GreatLakes
New member
Great idea. I would be sure to opt for the 300w inverter however, I have had poor luck with the smaller ones...Kudos
Check out my new DIY power back up! (400k of pics)
- Thread starter Playfair
- Start date
Some stupid questions?
Some stupid questions?
Playfair and Odenwell,
I am planning on putting together a power backup for my tank. I have been doing some comparison shopping as was going to take a trip to Radio Shack and some electronic stores. I have two questions.
What does "pdt" mean (3 pdt relay)? I will add it to my reference list...
Most of the power inverters I have seen have a voltage lower than 120v, usally 115v or 110v. Is this normal?
Some stupid questions?
Playfair and Odenwell,
I am planning on putting together a power backup for my tank. I have been doing some comparison shopping as was going to take a trip to Radio Shack and some electronic stores. I have two questions.
What does "pdt" mean (3 pdt relay)? I will add it to my reference list...
Most of the power inverters I have seen have a voltage lower than 120v, usally 115v or 110v. Is this normal?
Playfair,
Aside from my questions on the last post....I am also wondering what to do about the ground. Most big pumps have three prong plugs. I've noticed that you have included that in your transfer switch setup. But, where does the ground wire connect to on the relay?
Also, what is the "mode switch" for?
Thanks again!
Aside from my questions on the last post....I am also wondering what to do about the ground. Most big pumps have three prong plugs. I've noticed that you have included that in your transfer switch setup. But, where does the ground wire connect to on the relay?
Also, what is the "mode switch" for?
Thanks again!
Playfair
Premium Member
Above comments are correct about the fumes, I've read there is no problem trickle charging as long as the battery is free to vent. However, if the battery does fully discharge during usage, I may hook up a larger charger to bring it back up in a shorter amount of time, and will aim a small fan at it to disperse any gasses.
115v inverter will be fine, I would stay away from the 110v ones though (sounds like they are being cheap). Lower voltage produced means the current draw will be higher to get the same power. This means if a motor is rated at 1A at 120v, then at 110v it will draw 1.1 amps.
I was thinking the same thing as GreatLakes about using the larger inverter, I would rather the thing coasts along driving my pump than pushing it's rated limits. Plus, you could always add a second battery to extend run time/load capabilities without much trouble.
A far as the outlet ground (good question, gave this a lot of thought!) The house ground is tied to the output ground directly all the time (doesn't go through the relay). This means the inverter ground is not tied to anything. Even when the power fails, your house ground still works
115v inverter will be fine, I would stay away from the 110v ones though (sounds like they are being cheap). Lower voltage produced means the current draw will be higher to get the same power. This means if a motor is rated at 1A at 120v, then at 110v it will draw 1.1 amps.
I was thinking the same thing as GreatLakes about using the larger inverter, I would rather the thing coasts along driving my pump than pushing it's rated limits. Plus, you could always add a second battery to extend run time/load capabilities without much trouble.
A far as the outlet ground (good question, gave this a lot of thought!) The house ground is tied to the output ground directly all the time (doesn't go through the relay). This means the inverter ground is not tied to anything. Even when the power fails, your house ground still works
Playfair,
The item you labeled "mode switch"....what is that for??
I finally rigged my backup system together thanks to you. It is modified slightly from your design, so I'm still in the testing stage of its reliablity.
I used a 120v Quad Pole DT relay. And since I am using a inverter similar to yours, I also connected the inverter power line in series to the relay. Initial test running a 60w bulb off the system was fine for 15 min. So I took the unit into the house and plugged it to an Ampmaster. The setup worked for 10 sec and it stopped....no power from the inverter. Upon checking the wiring, I found on the relay, the terminal where the inverter power line was connected to had "melted".
My relay is the KEST KR1205N. Since it is the clear cube type, its easy to see the inside. It is rated at 5A 240VAC, so it is 10A at 120VAC. The Ampmaster draws about 150W. 150W divide by 12V= 12.5A. This is my deduction why the relay melted. The contacts couldn't take such high amperage.
Then the choices are either: A) to use another DPDT with a higher contact amperage or B) to double up on the contacts. I chose solution B. Instead of using one wire in running the power wire to the relay for the inverter, I split the wire into two and used two of the four poles on the relay. As a result all for poles on the relay was used. This split the amperage down to 10A each. I'm hoping this will solve the "melt down" problem. So far I've only tested the new wiring with two 60W light bulbs running off the inverter. Worked for 20 min so far. I'll test it on a pump tomorrow to see if that did it.
Another thing I've found is the input power wires of my 300W inverter getting very warm after running a 150W load for 2 hours. What size wires should I use for the inverter? I'm assuming when there is more output on the inverter, there is more current drawn and hence more heat buildup on the wires. At first I thought a 300W inverter will draw the same amount of amperage regardless of whether idle at no load or full load. This doesn't seem to be the case.
All this info may be common sense to electricians or people like you Playfair and Odenwell. For me it is still a brand new ballpark...so I figure I'll share this with others who are also building this unit....to save them from the same mistakes I had made.
