Bridging a 24V inverter and a 12V battery with a 24V->12V converter possible ?

[websurfer]

Hi all,
Has anyone achieved a setup with a (grid-tied) 24V inverter and a single 12V (lithium) battery by inserting in between a 24v->12v the two. I plan on purchasing another 12V battery later to raise to 24V (by putting the 2 batteries of 12v each in series) and suppress the 24v->2v converter in between. But for now I plan on purchasing just :
-a single 12v (lithium) battery
-a 24v->12v converter
-a 24v (grid-tied) inverter

Anyone done that before? Or at last would that work?
I believe the 24v->12v converter are bidirectional... right? for when the 12v battery would be powering the 24v inverter for DC->AC.

Thanks

 

[rmaddy]

Most converters are one-way. You would need a 12V->24V converter.

What size inverter? Let's say 2000W. 2000W / 12V = 166A. Given the conversion losses you probably would need a 200A converter. That's a very big and expensive converter.

You really should just get a 24V battery at half the capacity if cost is an issue. Then later you can add another 24V battery in parallel to get to where you want to be. Much better than trying to use a converter.

 

[Alice2021]

or you can contact the inverter supplier to replace 12V inverter with them ,which will be fast and cheaper

 

[Jordi]

The way I see it; you can put a DC-DC converter between the controller and the battery to step down the voltage from 24V to 12V. Then directly from the battery to the inverter another DC-DC converter to step the voltage up to 24V. For such setting BMS mandatory because you are messing with the controller protection (eg. overcharge stop).

If you do this for heavy use, say >100W (consumption and/or panels output); then I agree it makes no financial sense. But If you were happy with just 50W-100W I believe the converters could cost you 3-5 euros each on Aliexpress.

Normally the DC-DC buck converters are unidirectional and If you pay a little extra they have current regulation feature.

I wonder however if it is safe to have the 24V supply from the controller and the 24V from the converter both connected to the inverter.

 

[Zil]

No you can not. Get a second battery now. Forget converting 12V to 24V DC.