# What is the Best Battery Size?

5 Posts
Nov 7, 2008 03:05 pm
What is the Best Battery Size?

I have the AirX 400W 12VDC Wind Turbine and a 2500W Inverter. What is the best size battery to use in between the two? I could also go multiple batteries, if necessary. The inverter has connections for two batteries.

Nov 9, 2008 07:40 am
Re: What is the Best Battery Size?

Not trying to sound insulting or anything Stephen but, thats like asking, "I have some gasoline and tires, whats the best car for me to drive?"
Two things you need to know; how much power are you estimating to get and, what are your power needs converted into amphours at a given nominal voltage, all over a 24 hour period and Ohm's Law. Well, ok, three things.
Then there is personal preference. Some folks like sealed gel cells I prefer the traditional flooded cell.
I can give you an example that might help. Bear with me though 'cause I ain't no expert on wind power estimati'n.
Lets just say for example your Air X 400 produces an equivalent average over a years time of 2400 watts per 24 hour period (day/night) at the nominal voltage of 12.
That would be 2400 / 12 = 200 amphours.
Now if your are using close to 100% of his power during that same 24 hour period and you want to keep the battery bank in the top 20% of charge to prolong its over all life expectancy, simple multiply by 5. (Shallow cycling promotes more cycles.)
That would be 200 X 5 = 1000 amphour battery bank at 12 volts nominal.
Does this example help?
In this example you could run your 2500 inverter at full capacity for about 1 hour without going much below the 20% depth of discharge. Or any variable of this.
2500 / 12 = 208.
http://www.corrosion-doctors.org/Biographies/OhmBio.htm
http://www.corrosion-doctors.org/Biographies/VoltaBio.htm
http://www.corrosion-doctors.org/Biographies/AmperBio.htm
Truly amazing ain't it? I mean that this all took place almost two hundred years ago.
« Last Edit: Nov 9, 2008 07:50 am by Thomas Allen Schmidt »

5 Posts
Nov 9, 2008 09:08 am
Re: What is the Best Battery Size?

Thomas, I am not insulted. This is all a practical learning experience for me. I was a nuke electrician in the navy. So I am just replacing neutrons with wind. I understand all the laws of electricity and batteries. I just needed some help in picking out the right type 24DC vs 27DC vs ...

I bought a bad battery at Walmart and it was not working with my system. I just got a 24DC 70AH battery from Advance Auto Parts, and the system seems to be working well now.

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