Thanks for your replies in November! Just been spending some more time thinking about this and created a diagram of my new design.
My goals are:
- Creating a DC UPS: my DC equipment will keep running, even if there is no mains power
- Powering DC devices in my house using cheap electricity, stored in the LiFePo4 batteries overnight.
Here is my design:
My load will be around 80W and the Victron charger is 384W - so there should be enough to power the load and charge the battery at the same time.
The Sonoff switch will be used to switch the mains to charger on and off at different times of day.
A future enhancement will be to use a Smart Shunt to monitor the batteries and switch on the charger if the batteries get low - although based on a fixed load and schedule, hopefully this won’t happen.
A couple of things I am not certain about:
- Can I really just connect the load, charger and battery all together on a fused bus bar?
- If the charger is both charging the batteries and powering the load at the same time, is it able to detect the battery voltage and set the correct voltage for the state of charge?
- Can I connect two batteries together in series, with separate BMSs and all the cells remain balanced? Presumably the two BMS are unaware of each other?