BentleyJ
Solar Wizard
Am I the only one who wants to replace a wasteful, always-energized, golf cart type contactor with something else to eliminate the parasitic load? The stand-by current draw on a 200A contactor is 111mA while a 400 contactor uses a massive 345mA 24/7. Do the math for 30 days and it turns out to be significant.
Due to an unexpected, forced early retirement I finally had the time to come up with a couple of solutions.
1) Midnight Solar Remote Trip Breaker with PCB Control board to supply the required Momentary 24V nonpolarized pulse when the BMS relay opens. This approach is the most elegant because it combines the required Over Current Protection Device with a means of disconnecting the load when the BMS opens. Of course once the breaker trips, someone has to manually reset it. The PCB Control Board cost approx. $45 including PCB Fab, through hole components and shipping from the various suppliers.
2) A Permanent Magnet, Latching Contactor with PCB Control board to supply the required momentary current with correct polarity to Open or Close. The advantage to this approach is that the load will automatically be reconnected IF the problem is corrected and the BMS relay once again closes. A 12V Shallco latching contactor (300A Contacts) and PCB have been successfully tested. The PCB Control Board cost approx. $60. The 5F Maxwell SuperCaps account for $25 of that.
Waiting for a 48V AMETEK latching contactor (400A Contacts), PCB from the fab shop and a few through hole components. The Contactor is non-stock so the wait may be up to 6 weeks.
In the interest of keeping this brief, here are the YT links for the 2 items discussed above with more detailed info.
At the moment, there is no life cycle testing data on the PCB Controller boards. They are fairly simple, not much to go bad.
I do plan on installing the 48V system in my DIY battery cabinet as soon as the items arrive.
If anyone wants a fully assembled PCB Control board let me know I have a few components available. Alternatively, I would be happy to send the KiCAD files and BoM if you wish to build your own PCB.
Due to an unexpected, forced early retirement I finally had the time to come up with a couple of solutions.
1) Midnight Solar Remote Trip Breaker with PCB Control board to supply the required Momentary 24V nonpolarized pulse when the BMS relay opens. This approach is the most elegant because it combines the required Over Current Protection Device with a means of disconnecting the load when the BMS opens. Of course once the breaker trips, someone has to manually reset it. The PCB Control Board cost approx. $45 including PCB Fab, through hole components and shipping from the various suppliers.
2) A Permanent Magnet, Latching Contactor with PCB Control board to supply the required momentary current with correct polarity to Open or Close. The advantage to this approach is that the load will automatically be reconnected IF the problem is corrected and the BMS relay once again closes. A 12V Shallco latching contactor (300A Contacts) and PCB have been successfully tested. The PCB Control Board cost approx. $60. The 5F Maxwell SuperCaps account for $25 of that.
Waiting for a 48V AMETEK latching contactor (400A Contacts), PCB from the fab shop and a few through hole components. The Contactor is non-stock so the wait may be up to 6 weeks.
In the interest of keeping this brief, here are the YT links for the 2 items discussed above with more detailed info.
At the moment, there is no life cycle testing data on the PCB Controller boards. They are fairly simple, not much to go bad.
I do plan on installing the 48V system in my DIY battery cabinet as soon as the items arrive.
If anyone wants a fully assembled PCB Control board let me know I have a few components available. Alternatively, I would be happy to send the KiCAD files and BoM if you wish to build your own PCB.