The item you labeled "mode switch"....what is that for??
I finally rigged my backup system together thanks to you. It is modified slightly from your design, so I'm still in the testing stage of its reliablity.
I used a 120v Quad Pole DT relay. And since I am using a inverter similar to yours, I also connected the inverter power line in series to the relay. Initial test running a 60w bulb off the system was fine for 15 min. So I took the unit into the house and plugged it to an Ampmaster. The setup worked for 10 sec and it stopped....no power from the inverter. Upon checking the wiring, I found on the relay, the terminal where the inverter power line was connected to had "melted".
My relay is the KEST KR1205N. Since it is the clear cube type, its easy to see the inside. It is rated at 5A 240VAC, so it is 10A at 120VAC. The Ampmaster draws about 150W. 150W divide by 12V= 12.5A. This is my deduction why the relay melted. The contacts couldn't take such high amperage.
Then the choices are either: A) to use another DPDT with a higher contact amperage or B) to double up on the contacts. I chose solution B. Instead of using one wire in running the power wire to the relay for the inverter, I split the wire into two and used two of the four poles on the relay. As a result all for poles on the relay was used. This split the amperage down to 10A each. I'm hoping this will solve the "melt down" problem. So far I've only tested the new wiring with two 60W light bulbs running off the inverter. Worked for 20 min so far. I'll test it on a pump tomorrow to see if that did it.
Another thing I've found is the input power wires of my 300W inverter getting very warm after running a 150W load for 2 hours. What size wires should I use for the inverter? I'm assuming when there is more output on the inverter, there is more current drawn and hence more heat buildup on the wires. At first I thought a 300W inverter will draw the same amount of amperage regardless of whether idle at no load or full load. This doesn't seem to be the case.
All this info may be common sense to electricians or people like you Playfair and Odenwell. For me it is still a brand new ballpark...so I figure I'll share this with others who are also building this unit....to save them from the same mistakes I had made.
Something else I just realized.....if I want to run loads up to 300W off the inverter. That would be 300W/ 12V= 25A. Assuming each pole on the relay can handle 10A.
In order for 25A worth of current to pass, I would then need 3 relay poles at 10A each...is this correct?? If not, when the inverter is outputing max 300W, the relay will melt again?
In order for 25A worth of current to pass, I would then need 3 relay poles at 10A each...is this correct?? If not, when the inverter is outputing max 300W, the relay will melt again?
crypto
New member
I think your calculations are wrong for the relay to the pump. The pump is drawing at ~110V not 12V so 300W @ 110V = 2.7A. This would be the current through the relay from the inverter to the pump.
The current into the inverter, however, would be 25A. Just relay the power switch for the inverter, not the input to the inverter, otherwise you would need a heavy duty relay.
The current into the inverter, however, would be 25A. Just relay the power switch for the inverter, not the input to the inverter, otherwise you would need a heavy duty relay.
Crypto,
I should have clarify that....yes, you're right about the calculations, I neglected to mention I was hooking up the inverter input power to the relay. So inverter output is at 2.5A and input at 25A.
By the way, do I calculate with 110V or 120V for AC?
You mentioned to relay the power switch of the inverter.....how do I do that? Open inverter and desolder the switch? Please bear with me on this, I'm not an electrician, just a DIY freak...hehe...
I should have clarify that....yes, you're right about the calculations, I neglected to mention I was hooking up the inverter input power to the relay. So inverter output is at 2.5A and input at 25A.
By the way, do I calculate with 110V or 120V for AC?
You mentioned to relay the power switch of the inverter.....how do I do that? Open inverter and desolder the switch? Please bear with me on this, I'm not an electrician, just a DIY freak...hehe...
Playfair
Premium Member
Ermin- WHOA! Wrong leads to the relay!! Crypto is right, it's the very low current power switch that get's hooked to the relay, DEFINITELY not the input DC!!
Get a NEW relay, as yours sounds pretty toasted. I used 3 of the 4 poles; one each for the neutral and hot leg of the powered outlet, and one for the inverter power. You must open up the inverter and just run a pair of wires in SERIES with the power switch. The built in switch will have to be on to operate, but in the even you are running the unit and you need to shut off AC quickly, all you have to do is flip the switch.
Don't worry man, you are almost there, but email me if you are unsure about something! BTW, the mode switch silences allows the thing to be in standby, or to put it in a "test" mode, or to just silence the alarm buzzer when in use (let's me know it's running off battery) You can add that stuff later maybe...
Get a NEW relay, as yours sounds pretty toasted. I used 3 of the 4 poles; one each for the neutral and hot leg of the powered outlet, and one for the inverter power. You must open up the inverter and just run a pair of wires in SERIES with the power switch. The built in switch will have to be on to operate, but in the even you are running the unit and you need to shut off AC quickly, all you have to do is flip the switch.
