Old BMS Software Thread

[retepsnikrep]

I've simplified some new Slave & Master software which uses serial comms at 9600 baud on both buses now instead of pulses on the slavebus. I'm hoping this will give two benifits.

1) It's smaller and easier to understand.

2) It overcomes the slave load stuck on problem. As the serin routine has a timeout after 5 seconds where it turns off the load if no commands received.

So you can kill the master at anytime and the slaves will deactivate loads (if on) after 5 seconds.

Havent tested it yet.

I have also been looking at putting the slaves to sleep if the serin timesout to save power. This is possible and so is waking them, but not with this version of the slave PCB's as the special wake from sleep interrupt is only available on one pin GPIO2 which sadly is not allocated to the slave bus in this version.


The slave Commands had got a bit out of hand with 26, so i have chopped back to 13.

'***************************** Slave Commands ******************

' Command 01 = Send Cell Voltage on Master Bus
' Command 02 = Turn Off Loads
' Command 03 = Turn On Loads as Reqd
' Command 04 = Increase Load CutIn Voltage by 50mv
' Command 05 = Decrease Load CutIn Voltage by 50mv
' Command 06 = Set Slave Load CutIn Voltage Default
' Command 07 = Turn On Slave Load for 0.5 seconds (Flash Led)
' Command 08 = Report Slave Software Version Number
' Command 09 = Increase FailLow Cut Off Voltage by 50mv
' Command 10 = Decrease FailLow Cut Off Voltage by 50mv
' Command 11 = Increase FailHigh Cut in Voltage by 50mv
' Command 12 = Decrease FailHigh Cut in Voltage by 50mv
' Command 13 = Set FailHigh/Low Voltages to Default

Speed for the slaves is now fixed at 9600 baud.
There is no multi or single slave selection. All use the same software
No super slave selection. All use the same software

Hope to test in next couple of weeks but work is horribly busy.

[GregsGarage]

Peter,

I've been busy and haven't had time to work on my Matiz, but can you send me your latest versions and I will do some testing as well?

Thanks,

Greg

[GregsGarage]

Peter,

I have tried the new master and slave software you sent me on my 7 cell board. No cell voltage data is being received. Another thing I noticed is D7 and D9 are lit up solid (as well as D6 and D8). I think this would suggest that maybe the serial data is inverted? Anyway, no more time to tinker with this today, just a quick report.

Greg.

P.S. the boards work fine with your current working version of the software.

[retepsnikrep]

Thanks.

I might look at it tomorrow.

At the moment i'm making a 6A charger for one of my packs using 3 x meanwell 350w 48V modified switch mode psus for <£100 compared to nearly £600 for a Zivan NG3

Can you try the commands. send command 9 and see if the leds switch on the slaves in sequence, at least we would know then if we have got the comms right one way.

Can you scope the slave alive pin on the slaves to check they are running. It should toggle high/low every 5 seconds when the master is not attached or running. if we have the serial (slave command in) the wrong way round it may never time out as it thinks it has recieved the first bit due to being pulled low or high.

i suspect it is just the serial comms the wrong way up or down

[GregsGarage]

Is this the psu you are using?

I will try your suggestions tomorrow and report back.

[retepsnikrep]

Greg

I can't see your link at work. I got them from e-bay from sure electronics. Quick delivery and about £65 all in for three inc delivery from China with no customs charge etc. A bargain.

I'm just finishing the mods tomorrow so i can control them with the BMS. All have been modified to provide 60v output. Current limit has been reduced to around 6.5A to keep PSU under 400w total. Fan is modifed to run all the time. etc etc. Jeremy on here and the endless sphere forum started all this psu modding off and very useful it is too

I don't know the voltage of your pack but I would seriously consider using the meanwell supplies for your own charger. I have 50 cells and am aiming to charge to 180V max.

The 350w model is available in various voltages. The 48v one normally delivers 7.3A. It could possibly be modified to provide 90V as the caps are rated at 100V in which case I would only need two but of course the current would be limited to around 4 - 4.5A.

http://www.sure-electronics.net/measure ... 1.0_EN.pdf

http://www.sureelectronics.net/goods.php?id=458

Not sure if they are genuine meanwell but if not they are good enough clones to do the job.

[GregsGarage]

Peter,

Just done a bit of testing with the new software. Trying to send commands to the slaves has failed, tried command 9 and 7, nothing.

Put the scope on the first slave pin GP5 (slave alive), with the master off it toggles very fast and with the master on it toggles in sync with every alarm beep.

GP4 (slave data bus out) and GP1 (master data bus out)with the master off, both show a square wave that seems to have the same frequency as GP5 but is mostly on. It would seem that every time through the program loop the pins are briefly being commanded low. When the master is switched on GP1, GP3 (slave in) and GP4 all go high.

I think the data is just being inverted, but since all the slaves are toggling GP1 the master bus has a lot of noise on it.

Regarding the chargers, in principle I like the idea, problem is 3x 350 watt chargers gives about 1kw of power. With my 18kwh pack the charge time will be too long. I need to think about a higher power solution for myself, so I'll stick with the Zivan for now.

[retepsnikrep]

What voltage do you need for your pack? I have two 42-54v 50A 3kw supplies that I have modified to provide an adjustable BMS controlled output voltage. And it may be possible to get at least one more making a 165v 50A 9kw supply possible. I have used two before in series on the solar van which gave me a 6kw off board charger. Worked very well. Evan used three or four of the same supplies to charge his berlingo.

I agree sounds like the serial data is upside down i'll try and test next week.

[GregsGarage]

Peter, my pack is 48 cells, 120ah, so 3 of those would make for a very quick charger! I would need to check the recommended maximum charge current of the high power cells.

EDIT: max charge rate is 1/3C or 40 amps for the high power cells, those power supplies are a bit big unless the current can be turned down.

[martinwinlow]

Peter,

Did you get my email reply (on 010910) to yours?

What 50A 3kw supplies do you use, what do they cost and how complex is the mod as it would be nice to have a cheap backup charger or one I could install somewhere else for a fast(er) charge? Sounds like 3 would do nicely for my 120V pack of TS LFP160's.

Regards, MW.