bluetooth BMS?

[trazor]

I have installed this BMS last year. Over the winter i left my battery unattended and this BMS drained it flat. Had brand new cells that went to the bin. Had no chance to go through all the posts but is this known issue? I have 2 of them, 15S and 20S.
Balancing and charging was ok but parasitic drain is WTF?

It happened to me in couple months when I left the USB to serial adapter connected. Maybe it can happen too if you leave the bluetooth connection active the whole time. In my experience, if nothing of those two occurs, the discharge is minimal (IRC there is a post in this thread that has measures in micro ampere range)

 

[john61ct]

Whenever not cycling, bring to storage SoC and isolate the cells from everything, including BMS.

In any case check on them at least every few weeks, more frequently at first, then scale back as you see what self discharge actually is.

Just forgetting about them is not an option, maybe not as bad as owning a pet, but certainly require as much attention as say a cactus collection

 

[thundercamel]

For the record, both of my bikes using this 14s smart BMS barely drained at all over the winter, and I did nothing special with them. I still connected bluetooth to them once in a while to make sure the voltage wasn't getting low, and they weren't.

I've noticed that when bluetooth is connected to my phone, a blue LED comes on inside the bluetooth module, and it goes out when disconnected. I'm not sure if other BMS models have different behaviors.

 

[larsb]

6P20S 18650? At 2.5Ah and three months it'd take 7mA@72V or 0.5W consumption. That's huge, would correspond to an old bluetooth constantly in use if you believe Wikipedia.

 

[agniusm]

Whenever not cycling, bring to storage SoC and isolate the cells from everything, including BMS.

In any case check on them at least every few weeks, more frequently at first, then scale back as you see what self discharge actually is.

Just forgetting about them is not an option, maybe not as bad as owning a pet, but certainly require as much attention as say a cactus collection

Thats for me is not the option. The elctronics are capable these days to build and forget, probably not exactly this bms.
You can throw in you phone in a drawer and comback after a year and it will be alright. This is perhaps the difference between western products and chinese products. I am just amazed as there was time when all leading edge tech was comming from China

 

[larsb]

Well, aint exactly true.. I have several phones that died completely lying in a drawer. Cannot be charged or woken up, even with CPR treatment

 

[larsb]

Phone CPR: blow two times in the mic hole, push 30 times on home button. Repeat.

 

[Mormegil83]

Usually you don't need communication from charger to BMS. The charger just need to provide the power and stop when reaches max voltage. If the BMS considers there is any risk on the charge (over voltage, max temp, etc), it will open the circuit using onboard mosfets.
The usual lithiumbatterypcb.com bluetooth BMS do not reach 400 A discharge with the included mosfets. As flippy suggested, the best is to skip the BMS for the load (controller) and connect it in parallel only for charging batteries, using only the balancing, monitoring via bluetooth and charging protection functionality.

Here is a less powerful onboard charger that does not need any kind of signal to start delivering power: http://www.eastgem.net/on-board-charger.html

Thanks, again everyone for the great advice and input on my project! Man I wish I had seen that east gem charger months ago. $150 for a descent waterproof onboard charger, is exactly what I was looking for! And now I just bought a used 72v Delta-Q from eBay to mess with. It doesn't have the lithium profiles yet, but it was hard to pass up for $100. Who knows though I may have end up selling these two chargers and end up just going with that small and simple east gem charger.

Ok I'm done hijacking the thread. I was on topic originally, though. I hoped to use one of the blue tooth smart BMS units, but I guess it seems that they will not work for my current project.

Thanks again! Keep up the good work!

 

[john61ct]

Whenever not cycling, bring to storage SoC and isolate the cells from everything, including BMS.

In any case check on them at least every few weeks, more frequently at first, then scale back as you see what self discharge actually is.

Just forgetting about them is not an option, maybe not as bad as owning a pet, but certainly require as much attention as say a cactus collection

Thats for me is not the option. The elctronics are capable these days to build and forget, probably not exactly this bms.
You can throw in you phone in a drawer and comback after a year and it will be alright. This is perhaps the difference between western products and chinese products. I am just amazed as there was time when all leading edge tech was comming from China

Wut? I've never heard of a recent phone manufactured in the West, could you be more specific?

And I have murdered many many phones' batteries, even brand new ones, by letting them sit forgotten.

It really is just a matter of time.

The BMS functionality internal to both phone's firmware / circuitry prevents drawing down to the true dead flat stage during active cycling operations, so

that gives a bit of time, as you say maybe even years.

But self-discharge, while slower than many other chemistries, is still a thing.

For LI banks worth thousands of dollars, it would be stupid to ignore my reco above forever.

And if leaving cells connected to **anything**, including "PCM" or BMS type gear, the owner should certainly test / verify what rate parasitic loads are drawing, not take the vendors's word for it.

If your circumstances mean the bank value is less than going to this "trouble", so be it, but I doubt if it is too onerous for most.

 

[john61ct]

For the record, both of my bikes using this 14s smart BMS barely drained at all over the winter, and I did nothing special with them. I still connected bluetooth to them once in a while to make sure the voltage wasn't getting low, and they weren't.

Yes that last is the critical bit

 

[agniusm]

Not using this bms but here is my mounting of bt module:

 

[tumich]

Is it good default config for 10S version?

 

[trazor]

Is it good default config for 10S version?

Have you pressed the "Read" button already? Application show weird default values before reading the real config of the device.

