bluetooth BMS?

Batteries, Chargers, and Battery Management Systems.
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cycborg   1 kW

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Re: bluetooth BMS?

Post by cycborg » Jun 20 2019 9:56am

Headrc wrote:
Jun 20 2019 8:08am
Are you happy with that LLT BMS? I was considering buying one and trying it.
Other than the issue with proprietary bluetooth described above, I've been happy with them, although I've only had them installed for a week and a half. The 100 A one has not yet been on a vehicle, just monitoring and charging the battery, but I also have a 30 A version that I've installed on my bike with PhaseRunner and 9C motor. They both seem to do what they're supposed to in terms of basic function (HVC, LVC, balancing).

The ability to monitor things at the cell level is a huge advantage over BMSs without comms capability, and the ability to configure parameters as you like them is also a big deal. I like being able to control the FETs through the app, which eliminates the need to disconnect the battery or install a switch, with the consequent sparking or anti-sparking workarounds.

I've had some interaction with the specific vendor linked above and they're fairly responsive.

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thundercamel   1 kW

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Re: bluetooth BMS?

Post by thundercamel » Jun 20 2019 10:28am

cycborg wrote:
Jun 20 2019 9:56am
The ability to monitor things at the cell level is a huge advantage over BMSs without comms capability, and the ability to configure parameters as you like them is also a big deal. I like being able to control the FETs through the app, which eliminates the need to disconnect the battery or install a switch, with the consequent sparking or anti-sparking workarounds.

I've had some interaction with the specific vendor linked above and they're fairly responsive.
I totally agree with and emphasize the cell level monitoring. Now why didn't I think of using the switch before I bought my XT90 anti-spark connectors? Oh well, one less step :)
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Re: bluetooth BMS?

Post by Headrc » Jun 21 2019 9:35am

Thanks Cycborg that is helpful. I wish they had a better looking display available though.

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Re: bluetooth BMS?

Post by john61ct » Jun 21 2019 11:03am

Maybe Apple will get into the biz one day and such gear will get pretty.

Meantime, I'd rather functional improvements be the main priority

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Inwo   10 kW

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Re: 7S daisy chained smart "112S max" BMS

Post by Inwo » Jun 21 2019 10:36pm

ElectricGod wrote:
Jun 25 2018 10:23am
Back in May I got 5 of these BMS/balancers and an LCD. Over this past weekend I finally got time to set them up. The 4 pin JST connectors are labeled COM1 and COM2. They are the communications interconnects between each board and how you program via a USB adapter too. The right hand 7 pin connector goes to the LCD. The left hand 8 pin JST is the 7S balance connector.

https://www.aliexpress.com/store/produc ... 3de2sfucrn

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They can be daisy chained together up to 16 in a row. When you use them as a single 7S board, the mosfets can be used for up to 30 amps. When you chain them together, they become balancers. This is the boards on 32S, 16,000mah LIPO packs before and after securing them together with nylon spacers. The "stack" is about 1" thick. Board 1 is on top and board 5 is on the bottom.

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The documentation is not overly clear in some regards of wiring these BMS so in the end, I just ignored the manual and wired them with the balance connections only. I'm not using B-, C- or P- at all. Probably the LCD won't display charge or discharge amps as a result. Oh well. My LIPO packs are 4S each so I pulled out 9 4S JST male connectors and started chaining together the 5 BMS balance connections so they could span my 8 LIPO packs. The high pin in the first balance connector is common with the lowest pin in the second BMS balance connector. The second BMS high pin is common with the third BMS low pin...and so on. The LCD is plugged into the lowest BMS, but I don't know if that matters or not. With just the lowest 4S pack plugged in, a few seconds later I was seeing cell voltages on the LCD. There's an LED next to the COM2 connector that flashes randomly. As I plugged in more 4S sections, after a few seconds, they too would be added to the list and their LED would flash. Once all 5 boards were plugged together and had the full 32S connected, they all flash their LEDs at seemingly random intervals. I'm guessing the LED indicates data on the 4 wire buss. I don't know why, but the LCD won't display more than the first 28 cells. Maybe there's a setting in the BMS that tells it to scroll through the entire 32S or maybe I need a second LCD? The manual doesn't say and ICGOGOGO was clueless. They just wanted to sell another LCD...so that's on it's way and more boards too.


The manual is horribly incomplete and even though it's supposedly in English, all the screen shots are of the Chinese config app and then the actual settings are not explained at all. This is the first step in programming the BMS and that's literally all the better it gets for the rest of it.

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This is the English config application. Based on the pictures in the documentation, you enter commands in that lower left pane that tell the BMS what do to. However, the manual does not explain what you type there.

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This sequence of pictures is what the LCD shows. It sort "cycles" at random, but then the only thing that changes is the voltage at the bottom. As you can see the cell voltages are the same. So much for showing all 32 cells. There's no physical buttons to press on the LCD and no solder connections that could possibly be connections for buttons. I really wish it was back lit! Notice the temp reading (20C), I have no idea where the thermistor is. It's not on the LCD and looking at the boards closely there's not one on them either. I don't see in the STM32 docs that they have an internal thermistor. I'm wondering if this is fake data. In messing around, I couldn't get it to go up or down.


