ronbeatty
Member
What can I safely run off of a 2500 watt inverter, vacuum, saw, etc???
I have one in the back of my vehicle but it won't start a snowblower.![]()
Is that peak wattage or running wattage?What can I safely run off of a 2500 watt inverter, vacuum, saw, etc???
so how long will a 15 amp devise run on a 5000w inverter connected to a fully charged 200ah solar battery and no motor running to charge battery?
How long would it take a 800watt wind or solor panel to charge that 200 ah battery if in ideal conditions.
We avg 32kws per day; what size of solar/wind & battery system would we need to handle that?
John, here's your answers (mostly). Just for fun I will show the math and theory so you can run other scenarios without my help. Actual answers in bold type. Warning, lotsa dry math and stuff - everyone else can scroll on by...
We will assume your battery is a 12V flooded-cell lead acid type, and you bought a high-quality inverter that is 95% efficient. Also, the battery's voltage varies all over the place, from 10.5 fully depleted to 13.6 fully charged - 12V is an approximation that will give answers that are fairly accurate. Of course if your battery voltage is not 12V the numbers will change.
First, calculate the power drawn by the device. watts = amps X volts (more or less). So: 15A X 120V = 1800W.
Your inverter is not 100% efficient (no inverter is), so the inverter will draw (1800/0.95=1895) 1895 watts from the battery.
What is the current drawn from the battery? Amps = watts/volts - so (1895/12=158) the battery current will be 158 amps.
Houston, we have a problem. A battery's capacity (amp-hours or AH) is based on a maximum discharge rate of C/20 meaning one-twentieth of the amp-hour rating. This means your battery is 200AH only if the current is 10 amps or less. At high discharge rates the AH's rapidly decrease. Your rate is (200/158=1.27) or about C/1.3. Exact numbers vary depending on the make and model of battery, but you will likely get only about 45% of rated capacity at 158 amps, or 90AH out of your 200AH battery. Bummer, eh?
How long will the device run? 90AH means a load of 90A will last for one hour - but your load is 158A so - 90/158 = 0.57 hours, or 34 minutes. Your 15A doodad will run for 34 minutes, give-or-take. Yup, just 34 minutes.
By the way, this was a trick question, because the size of the inverter doesn't matter that much as long as it's big enough to run the load. In your example, a 2500W inverter would have been fine, as it's still more than the 1800W your load needs. The numbers would basically be the same.
Again with the trick questions - pumping 800W into a single 12V battery would result in a charge current of 67A. Great for a quick boost to get your truck started but run that much current for an hour or three and you'd boil the electrolyte away and ruin the battery in short order. Let's choose a modest 25A charger and spare the poor battery, shall we?
John, there is usually a reason(s) for this - suggest you get a company in to do an energy efficiency study on your home. Old AC unit, leaking ductwork, poor insulation, poorly sealed doors/windows, there are many possible deficiencies that can suck too much electricity! Your local utility can usually recommend a qualified firm. If you're using energy at 4 times the norm then finding out why will pay dividends way faster than just about anything else you can do.every month I get a letter from PGnE that our house consumes 4 times the energy of same houses in the area...
John, If you are trying to reduce your energy costs (and not trying to power your remote mountain cabin), then batteries/inverters are not your answer. you lose efficiency in all the conversions, and you have to replace expensive batteries every 3-5 years. Do some research into grid-tie inverters - they take your solar/wind power and inject it right back into your utility power, reducing your monthly bill, with no expensive batteries to maintain. Best bang for the buck.What if I connected 2 or 3 200ah batteries to the 800 w generator--
John, If you are trying to reduce your energy costs (and not trying to power your remote mountain cabin), then batteries/inverters are not your answer. you lose efficiency in all the conversions, and you have to replace expensive batteries every 3-5 years. Do some research into grid-tie inverters - they take your solar/wind power and inject it right back into your utility power, reducing your monthly bill, with no expensive batteries to maintain. Best bang for the buck.
https://en.wikipedia.org/wiki/Grid-tie_inverter
Example inverter (not necessarily recommending this one, just an example):
http://www.amazon.com/ALEKO®-WSB800-Solar-Panel-Inverter/dp/B00CA8OUTM
With your 800W PV array, and if you can count on a solid 8 hours a day of good sunlight, you could be generating about 6 kwh per day, an 18% reduction in energy you buy, if you're using 32 kwh per day.
If your load drops low enough then you will be sending excess generated power back out on the grid. The utility won't see this unless your meter is specifically set up to record co-generated power, and for that to be the case you usually have to have an agreement to sell power back to them.
Unless you're generating multi-kw I personally wouldn't involve the utility and all the hassle that comes with it. It's pretty rare for electricical demand to drop that low during the day anyway...