Probably just an invertor input voltage limitation.
Comment on Biwatt releases 4.5 kWh sodium-ion battery - Energy Storage
SatansMaggotyCumFart@lemmy.world 3 weeks ago
According to the manufacturer, up to four modules can be stacked together for a total storage capacity of 18 kWh, and up to four stacks can be connected in parallel for a total of 72 kWh.
Why is this?
I always thought you could connect as many batteries as you like in any configuration the voltage and storage required.
poVoq@slrpnk.net 3 weeks ago
SatansMaggotyCumFart@lemmy.world 3 weeks ago
In the batteries because I thought hooking them up in parallel increases the storage indefinitely without increasing voltage.
poVoq@slrpnk.net 3 weeks ago
Well in these stacks you usually have a single BMS and each battery is in series. So four units maximum is about 200-240 V and not exeeding that probably makes it simpler to build an inverter for a 240V regular house grid.
SatansMaggotyCumFart@lemmy.world 3 weeks ago
But my question is why only four stacks in parallel?
Why can’t you do eight in parallel because you’re only increasing storage but keeping the voltage the same.
If you read the rest of the thread you’ll see why I’m asking the questions here.
WhiteOakBayou@lemmy.world 3 weeks ago
I can’t answer the why but there was a warning sticker on my new lifepo4 batteries with similar limitations. So not chemistry dependent.
SatansMaggotyCumFart@lemmy.world 3 weeks ago
Holy shit those are pricey.
How do you like them?
WhiteOakBayou@lemmy.world 3 weeks ago
A lot. My use case is off grid camper living. We live in a camper about 4 months a year not counting weekend trips and vacations. Lead acid batteries have to be minded and hate being discharged below 50%. The lifepo4 batteries have a super low self discharge rate, don’t need any minding and can be discharged down to 15% or 10% before they start degrading. I would need 400 Ah of leadacid batteries to equal the 200 Ah I have now.
So weight and space savings, no maintenance, harder to damage. I definitely recommend.SatansMaggotyCumFart@lemmy.world 3 weeks ago
This runs my house and I’ll have to be replacing them in the next year or two so I’ll look into them.
Hamartiogonic@sopuli.xyz 3 weeks ago
In theory, you can stack cells any way you like, and calculate what the current, voltage and capacity should be. However, those simple calculations don’t consider what the effects might be. Due to material limitations, only certain voltages and currents are safe. Go beyond the limits, and things begin to burn.
Also, these are modules, not cells. Each module probably contains some sensitive electronics that certainly can’t handle any random voltage or current. My guess is, that’s where you’ll find the first bottle neck.