 

[tumich]

Thanks

 

[qiubosu]

Regarding the Bluetooth-
On initial powering up of my BMS, the Bluetooth module had a solid blue light, neither my phone or tablet would pick up the device.
After much messing around the solution was to unplug the balance cable, disconnect the Bluetooth module, reconnect the balance cable and THEN reconnect the Bluetooth module.
Open up your app and it will now let you connect
Once paired the solid blue light will come on

i refer to your post, unplug the balance connector (not the cables), unplug the bluetooth module from the Smart BMS PCB, then reconnect them again (leave the BMS connecting to the charger at the meantime), run the xiaoxiang app, but the software dashboard doesn't show up, while on my mobile it only shows "The device can be connected", "signal:Strong-22" etc text, and "Refresh" and "Fix" buttons. when go to Settings to pair the xiaoxiang BMS, it displays "Couldn't pair with xiaoxiang BMS because of an incorrect PIN or passkey". however the supplier didn't mention there is PIN or passkey required to connect the mobile app to the Smart BMS software via bluetooth.

would like to know how you make your BT work with the smart BMS, and what is the difference.

BTW i purchased this 7S 30A Smart BMS from https://www.aliexpress.com/item/32840764349.html?spm=a2g0s.9042311.0.0.27424c4dJ6rzZ9

 

[eee291]

That's because you don't pair the BMS, you just click on it in the App. Using the latest version also helps fix things for people on the newest android version.

 

[qiubosu]

I did pair the xiaoxiang BMS from my mobile phone Settings → Bluetooth, but get “Couldn't pair with xiaoxiang BMS because of an incorrect PIN or passkey”. I used my Huawei Android 5.1 and Tablet with Android 5.0 to try the old (V2.1.1011, V2.1.1022) and new version (V2.1.1024) of xiaoxiang BMS mobile apps, but all can't get the smart BMS software dashboard shown up in my mobile devices.

When pairing from my Tablet (Android 5.0), get different error message "Pairing rejected by xiaoxiang BMS".

Is anyone happened to the similar problem with the smart BMS with xiaoxiang mobile apps?

 

[eee291]

I meant you should not pair the BMS with the Phone. It connects directly through the App not the System Bluetooth settings. I suggest you unpair the BMS, reinstall the App and then try again.

 

[qiubosu]

i got the software working tonight, but it isn't stable, sometimes works, sometimes doesn't, and the software has some issues, e.g. when update the parameters and Submit, it can't update the system for some parameters.

anyway the smart BMS software does work, the Bluetooth apps on my mobile does connect to the Bluetooth module.

i just need to configure the system to match the design of the battery pack, and see how the whole ebike system and smart BMS actually work together when i bike the ebike electrically later.

 

[qiubosu]

i played around and the bluetooth apps of the smart BMS work on both of my Android mobile and tablet now. can update some parameters, but some parameters calculated from these updated parameters are incorrect, but in my opinion, this may not really affect how the charge & discharge work correctly (however it is good to make the calculations correct). the balance (both static and charge balance) works quite well and this is very important. the odd & even number series of cells are balanced in turn, which is good. with this Android mobile apps, some important parameters can't be adjusted, e.g. temperature sensors control parameters. some other parameters should be able to be adjusted also, e.g. hardware over & under voltage protection, charge overcurrent etc. for balance, it seems only can do balance when charge, but not when discharge, which is very important.

don't have the UART module to run on PC, and PC module software may be able to update more parameters.

anyway the smart BMS hardware and the Android mobile apps do work and do worth the money. this is my current findings of this smart BMS system when installed it onto the large 18650 Lithium battery pack I just built a few days ago.

 

[trazor]

i played around and the bluetooth apps of the smart BMS work on both of my Android mobile and tablet now. can update some parameters, but some parameters calculated from these updated parameters are incorrect, but in my opinion, this may not really affect how the charge & discharge work correctly (however it is good to make the calculations correct). the balance (both static and charge balance) works quite well and this is very important. the odd & even number series of cells are balanced in turn, which is good. with this Android mobile apps, some important parameters can't be adjusted, e.g. temperature sensors control parameters. some other parameters should be able to be adjusted also, e.g. hardware over & under voltage protection, charge overcurrent etc. for balance, it seems only can do balance when charge, but not when discharge, which is very important.

don't have the UART module to run on PC, and PC module software may be able to update more parameters.

anyway the smart BMS hardware and the Android mobile apps do work and do worth the money. this is my current findings of this smart BMS system when installed it onto the large 18650 Lithium battery pack I just built a few days ago.

This post explains accurately how the balance function works https://endless-sphere.com/forums/viewtopic.php?f=14&t=88676&start=225#p1361461

 

[flippy]

are there any programmable bluetooth bms that are just 1 cell high? i need to make a flat battery and 7cm is my thickness limit.

 

[Taswegian]

are there any programmable bluetooth bms that are just 1 cell high? i need to make a flat battery and 7cm is my thickness limit.

Do you mean a BMS that fits within the footprint of a single cell, ie 18 x 18 x 65 ?

(Edit - or maybe you're asking for longest BMS dimension to be no more than cell length?)

 

[tmho]

are there any programmable bluetooth bms that are just 1 cell high? i need to make a flat battery and 7cm is my thickness limit.

Mine is 70mm x 138mm x 17mm excluding the wires.

 

[flippy]

I need a 17S programmable bms that can be flush mounted against the side of a pack that is no higher then the cells itself. Length and thickness is not a limit, just width.
7cm can work if there are no wires coming out the sides.