bluetooth BMS?

Batteries, Chargers, and Battery Management Systems.
EbikeAus   100 W

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Re: bluetooth BMS?

Post by EbikeAus » Nov 02 2018 5:23am

eee291 wrote:
Nov 02 2018 4:11am
I connected the Balance wires then the B- worked for me just fine.

You can use either P- for discharge or C-. The difference is that you need only two wires soldered on the BMS compared to three wires if you use the P-.

An advantage to using the P- is that the BMS will run cooler because you are not heating up the charge Mosfets when discharging the Battery.
Also when using the C- port for both you can't overcharge the Battery via regen, which can happen if you go down a hill with regen right after charging.
Thanks for that :D
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xmtx   100 µW

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Re: bluetooth BMS?

Post by xmtx » Nov 03 2018 10:34am

eee291 wrote:
Nov 01 2018 1:28pm
How do figure that the BMS was shorted exactly?

A reason why your phone might not be able to connect to it could be that you have an outdated version that doesn't support the latest Smartphone firmware.

Here is the latest version: https://shouji.baidu.com/software/24043119.html
Hello, thanks for your help.

I know it was shorted, because I (at 4am), connected the battery -, to B- on the BMS, and then, the battery + on P- on the BMS.
Instead of wiring the load between P- and Battery +.
That's basically a 0 ohm load, and a lot of amps that should have gone through the BMS, and that, for several minutes, until I realised my screw up.
I know that the BMS is supposed to prevent actual overload, but I'm not sure if it's able to handle a short for several minutes without blowing a fuse.

The seller gave me this link for the application (he is helping me right now):
https://drive.google.com/file/d/1v6VG49 ... sp=sharing

I tried your link, but the error is still the same. It can see the bt device (xiaoxiang BMS), the bt receiver light in blue, but after few seconds, connection to it fails. Same for USB connection with my pc.

I tried shorting the K1 switch, while connecting, but the result was the same.
Do you know which key point I should check for voltage or resistance, in order to identify if it's fried or not?

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eee291   10 kW

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Re: bluetooth BMS?

Post by eee291 » Nov 03 2018 12:37pm

I doubt it is broken even if you kept it shorted for weeks.
That is why the BMS can turn the MOSFETs off and it will keep them off until you remove the short.

An easy way to check would be to measure the Voltage between B+ and C- or P- with a multimeter.

What exactly is the error on your PC?


Also, have you tried disconnecting and reconnecting the Balance wires? Maybe power-cycling it once will help.

Another thing I can think of, it's that maybe you have fewer cells connected than the minimum amount of required cells.
Happened to me when I tried to program the 20-30S BMS with just 12 Cells. The light would blink and it could be seen by the app but I couldn't connect to it.

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Re: bluetooth BMS?

Post by xmtx » Nov 03 2018 6:07pm

eee291 wrote:
Nov 03 2018 12:37pm
I doubt it is broken even if you kept it shorted for weeks.
That is why the BMS can turn the MOSFETs off and it will keep them off until you remove the short.
Hi again, alright, glad to hear that.
eee291 wrote:
Nov 03 2018 12:37pm
An easy way to check would be to measure the Voltage between B+ and C- or P- with a multimeter.
That's what I forgot to tell.
B+ to C- and B+ to P- both start a 24V, and stabilize down at 17-18V after a few seconds.
When I connect a load, even a small one (https://www.aliexpress.com/store/produc ... 77897.html set a 0A), it drops to 0V.
My battery is 14s (52V).
eee291 wrote:
Nov 03 2018 12:37pm
What exactly is the error on your PC?
On the pc, there is no error. I can see the device (COM10), but when I press start on the application, it just stalls at "Reading data"
All the info are at 0.
PC_app.JPG
eee291 wrote:
Nov 03 2018 12:37pm
Also, have you tried disconnecting and reconnecting the Balance wires? Maybe power-cycling it once will help.
I do disconnect and reconnect the balance wire every time. I know current is somewhat flowing, the BT module light up every time and I can see the BT device.
But got nothing on the leads, and, still can't connect to it.
eee291 wrote:
Nov 03 2018 12:37pm
Another thing I can think of, it's that maybe you have fewer cells connected than the minimum amount of required cells.
Happened to me when I tried to program the 20-30S BMS with just 12 Cells. The light would blink and it could be seen by the app but I couldn't connect to it.
My BMS is 14s, and all the cells are connected, I double checked the voltage they are all in order.
I get no light on the BMS.

