ronbeatty
Member
What can I safely run off of a 2500 watt inverter, vacuum, saw, etc???
Inverter question
- Thread starter ronbeatty
- Start date
Mike Draper
Member
- Joined
- Jan 13, 2008
- Messages
- 4,402
Ron, I have an inverter on my truck. I'll have to check the power on it. I have run the HOSS, 175 and cimex off of it before. No problems.
Matt Middleton
Member
I can run the 360I and two snail blowers. The engine is running with the Butler.
Desk Jockey
Member
I have one in the back of my vehicle but it won't start a snowblower. 
dgardner
Moderator
Ron, 2500W is about 21 amps, so any combination of loads that you could run on a single outlet (except hard-starting motors like a compressor) will likely be OK.
Keep in mind that full load (2500W) will draw 200 amps or so from your battery. A 1000W vacuum (8 amps) will draw about 80 amps from the battery. Unless you use the doodad you are plugging in to it for only a few minutes you need to be running the van's engine/alternator.
Keep in mind that full load (2500W) will draw 200 amps or so from your battery. A 1000W vacuum (8 amps) will draw about 80 amps from the battery. Unless you use the doodad you are plugging in to it for only a few minutes you need to be running the van's engine/alternator.
Nate The Great
Member
I have one in the back of my vehicle but it won't start a snowblower.
Start it at 54 seconds.... Everthing I hear snowblower.....
Is that peak wattage or running wattage?
you could problably run a residential styal sweeper, small microwave, mini fridge, power tool charger, corded power tools, flood lights, etc. just nothing continuious for very long.
i have a 5500watt in my one van and it takes 2 batteries hooked up to it to get 5500watts. one off the van battery, one off the tm battery.
the 5500watt will run the hoss for about 25 min, a sweeper for 15-20 min, trouble lights for an hour, a 2.9 am snale blower for 30-40 minutes <---- those i know for sure off a 5500watt with the tm and van running.
Papa John
Lifetime Supportive Member
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?
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?
ronbeatty
Member
Thanks for the great answers, doing some electrical panel work. I just need to run an LED work light and some power tools.
Goomer
Member
dgardner
Moderator
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?
First, how much energy was removed from the battery? Amps X volts = watts, then watts X hours = watt-hours. So: 12V X 158A X 0.57 hours = 1080 watt-hours.
Rule-of-thumb for lead-acid cells says you have to put in about twice as much as you take out, because the electrical/chemical conversion is not very efficient. Since we took out 1080wh, we have to put 2160wh back in.
Our charger can supply (12V X 25A = 300W) 300 watts, or said another way, 300 watt-hours every hour. It will take (2160wh/300w = 7.2h) or 7.2 hours to recharge the battery. If you find a fancy-dancy charger that says it can charge at a higher rate without damaging the battery, your time would proportionally decrease.
A big one!
Seriously, answering this would take a solid engineering effort and more info than you have provided. Not something that can be armchair engineered, not by me at least.
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?
First, how much energy was removed from the battery? Amps X volts = watts, then watts X hours = watt-hours. So: 12V X 158A X 0.57 hours = 1080 watt-hours.
Rule-of-thumb for lead-acid cells says you have to put in about twice as much as you take out, because the electrical/chemical conversion is not very efficient. Since we took out 1080wh, we have to put 2160wh back in.
Our charger can supply (12V X 25A = 300W) 300 watts, or said another way, 300 watt-hours every hour. It will take (2160wh/300w = 7.2h) or 7.2 hours to recharge the battery. If you find a fancy-dancy charger that says it can charge at a higher rate without damaging the battery, your time would proportionally decrease.
A big one!
Seriously, answering this would take a solid engineering effort and more info than you have provided. Not something that can be armchair engineered, not by me at least.
Papa John
Lifetime Supportive Member
Thank Dan!.... I think my brain just exploded..
What if I connected 2 or 3 200ah batteries to the 800 w generator-- would that protect the batteries and still take advantage of the full capabilities of the 800W devise? btw I will have an amp controller also installed to protect the batteries-- I just want to take full advantage of the charging.
Why am I asking--- every month I get a letter from PGnE that our house consumes 4 times the energy of same houses in the area... Just for Fun/exercise I'm going to hook that wind generator motor to
a 21 speed bicycle which will be made stationary. That will be connected to the batteries and invertor which will then power our big screen TV and video controllers.. The "Kids" will have to make the produce their own electricity if they want to watch TV or play games.
dgardner
Moderator
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.
Oh - and make sure there are no suspicious extension cords going over the fence into the neighbors house....
Desk Jockey
Member
Use a thermal camera. Like Dan said it's leaking out somewhere.
dgardner
Moderator
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.
Papa John
Lifetime Supportive Member
The Energy "Leak" could be our Rug cleaning plant in the Garage.. 
No batteries!? I didn't know that about Grid-tie in systems.. That's great to know and eliminates a substantial cost.-- Thanks Dan
No batteries!? I didn't know that about Grid-tie in systems.. That's great to know and eliminates a substantial cost.-- Thanks Dan
Bob Savage
Member
I have used a 2500 watt inverter in my van for various things (powers the LP heater circuit, the APO, etc.).
Rule of thumb is to make sure the battery you are drawing from is being re-charged while you are using the inverter, because they can draw a lot of amps. The TM has it's own battery, so I wired that battery and the van battery in parallel, so either the van's alternator (HD alternator) is charging them, or the Honda slide-in's charging system is charging them. I have a quick disconnect in case I want to isolate the batteries from each other.
This has worked quite well for over 10 years.
Rule of thumb is to make sure the battery you are drawing from is being re-charged while you are using the inverter, because they can draw a lot of amps. The TM has it's own battery, so I wired that battery and the van battery in parallel, so either the van's alternator (HD alternator) is charging them, or the Honda slide-in's charging system is charging them. I have a quick disconnect in case I want to isolate the batteries from each other.
This has worked quite well for over 10 years.
Papa John
Lifetime Supportive Member
With the grid tied invertor So how does the utility company know how much energy I'm pumping into the grid?-- or is that energy being using immediately by the rest of the house?
Again- Thank you for your time and knowledge.
dgardner
Moderator
If you're making, say, 800 watts, and you have enough load (lights, toaster, ac, whatever) to total at least that much then you are just using it and need that much less from the utility.
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...
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...
Papa John
Lifetime Supportive Member
I think I remember hearing that in California or maybe just SF bay area that the utility doesn't have to pay back homeowner/energy generator for extra energy.. and at 32kw useage per day I'll be way under.
Thanks for the info-- You have greatly simplified bicycle generator contraption. I'll post info about it when done and IF I don't electrocute myself.
