on my bench. I can pulll out a 32S BMS, load up this app and tell you tomorrow what I get. My phones run the latest LineageOS builds so that means android 7.1.2. You saw my screen shots from the Chinglish app. It would be an easy thing to try the VBMS app to see if I get the run button or not.

guys, there are 2 versions. the chinese version that has loads of gibberish and the option for setting passwords and the english one i put up above.

if you want a simple interface that tells you basic info during your driving you need the english app and hit run.
you can use the same app to set everything else but you only need the chinese one if you want to set a password and lock the settings. you cant change any settings anymore on the english app if you set a password, it becomes strictly a read only app. you can still turn the bms off and on but you cant use the settings menu anymore without unlocking it from the chinese app.

i set all the setttings on the bms and lock it with a chinese app and give the english app to customers. then they cant frock anything up anymore and claim warranty.

Reading the posts from a few months back, looks like it's usable except the lousy english app.
Concerning reliability, so far how many miles have you guys road tested this bms?
What's the max # of cells it can display on the lcd screen? I only see 18 on the seller page.
Does the "Automatic balance" function really work?