Smart BMS 4S 12V 150A LiFeP04 with temp. sensors

[Walef]

I bought a smart BMS board with Bluetooth advice and UART box with some other parts from AIiexpress, IC GOGOGO Store.

4S 12V Lifepo4 150A Continuous Lithium 3.2V Protection Board Bluetooth APP Computer UART Communication Balance Smart BMS

https://www.aliexpress.com/item/4000249910859.html?spm=a2g0s.9042311.0.0.68d54c4dcQ5S0c



The parts arrived, however, temp. sensors were missing.

Issue resolution, to get adequate response from the shop to close out open issues ihas been somehow difficult due to limited English communication.

After some initial set up problems with SW file re-naming, file unpacking and installation problems I got the

Xiaoxiang APP running and JBD tool software working on my PC.

Many thanks to Hackaday.io, I was able to download the JBD user manual which is a great help.


The BMS board chas been connected to 4x 3,2V in series LiFeP04 CALB cells, the Xiaxiang APP shows me false current reading. The displayed discharge current in APP is about one decimal digit smaller than the true measured current. The Xiaxiang APP doesn’t allow any adjustments for current.

Connecting the UART tool to the board I see the same readings. Current display is about 1/10 smaller than real measurements.
However, the JBD software has a calibration tab which allows calibrating the current flow for idle-, charge-, and discharge current
Any difference to the real current readings should be corrected with this tool.

When the battery draws discharge current the JBD software reads the current as charging current gives an error message not accepting the entry in the discharge box.

Has anybody experienced this kind of an issue on current offset and can guide me how to overcome this issue.

I case th

Thank's,
Waldemar

N.B.: With the wiring hook up, I started the balancing cable connection with the black cable to the main negative batt terminal and so on. The B- lead goes to the BMS B- and C- switches the negative to the consumer. Based on the wiring installation everything should be correctly connected.

some pictures see below:

 

[WingNut]

The BMS image oriented like that is the underside of the board. Here's it flipped over:


Compare your wiring to this.

 

[sid the seagull]

I’m keen to hear how you when with the 150a BMS . Does it heat up when passing high currents ? Is there any value in adding additional heat sinks to the unit ?

 

[Walef]

I’m keen to hear how you when with the 150a BMS . Does it heat up when passing high currents ? Is there any value in adding additional heat sinks to the unit ?

I've tested the assembly in high current condition, in step function, up to 100Amps for about 40min. As liad I uaef an inverter with a heat gun.
While testing I measured the heat disipations on wiring and connection surfaces. The FET's only marginaly heated up, I did expect more. This was fone through the entire test. The C- connection on the board heated up about 15 Kelvin above ambient temperature. The B- comnection about 10 Kelvin. It is obvious that the focus should be on a good surface connection wire terminal the PCB. I used quality copper crimp lugs with 2AWG stranded copper quality wire.
On the battery case cover I used the chinese post terminal connection, material is stainless steel. These connection showed the largest heat up with 100Amp load. I'd not recommend stainless steel, or steel, as conductor, instead I'll change the studs to brass terminals and the busbar to copper.
Hope this helps,
Waldemar

 

[sid the seagull]

Great information. I was planning on copper buzz bar , but I’d not considered brass for terminals. Brass is best , so I’ll use utilise that more than the steel nuts and bolts I was planning .
Thanx a ton !

 

[Walef]

Consider the following solution:
1. Grind a slot hole in the decklid.
2. Use a copper bar, square dim. (20x5)mm and S- bend the bar.
3. Prepare the bar for the brass studs and drill sunk holes into the bar for upper and lower stud connection.
4. Flame solder brass studs at one end of the bar.
5. Route copper bar through decklid.
6. Flame solder brass screws at the other end of the bar. Use countersunk head screw. This minimises the gap between decklid and bar.
7. Fix bar with 2 self tapping screws at lower decklid surface. Use plastic layer in between contact surfaces to ensure electrical isolation.

Hope this helps!
(Simple German Engineering, lol)
Waldemar

 

[MisterSandals]

Compare your wiring to this

Are you sure that is correct?
Shouldn’t the BMS balance wires have the + and first - wire hooked to the - end of the battery?
The - end has cell #1.

 

[WingNut]

Are you sure that is correct?
Shouldn’t the BMS balance wires have the + and first - wire hooked to the - end of the battery?
The - end has cell #1.

For this particular BMS board, the 5-wire connector is: Pin 0 to ground, pin 1 at 3.2V, pin 2 at 6.4V, pin 3 at 9.6V and pin 4 12.8V.

However, I'd suggest not using Pin 0 at all, ground comes from B- buss instead. See https://www.classbforum.com/forums/f23/diy-portable-useful-lifepo4-10057-14.html#post120343 for full explanation.

 

[MisterSandals]

For this particular BMS board

Ok, this is nearly opposite all other BMSs and devices that use balance leads.
I wonder why the split from convention; i cannot see any advantages to this.

EDIT: my statement is false here, this BMS has the same wire scheme, just wired quirky enough to fool me for a bit.

 

[WingNut]

Ok, this is nearly opposite all other BMSs and devices that use balance leads.
I wonder why the split from convention; i cannot see any advantages to this.

I just happened to notice that BC0 carried load current so I didn't use it. Since then, I found the wiring diagrams that support what I did. Same instructions here: https://www.lithiumbatterypcb.com/p...t-discharge-current-for-12v-lfp-battery-pack/ no need to use BC0.

 

[MisterSandals]

For this particular BMS board, the 5-wire connector is: Pin 0 to ground, pin 1 at 3.2V, pin 2 at 6.4V, pin 3 at 9.6V and pin 4 12.8V.

Yea, you have it right, i got to thinking otherwise because of the unusual placement of the balance wires on the diagram. I got confused with pin 1 being on the connecting bar near cell 2 (-) but that is essentially the same as being on cell 1 (+).

 

[WingNut]

The Carplounge app on Google Play: https://play.google.com/store/apps/details?id=com.carplounge.bms works great with this BMS. Full access to all settings.