I have a question around the use of the smart charger and 2 batteries . I have solar but no battery system connected to it . My nighttime loads are reasonably constant so I am thinking I can power them this way for far less then a battery attached to solar system .
With an Arduino (or similar) logic is
Controller is aware of Sunrise and Sunset and is also aware if solar is producing or not
So
Nighttime is afternoon and solar production has stopped
Daytime is Sunrise and solar production has started
Moving from Nighttime to Daytime automatically starts the charger
If Daytime then charge battery to 80% then power off the charger
When battery drops to 60% turn back on charger to top back up to 80%
If daytime and less than 1 hour before Nighttime (Remembered from previous day) regardless of charge level, charge to 80% turn off and turn back on when battery drops to 75% (assuming it wont)
If Nighttime power off charger but if battery drops to 20% power on charger to power to X %
Where X is load over last 1 hour multiplied by number of hours to Daytime
I would probably recommend a gx device Or a raspberry pie running Venus os You could use the generator start function to allow charging I am unsure if this charger will automatically start up when powered from the AC side If so, a contactor could just turn the power on and off to that. It is recommended to put a fuse on the charger too.
Thanks Adam . I tried to keep layout basic for this but would/will include fuse in charger and a battery isolator as well .
The instruction manual says “To stop charging isolate the power supply to the AC power cable” so I take from that removing power is the correct way to stop it ?? .
I will verify that with Victron as well .
To control the AC I am going to use a High amperage SSR like SSR-60DA Solid State Relay (no moving parts) .
Thanks again for your response.
The issue is whether this charge will automatically start up or whether you need to press the button or use your phone via Bluetooth do you have the charger? If so it might be worth checking that to start with do you know how to make your own X device with raspberry pie, there are YouTube tutorials on how to add release to it and things like that so you can try to solicit relay with a small relay or you could purchase the GX device but it’s .
You will end up with batteries that don’t have balanced cells.
This will then in turn affect your low cut off. So you system will shut down earlier than expected.
It is healthier to fully charge them.
You are planning on cycling daily so this weird notion of not fully charging is not logical.
Energy in and out between 20 and 80 is the same as between 40 and 100. The difference being cell balancing and efficiency.
Thank You LX I was just basing the 20 and 80 on the fact of what I have read says cells last longer if you only charge to 80% rather than 100% and the 20% is just based on the expected runtime of the cells under the load they are under during my “Nighttime” . If you are saying move that to 40%-100% that is easy to achieve.
So the bms already manages the cells between their range. When a manufacturer tells you its at 100% they mean 100% of the range you can use. Not 100% of the cell.
What batteries are you planning on using. In your layout you have shown Victron Smart Lithium batteries. These do not have a BMS inside them to provide safety shut down, you MUST fit an external Victron BMS and the associated gear for control. You do not show this in your layout. Victron do a range with an internal BMS, the Lithium SuperPack. Do not get the 2 types confused and check out the differences.