The only thing that could cause problem, is the P- solder touching the back of the mofset, but i guess, theses are supposed to be connected. On the picture, it's the grey cable soldered on the left.
BMS_PCB_low.jpg
I've connected another BMS to the battery, and I could draw 2A on it, so it's working
Thanks again for the help.

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Re: bluetooth BMS?

Post by xmtx » Nov 04 2018 5:52am

xmtx wrote:
Nov 03 2018 6:07pm
I've connected another BMS to the battery, and I could draw 2A on it, so it's working
Thanks again for the help.
I realise that my message was confusing.
I plugged a "dumb" BMS, to the battery, and got the battery working.
I don't want to use this BMS, as I can't set treshold on it, and it won't balance charge as well as the smart BMS.

My goal is to limit the battery between 2.9 and 4V/cell, in order to maximise it's life expectancy. And I also want to be able to easily bypass those settings when I need long range .

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ElectricGod   100 MW

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Re: bluetooth BMS?

Post by ElectricGod » Nov 05 2018 6:10pm

It sounds like the BMS is working, but the mosfets are turned off. In the APK on your phone, is the lock unlocked or locked? You want it locked to enable the BMS.

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Re: bluetooth BMS?

Post by EbikeAus » Nov 05 2018 11:23pm

I need your help guys!
I've wired the xiaoxang Bluetooth bms but having trouble pairing with my samsung phone.

Where do I get the app? Got no instruction from seller.
When I try to connect it says pairing rejected.
Any help would be great. Thanks
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Re: bluetooth BMS?

Post by EbikeAus » Nov 06 2018 12:08am

I managed to install and connect on samsung tablet but can't connect phone??
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Re: bluetooth BMS?

Post by ElectricGod » Nov 06 2018 12:44am

EbikeAus wrote:
Nov 06 2018 12:08am
I managed to install and connect on samsung tablet but can't connect phone??
Look back on this page...like 2 or 3 posts and you will find the app.

In BT settings you don't pair to the BMS. You pair via the app only.

It is possible you can't pair. I have 3 android phones and my newest phone which is months old won't pair. My next oldest phone is from 2015 and the oldest from 2012 and they both connect to any BMS without issues. Go figure.

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Re: bluetooth BMS?

Post by EbikeAus » Nov 06 2018 1:27am

ElectricGod wrote:
Nov 06 2018 12:44am
EbikeAus wrote:
Nov 06 2018 12:08am
I managed to install and connect on samsung tablet but can't connect phone??
Look back on this page...like 2 or 3 posts and you will find the app.

In BT settings you don't pair to the BMS. You pair via the app only.

It is possible you can't pair. I have 3 android phones and my newest phone which is months old won't pair. My next oldest phone is from 2015 and the oldest from 2012 and they both connect to any BMS without issues. Go figure.
Thanks for the response!
I think I've got it working on my s5.
I've ordered an s9 will have to see if that will work.
I ended up finding the app on a site called bmsbattery
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eee291   10 kW

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Re: bluetooth BMS?

Post by eee291 » Nov 06 2018 4:01am

The one on BMS battery is the old version.

Literally 5 post above yours I posted the link to the newest one.

Here it is again.
https://shouji.baidu.com/software/24043119.html

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Re: bluetooth BMS?

Post by EbikeAus » Nov 06 2018 4:30am

eee291 wrote:
Nov 06 2018 4:01am
The one on BMS battery is the old version.

Literally 5 post above yours I posted the link to the newest one.

Here it is again.
https://shouji.baidu.com/software/24043119.html
Thanks mate!
I did have a look...obviously not a very good one 😂

Well I can see why this is a popular thread. These bms are great, especially for the $.

