Using BYD-set as an "overflow" for a Pylontech-set

DIY
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1

I have used a 10kWh BYD-set providing power for our houseboat. I’m scaling up to a 20kWh Pylontech set, providing us with even more freedom :wink:

But… then I will have a perfectly working BYD-set (B-BOX 10.0) doing nothing :frowning:
I tried selling the set, but no interested parties yet :frowning:
The set is not produced by BYD anymore, which is the main reason to switch to Pylontech, but would be great for someone having/using such a 10kWh (or lower) set, wanting to expand.

Does someone have the “top-idea” to keep using the BYD-set as an addition/overflow to the setup with the 20kWh Pylontech batteries?
I was thinking to get a small MultiPlus connected to and maintaining that set.
Connecting that 10kWh set to my, quite standard, setup with (then) 20kWh Pylontech’s is what I’m looking for an answer to :wink:

2

Not possible without a dc to dc converter and not easy to implement as one has a higher charged voltage than the other by quite a margin.

So you want to sell them?

3

I know that the voltages differ. That’s why I thought of creating a seperate (non essential) “set” that is charged with by main setup and is used for feed in, as a 230V source, when needed.

But if anyone would want to buy the set from me (for expansion of an existing set) it would be a win-win I think…

4

Lol. Yeah.

Yes feedin is possible. You would have to use one system to control the other.

5

how?!

6

I’m running a BYD battery (via Solaredge inverter) in addition to a 3 phase Victron ESS with 30kWh Pylontech batteries.

See here: Victron MPII’s with Solaredge and 2 batteries - DIY - Victron Community

I’m controlling the BYD via the Solaredge inverter, which in turn is connected via MODBUS TCP to Home Assistant. Works well :wink:

7

There is an option to use the aux to feed in. (Other system will need a gx.)
Home assistant as well as mentioned.
Node red is also an option particularly if you have varying loads and don’t feed back to grid. There is a safety factor to consider such as feeding back to much and nowhere for the power to go.

What we did on our home system is split our DB up, used a smaller inverter for lights and a few other essentials. (It now has solar so this is not what we do now but) we used to have a conditional ac connect to the first system to charge during solar hours.