Old BMS Hardware Thread

[hohisilver]

Oh, and I forgot to mention now I've sorted out my controller issues my scooter now has a top speed of 50mph

[retepsnikrep]

HoHi RU Happy with how the BMS is performing?

Did it meet your expectations, would you recommend it?

Pos neg comments welcome.

Lots have things have been disucssed for V3 but what would you like to see?


Ditto Greg how is the Matiz?

[hohisilver]

Yes, I'm very pleased with it - it seems to be performing faultlessly and is doing the job admirably. I'd recommend it for the reasons I got it, as its functions are very comprehensive and it is a fun project to work on, but I think it may be a little over the top for someone who just wants an off the shelf solution to keep their lithium cells in balance.

As for V3, I've just been reading through the Master V3 thread and these are the most important things to me that have been mentioned:

A more powerful processor (faster, more memory etc.).
A better display driver chip.

One thing that I thought I'd seen mentioned on there but didn't notice it this time was an RTC. I sometimes find myself absent-mindedly looking for the time on the BMS display for some reason This would also enable the "timed charger start" to be easily implemented, and could also allow time-stamped logging.

That's all I can think of for now, I'll give it some more thought

[GregsGarage]

My Matiz is doing quite well. Since getting it on the road 2 months ago I have done 1500 miles so far. I can confirm it is capable of 70 mph and I think it should be capable of 85 mph, speed limited by motor rpm in 5th gear. Acceleration is good, much better than when it had it's 800cc engine. I get some cell voltage glitches, but usually doesn't set an alarm. I also send a command 6 before charging ( reset slave loads to default ) as it seems they may get out of sink after a drive. Again I suspect noise being received as false commands. Biggest problem is that the cells are quite out of balance. I estimate I can only get 90 of my 120ah out of the cells. 30 ah balancing will take a long time, I think I need something faster. I am going to build part of the Lee Hart Battery Balancer. I have ordered some circuit boards from Lee and will build the relay boards. Instead of his control board I will use a pic to read cell data and using some 3.6 volt 4 amp supplies charge the weakest cells. The idea is to push from the bottom while pulling from the top with the load resistors.

Lots of ideas for V3 of the master. After looking at the Maximite project, it might be possible to combine hohisilver's C code and the maximite code for a single chip master that drives the display, logs to SD card and any other features we can think of. Have a look at the Maximite project to see what is possible with the 32 bit pic micros.

Just some quick thoughts, must go as I am supposed to be fitting a shower and having a week off from EV tinkering.

[joshp1990]

Hi,

I've been having problems with the power supply to the master board. After switching on the 12V supply voltage there was no activity on the board. Also the L7805ABV voltage regulator got extremely hot. when putting a voltmeter across the terminals the output voltage started at 3V, and continued to drop the longer the device was on.

After reading up on voltage regulators, I've learned that they are inefficient and give off a lot of heat - but how much is too much? does anyone have more practical experience of this type of component? The master board has been functioning perfectly up until yesterday. What could have caused this type of failure?

Any help would be most appreciated

Thanks

Josh

[hohisilver]

It sounds like something's drawing a lot of current on your master board, the regulator on mine never gets too hot to touch - the only time I have had a problem with a regulator was the 7806 I use on a daughter board to power the pocket TV I use as a monitor, it draws a lot more than I expected and shut down when it got too hot. I ended up making a makeshift heat sink and fitted a small computer fan just to be on the safe side.

But I think there must be something wrong if your master board is drawing that much current, have you checked your connections and whether any other component is getting hot?

[retepsnikrep]

Something is connected the wrong way round or shorted or wrong component in wrong place

Did you build the board?

[joshp1990]

All is well. We were using the board you gave us to test with.

The problem came from putting the EEPROM in the wrong way after we loaded our new program onto the chip to test if it was working. The PIC16F886 got damaged so we have replaced it and all seems to be well again.

We were trying to test whether our programming was working, and the communication was successful. Over to the software thread for our next problem.. !

[danmachen]

thinking of replacing the EEPROM to check if that solves our problems, can we replace the EEPROM with another model? as it is just a data storage location can the part be interchanged in this way?

This is the one which we've been looking at:

http://www.onsemi.com/pub_link/Collater ... C512-D.PDF

would this cause any problems if this component was to be fitted onto master board V2? or does anyone know where to source the ATMLU818, or have they gone out of production?

[retepsnikrep]

Just remove the eeprom for the time being.

REM out this line by adding an ' at the begining.

Code: Select all

'   gosub CheckI2CTemp         'Gosub I2C Temp routine to collect/display battery temperature


Then add

Cells = 2 (Or whatever number you have)

on the next line after the below line

Code: Select all

      I2CREAD Scdeeprom,Sckeeprom,AT24C512B,I2CAddr,[Cells,Odo.Byte0,Odo.Byte1,Trip.Byte0,Trip.Byte1,_   
       Dist.Byte0,Dist.Byte1,Soc.Byte0,Soc.Byte1]  'Read data from I2c eeprom starting at addr 0


Now recompile and try it.

The problem may be it thinks it has 255 cells whcih could be corrupting ram memory.