What voltage do you guys start balancing at?
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eee291   10 kW

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Re: bluetooth BMS?

Post by eee291 » Nov 06 2018 5:14am

I just left it at the default 3.8V. My cells don't really need balancing.

I wish I calibrated the shunt though, it shows 0.5A more when charging and discharging. The BMS is closed off and now I can't get to it without destroying the watertight seal :cry:



BTW, does the newer App work with your phone now?

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Re: bluetooth BMS?

Post by EbikeAus » Nov 06 2018 5:40am

eee291 wrote:
Nov 06 2018 5:14am
I just left it at the default 3.8V. My cells don't really need balancing.

I wish I calibrated the shunt though, it shows 0.5A more when charging and discharging. The BMS is closed off and now I can't get to it without destroying the watertight seal :cry:



BTW, does the newer App work with your phone now?
I'm still using the older app as I'm in the middle of the first charge on this pack.
I'll look into the shunt calibration.
Mine was set to balance at 4v, I think i'll change it to 3.8.
Thanks
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Re: bluetooth BMS?

Post by thundercamel » Nov 06 2018 9:38am

If it's a good pack, then 4.0v is fine.
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Re: bluetooth BMS?

Post by xmtx » Nov 06 2018 1:10pm

ElectricGod wrote:
Nov 05 2018 6:10pm
It sounds like the BMS is working, but the mosfets are turned off. In the APK on your phone, is the lock unlocked or locked? You want it locked to enable the BMS.
Well, I can't even connect to the BMS, the connection fail each timeeither via BT or USB, there is no lock/unlock thing.

The seller asked me to brush the bms to remove any short, and to try to charge the battery via the BMS, maybe it will unlock it.
I'll keep you posted.

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Re: bluetooth BMS?

Post by ElectricGod » Nov 06 2018 1:49pm

EbikeAus wrote:
Nov 06 2018 4:30am
eee291 wrote:
Nov 06 2018 4:01am
The one on BMS battery is the old version.

Literally 5 post above yours I posted the link to the newest one.

Here it is again.
https://shouji.baidu.com/software/24043119.html
Thanks mate!
I did have a look...obviously not a very good one 😂

Well I can see why this is a popular thread. These bms are great, especially for the $.

What voltage do you guys start balancing at?
There's a few things that play into how you set the balance voltage:
1. LION tends to stay balanced a good bit better than does LIPO.
2. Any pack can have a weak cell in it. That cell will get out of balance much more easily than the rest of the cells in the pack.
3. A cell with less capacity than the rest in the pack will discharge faster and charge faster than the rest of the pack.
4. The capacity of your pack will effect how quickly you can balance. A 10Ah pack will balance much more quickly than a 64Ah pack. A 10Ah cell will draw down more quickly than a 64Ah cell.
5. The current capability of your charger plays into things too. I charge at 30 amps. It would not be hard to charge much faster than the BMS can balance.
6. The resistors in the BMS are fairly small and can sink a few hundred milliamps at most. You need to account for the "speed" at which you can balance when you are charging and account for this by setting the balance start voltage appropriately.

IE: Hard and fast voltages aren't really applicable. Set the balance voltage conservatively low at first. Watch how your pack charges on your charger. If you see your pack balances just fine at that conservatively low voltage, set it a bit higher. Watch the packs cell voltages over 2 or 3 more charge cycles. If they stay balanced and the new higher voltage, set it a little higher and watch the cells over 2 or 3 more charge cycles. After probably 10 charge cycles at most, you'll find the balance start voltage that works for you best.

Personally, I am hesitant to give you a balance start voltage and to tell you "this will work for you". Having said that, I have multiple LIPO packs that are fairly new and they start balancing at 3.9 volts. However as those LIPOs age, I'll want to set the voltage lower as some cells will lose capacity faster than others. I have a 20S LIPO pack that is made of 5 4S multistar packs. Some of the 10,000mah packs are older than the others. I set the balance start voltage to account for the older packs and their somewhat lesser capacity. This brings the entire pack to 4.1v per cell, but I start at 3.7 volts so the lower capacity or older cells can be kept from over charging while the newer cells continue to charge.

