Old BMS Hardware Thread

[f.mendes]

Eih Peter,

One more thing,

In master, why do you use Charger Relay and Charger Cutback?

Thank you.

Regards,

Francisco.

[retepsnikrep]

The Charger relay is a simple on/off fail safe.

Charger cutback can be a proportional control of the charger voltage depending on how your charger is configured or controlled.

So cutback operates first as cell voltage rises. If that fails to control cell voltage or some other fatal error occurs or cpu locks which causes watchdog to operate then relay is cut.

The relay should control you charger mains power supply

[retepsnikrep]

60 cells working.

I have now increased the number of cells in my Insight to 60 for a 200V 60 x 3.3V pack. I added a spare 16 cell board (10 channels in use) and seems to work fine. Reprogrammed Master for higher pack voltage. Max 225V

I did have to repair the board after dangling slave connection wires shorted it out on the 10 cell pack I had on the bench. I think it got reverse polarity & high voltage (33V) across four channels. Blew tops off the tantalum caps, and killed four channels. Had to replace 4 optos on slave bus side, 4 pics and one voltage ref diode. Live and learn.

The next slave boards will def have right angle D sockets on the boards for the slave channels, i'm fed up with wiring them up by hand and it's safer. See above!

[feken]

I would like to create the 26 cell slave board and have a pcb service create the board for me..
These pcb services need extended gerber files, are these available on the board? Can't seem to find them.

Or the files of the pcb software used, so I can create my own?

Thanks

[retepsnikrep]

Here are the pcb manufacturing (gerber) files for the 26 cell slave board.

I don't have the schematic or raw pcb files Greg did the schematic and our pcb man did the layout.

I don't know what software either of them used.

[feken]

Great thanks

[GregsGarage]

The 26 cell schematic is here. http://www.go-ev.co.uk/projects/bms/26cell100510.sch

It was created with gEDA, an open source program, but not cross platform, it is designed for Linux. I would like to find an open source cross platform program for schematics and pcb design that will run on PC, Mac and Linux. So far I have found Kicad and Fritzing. Settling on one EDA tool would make it easier to share and update board designs in the future. Anyone have any thoughts on this?

[dillond666]

I've been trying Kicad again and am doing better with it now, could be a winner.
The fact you can mess about with package footprints could be handy I think.

Eagle can be obtained on a "not for profit licence" but it's still about £85
too much for a tight arsed Scotsman like me

There is also RS components software "Design spark pcb" free but it's windows only so far.

OFF TOPIC :
Greg, I noticed ages ago in one of your pictures that you use the same bench PSU as I do (cheapskate )
I put a 500 ohm pot in series with the main voltage pot to get a fine adjustment, which is handy for BMS calibrating
etc. Not rocket science I know but it's been quite handy.

Derek

[GregsGarage]

Thanks for the tip Derek, I've just been tapping the knob with my finger till I get the voltage I require.

[dillond666]

Almost finished my schematic in KiCad (8 battery lead acid slave board). I have made a
couple of schematic parts and component footprints as I went along. There wasn't a good
way to grab an image though so after a bit of farting about I got a .png of my efforts.

Viewable here http://dillonworld.co.uk/ then select slavemulti.png.

D33 represents the led on the avago fibre optic transmitter and I have mapped the symbol
to use my own footprint for doing the pcb layout. KiCad gets a thumbs up so far. If anyone
should spot any errors please let me know.

Derek