Question by renjith v: How much watts of current an inverter takes to charge its battery to run an electric appliance.?
How much current an inverter consumes to charge the battery to run a 100W home appliance for one hour. I would like to know is it economical to use inverters instead of electricity supplied by government, at peak times. To be precise, if an inverter works for 500 w equipments conteneously for 8 hours, the total output is 4 KW, whether the current required to charge the battery will be 4kw or more?
Best answer:
Answer by Ecko
A 500W load for 8 hours is 4KWh. If this was from an inverter with 80% efficiency it would require 5KWh from the battery. The energy to recharge the battery is 1.4 times the energy delivered by the battery, so 7.5KWh. Therefore it takes 7.5KWh to provide 4KWh when using a battery. As a ratio, this is 1.875, or uses 188% of the energy provided. For the 100W appliance it could be a slightly higher percentage using a 500W inverter, as the efficiency may be slightly lower taking 100W from a 500W inverter.
The battery for the 500W for 8h calculation would be at least 250Ah @ 24V.
As you can see there is no economic advantage whatever – it is all to do with having better quality power during peak periods, assuming there is sufficient power on average to make up the extra requirement to charge the battery etc..
Know better? Leave your own answer in the comments!
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Kd Daniels says:
February 10, 2013 at 4:21 pm (UTC 0)
That all depends on the type of charging used and the size of the inverter. For example a 1800W inverter will use less power to charge than a 3600W inverter, but will also discharge quicker when using 1800w appliances. The discharge however will be in kilowatt hours, not just kilowatts.
It could be economical if you use it right, but you need to look at a technical manual for the precise figures which will determine whether its worth it or not.
Get a generator 🙂
Icreonglobal says:
February 10, 2013 at 5:17 pm (UTC 0)
Its totally depends on battery capacity, as we know batteries are different capacity so, I think it would not be fine if we set some value for the same.As I know the researchers who are doing the practice for the same they will analyze the thing betters.
BDBatteries.com says:
February 10, 2013 at 5:41 pm (UTC 0)
This is a 4 part question.
Your Batteries:
The german scientist Peukert had the same question. So he came up with an answer, and now we use this set of equations to determine the efficiency of batteries on the market today. Your common flooded battery is 40-60% efficient at high amperage rates. An AGM flooded lead acid battery is 80-90% efficient. Use this link to understand the equations, and the math involved.
http://www.bdbatteries.com/peukert.php
Your inverter:
If the DC-AC inverter is a pure sine wave inverter, is probably 90% – 95% efficient. These are usually grid tie inverters, starting in the Thousands of dollar range. If the DC-AC inverter is a modified sine wave inverter, it is only 60% – 85% efficient, but available at places like Wal Mart.
Your Charger:
A battery charger reloads the power into the battery, or power tank for the inverter to use. The chargers today are usually 80-95% efficient again. As a battery approaches fully charged state, the efficiency drastically reduces.
Then we multply it all:
Charger x Battery x Inverter = total efficiency
Assuming AGM batteries, grid inverter, and a good charger.
90% x 90% x 90% = 73%
To push 8KW through a 73% efficient system, you need 127% of the power.
4KWH x 1.27 = 5.08KWH
Conclusion, Batteries are the only electrical device that can actually store power.
They are not as efficient as using the power directly from the generator or panel.
However batteries can store and clean that power. Flipping power from AC to DC (battery Charging), storing the power (in the battery), and then converting power back from DC to AC (in the inverter) is a series of 3 steps. Each step has loss involved.
This loss is reasonable if it serves a purpose. For instance this process insulates sensitive electronics like computers, scientific instruments, LCD Big screen televisions, and stereos from the inconsistencies in the power grid. By switching AC to DC you remove all spikes, sags, transients, and lags. When the inverter pushes the computer from the DC power, it is a perfect power source. For lag, sag, spike, and transient information click on this link.
http://www.bdbatteries.com/lagsagspike.php
You have a battery backup for your laptop onboard. The battery backup for your desktop is in a little black box under your desk for the same reason.
Another reasonable place for loss, applications where power can not go down. For instance, in a hospital or records room, the batteries allow the load to be powered when the power goes out. The batteries must have sufficient capacity to drive the load for an hour or so. This time frame is long enough for maintenance to turn on the generators and switch over. The generators power the load, and recharge the batteries for the ensuing switch back to grid power.