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I want to mention the balance connector some more. Silk screened on the back side of the board is this battery layout. It is accurate for the BMS.

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On the top side of the board, notice the orientation of the balance connector. This is exactly opposite of an actual balance connector on a battery pack. If you attempt to plug in a batteries balance lead directly into this connector, you will destroy the BMS. Where B- is silk screened on the board, in an actual battery balance cable, that's B+. DON'T plug a battery pack directly into the BMS!!! I didn't do it, but a friend who also has these boards did and fried at least one of his boards.

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Notice the balancing resistors. 3R3 or 3.3 ohms at 4.2 volts per cell that's 1.27 amps. The specs on ICGOGOGO say "balance the current 60mA-1.2A (4.2V)". OK close enough to V/R=I, but then look at those 7 tiny mosfets or transistors on the board. They clearly connect to the resistors and source to drain across each cell. Do you seriously think they can handle 1.2 amps? My guess is that "1.2" amps is more like momentary drain and reality is more like 500mA continuous. The 4 pin packages are KPC357NT opto-isolators. I think the lowest mosfet is controlled directly by the STM32 CPU and the other 6 channels are behind the 6 opto-isolators.

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IMHO, the mosfets are pretty useless and I'll never use them. I bought this board purely for it's daisy chain balancing ability at 112 cells. I intend to use 48S. The mosfets are NCE1540's. They are good for virtually nothing I'm likely to ever do where I need mosfets. I seriously doubt I'd ever build an EV that maxed out at 30 amps.

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This is in the manual. Currently I don't have it jumpered at all on any of the boards. My theory, is to set this up in programming and NOT use these jumpers. That's how every other smart BMS works. It is cool that it will support LTO and LION. Most BMS won't do the full range of lithium chemistries.

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I have this system connected to 4 x 10s lto 60ah modules. 40s total.
5 cells on each of 8 boards. [Keeps each module on its own section in app]
A second LCD displays over run from first LCD.
New boards have 10ohm shunts.
Balance current settings have no effect on duty cycle of shunt current.
30% balance, rising to 40% when current is sensed.
Hvc and lvc can be set..
First board in string is master, and c- output controls charger from all 40s. 150v fets should work great for my 100v charger.
Drive a relay or connect small charger and load direct.
Screenshot_20190621-174944.jpg
Screenshot_20190621-194236.jpg
Screenshot_20190621-194236.jpg (61.29 KiB) Viewed 3337 times
Hope these are correct screen shots.

I have questions to go go, but clueless. Balance works, settings for current do not.
Might need uart to pc, but I'm not smart enough for this Chinese nightmare.
Love these boards as they work for most any string and chem. Smoke one? Throw it out keep the other 7. Smoke the Mosfets? Shift it out of the master position.
Have parallel modules? These don't care. Each 7s section is isolated. In theory, use one bms system for 2 or 3 discrete batteries. Read up to 112 cells on 1 app.
Last edited by Inwo on Jun 22 2019 9:09am, edited 1 time in total.

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Inwo   10 kW

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Re: bluetooth BMS?

Post by Inwo » Jun 21 2019 10:44pm

Let me try again. That screen shot is from my 12s testing.
Screenshot_20190619-201540.jpg
This is 40s before I leaned to set voltage limits.
Red is over volts, green is under volts.

Notice by putting 5s on each board, each 10s module is displayed on 2 even lines.
Boards don't care, any number of cells on each 7s max xh connector.

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tmho   100 W

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Re: bluetooth BMS?

Post by tmho » Jun 23 2019 3:35am

I finally finished my battery pack with the bluetooth BMS. But something strange that I cannot understand why.

I set the no. of cell (14s) and the capacity (13.5AH) of the pack. And I got the following readings from the app.

Voltage of the pack: 51.7V
Capacity of the pack: 7.006AH (52%)
Highest voltage of the cells: 3.691V
Lowest voltage of the cells: 3.688V

Then I started to charge the pack. I saw the voltage and capacity went up gradually and that was normal. After charging for about half an hour, I stopped the charging by unplugging the charger. And I got the following readings from the app which I think should also be normal. (Sorry, I did not take a screenshot)

Voltage of the pack: 55.1V
Capacity of the pack: 9.091AH (68%)

But after that, I found the capacity reading still going up. At about 40 minutes after unplugging the charger, I got the following readings.

Voltage of the pack: 54.1V
Capacity of the pack: 9.530AH (71%)
Highest voltage of the cells: 3.860V
Lowest voltage of the cells: 3.858V
Screenshot_2019-06-23-00-55-19.png
screenshot of app
Why the capacity of the pack continue to increase after the charging had stopped? Is something wrong with the app?

PS: so far after the above screenshot, the capacity reading stays at 9.530Ah without going further up.

john61ct   1 GW

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Re: bluetooth BMS?

Post by john61ct » Jun 23 2019 12:45pm

Depends on how that BMS is calculating %SoC.

All of the various methodologies are guesstimates at best.

Accuracy can only be (approximately) benchmarked against constant-current load testing.

