We want to install an inverter to run fans and tv/dvd player while out overnight. Any ideas on how much power we'd need and what type of inverter is best?
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Hi Hanley, I replaced our 1600 watt inverter...
with an Xantrex Freedom 25 (2,500 watt) four years ago. Very pleased with it's performance even though it was a remarketed product (probably a return or factory blem); looked brand new to me. I was going to replace it with a Freedom 20, but went with Hunter's unsolicited recommendations. Our boat has 480ah from two 8Ds. The system handles most everything well except the microwave draw. It does okay but you can hear it working to deliver the juice. You can run through the caculations to determine the size you need by adding up the expected wattage demand at a given time. Depending on your needs and house bank capacity, I would think a Freedom 15 or 20 would serve you well. I bought mine through Xantrex's on line store (store4power.com, as I recall), or Google Xantrex. I would also install a Link 1000 battery monitor system while you're at it. The system runs fine without it, but it helps to keep track of power consumption. Terry P.S. I installed our unit with minimal tools. It also needs to be somewhat close to your house bank because of the DC power cables that run to your bank.
with an Xantrex Freedom 25 (2,500 watt) four years ago. Very pleased with it's performance even though it was a remarketed product (probably a return or factory blem); looked brand new to me. I was going to replace it with a Freedom 20, but went with Hunter's unsolicited recommendations. Our boat has 480ah from two 8Ds. The system handles most everything well except the microwave draw. It does okay but you can hear it working to deliver the juice. You can run through the caculations to determine the size you need by adding up the expected wattage demand at a given time. Depending on your needs and house bank capacity, I would think a Freedom 15 or 20 would serve you well. I bought mine through Xantrex's on line store (store4power.com, as I recall), or Google Xantrex. I would also install a Link 1000 battery monitor system while you're at it. The system runs fine without it, but it helps to keep track of power consumption. Terry P.S. I installed our unit with minimal tools. It also needs to be somewhat close to your house bank because of the DC power cables that run to your bank.
To determine the size of the inverter you
need to determine the amounts of the loads you will be drawing concurrently and the storage capacity of your house battery bank. An inverter needs to be of adequate power to handle the loads that you intend to use and the size of the battery bank will determine the maximum amount of time that you can use them before recharging. Inverters are rated in watts while the appliance loads are rated in amps. The formula Watts=Amps X Volts can help you convert from one to the other and to determine the size of the inverter needed. A fan draws about .3 amps at 120V and a 13" TV/DVD combo about .4 amps for a total of .7 amps at 120v. That translates to about 85 Watts and to 7 Amp hours at 12V. An inverter is only about 85% efficient so the load at 12V on your batteries will be closer to 8 amp/hours. If that is all that you are going to be running then you could very well do with a 200 Watts inverter. For inverters that size you need not go expensive and you can pick a Vector brand one for under $30. If you want affordable extra capacity get a 400 watts one for under $50. Up to a 400 watts inverter the lnstallation is largely simplified as you can use them with a regular 12V plug. In excess of 400 Watts it is recommended that the unit be hardwired with an adequately sized breaker. The installation cost in materials of a 1,500 to 3,000 watts inverter will run you around $100. These larger inverters are used to run larger combined loads which may include refrigeration and microwave ovens. You may take into account your future usage needs when purchasing a unit. A small portable unit never goes to waste as you can transfer it to your vehicle or use to run small loads rather than powering the larger unit. For the needs that you have mentioned I would go for a 400 watts portable unit. You will hear about "perfect sine waves" "90-95% efficiency" that all translates to $$. Fans are not very sophisticated electronically and the TV/DVD combos are very forgiving and can operate quite well with portable inverters so expending extra money is not necessary. Let me mentin that running time is related to the size of your battery bank. For example a battery rated at 105 amps should only be discharged to 52 amps or 50% of its storage capacity before recharging. If you are going to draw 8 amps/hour at 12V for the fan and tv you can only run them for 6.5 hours before reaching your 50% guideline. Larger battery capacity or reduced loads will allow you to operate more time. Hope this helps you. This is a simplified explanation, for larger installations or applications I would suggest you familiarize yourself with basic electrical formulas, wire sizing, breakers, battery choices and recharging systems.
need to determine the amounts of the loads you will be drawing concurrently and the storage capacity of your house battery bank. An inverter needs to be of adequate power to handle the loads that you intend to use and the size of the battery bank will determine the maximum amount of time that you can use them before recharging. Inverters are rated in watts while the appliance loads are rated in amps. The formula Watts=Amps X Volts can help you convert from one to the other and to determine the size of the inverter needed. A fan draws about .3 amps at 120V and a 13" TV/DVD combo about .4 amps for a total of .7 amps at 120v. That translates to about 85 Watts and to 7 Amp hours at 12V. An inverter is only about 85% efficient so the load at 12V on your batteries will be closer to 8 amp/hours. If that is all that you are going to be running then you could very well do with a 200 Watts inverter. For inverters that size you need not go expensive and you can pick a Vector brand one for under $30. If you want affordable extra capacity get a 400 watts one for under $50. Up to a 400 watts inverter the lnstallation is largely simplified as you can use them with a regular 12V plug. In excess of 400 Watts it is recommended that the unit be hardwired with an adequately sized breaker. The installation cost in materials of a 1,500 to 3,000 watts inverter will run you around $100. These larger inverters are used to run larger combined loads which may include refrigeration and microwave ovens. You may take into account your future usage needs when purchasing a unit. A small portable unit never goes to waste as you can transfer it to your vehicle or use to run small loads rather than powering the larger unit. For the needs that you have mentioned I would go for a 400 watts portable unit. You will hear about "perfect sine waves" "90-95% efficiency" that all translates to $$. Fans are not very sophisticated electronically and the TV/DVD combos are very forgiving and can operate quite well with portable inverters so expending extra money is not necessary. Let me mentin that running time is related to the size of your battery bank. For example a battery rated at 105 amps should only be discharged to 52 amps or 50% of its storage capacity before recharging. If you are going to draw 8 amps/hour at 12V for the fan and tv you can only run them for 6.5 hours before reaching your 50% guideline. Larger battery capacity or reduced loads will allow you to operate more time. Hope this helps you. This is a simplified explanation, for larger installations or applications I would suggest you familiarize yourself with basic electrical formulas, wire sizing, breakers, battery choices and recharging systems.
