Two 100aH/24v batteries?????

[Rbertalotto]

Are two 24v, 100aH batteries in parallel the same as four 12v batteries in parallel? IE 400aH?

 

[Madcodger]

Not the same number of amp hours, but the same number of available watts (storage), which is what I suspect you are after.

2 x 24 x 100 = 4800
4 x 12 x 100 = 4800

You actually get more watts than that because you're dealing with somewhat higher voltages, but this gives you the concept.

The thing to keep in mind, though, is that lower voltages mean bigger wire sizes are required because each wire will be carrying a larger number of amps. Many people like 12V because it works well with vehicle systems, but if in a building, 24 or 48 volts is generally easier. I built my small "shed" system as 24 V, and wish I had gone with 48 V instead.

 

[Tomthumb62]

48v 100Ah =
24v 200Ah =
12v 400Ah =
6v 800Ah

 

[Q-Dog]

Are two 24v, 100aH batteries in parallel the same as four 12v batteries in parallel? IE 400aH?

2 X 24v, 100aH = 200 aH. 4 X 12v, 100 aH = 400 aH. They are the same in watt hours.

 

[Wattsinwattsout]

As you increase the voltage as mentioned the cable size can be reduced. Another benefit is less heat or waste in the system. If you reduce resistance less heat is produced.

Another way to look at it
3000w/12v = 250amp
3000w/24v = 125amp
3090w/48v = 61.5amp

The higher voltage generally produces less heat which equals less waste. However, on the flip side the higher the voltage the higher the shock injury risk becomes.

 

[Supervstech]

Are two 24v, 100aH batteries in parallel the same as four 12v batteries in parallel? IE 400aH?

What is your actual question about? "The same as" is kind of a misleading statement.
What are you wanting to know?
Because, 4 12V batteries in parallel would be 12V
And two 24V batteries in parallel would be 24V.

 

[Supervstech]

Are two 24v, 100aH batteries in parallel the same as four 12v batteries in parallel? IE 400aH?

Since you can make a 24V 100Ah bank with two 12V 100Ah batteries, yes, doubling that, you can make 200Ah of 24V batteries with 400Ah of 12V batteries.
I think that is the best correct way to answer the first question.

 

[JWLV]

This is what a 48V shock looks like, courtesy of the one and only @Will Prowse

 

[Supervstech]

This is what a 48V shock looks like, courtesy of the one and only @Will Prowse

Incorrect...
This is what a 48V SHORT looks like...
A SHOCK is done to a person...