Multi-Cell Slave-Version 2

Threads relating to the BMS system begun by Peter Perkins

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Re: Multi-Cell Slave-Version 2

Postby GregsGarage » Wed Jul 18, 2012 4:25 pm

Mike,

You said you do programming with the arduino. How about using one of microchips free c compilers. It would be nice to have a version of the code that could be developed and compiled using freely, preferably open source tools. PBP is nice for us non-programmers and has been a great help getting this project off the ground, but it comes at a price and this has limited the amount of people who can help with development. Peters code is very well documented and a decent programmer should be able to port it to C without too much bother. Once the framework is there it is much easier to hack little bits and make tweaks.

Regarding the CALB warranty requirements, could you send me a link to the full documents, I would like to look at them and see if a way forward with the 6802 board can be found.
Greg Fordyce

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http://www.evalbum.com/4191

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Re: Multi-Cell Slave-Version 2

Postby retepsnikrep » Wed Jul 18, 2012 6:36 pm

I suspect they are unlikely to regard our BMS as suitable for there warranty terms but you never know. I would get it in writing in triplicate that they are happy if they agree. Good luck.
Regards Peter

Two MK1 Honda Insight's. One running 20ah A123 Lithium pack. One 8ah BetterBattery Nimh pack.
One HCH1 Civic Hybrid running 60ah A123 Lithium pack.

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Re: Multi-Cell Slave-Version 2

Postby GregsGarage » Wed Jul 18, 2012 9:09 pm

Hi Peter, how's the holiday? I think we can have a good chance at getting our bms to a level that would suit CALB's warranty requirements, and I would like to get it there.

Mike,

Thanks for sending me the CALB info. The main thing they want is data logging of at least the previous week and also a fault code history, so things like high or low cell warnings, temperature warnings, etc. And of course keeping the cell voltages and temperatures within limits. Regarding cell balancing, you can take the view that they require a bms that does cell balancing, or you could take the view that any cell balancing is done by a bms. Not quite the same, but I think either approach should suit their requirements. I am proposing the latter approach. What I want to do with the 6802 system is to move the cell balancing off board of the vehicle so that for daily use we just monitor and log data as per their warranty requirements, and then once a year, or more often if necessary, when you are checking and tighten cell connections we attach an off board balancer to the cells. This balancer will charge each cell in a CV mode up to maybe 3.8 volts and stop charging when current drops to 0.05C, logging data while doing this including measuring ah required to get each cell to this level. I have not worked out the specific details yet for this device, my main focus has been working on the 6802 board. Maybe you could forward this onto CALB and see if they have any objections in principle to this approach.
Greg Fordyce

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http://www.evalbum.com/4191

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Snap shot of files

Postby GregsGarage » Thu Dec 20, 2012 7:50 pm

Here's my development folder for the 4 cell slave. This is unfinished and untested. There is a software folder, but again this is unfinished and untested. Peter's 12F1822 software may work with these boards but the schematics will need to be compared for pin compatibility. Kicad has been used for schematic and pcb layout. I am making these availible if anyone wants to continue work on it. I am at the moment focussing on the LTC6802 slaves, but should be able to answer some questions regarding this design.
Attachments
SlaveVer2-UNTESTED.zip
Snap shot of development files. *UNTESTED*
(8.33 MiB) Downloaded 578 times
Greg Fordyce

Daewoo Matiz
http://www.evalbum.com/4191


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