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Forum Index : Electronics : UPS as an inverter?
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readyakira Senior Member  Joined: 17/07/2008 Location: United StatesPosts: 114 |
I have a battery backup system made by APC it is model#bk650mc question is how efficient is it? since I aquired it free I figured it would make a decent inverter for some small stuff. And what happens if I plug it in? will it over take my solar charge controller? Don't you think Free/Renewable energy should be mandatory in new buildings? |
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| VK4AYQ Guru  Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Ready I cant find a ref on yours but I have several I use to power computer in emergency and they work OK, they had a 12 volt internal battery that was to small to be useful so I connected to my 12 volt light system thats on all the time, works well with no regulator problems and gives the full 350 watt rating at 30 amps draw from battery, they are controlled by USB from the computer so if yours has that, you would have to disable it to use on other appliences. Wont start my small fridge but will run the small TV and stereo. All the best Bob Foolin Around |
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| readyakira Senior Member Joined: 17/07/2008 Location: United StatesPosts: 114 |
mine will run my 47"lcd. What I was thinking was that if I had enough batteries I could run a few things when the power goes out. Like the TV modem few lights and a fan. Of course most I can run 12v except the TV and sound system. so I figured 2 of those would come in handy. I would run the lights from the bank whenever and the TV and fan would only be run when power is out so my small collection of solar cells can keep the batteries charged when the sun is shining. I really need to get one of those killawatt thingies so I can do the math to know how many batteries I need and how much I can run full time from the solar. I only have 60w of solar right now and it runs 2 lights, my cell phone charger and modem easily. by mid day the 1 regular car battery is full. The local golf cart shop sold all their used batteries the other day for core charges on new ones so I have to wait till I can purchase a few. I was looking to pick up at least 4 6v'ers to start. Don't you think Free/Renewable energy should be mandatory in new buildings? |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Ready Sounds like you are bitten by the solar bug, you can expand your batteries to do what you want without to much expense if you have access to a supply of used golf cart batteries, so what you need to do is get as many solar panels as you can afford, try to save to buy one a month is a good target, buy the same panels make / model all the time if you can so they match up better. A mppt controller is a good investment and a desulphator for sure if you are buying second hand batteries. Usable power is best kept to 50% of the rated battery AH for good battery life. Most appliances have a wattage rating stamped on the ID plate so that's a good start. A power meter is handy so you can check for yourself what they use. A system volt meter is good to monitor the system voltage and it will tell you if you are overloading the battery capacity. Also a amp meter in the inverter feed line as amps draw and volts on the meter will give you an actual power draw including losses and inefficiencies. A X V = watts If you have excess capacity you can set up a plug and play grid feed inverter and feed it back into the grid to save a bit of money on your utility bill. You can use the dump controller in the forum to control the switch in of the GTI, set it just below the cut off voltage of the controller. You could also use the excess power for hot water by fitting a 24 volt heater element available on ebay and set it up on the dump load controller. Once you start the possibilities are endless. All the best Bob Foolin Around |
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SSW_squall Senior Member Joined: 20/03/2010 Location: AustraliaPosts: 111 |
Check out this thread, using UPS's as inverter: APC UPS inverter AB Einstein: Everything should be made as simple as possible, but not one bit simpler |
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| readyakira Senior Member Joined: 17/07/2008 Location: United StatesPosts: 114 |
what is a mppt controller? i see you all talk about mppt but dont know what that means.... Don't you think Free/Renewable energy should be mandatory in new buildings? |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Ready MPPT stands for Maximum Power Point Tracking. A MPPT controller lets the panels operate at the most efficient voltage and gets more watts from the panel rather than tying the panel to the battery voltage as a normal controller or direct panel connection to the battery will. Solar panels have a current rating that is more or less constant in direct sunlight usually around say 5 amps in a 180 watt panel but the voltage could be as high as 36 volts in a 24 volt charge panel. eg; 5 amps times 36 volt = 180 watts in optimum power point setting. Tied to battery voltage it is 5 amps times 24 volts = 120 watts a loss of 60 watts, the MPPT regulator lets the panel operate at the higher voltage with the same amps thereby recovering most of the lost 60 watts, in practice usually 40 watts or a bit over 30% power that would otherwise be lost due to voltage mismatch between the panel and the battery. All the best Bob Foolin Around |
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| readyakira Senior Member Joined: 17/07/2008 Location: United StatesPosts: 114 |
Is that a circuit I would need to buy as it needs programing? or is it something I could possibly build. I am getting ready to buy the materials to make a few of the desulphators posted here and could buy the parts for one of those at the same time. Don't you think Free/Renewable energy should be mandatory in new buildings? |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Ready I don't know of a circuit on the forum for a MPPT unit, there are several commercial ones around on ebay but not cheap unfortunately. I am trying to make one for myself at the moment so I will let you have look when I get it to stop letting the smoke out of the Fets. Basically it is a DC / DC converter with input at 36 volts {the maximum power point of the panels} to 27 volts to float the batteries with current limitation and input voltage controlling the mark space ratio of the fets to give some regulation on the voltage. Sorry I am no further help maybe some of the other members may have some useful comments. All the best Bob Foolin Around |
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