Hello to all forum members reading this and thanks to Will Prowse for providing this forum. I bought your book (@Will) but I cannot find an answer to the following problem.
I have begun assembling a few LiFePO4 batteries into a nominal 24 volts system to power at least a part of our house with 230 volts (I am European, Dutch to be precise) for lighting, laptops, television and audio devices. I arrived at 24 volts because it limits the needed diameter of the cables to and from the batteries while preventing some losses (voltage drop) because of needed longer cables. A bit like the golden middle. Not 12 volts, not 48 volts, but yeah, perhaps the sensible thing to do.
Being located in Europe and, as we all are, in the middle of worldwide troubles, I do not have the same level of choice in inverters and stuff as some of you in America do. Especially finding low frequency power inverters, like the AIMS models for example, is very difficult. I managed to buy one 24 volts to 230 volts 1000 Watts nominal LF inverter (so with a big transformer inside) and while that worked perfectly fine, I soon found out it was not enough for my needs. Getting a 6000 Watts or 8000 Watts version was in a way overkill and I couldn't get my hands on one for a good price anyway, but now I found 3000 Watts nominal (9000 watts peak) LF inverters but they use ONLY 12 volts ! And 24 volts or higher is simply not available anymore. Don't know why, but that is what I'm being told now. They can't deliver 24 volts versions anymore. It's weird.
Now I know that I can use the inverter as a 12 volts input thing, but that means my existing cables are no good anymore and I have to rearrange my battery pack from hooking them up in parallel AND in series (to get 24 volts and a reasonable numbers of loaded amps) to fully and exclusively in series (12 volts) with very, very thick and expensive new cables to go to the inverter.
Nominally 3000 watts from 12 volts means a current through those supply cables of nominally 250 amps, but IF and WHEN something would draw a peak of 9000 watts (this is possible on an LF inverter like this) than we would be talking about a very short burst of 750 amps ! With the 24 volts setup this would have been half of those values.... (and a fraction of the cost of the cables)
So this got me thinking that if my only choice right now is to buy 12 volt versions of the 3000 Watts LF inverters in Europe, than what if I hook up 2 of them in series - next to one another - and sharing the existing 24 volts battery and cables setup ? So one 12 volt battery input from the inverter connected on one side to one pole of the 24 volts batterypack and then a cable from the other inverter input to the other 12 volt inverter input and then finally the last remaining 12 volt input of the second 12 volts inverter hooked up to the other pole of the 24 volts batterypack.
Would this work ? (and why not then ?)
Is this at all safe ?
Am I a genius or a dimwit for coming up with this ? ;-p
( "Come on, come on, come on, I can take it !" )
and am I wrong or right in thinking this would, on the output side of things, give me 3000 + 3000 watss nominal available on the shared 230 volts house circuit (one group of my house will be hooked up to this, the rest of the groups will remain on the grid) or not ? Will there be a problem with the phases or something when two identical power inverters put their output into the same 230 volts closed circuit ?
I could not find anything about this particular situation, so I decided to pose the question here. Hope somebody has an insight or two. Thanks in advance for your time and possible effort.
By the way, 3000 Watts nominal should actually be enough for my needs, maybe short periods of 3500 or 3800 Watts maybe as a luxury, but I certainly don't need 6000 Watts and will therefore never put such a strain on it, but I guess superfluous power headroom never hurted anyone. Right ?
EDITED to get rid of typos and clear things up a bit better.
I have begun assembling a few LiFePO4 batteries into a nominal 24 volts system to power at least a part of our house with 230 volts (I am European, Dutch to be precise) for lighting, laptops, television and audio devices. I arrived at 24 volts because it limits the needed diameter of the cables to and from the batteries while preventing some losses (voltage drop) because of needed longer cables. A bit like the golden middle. Not 12 volts, not 48 volts, but yeah, perhaps the sensible thing to do.
Being located in Europe and, as we all are, in the middle of worldwide troubles, I do not have the same level of choice in inverters and stuff as some of you in America do. Especially finding low frequency power inverters, like the AIMS models for example, is very difficult. I managed to buy one 24 volts to 230 volts 1000 Watts nominal LF inverter (so with a big transformer inside) and while that worked perfectly fine, I soon found out it was not enough for my needs. Getting a 6000 Watts or 8000 Watts version was in a way overkill and I couldn't get my hands on one for a good price anyway, but now I found 3000 Watts nominal (9000 watts peak) LF inverters but they use ONLY 12 volts ! And 24 volts or higher is simply not available anymore. Don't know why, but that is what I'm being told now. They can't deliver 24 volts versions anymore. It's weird.
Now I know that I can use the inverter as a 12 volts input thing, but that means my existing cables are no good anymore and I have to rearrange my battery pack from hooking them up in parallel AND in series (to get 24 volts and a reasonable numbers of loaded amps) to fully and exclusively in series (12 volts) with very, very thick and expensive new cables to go to the inverter.
Nominally 3000 watts from 12 volts means a current through those supply cables of nominally 250 amps, but IF and WHEN something would draw a peak of 9000 watts (this is possible on an LF inverter like this) than we would be talking about a very short burst of 750 amps ! With the 24 volts setup this would have been half of those values.... (and a fraction of the cost of the cables)
So this got me thinking that if my only choice right now is to buy 12 volt versions of the 3000 Watts LF inverters in Europe, than what if I hook up 2 of them in series - next to one another - and sharing the existing 24 volts battery and cables setup ? So one 12 volt battery input from the inverter connected on one side to one pole of the 24 volts batterypack and then a cable from the other inverter input to the other 12 volt inverter input and then finally the last remaining 12 volt input of the second 12 volts inverter hooked up to the other pole of the 24 volts batterypack.
Would this work ? (and why not then ?)
Is this at all safe ?
Am I a genius or a dimwit for coming up with this ? ;-p
( "Come on, come on, come on, I can take it !" )
and am I wrong or right in thinking this would, on the output side of things, give me 3000 + 3000 watss nominal available on the shared 230 volts house circuit (one group of my house will be hooked up to this, the rest of the groups will remain on the grid) or not ? Will there be a problem with the phases or something when two identical power inverters put their output into the same 230 volts closed circuit ?
I could not find anything about this particular situation, so I decided to pose the question here. Hope somebody has an insight or two. Thanks in advance for your time and possible effort.
By the way, 3000 Watts nominal should actually be enough for my needs, maybe short periods of 3500 or 3800 Watts maybe as a luxury, but I certainly don't need 6000 Watts and will therefore never put such a strain on it, but I guess superfluous power headroom never hurted anyone. Right ?
EDITED to get rid of typos and clear things up a bit better.
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