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There are many online calculators which give battery,panel,charger sizing for offgrid solar systems.I want to ask you that if e.g. a calculator gives 100Ah battery needed for a particular system to run for 6 hours then for the 1st time should i connect the battery totally empty to test results of that calculator practically or should i connect battery totally charged for the 1st time and check the calculator practically in next few cycles of battery in coming days???
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Batteries have to be broken in so to speak to build up the plate capacity. They have to be cycled 10 to 30 times before they reach their full rated capacity. As with any battery, be sure to fully charge it before placing into service.
Now one word of warning here. I have found most of the web sites on-line calculators for battery systems to be way to conservative, meaning undersized. I do not know if this is done out of ignorance, but I am more inclined it is done to suck you in. What I mean is you figure you need say 2 Kwh per day, and want to use a 24 volt battery system. You plug in your location, loads ect. and it comes back and tells you need a 250 AMP Hour battery string at 24 volts, 400 watt solar panel array. and 20 amp charge controller. So you buy all the equipment then find out, it does not do the job it is suppose to do, so now you have to buy more.
So for the above system the real numbers are a 625 Ah battery @ 24 volts, a 1000 watt solar panel, and a 50 amp charge controller. Now you are stuck buying 3 times more equipment to make it work. Had you known that to begin with, you might of decided it just cost too much and you now realize you are paying 20 times more for electricity if you had just bought it from the power company in the first place.MSEE, PE
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