# battery



## mike3367 (Dec 15, 2004)

im looking at a battery on ebay that 36volts at 1500 amp hours. but im trying to figure out how many watts a day it can do and cant seem to figure the math out. my elecric bill i used 1547 kilowatts if im doing my math right that is 515 watts a day? if so how well would a couple of these batterys hold out ? i know my watts are way to high but the house is total electric and just trying to figure out how to figure the math on these batterys


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## Nevada (Sep 9, 2004)

mike3367 said:


> im looking at a battery on ebay that 36volts at 1500 amp hours. but im trying to figure out how many watts a day it can do and cant seem to figure the math out. my elecric bill i used 1547 kilowatts if im doing my math right that is 515 watts a day? if so how well would a couple of these batterys hold out ? i know my watts are way to high but the house is total electric and just trying to figure out how to figure the math on these batterys


You used 1547 KWH (kilowatt hours) per month. So each day you would use about 52 KWH.

36 volts delivering 1500 amp hours would be 54,000 watt hours, or about 54 KWH. In other words, that battery would hold about 1 day of your current consumption, assuming zero loss on inverting (you should assume about a 25% loss on charging & inverting when you do your actual calculations).

My concern with those batteries is if they would be compatible with commercial chargers & inverters. Most common equipment runs at 12 or 24 volts.

You shouldn't try to meet your current usage with an off-grid system though. You need to change everything over to gas that you can, and then look for ways to economize from there. 

You're going to need a lot of solar panels to make 50 KWH per day. In fact, if you can make 100 watts for 10 hours each day from each solar panel, you'll need about 50 of them to generate 1 day of usage. That's about $25,000 worth of commercial panels. So you see, it really pays to adjust your lifestyle to being off-grid.


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## wy_white_wolf (Oct 14, 2004)

1547KW divided by 30 days (check bill for verification) equals 51.6KW per day

A 36v 1500AH battery bank would be 54KW. But you only want to operate on the top 20% of the batteries so you have 10.8kw regularly usable.

Mind posting the link to them as I haven't noticed any battery banks that big on EBAY.


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## mike3367 (Dec 15, 2004)

changing over not gonna happen as im in the city limits here after they annex us so no propane and there dont seem top be any gas lines or meters i can see here the link maybe not ebay sorry bout that....http://forklift.stackpoint.com/Forklift-Parts-Accessories/Batteries-and-Chargers


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## Jim-mi (May 15, 2002)

There's some really interesting stuff on that link.
And lots of 3 phase stuff.
Caution . . .don't run most of those chargers threw your handy "kill-a-watt" meter . . . .instant smoke..............


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## wy_white_wolf (Oct 14, 2004)

That would work nicely.

Personally, I'd inquire with them about 48v batteries. You'd have a larger selection of charge controllers and inverters with a 48v system. An 1125AH 48v battery would hold the same wattage.


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## wy_white_wolf (Oct 14, 2004)

Jim-mi said:


> There's some really interesting stuff on that link.
> And lots of 3 phase stuff.
> Caution . . .don't run most of those chargers threw your handy "kill-a-watt" meter . . . .instant smoke..............


.

My kill-a-watt meter aint gonna smoke one of them chargers! LOL


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## mike3367 (Dec 15, 2004)

would solar panels with a charger those big batterys up ?


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## Jim-mi (May 15, 2002)

No . . I mean that most of those BIG hunkers (chargers) will draw far more current than a kill-o-watt can handle.
Thats industrial grade big stuff.

Yes PV panels would charge those BIG batts up.
To do it proper tho, it would take many $$$$ worth of Panels.

Not much (if any) 'home' stuff offered any more in 36 volts.
Good inverters are going to be 24 or 48 vdc


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## mike3367 (Dec 15, 2004)

to bring this up i know you said big bucks, but how many watts of solar panels would it take to do the job to charge such big battery bank. ive tried to look it up but cant seem to find a answer i understand


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## wy_white_wolf (Oct 14, 2004)

mike3367 said:


> to bring this up i know you said big bucks, but how many watts of solar panels would it take to do the job to charge such big battery bank. ive tried to look it up but cant seem to find a answer i understand


All depends on how much you use out of it. Don't use any any an it doesn't need charged. Use 1000 watts and you need to put 1500 watts back in.

That said. For 12 volt a good rule to follow is 1 watt of panel for every Ah of battery if you have a 4 hour sun day. So, I would assume 3 watts per AH on a 36v battery would be about right. So that 1500 AH battery would like about 4500 watts in panels.


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