dillond666 wrote:Hi casemod,
Glad to see someone playing with my board I just noticed I didn't put the schematic in the KiCad files on my webpage so I'll get that fixed
The current drain on the first three cells is of the order of 0.6mA so I'm not overly worried.
I will be manually balancing periodically (supposedly). I am using 40aH per day from a 100aH pack so I reckon I'm within safe limits.
The dc-dc is probably a more correct solution though from a design point of view.
I tied myself in knots for ages thinking about the startup circuit, thinking there must be a way to do a capacitor isolated circuit. There must be an elegant way but in the end I just went with a way I knew would work.
I'm interested to see any refinements you make to the design, please post your progress on this thread.
EDIT: uploaded schematic into KiCad files.
Its a great circuit. Simle, efective and not dependent on software.
I am looking into a way to implement with greg design as a fail safe, so I can operate each or both.
I am using a 10Ah battery (at 650V), so I would run out of balance much quicker
I did a change to the schematic that will "patch" this - Instead of a permanent voltage regulator zener/resistor I placed the zenner after after the opto coupler. So the idea is it will only drain/regulate if the OC is ON, about 1% of the total time, reducing to uA when the BMS is off.
I am also replacing some of your conectors with USB/Audio ports. This would make for a simple way to interconnect several units and the charger together and droping the relays. Instead a daisy chain signal is sent to the master that should disconect the master contactor if one of the packs reaches LVC or HVC. The charger would also be able to read this in case you take the battery out.
Now one problem I am having... I am new to kicad (Cadsoft Eagle user). I am adding components to the schematic, however they dont revert into the board, I only have the option to start the board from scratch. I would like to keep with my layout routing only the new components. Any advice on this?