Installing inverter in 50 amp system
Home Forums How-To Installing inverter in 50 amp system Installing inverter in 50 amp system Add a New Topic Reply to Post Page: 1 User Post 4:22 pm May 17, 2015 azdieselguy Mo...
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Hi,
It is common to install a 1,500 watt inverter, but larger ones are not so common. I installed a 1,500 watt inverter in my RV back in 1997, when it was new, and hardly ever use it. I would rather use the more energy efficient 150 or 300 watt inverter that plugs into a cigarette lighter receptacle that I installed near my TV and another near my VCR.
I installed a 1,500 watt inverter in a fifth wheel for another RV.Net member back in 2006. For that installation, he wanted to run a CPAP machine, and things like the microwave, and a circuit in his RV so he could run the TV set.
What I did was find the three 20 amp circuit breakers that fed the areas he wanted powered up. I disconnected those from the 20 amp breakers. I connected each of those to the new 4 circuit panel, with a 30 amp main fed from the transfer switch, the 3 each 20 amp breakers feeding the other lines.
All of this took me about 6 hours to set up. I had already installed a inverter in my motorhome, and install air conditioners for a living.
What would I recommend? Install a couple of cigarette lighters in the RV where you might want to power something. Buy a $30 inverter in the 300 - 500 watt range. Run #10 wire to the cigarette lighter locations, both +12 and ground wires. Fuse those at 20 amps, unless you really want to connect a 300 watt loan, and #10 wire is good for 30 amps, so you could use that fuse size.
It is actually 'better' to have the inverter closer to the battery, then run #14 gauge extension cords around the RV to power what you want. Or 16 gauge extension cords. These are good for over 10 amps at 120 volts. But you also need to have the inverter someplace that you can turn it on and off when needed.
So the inverter converts 12 VDC into 120 VAC. I estimate that the amperage is about 1/10 the wattage of the 120 volt appliance. So a 100 watt TV will use about 0.9 amps at 120 VAC, and about 10 amps 12 VDC that once converted to 120 VAC will use all 10 amps to make up for the inverter efficiency.
300 watt blender = about 30 amps from the battery.
20 watt laptop - 2 amps from the battery each hour.
How much battery power do you have? I have a set of 4 golf cart batteries, with a 440 amp hour capacity.
If you only have one battery, it will be good for something between 50 amp hours (group 24) to 100 amp hours (group 27 or 31). Golf cart batteries are normally about 220 amp hours, and because they are 67 pound "Easy to Carry" 1/2 of a 12 volt battery, it takes two to get 220 amp hours at 12 volt (a massive 135 pound battery in two easy to carry sections). (Hint, they are not that easy to carry, especially if removing 4 of them and installing 4 new ones, then relocating the old 4 to someplace else, it is like spending 4 hours at the Gym weight lifting, but it is much easier to move than a 120 pound 8D battery that is also 200 amp hours).
So you need at least a pair of batteries to power a inverter. The guy with a CPAP machine required 4 batteries, total of about 400 AH, and would charge them with 4 each 100 watt solar panels. The battery would start out full on Friday, then be discharged to the point the CPAP would not work much on Sunday morning, so he would have to run a generator to charge the battery sometime on Saturday or sunday.
Good luck with your project!
Fred.
It is common to install a 1,500 watt inverter, but larger ones are not so common. I installed a 1,500 watt inverter in my RV back in 1997, when it was new, and hardly ever use it. I would rather use the more energy efficient 150 or 300 watt inverter that plugs into a cigarette lighter receptacle that I installed near my TV and another near my VCR.
I installed a 1,500 watt inverter in a fifth wheel for another RV.Net member back in 2006. For that installation, he wanted to run a CPAP machine, and things like the microwave, and a circuit in his RV so he could run the TV set.
What I did was find the three 20 amp circuit breakers that fed the areas he wanted powered up. I disconnected those from the 20 amp breakers. I connected each of those to the new 4 circuit panel, with a 30 amp main fed from the transfer switch, the 3 each 20 amp breakers feeding the other lines.
All of this took me about 6 hours to set up. I had already installed a inverter in my motorhome, and install air conditioners for a living.
What would I recommend? Install a couple of cigarette lighters in the RV where you might want to power something. Buy a $30 inverter in the 300 - 500 watt range. Run #10 wire to the cigarette lighter locations, both +12 and ground wires. Fuse those at 20 amps, unless you really want to connect a 300 watt loan, and #10 wire is good for 30 amps, so you could use that fuse size.
It is actually 'better' to have the inverter closer to the battery, then run #14 gauge extension cords around the RV to power what you want. Or 16 gauge extension cords. These are good for over 10 amps at 120 volts. But you also need to have the inverter someplace that you can turn it on and off when needed.
So the inverter converts 12 VDC into 120 VAC. I estimate that the amperage is about 1/10 the wattage of the 120 volt appliance. So a 100 watt TV will use about 0.9 amps at 120 VAC, and about 10 amps 12 VDC that once converted to 120 VAC will use all 10 amps to make up for the inverter efficiency.
300 watt blender = about 30 amps from the battery.
20 watt laptop - 2 amps from the battery each hour.
How much battery power do you have? I have a set of 4 golf cart batteries, with a 440 amp hour capacity.
If you only have one battery, it will be good for something between 50 amp hours (group 24) to 100 amp hours (group 27 or 31). Golf cart batteries are normally about 220 amp hours, and because they are 67 pound "Easy to Carry" 1/2 of a 12 volt battery, it takes two to get 220 amp hours at 12 volt (a massive 135 pound battery in two easy to carry sections). (Hint, they are not that easy to carry, especially if removing 4 of them and installing 4 new ones, then relocating the old 4 to someplace else, it is like spending 4 hours at the Gym weight lifting, but it is much easier to move than a 120 pound 8D battery that is also 200 amp hours).
So you need at least a pair of batteries to power a inverter. The guy with a CPAP machine required 4 batteries, total of about 400 AH, and would charge them with 4 each 100 watt solar panels. The battery would start out full on Friday, then be discharged to the point the CPAP would not work much on Sunday morning, so he would have to run a generator to charge the battery sometime on Saturday or sunday.
Good luck with your project!
Fred.