I forgot to mention that some inverters are
quite noisy due to the cooling fans. For best operation they should be connected close to the batteries. If you need to extend the location of the unit do it at the 120V circuit which is more efficient than if you were to extend the 12V side. For example if your TV is across the cabin from the battery banks, install the inverter close to the batteries to minimize wiring and then run a 120V extension cord to the TV. It will be best to place the TV or Radio away from the inverter. I run a 1,500 watts inverter mainly to have refrigeration while underway. I have it hooked up to my house battery bank. I run #2 gauge wires to the batteries and a 200 amp breaker. The refrigerator draws 1.3 amp at 120V or 13 amps at 12V or 15 amps accounting for inefficiency. 15 amps at 12 volts are 180 watts but the issue is that to start the compressor motor when cycling it may take up to 5 times the power required to run it. So around 900 watts may be required to start the compressor motor. In hot weather with a cold refrigerator and 1/2 full with beer and food it will cycle every 20 minutes for 3 minutes at a time. My stored power usage per hour is .75 amps per hour. At that consumption rate I will only use 18 amps per 24 hours. With compressor start-up surges I'll round it up to 20 amps per 24 hours. At 50% discharge I have available a capacity of 130 amp which would allow me to safely run the refrigerator for 6 days but since I also use 12V power for fans, radio and lights the capability is closer to 3 days. In order to be able to have A/C at anchor I run a Honda eu2000 generator; but that is another project.
quite noisy due to the cooling fans. For best operation they should be connected close to the batteries. If you need to extend the location of the unit do it at the 120V circuit which is more efficient than if you were to extend the 12V side. For example if your TV is across the cabin from the battery banks, install the inverter close to the batteries to minimize wiring and then run a 120V extension cord to the TV. It will be best to place the TV or Radio away from the inverter. I run a 1,500 watts inverter mainly to have refrigeration while underway. I have it hooked up to my house battery bank. I run #2 gauge wires to the batteries and a 200 amp breaker. The refrigerator draws 1.3 amp at 120V or 13 amps at 12V or 15 amps accounting for inefficiency. 15 amps at 12 volts are 180 watts but the issue is that to start the compressor motor when cycling it may take up to 5 times the power required to run it. So around 900 watts may be required to start the compressor motor. In hot weather with a cold refrigerator and 1/2 full with beer and food it will cycle every 20 minutes for 3 minutes at a time. My stored power usage per hour is .75 amps per hour. At that consumption rate I will only use 18 amps per 24 hours. With compressor start-up surges I'll round it up to 20 amps per 24 hours. At 50% discharge I have available a capacity of 130 amp which would allow me to safely run the refrigerator for 6 days but since I also use 12V power for fans, radio and lights the capability is closer to 3 days. In order to be able to have A/C at anchor I run a Honda eu2000 generator; but that is another project.
Practical Answer
I used a Freedom 10 inverter / charger on my h34 to run the fridge for ten years. Today that unit costs $800 - $1000. If you only want to run a fan and TV go to Harbor Freight and buy a 700 watt inverter for $49. I have one on my power boat and fing them to work well. I already had a charger on the vessel
I used a Freedom 10 inverter / charger on my h34 to run the fridge for ten years. Today that unit costs $800 - $1000. If you only want to run a fan and TV go to Harbor Freight and buy a 700 watt inverter for $49. I have one on my power boat and fing them to work well. I already had a charger on the vessel
Some ideas for Inverters
Hanley, Your loads are small so a 250W - 500W inverter would do the trick but you have to be carefull. A pure sine wave inverter would work for you - no question. Your ac fans really dont care about waveshape (type of AC wave from inverter) but your tv/vcr may have some electronics inside that may be incompatable with anything other than a pure sine inverter. Unfortunately, mfgrs. do not test their equipment with modified sine wave inverters so, they cannot tell you if it will be OK. So, the only thing you can do is take a chance and try it. I would check on the return policy and make sure that if the inverter does not work for you, can it be returned or exchanged with another type or brand. This is very important!!!! If they have a liberal return policy, go cheap and try the 250W inverter. If it does not work, return and upgrade.
Hanley, Your loads are small so a 250W - 500W inverter would do the trick but you have to be carefull. A pure sine wave inverter would work for you - no question. Your ac fans really dont care about waveshape (type of AC wave from inverter) but your tv/vcr may have some electronics inside that may be incompatable with anything other than a pure sine inverter. Unfortunately, mfgrs. do not test their equipment with modified sine wave inverters so, they cannot tell you if it will be OK. So, the only thing you can do is take a chance and try it. I would check on the return policy and make sure that if the inverter does not work for you, can it be returned or exchanged with another type or brand. This is very important!!!! If they have a liberal return policy, go cheap and try the 250W inverter. If it does not work, return and upgrade.
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