flight-guardian
11-06-2011, 08:36 AM
I have tweenage kids therefore I am a big believer in inverters to run the TV, charge computers and cell phones, and power other misc electrical equipment. I had a very basic 800w Harbor Freight inverter installed in my last TH but the install left a lot to be desired...remote switching wasnt there, it was far from the batteries so it was not efficient, it only powered 2 receptacles in the very back of the TH. So here is how I fixed all those issue with my new TH. Hopefully this write up will help to demystify some things and help some with designing their system.
Where to put it...inverters should be as close to the power supply batteries as possible. DC voltage drops as it travels away from the source so the further away the inverter is from the batteries the lower the its input voltage will be due to line loss. For the Samlex Modified Sine Wave 1500continuous/3000 momentary watt inverter the manufacturer recommended no more than 5 feet of #4AWG cable for the supply. I got it to 6 feet so pretty close.
http://www.keystoneforums.com/attachments/photobucket/img_22806_0_ea8c211c45d0aeae8cf7b4a2a6fd1ec3.jpg
The batteries being mounted on the hitch frame just in front of this photo. The cables go up into the very front wall and come out into the pass through space. I mounted the inverter to the ceiling of the pass through space to keep it from getting bashed up by equipment. The positive cable has a 200ADC fuse in line to protect the system.
My TH can have 2 power sources plugged in at the same time...shore power can be plugged in without unplugging the generator supply. If the generator is started the control system sees the gen power and chooses it as priority over shore power. As you can see I have the shore power cable plugged directly into the inverter powering every circuit in the coach. I wanted this because I wanted to have access to every AC outlet on inverter power. It does however cause some problems. (explained later)
This is the space in the coach where all the wiring comes together. It is pretty much in the middle and directly above the refer.
http://www.keystoneforums.com/attachments/photobucket/img_22806_1_298baa06bbaa7fba3f16de3d042906b2.jpg
I added a very simple voltage meter next to the battery disconnect. Wired it into the fused side of the radio power supply.
You should also notice the unlabeled toggle switch on the lower left of the photo. This switch toggles off/on 3 things - the AC, microwave, and charger converter. Very important to turn these items off when the inverter is powering the coach as the inverter is not near big enough to run the AC, the inverter is modified sine wave so can't run the microwave, and the inverter would be horribly inefficient if it were trying to charge the batteries while its using battery power to do so. The switch will eventually be labled something like this: "ON - Home or Site With External AC" and "OFF - Dry Camping With Inverter ON".
The problem with using a manual toggle switch to turn certain things off is you have to remember to turn the switch back on when you start the gen, most importantly the charger converter. We do mostly dry camping and it is imperative that every time the gen is started the batts are getting a little charge. So I installed a 3 pole contactor to handle this job.
http://www.keystoneforums.com/attachments/photobucket/img_22806_2_b281920b3e16af0ef514b5011d591f2f.jpg
This is a 3 pole Normally Open Contactor with a 120VAC activation coil. It is rated at 25Amps AC per circuit. The 3 switched items are wired into and out of the contactor. The activation coil is wired to the generator supply cable. When the generator starts to produce AC power the coil senses the power, closes the contacts, and power heads toward the 3 pieces of equipment bypassing the ON/OFF switch. When the gen is de-powered the contactor opens and the power supply to the 3 items once again defers to the ON/OFF switch.
So when we head to the dez we throw the ON/OFF toggle switch into the off position and that is where it stays until we get home. Everything else is automated...except the turning on and off of the inverter. I can't tell you what a pita it always was for me to go out into the 35 degree windy cold a$$ night to turn the thing off (or unplug it) after watching a movie before bed. Most of the time I chose to stay warm and let it run needlessly all night long.
So here is the very simple little remote on/off control and monitor panel for the inverter. And it's mounted right next to my bed. Ahhhh life is good.
http://www.keystoneforums.com/attachments/photobucket/img_22806_3_6fc36b91a5bd9aab452558dea0e14b95.jpg
So, I am not an electrician or electrical engineer. I have tested the system and it seems to work as I have designed it. No smoke from anything. No fuses/breakers blowing. I hope it stays that way.