Don't worry man, you are almost there, but email me if you are unsure about something! BTW, the mode switch silences allows the thing to be in standby, or to put it in a "test" mode, or to just silence the alarm buzzer when in use (let's me know it's running off battery) You can add that stuff later maybe...
Playfair,
Everything made sense to me until I really come to build it myself....whew...that was it!! Just modify the switch.... I tapped it at the input wires instead. Now I think about it...I think that's what you said to Odenwell,
"The only major difference in our designs is that I use a 120v relay to cut both neutral and hot to the pump as well as switch on/off the inverter through the low amperage power switch instead of cutting the main supply leg (25 amps!). This allows me to run equipment off the same outlet for both house power and backup power. "
I'll post some pics of my setup later. Definitely not as clean looking as yours...but it will do the job!
Everything made sense to me until I really come to build it myself....whew...that was it!! Just modify the switch.... I tapped it at the input wires instead. Now I think about it...I think that's what you said to Odenwell,
"The only major difference in our designs is that I use a 120v relay to cut both neutral and hot to the pump as well as switch on/off the inverter through the low amperage power switch instead of cutting the main supply leg (25 amps!). This allows me to run equipment off the same outlet for both house power and backup power. "
I'll post some pics of my setup later. Definitely not as clean looking as yours...but it will do the job!
Just a quick thought ..
A freind of mine once had a very large ups unit
that ran off semi batterys ..
now in this ups it had fans to disapate gases and stuff .
so heres the idea based on that ups
get a plastic box to hold your batterys, inverts , and so forth. put some vent holes in the box for a fan and exashust hole big enough to handel a 2 inch pipe bigger and run it to the ouside world
like the dryer vents are in your house
just a quick thought for those wired about the gases
A freind of mine once had a very large ups unit
that ran off semi batterys ..
now in this ups it had fans to disapate gases and stuff .
so heres the idea based on that ups
get a plastic box to hold your batterys, inverts , and so forth. put some vent holes in the box for a fan and exashust hole big enough to handel a 2 inch pipe bigger and run it to the ouside world
like the dryer vents are in your house
just a quick thought for those wired about the gases
I just finished rerouting the wire. This time it is to the switch. Should work now, but I'm testing it outside the house in case it frys again. I plugged two 40W bulbs and a pond pump to it. That should be at least 110W of load. I'll see how long would that last.
I have another idea.... would it be worth it to plug the 12V battery charger also to the output? The original charger will have to be either rerouted or a second charger may be needed. But the idea is to "recirculate" some of the power back to the battery. The only catch is the current draw from the charger vs its output power. If the charger takes 1A to run and only put out 750mA, then it will be counter productive.
I have another idea.... would it be worth it to plug the 12V battery charger also to the output? The original charger will have to be either rerouted or a second charger may be needed. But the idea is to "recirculate" some of the power back to the battery. The only catch is the current draw from the charger vs its output power. If the charger takes 1A to run and only put out 750mA, then it will be counter productive.
crypto
New member
no such thing as a perpetual motion machine, i.e. you cant keep the battery charged by charging it from itself. the efficiency will be (much) less than 100%. all you would be doing is making an expensive and poor heater since the lost energy would be converted to heat.
the inverter will only be pulling from the battery what is needed, so even if it is rated for 300W its not pulling that unless you have a 300W device on the output.
the inverter will only be pulling from the battery what is needed, so even if it is rated for 300W its not pulling that unless you have a 300W device on the output.
schwaggs
you could hack the inside of the charger to hook on up ther
or get a 110 muffin fan and plug it straight in to the the wall out let , so when poor goes out
fans turn off , when power comes back on and batterys start charging again fan kick on and suck out blow out gasses and help cool the inverter back down
or add a 12 volt fan like those clip on one you can get for cars and wire it in ,,, and if you want longer run time , add a second battery in parrell with the first
you could hack the inside of the charger to hook on up ther
or get a 110 muffin fan and plug it straight in to the the wall out let , so when poor goes out
fans turn off , when power comes back on and batterys start charging again fan kick on and suck out blow out gasses and help cool the inverter back down
or add a 12 volt fan like those clip on one you can get for cars and wire it in ,,, and if you want longer run time , add a second battery in parrell with the first
schwaggs
you could hack the inside of the charger to hook on up ther
or get a 110 muffin fan and plug it straight in to the the wall outlet , so when powor goes out
fans turn off , when power comes back on and batterys start charging again fan kick on and suck out or blows(person preference) out gasses and help cool the inverter back down
or add a 12 volt fan like those clip on one you can get for cars and wire it in ,,, and if you want longer run time , add a second battery in parrell with the first
you could hack the inside of the charger to hook on up ther
or get a 110 muffin fan and plug it straight in to the the wall outlet , so when powor goes out
fans turn off , when power comes back on and batterys start charging again fan kick on and suck out or blows(person preference) out gasses and help cool the inverter back down
or add a 12 volt fan like those clip on one you can get for cars and wire it in ,,, and if you want longer run time , add a second battery in parrell with the first