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Re: bluetooth BMS?

Post by EbikeAus » Nov 06 2018 7:40pm

Thanks for the detailed response!

This pack is 14s5p of recycled 25r. They look like they will balance up nicely.
I'll do as you recommend and cycle them a few times
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Re: bluetooth BMS?

Post by trazor » Nov 06 2018 9:14pm

eee291 wrote:
Nov 06 2018 5:14am
I just left it at the default 3.8V. My cells don't really need balancing.

I wish I calibrated the shunt though, it shows 0.5A more when charging and discharging. The BMS is closed off and now I can't get to it without destroying the watertight seal :cry:



BTW, does the newer App work with your phone now?
I purchased 3 JBD BMS and all of them had 20% discrepancy to inline multimeter at around 10 amps. I think shunt calibration is a must in these BMS. I don't know why. Voltages are very well calibrated though.

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Re: bluetooth BMS?

Post by ElectricGod » Nov 06 2018 11:20pm

EbikeAus wrote:
Nov 06 2018 4:30am
eee291 wrote:
Nov 06 2018 4:01am
The one on BMS battery is the old version.

Literally 5 post above yours I posted the link to the newest one.

Here it is again.
https://shouji.baidu.com/software/24043119.html
Thanks mate!
I did have a look...obviously not a very good one 😂

Well I can see why this is a popular thread. These bms are great, especially for the $.

What voltage do you guys start balancing at?
FYI...this link is to version 2.1.1022

https://shouji.baidu.com/software/24043119.html

I'm pretty sure I got that exact version from the battery BMS site.

Either that or they have the 2.1.1011 version.

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Re: bluetooth BMS?

Post by Doit » Nov 08 2018 3:57pm

aethyr wrote:
Jun 02 2017 12:57pm
Has anybody used a BMS like this: https://www.aliexpress.com/item/20S-50A ... 39362.html?

Its bluetooth enabled with an android app so you can configure everything in software, as well as monitor pack voltages.

I think I'm going to order it and try it out, but I'm curious if anyone else has seen/used a BMS like this. The only problem is that 50A is below my needs, so I'll use this just for charging. This should be fine, since my controller has LVC and I can actually monitor individual cell voltages from the phone app.
Guys, I enjoyed reading your thread. Is it possible to modify the discharge current through its software? my 84v pack has a maximum 40A discharge couldn't go more than that. as above BMS specification, it has 50A continuous discharge not sure if I can change that?

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eee291   10 kW

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Re: bluetooth BMS?

Post by eee291 » Nov 08 2018 4:08pm

You can with the PC software and adapter.https://www.aliexpress.com/item/7S-24V- ... 3c00Fx15aD
Select UART Box wire

The software can be found some pages back
You can increase the Current limit to whatever you want but mind the BMS temp.
You can always do what ElectricGod and others have done and mod the BMS.
Last edited by eee291 on Nov 08 2018 4:12pm, edited 1 time in total.

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Re: bluetooth BMS?

Post by Doit » Nov 08 2018 4:09pm

eee291 wrote:
Nov 08 2018 4:08pm
You can with the PC software and adapter.
many thanks :bigthumb:

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Re: bluetooth BMS?

Post by ichiban » Nov 09 2018 12:04pm

I really wish there were some "conclusions" for this thread, completed with references (to page # + links). Since this is very lengthy, 32 pages up to here with tons of detail.

The gurus here talked about deep techs based on their long experience. Half of which I don't even have a clue what the heck they are. BMS is a crucial device we all need to take good care of our precious packs. However, it works complicatedly and with variations among models and makes - not to mention those with newer BT function to ease (or to complicate) the operation even more, especially for newbies.

The experts will say most BMS simply work straightforward as it can get... :?

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Re: bluetooth BMS?

Post by ichiban » Nov 09 2018 12:06pm

And I have bought one 14s BT BMS from JBD (AliExpress) waiting for my new 14s7p & 14s5p packs assy soon.

Hopefully, there wouldn't be much problems connecting to them.

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