Comments? Suggestions? Let me know.
-Eric
Where to put it...inverters should be as close to the power supply batteries as possible. DC voltage drops as it travels away from the source so the further away the inverter is from the batteries the lower the its input voltage will be due to line loss. For the Samlex Modified Sine Wave 1500continuous/3000 momentary watt inverter the manufacturer recommended no more than 5 feet of #4AWG cable for the supply. I got it to 6 feet so pretty close.
http://www.keystoneforums.com/attachments/photobucket/img_22806_0_ea8c211c45d0aeae8cf7b4a2a6fd1ec3.jpg
The batteries being mounted on the hitch frame just in front of this photo. The cables go up into the very front wall and come out into the pass through space. I mounted the inverter to the ceiling of the pass through space to keep it from getting bashed up by equipment. The positive cable has a 200ADC fuse in line to protect the system.
My TH can have 2 power sources plugged in at the same time...shore power can be plugged in without unplugging the generator supply. If the generator is started the control system sees the gen power and chooses it as priority over shore power. As you can see I have the shore power cable plugged directly into the inverter powering every circuit in the coach. I wanted this because I wanted to have access to every AC outlet on inverter power. It does however cause some problems. (explained later)
This is the space in the coach where all the wiring comes together. It is pretty much in the middle and directly above the refer.
http://www.keystoneforums.com/attachments/photobucket/img_22806_1_298baa06bbaa7fba3f16de3d042906b2.jpg
I added a very simple voltage meter next to the battery disconnect. Wired it into the fused side of the radio power supply.
You should also notice the unlabeled toggle switch on the lower left of the photo. This switch toggles off/on 3 things - the AC, microwave, and charger converter. Very important to turn these items off when the inverter is powering the coach as the inverter is not near big enough to run the AC, the inverter is modified sine wave so can't run the microwave, and the inverter would be horribly inefficient if it were trying to charge the batteries while its using battery power to do so. The switch will eventually be labled something like this: "ON - Home or Site With External AC" and "OFF - Dry Camping With Inverter ON".
The problem with using a manual toggle switch to turn certain things off is you have to remember to turn the switch back on when you start the gen, most importantly the charger converter. We do mostly dry camping and it is imperative that every time the gen is started the batts are getting a little charge. So I installed a 3 pole contactor to handle this job.
http://www.keystoneforums.com/attachments/photobucket/img_22806_2_b281920b3e16af0ef514b5011d591f2f.jpg
This is a 3 pole Normally Open Contactor with a 120VAC activation coil. It is rated at 25Amps AC per circuit. The 3 switched items are wired into and out of the contactor. The activation coil is wired to the generator supply cable. When the generator starts to produce AC power the coil senses the power, closes the contacts, and power heads toward the 3 pieces of equipment bypassing the ON/OFF switch. When the gen is de-powered the contactor opens and the power supply to the 3 items once again defers to the ON/OFF switch.
So when we head to the dez we throw the ON/OFF toggle switch into the off position and that is where it stays until we get home. Everything else is automated...except the turning on and off of the inverter. I can't tell you what a pita it always was for me to go out into the 35 degree windy cold a$$ night to turn the thing off (or unplug it) after watching a movie before bed. Most of the time I chose to stay warm and let it run needlessly all night long.
So here is the very simple little remote on/off control and monitor panel for the inverter. And it's mounted right next to my bed. Ahhhh life is good.
http://www.keystoneforums.com/attachments/photobucket/img_22806_3_6fc36b91a5bd9aab452558dea0e14b95.jpg
So, I am not an electrician or electrical engineer. I have tested the system and it seems to work as I have designed it. No smoke from anything. No fuses/breakers blowing. I hope it stays that way.
Comments? Suggestions? Let me know.
-Eric