Batteries For Home Standby Power

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using your peak 5 kw, 20 A, size for 25
assume avg draw is 50%
size for 3 days
ahr = 3 x 24 x 50% x 25 = 1275 ahr, use 1400 (+10%)

dc bus ~ 2 sqrt2/Pi x 240 = 216
assume 12 vdc 100 ahr std ups battery
216/12 = 18 battery per string for 100 ahr
so need 1400/100 = 14 strings or 14 x 18 = 252 batteries

you need to split the system into 2 pnls
norm and emergency
service into norm with branch to ups then to emerg pnl

battery vol ~ 350 cu ft or ~ 16' long x 3' deep x 8' tall
ups ~ $7k
batteries ~ $18k
plus freight, install, etc...freight alone might be a few k
plus pnl work and any space requirements
 
Ingenieur said:
using your peak 5 kw, 20 A, size for 25
assume avg draw is 50%
size for 3 days
ahr = 3 x 24 x 50% x 25 = 1275 ahr, use 1400 (+10%)

dc bus ~ 2 sqrt2/Pi x 240 = 216
assume 12 vdc 100 ahr std ups battery
216/12 = 18 battery per string for 100 ahr
so need 1400/100 = 14 strings or 14 x 18 = 252 batteries

you need to split the system into 2 pnls
norm and emergency
service into norm with branch to ups then to emerg pnl

battery vol ~ 350 cu ft or ~ 16' long x 3' deep x 8' tall
ups ~ $7k
batteries ~ $18k
plus freight, install, etc...freight alone might be a few k
plus pnl work and any space requirements
Click to expand...
I think it was four days.
 
using your peak 5 kw, 20 A
assume avg draw 2kw or 40% of peak
size for 4 days
ahr = 4 x 24 x 40% x 20 = 768 ahr, use 800 (+5%)

dc bus ~ 2 sqrt2/Pi x 240 = 216
assume 12 vdc 100 ahr std ups battery
216/12 = 18 battery per string for 100 ahr
so need 800/100 = 8 strings or 8 x 18 = 144 batteries


battery vol ~ 200 cu ft or ~ 16' long x 1.5' deep x 8' tall
ups ~ $7k
batteries ~ $10k
plus freight, install, etc...freight alone might be a few k
plus pnl work and any space requirements

price goes down
 
Ingenieur said:
????
Click to expand...
From the OP
I’m looking for some feedback on how practical this concept is. I would assume the system would need about 5kw peak load and have an average output of 2kw. These numbers are just shooting from the hip. If these numbers are anywhere near close, how big of a battery would I need to survive a power outage for four days?
Click to expand...
 
surprised you did not catch the math error lol

using your peak 5 kw, 20 A, size for 25
assume avg draw is 50%
size for 3 days
ahr = 3 x 24 x 50% x 25 = 900 ahr, use 1000 (+10%)

dc bus ~ 2 sqrt2/Pi x 240 = 216
assume 12 vdc 100 ahr std ups battery
216/12 = 18 battery per string for 100 ahr
so need 1000/100 = 10 strings or 10 x 18 = 180 batteries

you need to split the system into 2 pnls
norm and emergency
service into norm with branch to ups then to emerg pnl

battery vol ~ 260 cu ft or ~ 16' long x 3' deep x 5' tall
ups ~ $7k
batteries ~ $12k
plus freight, install, etc...freight alone might be a few k
plus pnl work and any space requirements
 
Besoeker said:
Because that is what he was asked to offer.
Click to expand...
I like how you selectively edit posts to take shots at members lol

just because you are asked to do something doesn't mean it should not be questioned
and you have an ethical obligation to express those concerns to the client

please stay on tooic ;)
 
100% coverage for all potential events is not possible. 99% is more expensive than 90%. 99.9% is more expensive than 99%. How many 9's do you wish to buy?
 
he could do much more for the same or less (ac, hw, etc)
put the genset inside, less footprint than the ups/batteries
sound proof room and enclosure, vibration isolators
residential or hospital critical grade muffler discharged to a small baffled 'closet' vented to ext
small pvc pipe for intake air
no louder than a cond unit
research the noise ordinance home owner regs, must give a max dB at a property line or adjacent unit

why not a ng fuel cell or nuclear reactor?
a gaggle of hamsters?
convection oven, after all more elec power out than in?
 
ggunn said:
100% coverage for all potential events is not possible. 99% is more expensive than 90%. 99.9% is more expensive than 99%. How many 9's do you wish to buy?
Click to expand...

and how frequent are outtages? records are available
what are the consequences? take out food? eat cereal? no hot shower for a few days?
 
Ingenieur said:
I like how you selectively edit posts to take shots at members lol

just because you are asked to do something doesn't mean it should not be questioned
and you have an ethical obligation to express those concerns to the client

please stay on tooic ;)
Click to expand...
Like it or not I just prefer to stick to facts.
Shall we now wait to see if we get any feedback from the OP?
 
Besoeker said:
Mods, I think the OP has been given answers. The topic is done and should be closed.
Click to expand...

I have learned enough to be able to give the customer an idea what he wants will cost. No surprise, he won’t spend the money it would take. He probably that he could get a few batteries and an inverter and that would do the job. Reminds me of a carpenter fried who once bought a tiny inverter that plugged into a 12 volt cigarette lighter. I think it was rated 25 Watts. I disappointed him with the info on how much power that is. He thought he could run a skill saw.
 
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