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tmho   100 W

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Re: bluetooth BMS?

Post by tmho » Jun 23 2019 1:15pm

john61ct wrote:
Jun 23 2019 12:45pm
Depends on how that BMS is calculating %SoC.

All of the various methodologies are guesstimates at best.

Accuracy can only be (approximately) benchmarked against constant-current load testing.
Thanks for your reply.
I think the capacity increase after charging has stopped is not the real situation. If I am correct, then the methodology they are using is not good. Why don't they just do the calculation based on charge current, charge voltage and time (then once charge current = 0, the capacity will not increase)? This should not be difficult for them to do. Or the capacity should really rise a bit after stop charging?

Or am I using an out dated app? My BMS is as shown below. Does anyone with the same brand has the same problem or not?
IMG_1375a.jpg

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Re: bluetooth BMS?

Post by john61ct » Jun 23 2019 1:26pm

I've never heard of anyone relying on BMS only for accurate SoC data, even those costing many hundreds of dollars.

Much less doing benchmarking to determine the accuracy of their guesstimations.

That functionality is a minor sideline, not essential to their primary function of protecting the bank.

Most users just rely on accuracy at the top and bottom, from whatever regulates their stop-charge for the former, and their working LVC at the bottom.

Voltage levels and rough Ah counting are usually good enough for in between.

Headrc   100 W

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Re: bluetooth BMS?

Post by Headrc » Jun 24 2019 8:46pm

Has anyone used this with an Android tablet instead of a smart phone? Is it only for an app on a smart phone?

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flippy   1 MW

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Re: bluetooth BMS?

Post by flippy » Jun 27 2019 3:36am

the app does not care if its a tablet. it might just look weird because of the screen size
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Headrc   100 W

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Re: bluetooth BMS?

Post by Headrc » Jul 04 2019 11:32pm

Thanks ....that might be an interesting thing to try.

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Re: bluetooth BMS?

Post by majkl » Jul 26 2019 6:11am

Wondering if someone can point me to a good bms that would support 12lipo and 13-14 lion later on?
Almost all listings require you to choose cell count at purchase, but I would like it to be configurable by user (prefferably by app).
30A model should be enough.

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Re: bluetooth BMS?

Post by agniusm » Aug 08 2019 3:35am

Headrc wrote:
Jun 24 2019 8:46pm
Has anyone used this with an Android tablet instead of a smart phone? Is it only for an app on a smart phone?
Works fine on 10" and 7" tablets

krlenjuska   10 W

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Re: bluetooth BMS?

Post by krlenjuska » Aug 14 2019 3:44pm

Is there any 6S smart bms? I can see 3S-5S and 7S + but cant find 6S anywhere...

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Re: bluetooth BMS?

Post by john61ct » Aug 14 2019 9:12pm

https://bit.ly/33BT6qA

add

site:alibaba.com

if you only want to search there

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Re: bluetooth BMS?

Post by john61ct » Aug 14 2019 9:14pm

Also many BMS designed for 7-8S will handle 6S just fine

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Re: bluetooth BMS?

Post by gatorsean » Aug 15 2019 11:28pm

So much great info in this thread!

I am looking to buy a 14s bms with bluetooth. Is this 60A unit from JBD still the best bang/buck recommendation https://www.aliexpress.com/item/32794186005.html

Perhaps more experienced users point would point me in a different direction?

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thundercamel   1 kW

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Re: bluetooth BMS?

Post by thundercamel » Aug 16 2019 9:47am

I have two of those exact units working great for the last year. Buy one of the PC adapters as well, to access a few settings that aren't available in the bluetooth app, such as temperature limits.
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grga   1 W

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Re: bluetooth BMS?

Post by grga » Aug 20 2019 2:28pm

I'd need one for 20S pack, around 100A, just to be safe, because I actually don't plan to go with more than 60A from battery. Bluetooth option required, or some nice color LCD display...

Do you guys have some best buy suggestion?

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Re: bluetooth BMS?

Post by trazor » Aug 26 2019 11:24pm

grga wrote:
Aug 20 2019 2:28pm
I'd need one for 20S pack, around 100A, just to be safe, because I actually don't plan to go with more than 60A from battery. Bluetooth option required, or some nice color LCD display...

Do you guys have some best buy suggestion?
Sure, half of this thread talks about the "JBD" bms: https://www.aliexpress.com/item/32820588136.html

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Re: bluetooth BMS?

Post by grga » Aug 26 2019 11:29pm

Thanks! :thumb:

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Re: bluetooth BMS?

Post by john61ct » Aug 27 2019 4:15am

Which is considered "the best" for build quaily, longevity?

Higher price is OK.

How about higher current for faster balancing?

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Re: bluetooth BMS?

Post by transposon » Sep 11 2019 8:04pm

I would also like to know what the current recommendation is. I am building a homemade pack from different 18650s so I would like something with a high balancing current in case the pack is prone to going out of balance. Right now now I am considering just breaking a 14s pack in 2 7s sections for charging on a hobby charger and reconnecting them when its time to ride, but this would be a pain.

Any suggestions are appreciated.

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