Ener Battery bank endurance question

[WiWatcher]

Power study with Kill-a-watt


Circuit 1 0.43kw 379hrs 1.134w/hour

Circuit 2 0.22kw 300hrs 0.733w/hour

Circuit 3 0.78kw 312hrs 2.5w/hour

Total 4.367w/hour

Total rounded 5w/hour



5w/hour = 120w/day (120v) = 1A

5w/hour = 120w/day (12v) = 10A

Efficiency of inverter (theoretical) at 90% and then rounded down to 85% = draw of 11.76A, rounded up = 12A/day

Power bank - four 6v 230AH batteries (two pairs of batteries each connected in series then connected in parallel) = 460AH

Maximum discharge of battery bank wanted to be no greater than 30% = 138AH, round down = 120AH = 10 days power

Note – All rounding up and down meant to allow for greater system long term endurance and to allow for the unforeseen.

 

[buttie]

A couple of other factors, inverter idle current and ambient temp.

 

[WiWatcher]

"no load current" is listed as 0.3A to 0.6A but no time duration listed, that amount might be able to be absorbed into my rounding factors, especially since the efficiency is listed as greater then or equal to 90%. The ambient temp can be anywhere from 32F to 80F. I am just trying to figure out if I made any basic math mistakes or have a wrong assumption somewhere.

 

[Toosh]

This was a lot of work. Congrats to you.
I love my Kill-A-Watt

 

[WiWatcher]

May have been a lot of work but bank only lasted about 4 hours. New back to old plan, running gen set, running gen for 1.5 hours out of each 8 hours. Battery bank should be ok to run blower on wood furnace during the other 6.6 hours (that is circuit 2).

 

[Samuel Adams]

Don’t forget to factor in lightning strikes.

Can be very detrimental to system longevity….even terminal, like….permanently.

 

[tech]

If you take your kil-a-watt reads while on the grid but run a modified sine wave inverter you'll likely have skewed readings, especially if motors are involved.

 

[tech]

Circuit 2 0.22kw 300hrs 0.733w/hour

Battery bank should be ok to run blower on wood furnace during the other 6.6 hours (that is circuit 2).

Something is wrong here. I have never seen a blower only draw 3/4 a watt...unless you're using a small computer-type fan that's about an inch and a half in diameter. That translates to 0.006 amps! That's less than your inverter idle current.
That would certainly explain why your 10 day estimate turned into 4 hours.

Might want to recheck your kill-a-watt readings...to me, that seems the most likely explanation. The other readings are suspect as well.

On the bright side, your math checks out

ETA: might want to look at the power factor of your circuits too.