affordable 2000w inverter

BFL13 wrote:
Using the calculator above, my 0.6v drop with 12v works with cu #1AWG at 24 ft round trip at 100 amps.

If I just change to 24v and 50 amps, leave the wiring the same, voltage drop should be half (not double) but percentage drop is 1/4.
...

The calculator isn't switching from parallel to series configuration. But that's what we are doing with the batteries (or resistors).

When you take two resistors/batteries (each with R internal resistance) and put them in parallel, the overall resistance is halved. In series the overall resistance is doubled.

In parallel, overall current is 2x that in series with that same load in watts. Say 100A at 12V and 50A at 24V at 1200W (VA).

So Vd = 100 x R/2 = 50 x R, at 12V
and Vd = 50 x 2/R = 100 x R, at 24V

So twice the voltage drop when configured in series at 24V when compared to configured in parallel at 12V. But the same % drop and same wattage drop. Theoretically ...

pianotuna wrote:
the 1 +1 = 2.7 comes from the video. I.E. Puekert effect. The load was put on a high quality industrial battery (10 hour rate 100 amps) and then put on two of the jars wired in a balanced manner.

The single battery lasted for about 21 minutes. The dual batteries lasted for about 1 hour.

Ah, sorry. Low bandwith here so I didn't watch the video.

But Peukert is all about capacity, not voltage drop AFAIK.

Not sure how V drop per amp of load varies with load. Is it linear or does it exponentially increase sort of like Peukert's Ah capacity decreases with load.

the 1 +1 = 2.7 comes from the video. I.E. Puekert effect. The load was put on a high quality industrial battery (10 hour rate 100 amps) and then put on two of the jars wired in a balanced manner.

The single battery lasted for about 21 minutes. The dual batteries lasted for about 1 hour.

pianotuna wrote:
No,

The watt hours go up by 2.7 rather than just 2 for the given load.

brulaz wrote:

RasMouSein wrote:

...
But parallel had more than twice of amp hours. 1+1=2.7 :)
...

But the same watt hours.

When I switched to 24V I had to change all my thinking to watts to keep things straight.

My 12V bank had about 430Ah or 5.16 kWh
Reconfigured as 24V it is 215Ah but still 5.16 kWh

Yes, I dunno where 1+1=2.7 comes from.

No,

The watt hours go up by 2.7 rather than just 2 for the given load.

brulaz wrote:

RasMouSein wrote:

...
But parallel had more than twice of amp hours. 1+1=2.7 :)
...

But the same watt hours.

When I switched to 24V I had to change all my thinking to watts to keep things straight.

My 12V bank had about 430Ah or 5.16 kWh
Reconfigured as 24V it is 215Ah but still 5.16 kWh

RasMouSein wrote:

...
But parallel had more than twice of amp hours. 1+1=2.7 :)
...

But the same watt hours.

When I switched to 24V I had to change all my thinking to watts to keep things straight.

My 12V bank had about 430Ah or 5.16 kWh
Reconfigured as 24V it is 215Ah but still 5.16 kWh

Using the calculator above, my 0.6v drop with 12v works with cu #1AWG at 24 ft round trip at 100 amps.

If I just change to 24v and 50 amps, leave the wiring the same, voltage drop should be half (not double) but percentage drop is 1/4.

So the idea I had that 1.2 with 24 is equivalent to 0.6 with 12 is wrong by a whole bunch. I have not figured out what is going on though.

Does that mean his 1.2v drop with 24v is really horrible? But it doesn't seem to make it any worse for hitting the inverter's alarm?

Also I remember doing voltage drops and Rs, that the R of a wire does not change. The amps change which changes V.

brulaz wrote:
Google tells me that a battery can be treated as a simple resistor with respect to voltage drop. And so can all the wires and connectors. Apparently then Ohm's law applies.

Example:
A single 12V battery with 50A load (600W) has Vd voltage drop

Two 12V batteries in parallel, with 100A load (50A each, 1200W total), also has Vd voltage drop. Half the internal resistance but twice the current so Vd remains the same.

Two 12V batteries in series, with 50A load (@ 24V, 1200W total), has 2xVd voltage drop? Twice the internal resistance of a single battery but the same 50A current, so TWICE the voltage drop.

But, percentage-wise the Voltage drop of two batteries in parallel is the same as two in series. And the wattage (VA) drops is the same.

No idea if this happens in practice though.

I'm gonna try my way hehe
All for a same load 1200w (I didn't like you changed that hehe)
My 12v Crown as a R=0.0091ohm

Single @12v=100a X0.0091ohm=0.91Vd

parallel 1/2 resistance 0.0091/2=0.00455ohm
@12v=100a X0.00455=0.455Vd

Series X2 ressistance 0.0091X2=0.0182ohm
@24v=50a X0,0182=0.91Vd

It would seem as far as internal resistance it's better 12v parralel ??
I'm getting something a bit different... :h
What am I missing ?


EDIT
I see now, like you said pourcantage wise.
@12v 0.455Vd/12vX100= 3.8%
@24v 0.91Vd/24vX100= 3.8%

got it

Edit #2

But parallel had more than twice of amp hours. 1+1=2.7 :)

Check this video

https://www.youtube.com/watch?v=snaJxB_psg8

brulaz wrote:
Google tells me that a battery can be treated as a simple resistor with respect to voltage drop. And so can all the wires and connectors. Apparently then Ohm's law applies.

Example:
A single 12V battery with 50A load (600W) has Vd voltage drop

Two 12V batteries in parallel, with 100A load (50A each, 1200W total), also has Vd voltage drop. Half the internal resistance but twice the current so Vd remains the same.

Two 12V batteries in series, with 50A load (@ 24V, 1200W total), has 2xVd voltage drop? Twice the internal resistance of a single battery but the same 50A current, so TWICE the voltage drop.

But, percentage-wise the Voltage drop of two batteries in parallel is the same as two in series. And the wattage (VA) drops is the same.

No idea if this happens in practice though.

Playing with this is interesting--keep everything the same except amps and just change from 24 to 12. Check absolute and percentage voltage drops. Not what I was expecting. (scroll down to calculator)

https://www.powerstream.com/Wire_Size.htm

One warning>
Inverters come in 2x2 types

One is an inverter/charger with power pass through. This is what I need, they are more expensive of course (Well I need the power pass though at the minimum)

And the other of the 2's on this one is Stand Alone (No power pass through) Use an external transfer switch with this type.

The second is Pure Sine wave.. Works with EVERYTHING, Just like shore power again more expensive.

And MSW. May cause radio or television or satellite TV interference, some devices may run "HOT" compared to what they run on shore power. I do not recommend.